vcl: refactor vcl session
[vpp.git] / src / vcl / vppcom.c
index 2e867c7..3cd2e76 100644 (file)
@@ -21,6 +21,8 @@
 #include <vpp/api/vpe_msg_enum.h>
 #include <vnet/session/application_interface.h>
 #include <vcl/vppcom.h>
+#include <vcl/vcl_event.h>
+#include <vcl/vcl_debug.h>
 #include <vlib/unix/unix.h>
 #include <vppinfra/vec_bootstrap.h>
 
@@ -66,14 +68,18 @@ typedef enum
 
 typedef enum
 {
-  STATE_START,
-  STATE_CONNECT,
-  STATE_LISTEN,
-  STATE_ACCEPT,
-  STATE_DISCONNECT,
-  STATE_FAILED
+  STATE_START = 0x01,
+  STATE_CONNECT = 0x02,
+  STATE_LISTEN = 0x04,
+  STATE_ACCEPT = 0x08,
+  STATE_CLOSE_ON_EMPTY = 0x10,
+  STATE_DISCONNECT = 0x20,
+  STATE_FAILED = 0x40
 } session_state_t;
 
+#define SERVER_STATE_OPEN  (STATE_ACCEPT|STATE_CLOSE_ON_EMPTY)
+#define CLIENT_STATE_OPEN  (STATE_CONNECT|STATE_CLOSE_ON_EMPTY)
+
 typedef struct epoll_event vppcom_epoll_event_t;
 
 typedef struct
@@ -93,41 +99,70 @@ typedef struct
   ip46_address_t ip46;
 } vppcom_ip46_t;
 
-typedef struct
+enum
 {
-  volatile session_state_t state;
+  VCL_SESS_ATTR_SERVER,
+  VCL_SESS_ATTR_CUT_THRU,
+  VCL_SESS_ATTR_VEP,
+  VCL_SESS_ATTR_VEP_SESSION,
+  VCL_SESS_ATTR_LISTEN,                // SOL_SOCKET,SO_ACCEPTCONN
+  VCL_SESS_ATTR_NONBLOCK,      // fcntl,O_NONBLOCK
+  VCL_SESS_ATTR_REUSEADDR,     // SOL_SOCKET,SO_REUSEADDR
+  VCL_SESS_ATTR_REUSEPORT,     // SOL_SOCKET,SO_REUSEPORT
+  VCL_SESS_ATTR_BROADCAST,     // SOL_SOCKET,SO_BROADCAST
+  VCL_SESS_ATTR_V6ONLY,                // SOL_TCP,IPV6_V6ONLY
+  VCL_SESS_ATTR_KEEPALIVE,     // SOL_SOCKET,SO_KEEPALIVE
+  VCL_SESS_ATTR_TCP_NODELAY,   // SOL_TCP,TCP_NODELAY
+  VCL_SESS_ATTR_TCP_KEEPIDLE,  // SOL_TCP,TCP_KEEPIDLE
+  VCL_SESS_ATTR_TCP_KEEPINTVL, // SOL_TCP,TCP_KEEPINTVL
+  VCL_SESS_ATTR_MAX
+} vppcom_session_attr_t;
+
+#define VCL_SESS_ATTR_SET(ATTR, VAL)            \
+do {                                            \
+  (ATTR) |= 1 << (VAL);                         \
+ } while (0)
+
+#define VCL_SESS_ATTR_CLR(ATTR, VAL)            \
+do {                                            \
+  (ATTR) &= ~(1 << (VAL));                      \
+ } while (0)
+
+#define VCL_SESS_ATTR_TEST(ATTR, VAL)           \
+  ((ATTR) & (1 << (VAL)) ? 1 : 0)
 
-  svm_fifo_t *server_rx_fifo;
-  svm_fifo_t *server_tx_fifo;
+typedef struct
+{
+#define _(type, name) type name;
+  foreach_app_session_field
+#undef _
+  u32 sndbuf_size;             // VPP-TBD: Hack until support setsockopt(SO_SNDBUF)
+  u32 rcvbuf_size;             // VPP-TBD: Hack until support setsockopt(SO_RCVBUF)
+  u32 user_mss;                        // VPP-TBD: Hack until support setsockopt(TCP_MAXSEG)
   u8 *segment_name;
   u32 sm_seg_index;
   u32 client_context;
   u64 vpp_handle;
-  unix_shared_memory_queue_t *vpp_event_queue;
 
   /* Socket configuration state */
-  /* TBD: covert 'is_*' vars to bit in u8 flags; */
-  u8 is_server;
-  u8 is_listen;
-  u8 is_cut_thru;
-  u8 is_nonblocking;
   u8 is_vep;
   u8 is_vep_session;
+  u32 attr;
   u32 wait_cont_idx;
   vppcom_epoll_t vep;
-  u32 vrf;
-  vppcom_ip46_t lcl_addr;
-  vppcom_ip46_t peer_addr;
-  u16 lcl_port;                        // network order
-  u16 peer_port;               // network order
-  u8 proto;
+  int libc_epfd;
   u64 client_queue_address;
   u64 options[16];
-} session_t;
+  vce_event_handler_reg_t *poll_reg;
+#if VCL_ELOG
+  elog_track_t elog_track;
+#endif
+} vcl_session_t;
 
 typedef struct vppcom_cfg_t_
 {
   u64 heapsize;
+  u32 vpp_api_q_length;
   u64 segment_baseva;
   u32 segment_size;
   u32 add_segment_size;
@@ -145,25 +180,29 @@ typedef struct vppcom_cfg_t_
   f64 app_timeout;
   f64 session_timeout;
   f64 accept_timeout;
+  u32 event_ring_size;
+  char *event_log_path;
+  u8 *vpp_api_filename;
 } vppcom_cfg_t;
 
 typedef struct vppcom_main_t_
 {
   u8 init;
   u32 debug;
-  u32 *client_session_index_fifo;
-  volatile u32 bind_session_index;
   int main_cpu;
 
-  /* vpe input queue */
-  unix_shared_memory_queue_t *vl_input_queue;
+  /* FIFO for accepted connections - used in epoll/select */
+  clib_spinlock_t session_fifo_lockp;
+  u32 *client_session_index_fifo;
+
+  /* vpp input queue */
+  svm_queue_t *vl_input_queue;
 
   /* API client handle */
   u32 my_client_index;
-
   /* Session pool */
   clib_spinlock_t sessions_lockp;
-  session_t *sessions;
+  vcl_session_t *sessions;
 
   /* Hash table for disconnect processing */
   uword *session_index_by_vpp_handles;
@@ -174,7 +213,7 @@ typedef struct vppcom_main_t_
   clib_bitmap_t *ex_bitmap;
 
   /* Our event queue */
-  unix_shared_memory_queue_t *app_event_queue;
+  svm_queue_t *app_event_queue;
 
   /* unique segment name counter */
   u32 unique_segment_index;
@@ -187,6 +226,18 @@ typedef struct vppcom_main_t_
 
   vppcom_cfg_t cfg;
 
+  /* Event thread */
+  vce_event_thread_t event_thread;
+
+  /* IO thread */
+  vppcom_session_io_thread_t session_io_thread;
+
+#ifdef VCL_ELOG
+  /* VPP Event-logger */
+  elog_main_t elog_main;
+  elog_track_t elog_track;
+#endif
+
   /* VNET_API_ERROR_FOO -> "Foo" hash table */
   uword *error_string_by_error_number;
 } vppcom_main_t;
@@ -202,22 +253,36 @@ static vppcom_main_t _vppcom_main = {
 
 static vppcom_main_t *vcm = &_vppcom_main;
 
-#define VCL_LOCK_AND_GET_SESSION(I, S)                  \
-do {                                                    \
-  clib_spinlock_lock (&vcm->sessions_lockp);            \
-  rv = vppcom_session_at_index (I, S);                  \
-  if (PREDICT_FALSE (rv))                               \
-    {                                                   \
-      clib_spinlock_unlock (&vcm->sessions_lockp);      \
-                                                        \
-      if (VPPCOM_DEBUG > 0)                             \
-        clib_warning ("[%s] ERROR: Invalid ##I (%u)!",  \
-                      getpid (), I);                  \
-                                                        \
-      goto done;                                        \
-    }                                                   \
+#define VCL_SESSION_LOCK_AND_GET(I, S)                          \
+do {                                                            \
+  clib_spinlock_lock (&vcm->sessions_lockp);                    \
+  rv = vppcom_session_at_index (I, S);                          \
+  if (PREDICT_FALSE (rv))                                       \
+    {                                                           \
+      clib_spinlock_unlock (&vcm->sessions_lockp);              \
+      clib_warning ("VCL<%d>: ERROR: Invalid ##I (%u)!",        \
+                    getpid (), I);                              \
+      goto done;                                                \
+    }                                                           \
 } while (0)
 
+#define VCL_SESSION_LOCK() clib_spinlock_lock (&(vcm->sessions_lockp))
+#define VCL_SESSION_UNLOCK() clib_spinlock_unlock (&(vcm->sessions_lockp))
+
+#define VCL_IO_SESSIONS_LOCK() \
+  clib_spinlock_lock (&(vcm->session_io_thread.io_sessions_lockp))
+#define VCL_IO_SESSIONS_UNLOCK() \
+  clib_spinlock_unlock (&(vcm->session_io_thread.io_sessions_lockp))
+
+#define VCL_ACCEPT_FIFO_LOCK() clib_spinlock_lock (&(vcm->session_fifo_lockp))
+#define VCL_ACCEPT_FIFO_UNLOCK() \
+  clib_spinlock_unlock (&(vcm->session_fifo_lockp))
+
+#define VCL_EVENTS_LOCK() \
+  clib_spinlock_lock (&(vcm->event_thread.events_lockp))
+#define VCL_EVENTS_UNLOCK() \
+  clib_spinlock_unlock (&(vcm->event_thread.events_lockp))
+
 static const char *
 vppcom_app_state_str (app_state_t state)
 {
@@ -272,6 +337,10 @@ vppcom_session_state_str (session_state_t state)
       st = "STATE_ACCEPT";
       break;
 
+    case STATE_CLOSE_ON_EMPTY:
+      st = "STATE_CLOSE_ON_EMPTY";
+      break;
+
     case STATE_DISCONNECT:
       st = "STATE_DISCONNECT";
       break;
@@ -288,17 +357,19 @@ vppcom_session_state_str (session_state_t state)
   return st;
 }
 
+
 /*
  * VPPCOM Utility Functions
  */
+
 static inline int
-vppcom_session_at_index (u32 session_index, session_t * volatile *sess)
+vppcom_session_at_index (u32 session_index, vcl_session_t * volatile *sess)
 {
   /* Assumes that caller has acquired spinlock: vcm->sessions_lockp */
   if (PREDICT_FALSE ((session_index == ~0) ||
                     pool_is_free_index (vcm->sessions, session_index)))
     {
-      clib_warning ("[%d] invalid session, sid (%u) has been closed!",
+      clib_warning ("VCL<%d>: invalid session, sid (%u) has been closed!",
                    getpid (), session_index);
       return VPPCOM_EBADFD;
     }
@@ -316,27 +387,29 @@ vppcom_session_table_add_listener (u64 listener_handle, u32 value)
   hash_set (vcm->session_index_by_vpp_handles, listener_handle, value);
 }
 
-static inline session_t *
+static inline vcl_session_t *
 vppcom_session_table_lookup_listener (u64 listener_handle)
 {
   uword *p;
   u64 handle = listener_handle | (1ULL << 63);
+  vcl_session_t *session;
+
   p = hash_get (vcm->session_index_by_vpp_handles, handle);
   if (!p)
     {
-      clib_warning ("[%d] couldn't find listen session: unknown vpp "
+      clib_warning ("VCL<%d>: couldn't find listen session: unknown vpp "
                    "listener handle %llx", getpid (), listener_handle);
       return 0;
     }
   if (pool_is_free_index (vcm->sessions, p[0]))
     {
-      if (VPPCOM_DEBUG > 1)
-       clib_warning ("[%d] invalid listen session, sid (%u)", getpid (),
-                     p[0]);
+      VDBG (1, "VCL<%d>: invalid listen session, sid (%u)", getpid (), p[0]);
       return 0;
     }
 
-  return pool_elt_at_index (vcm->sessions, p[0]);
+  session = pool_elt_at_index (vcm->sessions, p[0]);
+  ASSERT (session->session_state & STATE_LISTEN);
+  return session;
 }
 
 static inline void
@@ -346,26 +419,50 @@ vppcom_session_table_del_listener (u64 listener_handle)
   hash_unset (vcm->session_index_by_vpp_handles, listener_handle);
 }
 
+static inline void
+vppcom_send_accept_session_reply (u64 handle, u32 context, int retval)
+{
+  vl_api_accept_session_reply_t *rmp;
+
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  memset (rmp, 0, sizeof (*rmp));
+  rmp->_vl_msg_id = ntohs (VL_API_ACCEPT_SESSION_REPLY);
+  rmp->retval = htonl (retval);
+  rmp->context = context;
+  rmp->handle = handle;
+  vl_msg_api_send_shmem (vcm->vl_input_queue, (u8 *) & rmp);
+}
+
 static int
 vppcom_connect_to_vpp (char *app_name)
 {
   api_main_t *am = &api_main;
+  vppcom_cfg_t *vcl_cfg = &vcm->cfg;
+  int rv = VPPCOM_OK;
 
-  if (VPPCOM_DEBUG > 0)
-    printf ("\nConnecting to VPP api...");
-  if (vl_client_connect_to_vlib ("/vpe-api", app_name, 32) < 0)
+  if (!vcl_cfg->vpp_api_filename)
+    vcl_cfg->vpp_api_filename = format (0, "/vpe-api%c", 0);
+
+  VDBG (0, "VCL<%d>: app (%s) connecting to VPP api (%s)...",
+       getpid (), app_name, vcl_cfg->vpp_api_filename);
+
+  if (vl_client_connect_to_vlib ((char *) vcl_cfg->vpp_api_filename, app_name,
+                                vcm->cfg.vpp_api_q_length) < 0)
     {
-      clib_warning ("[%d] connect to vpp (%s) failed!", getpid (), app_name);
-      return VPPCOM_ECONNREFUSED;
+      clib_warning ("VCL<%d>: app (%s) connect failed!", getpid (), app_name);
+      rv = VPPCOM_ECONNREFUSED;
     }
+  else
+    {
+      vcm->vl_input_queue = am->shmem_hdr->vl_input_queue;
+      vcm->my_client_index = (u32) am->my_client_index;
+      vcm->app_state = STATE_APP_CONN_VPP;
 
-  vcm->vl_input_queue = am->shmem_hdr->vl_input_queue;
-  vcm->my_client_index = am->my_client_index;
-  if (VPPCOM_DEBUG > 0)
-    printf (" connected!\n");
+      VDBG (0, "VCL<%d>: app (%s) is connected to VPP!", getpid (), app_name);
+    }
 
-  vcm->app_state = STATE_APP_CONN_VPP;
-  return VPPCOM_OK;
+  vcl_evt (VCL_EVT_INIT, vcm);
+  return rv;
 }
 
 static u8 *
@@ -388,7 +485,7 @@ vppcom_init_error_string_table (void)
 {
   vcm->error_string_by_error_number = hash_create (0, sizeof (uword));
 
-#define _(n,v,s) hash_set (vcm->error_string_by_error_number, -v, s);
+#define _(n, v, s) hash_set (vcm->error_string_by_error_number, -v, s);
   foreach_vnet_api_error;
 #undef _
 
@@ -405,9 +502,10 @@ vppcom_wait_for_app_state_change (app_state_t app_state)
       if (vcm->app_state == app_state)
        return VPPCOM_OK;
     }
-  if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] timeout waiting for state %s (%d)", getpid (),
-                 vppcom_app_state_str (app_state), app_state);
+  VDBG (0, "VCL<%d>: timeout waiting for state %s (%d)", getpid (),
+       vppcom_app_state_str (app_state), app_state);
+  vcl_evt (VCL_EVT_SESSION_TIMEOUT, vcm, app_state);
+
   return VPPCOM_ETIMEDOUT;
 }
 
@@ -417,50 +515,37 @@ vppcom_wait_for_session_state_change (u32 session_index,
                                      f64 wait_for_time)
 {
   f64 timeout = clib_time_now (&vcm->clib_time) + wait_for_time;
-  session_t *volatile session;
+  vcl_session_t *volatile session;
   int rv;
 
   do
     {
-      clib_spinlock_lock (&vcm->sessions_lockp);
+      VCL_SESSION_LOCK ();
       rv = vppcom_session_at_index (session_index, &session);
       if (PREDICT_FALSE (rv))
        {
-         clib_spinlock_unlock (&vcm->sessions_lockp);
+         VCL_SESSION_UNLOCK ();
          return rv;
        }
-      if (session->state == state)
+      if (session->session_state & state)
        {
-         clib_spinlock_unlock (&vcm->sessions_lockp);
+         VCL_SESSION_UNLOCK ();
          return VPPCOM_OK;
        }
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-    }
-  while (clib_time_now (&vcm->clib_time) < timeout);
-
-  if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] timeout waiting for state %s (%d)", getpid (),
-                 vppcom_session_state_str (state), state);
-  return VPPCOM_ETIMEDOUT;
-}
-
-static inline int
-vppcom_wait_for_client_session_index (f64 wait_for_time)
-{
-  f64 timeout = clib_time_now (&vcm->clib_time) + wait_for_time;
+      if (session->session_state & STATE_FAILED)
+       {
+         VCL_SESSION_UNLOCK ();
+         return VPPCOM_ECONNREFUSED;
+       }
 
-  do
-    {
-      if (clib_fifo_elts (vcm->client_session_index_fifo))
-       return VPPCOM_OK;
+      VCL_SESSION_UNLOCK ();
     }
   while (clib_time_now (&vcm->clib_time) < timeout);
 
-  if (wait_for_time == 0)
-    return VPPCOM_EAGAIN;
+  VDBG (0, "VCL<%d>: timeout waiting for state 0x%x (%s)", getpid (), state,
+       vppcom_session_state_str (state));
+  vcl_evt (VCL_EVT_SESSION_TIMEOUT, session, session_state);
 
-  if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] timeout waiting for client_session_index", getpid ());
   return VPPCOM_ETIMEDOUT;
 }
 
@@ -492,9 +577,8 @@ vppcom_app_session_enable (void)
       rv = vppcom_wait_for_app_state_change (STATE_APP_ENABLED);
       if (PREDICT_FALSE (rv))
        {
-         if (VPPCOM_DEBUG > 0)
-           clib_warning ("[%d] Session enable timed out, rv = %s (%d)",
-                         getpid (), vppcom_retval_str (rv), rv);
+         VDBG (0, "VCL<%d>: application session enable timed out! "
+               "returning %d (%s)", getpid (), rv, vppcom_retval_str (rv));
          return rv;
        }
     }
@@ -507,7 +591,7 @@ static void
 {
   if (mp->retval)
     {
-      clib_warning ("[%d] session_enable_disable failed: %U", getpid (),
+      clib_warning ("VCL<%d>: session_enable_disable failed: %U", getpid (),
                    format_api_error, ntohl (mp->retval));
     }
   else
@@ -534,12 +618,15 @@ vppcom_app_send_attach (void)
     (vcm->cfg.app_scope_global ? APP_OPTIONS_FLAGS_USE_GLOBAL_SCOPE : 0) |
     (app_is_proxy ? APP_OPTIONS_FLAGS_IS_PROXY : 0);
   bmp->options[APP_OPTIONS_PROXY_TRANSPORT] =
-    (vcm->cfg.app_proxy_transport_tcp ? 1 << TRANSPORT_PROTO_TCP : 0) |
-    (vcm->cfg.app_proxy_transport_udp ? 1 << TRANSPORT_PROTO_UDP : 0);
-  bmp->options[SESSION_OPTIONS_SEGMENT_SIZE] = vcm->cfg.segment_size;
-  bmp->options[SESSION_OPTIONS_ADD_SEGMENT_SIZE] = vcm->cfg.add_segment_size;
-  bmp->options[SESSION_OPTIONS_RX_FIFO_SIZE] = vcm->cfg.rx_fifo_size;
-  bmp->options[SESSION_OPTIONS_TX_FIFO_SIZE] = vcm->cfg.tx_fifo_size;
+    (u64) ((vcm->cfg.app_proxy_transport_tcp ? 1 << TRANSPORT_PROTO_TCP : 0) |
+          (vcm->cfg.app_proxy_transport_udp ? 1 << TRANSPORT_PROTO_UDP : 0));
+  bmp->options[APP_OPTIONS_SEGMENT_SIZE] = vcm->cfg.segment_size;
+  bmp->options[APP_OPTIONS_ADD_SEGMENT_SIZE] = vcm->cfg.add_segment_size;
+  bmp->options[APP_OPTIONS_RX_FIFO_SIZE] = vcm->cfg.rx_fifo_size;
+  bmp->options[APP_OPTIONS_TX_FIFO_SIZE] = vcm->cfg.tx_fifo_size;
+  bmp->options[APP_OPTIONS_PREALLOC_FIFO_PAIRS] =
+    vcm->cfg.preallocated_fifo_pairs;
+  bmp->options[APP_OPTIONS_EVT_QUEUE_SIZE] = vcm->cfg.event_queue_size;
   if (nsid_len)
     {
       bmp->namespace_id_len = nsid_len;
@@ -558,11 +645,11 @@ vppcom_app_attach (void)
   rv = vppcom_wait_for_app_state_change (STATE_APP_ATTACHED);
   if (PREDICT_FALSE (rv))
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] application attach timed out, rv = %s (%d)",
-                     getpid (), vppcom_retval_str (rv), rv);
+      VDBG (0, "VCL<%d>: application attach timed out! returning %d (%s)",
+           getpid (), rv, vppcom_retval_str (rv));
       return rv;
     }
+
   return VPPCOM_OK;
 }
 
@@ -590,14 +677,14 @@ vl_api_application_attach_reply_t_handler (vl_api_application_attach_reply_t *
   memset (a, 0, sizeof (*a));
   if (mp->retval)
     {
-      clib_warning ("[%d] attach failed: %U", getpid (),
+      clib_warning ("VCL<%d>: attach failed: %U", getpid (),
                    format_api_error, ntohl (mp->retval));
       return;
     }
 
   if (mp->segment_name_length == 0)
     {
-      clib_warning ("[%d] segment_name_length zero", getpid ());
+      clib_warning ("VCL<%d>: segment_name_length zero", getpid ());
       return;
     }
 
@@ -611,14 +698,13 @@ vl_api_application_attach_reply_t_handler (vl_api_application_attach_reply_t *
   vec_reset_length (a->new_segment_indices);
   if (PREDICT_FALSE (rv))
     {
-      clib_warning ("[%d] svm_fifo_segment_attach ('%s') failed", getpid (),
-                   mp->segment_name);
+      clib_warning ("VCL<%d>: svm_fifo_segment_attach ('%s') failed",
+                   getpid (), mp->segment_name);
       return;
     }
 
   vcm->app_event_queue =
-    uword_to_pointer (mp->app_event_queue_address,
-                     unix_shared_memory_queue_t *);
+    uword_to_pointer (mp->app_event_queue_address, svm_queue_t *);
 
   vcm->app_state = STATE_APP_ATTACHED;
 }
@@ -628,7 +714,7 @@ vl_api_application_detach_reply_t_handler (vl_api_application_detach_reply_t *
                                           mp)
 {
   if (mp->retval)
-    clib_warning ("[%d] detach failed: %U", getpid (), format_api_error,
+    clib_warning ("VCL<%d>: detach failed: %U", getpid (), format_api_error,
                  ntohl (mp->retval));
 
   vcm->app_state = STATE_APP_ENABLED;
@@ -638,46 +724,10 @@ static void
 vl_api_disconnect_session_reply_t_handler (vl_api_disconnect_session_reply_t *
                                           mp)
 {
-  uword *p;
-  u32 session_index = ~0;
-
-  p = hash_get (vcm->session_index_by_vpp_handles, mp->handle);
-  if (p)
-    {
-      session_t *session = 0;
-      int rv;
-
-      session_index = p[0];
-      hash_unset (vcm->session_index_by_vpp_handles, mp->handle);
-      clib_spinlock_lock (&vcm->sessions_lockp);
-      rv = vppcom_session_at_index (session_index, &session);
-      if (PREDICT_FALSE (rv))
-       {
-         if (VPPCOM_DEBUG > 1)
-           clib_warning ("[%d] invalid session, sid %u has been closed!",
-                         getpid (), session_index);
-       }
-      else
-       {
-         if (VPPCOM_DEBUG > 1)
-           clib_warning ("[%d] vpp handle 0x%llx, sid %u disconnected!",
-                         getpid (), mp->handle, session_index);
-
-         session->state = STATE_DISCONNECT;
-       }
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-    }
-  else
-    {
-      if (VPPCOM_DEBUG > 1)
-       clib_warning ("[%d] couldn't find session: unknown vpp handle 0x%llx",
-                     getpid (), mp->handle);
-    }
-
   if (mp->retval)
-    clib_warning ("[%d] disconnect_session vpp handle 0x%llx, sid %u "
-                 "failed: %U", getpid (), mp->handle, session_index,
-                 format_api_error, ntohl (mp->retval));
+    clib_warning ("VCL<%d>: vpp handle 0x%llx: disconnect session failed: %U",
+                 getpid (), mp->handle, format_api_error,
+                 ntohl (mp->retval));
 }
 
 static void
@@ -695,75 +745,62 @@ vl_api_map_another_segment_t_handler (vl_api_map_another_segment_t * mp)
   vec_reset_length (a->new_segment_indices);
   if (PREDICT_FALSE (rv))
     {
-      clib_warning ("[%d] svm_fifo_segment_attach ('%s') failed",
+      clib_warning ("VCL<%d>: svm_fifo_segment_attach ('%s') failed",
                    getpid (), mp->segment_name);
       return;
     }
-  if (VPPCOM_DEBUG > 1)
-    clib_warning ("[%d] mapped new segment '%s' size %d", getpid (),
-                 mp->segment_name, mp->segment_size);
+
+  VDBG (1, "VCL<%d>: mapped new segment '%s' size %d", getpid (),
+       mp->segment_name, mp->segment_size);
+}
+
+static void
+vl_api_unmap_segment_t_handler (vl_api_unmap_segment_t * mp)
+{
+
+/*
+ * XXX Need segment_name to session_id hash,
+ * XXX - have sessionID by handle hash currently
+ */
+
+  VDBG (1, "Unmapped segment '%s'", mp->segment_name);
 }
 
 static void
 vl_api_disconnect_session_t_handler (vl_api_disconnect_session_t * mp)
 {
-  session_t *session = 0;
-  vl_api_disconnect_session_reply_t *rmp;
   uword *p;
-  int rv = 0, rval;
 
   p = hash_get (vcm->session_index_by_vpp_handles, mp->handle);
-  if (VPPCOM_DEBUG > 0)
+  if (p)
     {
-      if (!p)
-       {
-         clib_warning ("[%d] request to disconnect invalid handle (%u)!",
-                       getpid (), mp->handle);
-         rv = -11;
-         goto done;
-       }
-      clib_warning ("[%d] disconnecting handle %u sid (%u)!", getpid (),
-                   mp->handle, p[0]);
-    }
+      int rv;
+      vcl_session_t *session = 0;
+      u32 session_index = p[0];
 
-  goto done;
+      VCL_SESSION_LOCK_AND_GET (session_index, &session);
+      session->session_state = STATE_CLOSE_ON_EMPTY;
 
-  if (p)
-    {
-      clib_spinlock_lock (&vcm->sessions_lockp);
-      rval = vppcom_session_at_index (p[0], &session);
-      if (PREDICT_FALSE (rval))
-       {
-         if (VPPCOM_DEBUG > 1)
-           clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                         getpid (), p[0]);
-       }
-      else
-       pool_put (vcm->sessions, session);
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      hash_unset (vcm->session_index_by_vpp_handles, mp->handle);
+      VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: setting state to 0x%x "
+           "(%s)", getpid (), mp->handle, session_index,
+           session->session_state,
+           vppcom_session_state_str (session->session_state));
+      VCL_SESSION_UNLOCK ();
+      return;
+
+    done:
+      VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: session lookup failed!",
+           getpid (), mp->handle, session_index);
     }
   else
-    {
-      clib_warning ("[%d] couldn't find session: unknown vpp handle 0x%llx",
-                   getpid (), mp->handle);
-      rv = -11;
-    }
-
-done:
-  rmp = vl_msg_api_alloc (sizeof (*rmp));
-  memset (rmp, 0, sizeof (*rmp));
-
-  rmp->_vl_msg_id = ntohs (VL_API_DISCONNECT_SESSION_REPLY);
-  rmp->retval = htonl (rv);
-  rmp->handle = mp->handle;
-  vl_msg_api_send_shmem (vcm->vl_input_queue, (u8 *) & rmp);
+    clib_warning ("VCL<%d>: vpp handle 0x%llx: session lookup by "
+                 "handle failed!", getpid (), mp->handle);
 }
 
 static void
 vl_api_reset_session_t_handler (vl_api_reset_session_t * mp)
 {
-  session_t *session = 0;
+  vcl_session_t *session = 0;
   vl_api_reset_session_reply_t *rmp;
   uword *p;
   int rv = 0;
@@ -772,24 +809,35 @@ vl_api_reset_session_t_handler (vl_api_reset_session_t * mp)
   if (p)
     {
       int rval;
-      clib_spinlock_lock (&vcm->sessions_lockp);
+      VCL_SESSION_LOCK ();
       rval = vppcom_session_at_index (p[0], &session);
       if (PREDICT_FALSE (rval))
        {
-         if (VPPCOM_DEBUG > 1)
-           clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                         getpid (), p[0]);
+         rv = VNET_API_ERROR_INVALID_VALUE_2;
+         clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx, sid %u: "
+                       "session lookup failed! returning %d %U",
+                       getpid (), mp->handle, p[0],
+                       rv, format_api_error, rv);
        }
       else
-       pool_put (vcm->sessions, session);
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      hash_unset (vcm->session_index_by_vpp_handles, mp->handle);
+       {
+         /* TBD: should this disconnect immediately and
+          * flush the fifos?
+          */
+         session->session_state = STATE_CLOSE_ON_EMPTY;
+
+         VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: state set to %d "
+               "(%s)!", getpid (), mp->handle, p[0], session->session_state,
+               vppcom_session_state_str (session->session_state));
+       }
+      VCL_SESSION_UNLOCK ();
     }
   else
     {
-      clib_warning ("[%d] couldn't find session: unknown vpp handle 0x%llx",
-                   getpid (), mp->handle);
-      rv = -11;
+      rv = VNET_API_ERROR_INVALID_VALUE;
+      clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx: session lookup "
+                   "failed! returning %d %U",
+                   getpid (), mp->handle, rv, format_api_error, rv);
     }
 
   rmp = vl_msg_api_alloc (sizeof (*rmp));
@@ -803,182 +851,186 @@ vl_api_reset_session_t_handler (vl_api_reset_session_t * mp)
 static void
 vl_api_connect_session_reply_t_handler (vl_api_connect_session_reply_t * mp)
 {
-  session_t *session;
+  vcl_session_t *session = 0;
   u32 session_index;
   svm_fifo_t *rx_fifo, *tx_fifo;
-  u8 is_cut_thru = 0;
-  int rv;
-
-  if (mp->retval)
-    {
-      clib_warning ("[%d] connect failed: %U", getpid (), format_api_error,
-                   ntohl (mp->retval));
-      return;
-    }
+  int rv = VPPCOM_OK;
 
   session_index = mp->context;
-  if (VPPCOM_DEBUG > 1)
-    clib_warning ("[%d] session_index = %d 0x%08x", getpid (),
-                 session_index, session_index);
-
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  if (pool_is_free_index (vcm->sessions, session_index))
-    {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 1)
-       clib_warning ("[%d] invalid session, sid %d is closed!",
-                     getpid (), session_index);
-      return;
-    }
-
-  /* We've been redirected */
-  if (mp->segment_name_length > 0)
+  VCL_SESSION_LOCK_AND_GET (session_index, &session);
+done:
+  if (mp->retval)
     {
-      static svm_fifo_segment_create_args_t _a;
-      svm_fifo_segment_create_args_t *a = &_a;
-
-      is_cut_thru = 1;
-      memset (a, 0, sizeof (*a));
-      a->segment_name = (char *) mp->segment_name;
-      if (VPPCOM_DEBUG > 1)
-       clib_warning ("[%d] cut-thru segment: %s\n",
-                     getpid (), a->segment_name);
-
-      rv = svm_fifo_segment_attach (a);
-      vec_reset_length (a->new_segment_indices);
-      if (PREDICT_FALSE (rv))
+      clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx, sid %u: "
+                   "connect failed! %U",
+                   getpid (), mp->handle, session_index,
+                   format_api_error, ntohl (mp->retval));
+      if (session)
+       {
+         session->session_state = STATE_FAILED;
+         session->vpp_handle = mp->handle;
+       }
+      else
        {
-         clib_spinlock_unlock (&vcm->sessions_lockp);
-         clib_warning ("[%d] sm_fifo_segment_attach ('%s') failed",
-                       getpid (), a->segment_name);
-         return;
+         clib_warning ("[%s] ERROR: vpp handle 0x%llx, sid %u: "
+                       "Invalid session index (%u)!",
+                       getpid (), mp->handle, session_index);
        }
+      goto done_unlock;
     }
 
+  if (rv)
+    goto done_unlock;
+
   /*
    * Setup session
    */
-  session = pool_elt_at_index (vcm->sessions, session_index);
-  session->is_cut_thru = is_cut_thru;
-  session->vpp_event_queue = uword_to_pointer (mp->vpp_event_queue_address,
-                                              unix_shared_memory_queue_t *);
+  if (vcm->session_io_thread.io_sessions_lockp)
+    {
+      // Add this connection to the active io sessions list
+      VCL_IO_SESSIONS_LOCK ();
+      u32 *active_session_index;
+      pool_get (vcm->session_io_thread.active_session_indexes,
+               active_session_index);
+      *active_session_index = session_index;
+      VCL_IO_SESSIONS_UNLOCK ();
+    }
+  session->vpp_evt_q = uword_to_pointer (mp->vpp_event_queue_address,
+                                        svm_queue_t *);
 
   rx_fifo = uword_to_pointer (mp->server_rx_fifo, svm_fifo_t *);
   rx_fifo->client_session_index = session_index;
   tx_fifo = uword_to_pointer (mp->server_tx_fifo, svm_fifo_t *);
   tx_fifo->client_session_index = session_index;
 
-  session->server_rx_fifo = rx_fifo;
-  session->server_tx_fifo = tx_fifo;
+  session->rx_fifo = rx_fifo;
+  session->tx_fifo = tx_fifo;
   session->vpp_handle = mp->handle;
-  session->lcl_addr.is_ip4 = mp->is_ip4;
-  clib_memcpy (&session->lcl_addr.ip46, mp->lcl_ip,
-              sizeof (session->peer_addr.ip46));
-  session->lcl_port = mp->lcl_port;
-  session->state = STATE_CONNECT;
+  session->transport.is_ip4 = mp->is_ip4;
+  clib_memcpy (&session->transport.lcl_ip, mp->lcl_ip,
+              sizeof (session->transport.rmt_ip));
+  session->transport.lcl_port = mp->lcl_port;
+  session->session_state = STATE_CONNECT;
 
   /* Add it to lookup table */
   hash_set (vcm->session_index_by_vpp_handles, mp->handle, session_index);
 
-  if (VPPCOM_DEBUG > 1)
-    clib_warning ("[%d] client sid %d, vpp handle 0x%llx\n"
-                 "  session_rx_fifo %p, refcnt %d\n"
-                 "  session_tx_fifo %p, refcnt %d",
-                 getpid (), session_index, mp->handle,
-                 session->server_rx_fifo,
-                 session->server_rx_fifo->refcnt,
-                 session->server_tx_fifo, session->server_tx_fifo->refcnt);
-
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: connect succeeded! "
+       "session_rx_fifo %p, refcnt %d, session_tx_fifo %p, refcnt %d",
+       getpid (), mp->handle, session_index, session->rx_fifo,
+       session->rx_fifo->refcnt, session->tx_fifo, session->tx_fifo->refcnt);
+done_unlock:
+  VCL_SESSION_UNLOCK ();
 }
 
 static void
-vppcom_send_connect_sock (session_t * session, u32 session_index)
+vppcom_send_connect_sock (vcl_session_t * session, u32 session_index)
 {
   vl_api_connect_sock_t *cmp;
 
   /* Assumes caller as acquired the spinlock: vcm->sessions_lockp */
-  session->is_server = 0;
   cmp = vl_msg_api_alloc (sizeof (*cmp));
   memset (cmp, 0, sizeof (*cmp));
   cmp->_vl_msg_id = ntohs (VL_API_CONNECT_SOCK);
   cmp->client_index = vcm->my_client_index;
   cmp->context = session_index;
 
-  if (VPPCOM_DEBUG > 1)
-    clib_warning ("[%d] session_index = %d 0x%08x",
-                 getpid (), session_index, session_index);
-
-  cmp->vrf = session->vrf;
-  cmp->is_ip4 = session->peer_addr.is_ip4;
-  clib_memcpy (cmp->ip, &session->peer_addr.ip46, sizeof (cmp->ip));
-  cmp->port = session->peer_port;
-  cmp->proto = session->proto;
+  cmp->is_ip4 = session->transport.is_ip4;
+  clib_memcpy (cmp->ip, &session->transport.rmt_ip, sizeof (cmp->ip));
+  cmp->port = session->transport.rmt_port;
+  cmp->proto = session->session_type;
   clib_memcpy (cmp->options, session->options, sizeof (cmp->options));
   vl_msg_api_send_shmem (vcm->vl_input_queue, (u8 *) & cmp);
 }
 
 static inline void
-vppcom_send_disconnect (session_t * session)
+vppcom_send_disconnect_session_reply (u64 vpp_handle, u32 session_index,
+                                     int rv)
+{
+  vl_api_disconnect_session_reply_t *rmp;
+
+  VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: sending disconnect msg",
+       getpid (), vpp_handle, session_index);
+
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  memset (rmp, 0, sizeof (*rmp));
+
+  rmp->_vl_msg_id = ntohs (VL_API_DISCONNECT_SESSION_REPLY);
+  rmp->retval = htonl (rv);
+  rmp->handle = vpp_handle;
+  vl_msg_api_send_shmem (vcm->vl_input_queue, (u8 *) & rmp);
+}
+
+static inline void
+vppcom_send_disconnect_session (u64 vpp_handle, u32 session_index)
 {
   vl_api_disconnect_session_t *dmp;
 
-  /* Assumes caller as acquired the spinlock: vcm->sessions_lockp */
+  VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: sending disconnect msg",
+       getpid (), vpp_handle, session_index);
+
   dmp = vl_msg_api_alloc (sizeof (*dmp));
   memset (dmp, 0, sizeof (*dmp));
   dmp->_vl_msg_id = ntohs (VL_API_DISCONNECT_SESSION);
   dmp->client_index = vcm->my_client_index;
-  dmp->handle = session->vpp_handle;
+  dmp->handle = vpp_handle;
   vl_msg_api_send_shmem (vcm->vl_input_queue, (u8 *) & dmp);
 }
 
 static void
 vl_api_bind_sock_reply_t_handler (vl_api_bind_sock_reply_t * mp)
 {
-  session_t *session = 0;
+  vcl_session_t *session = 0;
+  u32 session_index = mp->context;
   int rv;
 
+  VCL_SESSION_LOCK_AND_GET (session_index, &session);
+done:
   if (mp->retval)
-    clib_warning ("[%d] bind failed: %U", getpid (), format_api_error,
-                 ntohl (mp->retval));
-
-  ASSERT (vcm->bind_session_index != ~0);
-
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  rv = vppcom_session_at_index (vcm->bind_session_index, &session);
-  if (rv == VPPCOM_OK)
     {
-      session->vpp_handle = mp->handle;
-      session->lcl_addr.is_ip4 = mp->lcl_is_ip4;
-      clib_memcpy (&session->lcl_addr.ip46, mp->lcl_ip,
-                  sizeof (session->peer_addr.ip46));
-      session->lcl_port = mp->lcl_port;
-      vppcom_session_table_add_listener (mp->handle, vcm->bind_session_index);
-      session->state = mp->retval ? STATE_FAILED : STATE_LISTEN;
-      vcm->bind_session_index = ~0;
+      clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx, "
+                   "sid %u: bind failed: %U",
+                   getpid (), mp->handle, session_index,
+                   format_api_error, ntohl (mp->retval));
+      rv = vppcom_session_at_index (session_index, &session);
+      if (rv == VPPCOM_OK)
+       {
+         session->session_state = STATE_FAILED;
+         session->vpp_handle = mp->handle;
+       }
+      else
+       {
+         clib_warning ("[%s] ERROR: vpp handle 0x%llx, sid %u: "
+                       "Invalid session index (%u)!",
+                       getpid (), mp->handle, session_index);
+       }
+      goto done_unlock;
     }
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+
+  session->vpp_handle = mp->handle;
+  session->transport.is_ip4 = mp->lcl_is_ip4;
+  session->transport.lcl_ip = to_ip46 (mp->lcl_is_ip4 ? IP46_TYPE_IP4 :
+                                      IP46_TYPE_IP6, mp->lcl_ip);
+  session->transport.lcl_port = mp->lcl_port;
+  vppcom_session_table_add_listener (mp->handle, session_index);
+  session->session_state = STATE_LISTEN;
+
+  VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: bind succeeded!",
+       getpid (), mp->handle, mp->context);
+done_unlock:
+  VCL_SESSION_UNLOCK ();
 }
 
 static void
 vl_api_unbind_sock_reply_t_handler (vl_api_unbind_sock_reply_t * mp)
 {
-  session_t *session = 0;
-
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  session = vppcom_session_table_lookup_listener (vcm->bind_session_index);
-
-  if (session)
-    {
-      if ((VPPCOM_DEBUG > 1) && (mp->retval))
-       clib_warning ("[%d] unbind failed: %U", getpid (), format_api_error,
-                     ntohl (mp->retval));
+  if (mp->retval)
+    clib_warning ("VCL<%d>: ERROR: sid %u: unbind failed: %U",
+                 getpid (), mp->context, format_api_error,
+                 ntohl (mp->retval));
 
-      vppcom_session_table_del_listener (vcm->bind_session_index);
-      vcm->bind_session_index = ~0;
-      session->state = STATE_START;
-    }
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  else
+    VDBG (1, "VCL<%d>: sid %u: unbind succeeded!", getpid (), mp->context);
 }
 
 u8 *
@@ -1064,49 +1116,52 @@ format_ip46_address (u8 * s, va_list * args)
     format (s, "%U", format_ip6_address, &ip46->ip6);
 }
 
-static inline void
-vppcom_send_accept_session_reply (u32 handle, int retval)
-{
-  vl_api_accept_session_reply_t *rmp;
-
-  rmp = vl_msg_api_alloc (sizeof (*rmp));
-  memset (rmp, 0, sizeof (*rmp));
-  rmp->_vl_msg_id = ntohs (VL_API_ACCEPT_SESSION_REPLY);
-  rmp->retval = htonl (retval);
-  rmp->handle = handle;
-  vl_msg_api_send_shmem (vcm->vl_input_queue, (u8 *) & rmp);
-}
-
 static void
 vl_api_accept_session_t_handler (vl_api_accept_session_t * mp)
 {
   svm_fifo_t *rx_fifo, *tx_fifo;
-  session_t *session, *listen_session;
+  vcl_session_t *session, *listen_session;
   u32 session_index;
+  vce_event_connect_request_t *ecr;
+  vce_event_t *ev;
+  int rv;
+  u32 ev_idx;
+  uword elts = 0;
+
+  VCL_SESSION_LOCK ();
+
+  VCL_ACCEPT_FIFO_LOCK ();
+  elts = clib_fifo_free_elts (vcm->client_session_index_fifo);
+  VCL_ACCEPT_FIFO_UNLOCK ();
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  if (!clib_fifo_free_elts (vcm->client_session_index_fifo))
+  if (!elts)
     {
-      clib_warning ("[%d] client session queue is full!", getpid ());
-      vppcom_send_accept_session_reply (mp->handle,
+      clib_warning ("VCL<%d>: client session queue is full!", getpid ());
+      vppcom_send_accept_session_reply (mp->handle, mp->context,
                                        VNET_API_ERROR_QUEUE_FULL);
-      clib_spinlock_unlock (&vcm->sessions_lockp);
+      VCL_SESSION_UNLOCK ();
       return;
     }
 
   listen_session = vppcom_session_table_lookup_listener (mp->listener_handle);
   if (!listen_session)
     {
-      clib_warning ("[%d] ERROR: couldn't find listen session: unknown vpp "
-                   "listener handle %llx", getpid (), mp->listener_handle);
-      clib_spinlock_unlock (&vcm->sessions_lockp);
+      clib_warning ("VCL<%d>: ERROR: couldn't find listen session: "
+                   "unknown vpp listener handle %llx",
+                   getpid (), mp->listener_handle);
+      vppcom_send_accept_session_reply (mp->handle, mp->context,
+                                       VNET_API_ERROR_INVALID_ARGUMENT);
+      VCL_SESSION_UNLOCK ();
       return;
     }
 
+  /* TODO check listener depth and update */
+  /* TODO on "child" fd close, update listener depth */
+
   /* Allocate local session and set it up */
   pool_get (vcm->sessions, session);
   memset (session, 0, sizeof (*session));
-  session_index = session - vcm->sessions;
+  session_index = (u32) (session - vcm->sessions);
 
   rx_fifo = uword_to_pointer (mp->server_rx_fifo, svm_fifo_t *);
   rx_fifo->client_session_index = session_index;
@@ -1114,263 +1169,162 @@ vl_api_accept_session_t_handler (vl_api_accept_session_t * mp)
   tx_fifo->client_session_index = session_index;
 
   session->vpp_handle = mp->handle;
-  session->server_rx_fifo = rx_fifo;
-  session->server_tx_fifo = tx_fifo;
-  session->vpp_event_queue = uword_to_pointer (mp->vpp_event_queue_address,
-                                              unix_shared_memory_queue_t *);
-  session->state = STATE_ACCEPT;
-  session->is_cut_thru = 0;
-  session->is_server = 1;
-  session->peer_port = mp->port;
-  session->peer_addr.is_ip4 = mp->is_ip4;
-  clib_memcpy (&session->peer_addr.ip46, mp->ip,
-              sizeof (session->peer_addr.ip46));
+  session->client_context = mp->context;
+  session->rx_fifo = rx_fifo;
+  session->tx_fifo = tx_fifo;
+  session->vpp_evt_q = uword_to_pointer (mp->vpp_event_queue_address,
+                                        svm_queue_t *);
+  session->session_state = STATE_ACCEPT;
+  session->transport.rmt_port = mp->port;
+  session->transport.is_ip4 = mp->is_ip4;
+  session->transport.rmt_ip = to_ip46 (mp->is_ip4 ? IP46_TYPE_IP4 :
+                                      IP46_TYPE_IP6, mp->ip);
 
   /* Add it to lookup table */
   hash_set (vcm->session_index_by_vpp_handles, mp->handle, session_index);
-  session->lcl_port = listen_session->lcl_port;
-  session->lcl_addr = listen_session->lcl_addr;
-
-  /* TBD: move client_session_index_fifo into listener session */
-  clib_fifo_add1 (vcm->client_session_index_fifo, session_index);
+  session->transport.lcl_port = listen_session->transport.lcl_port;
+  session->transport.lcl_ip = listen_session->transport.lcl_ip;
 
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  /* Create an event for handlers */
 
-  if (VPPCOM_DEBUG > 1)
-    {
-      u8 *ip_str = format (0, "%U", format_ip46_address, &mp->ip, mp->is_ip4);
-      clib_warning ("[%d] received request to accept session (sid %d) "
-                   "from %s:%d", getpid (), session_index, ip_str,
-                   clib_net_to_host_u16 (mp->port));
-      vec_free (ip_str);
-    }
-}
-
-static void
-vppcom_send_connect_session_reply (session_t * session, int retval)
-{
-  vl_api_connect_session_reply_t *rmp;
-  u32 len;
-  unix_shared_memory_queue_t *client_q;
-
-  rmp = vl_msg_api_alloc (sizeof (*rmp));
-  memset (rmp, 0, sizeof (*rmp));
+  VCL_EVENTS_LOCK ();
 
-  rmp->_vl_msg_id = ntohs (VL_API_CONNECT_SESSION_REPLY);
-  rmp->context = session->client_context;
-  rmp->retval = htonl (retval);
-  rmp->handle = session->vpp_handle;
-  rmp->server_rx_fifo = pointer_to_uword (session->server_rx_fifo);
-  rmp->server_tx_fifo = pointer_to_uword (session->server_tx_fifo);
-  rmp->vpp_event_queue_address = pointer_to_uword (session->vpp_event_queue);
-  rmp->segment_size = vcm->cfg.segment_size;
-  len = vec_len (session->segment_name);
-  rmp->segment_name_length = clib_min (len, sizeof (rmp->segment_name));
-  clib_memcpy (rmp->segment_name, session->segment_name,
-              rmp->segment_name_length - 1);
-  clib_memcpy (rmp->lcl_ip, session->lcl_addr.ip46.as_u8,
-              sizeof (rmp->lcl_ip));
-  rmp->is_ip4 = session->lcl_addr.is_ip4;
-  client_q = uword_to_pointer (session->client_queue_address,
-                              unix_shared_memory_queue_t *);
-  ASSERT (client_q);
-  vl_msg_api_send_shmem (client_q, (u8 *) & rmp);
-}
+  pool_get (vcm->event_thread.vce_events, ev);
+  ev_idx = (u32) (ev - vcm->event_thread.vce_events);
+  ecr = vce_get_event_data (ev, sizeof (*ecr));
+  ev->evk.eid = VCL_EVENT_CONNECT_REQ_ACCEPTED;
+  listen_session = vppcom_session_table_lookup_listener (mp->listener_handle);
+  ev->evk.session_index = (u32) (listen_session - vcm->sessions);
+  ecr->accepted_session_index = session_index;
 
-/*
- * Acting as server for redirected connect requests
- */
-static void
-vl_api_connect_sock_t_handler (vl_api_connect_sock_t * mp)
-{
-  u32 session_index;
-  session_t *session = 0;
+  VCL_EVENTS_UNLOCK ();
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  if (!clib_fifo_free_elts (vcm->client_session_index_fifo))
-    {
-      if (VPPCOM_DEBUG > 1)
-       clib_warning ("[%d] client session queue is full!", getpid ());
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      /* TBD: fix handle */
-      vppcom_send_accept_session_reply (0, VNET_API_ERROR_QUEUE_FULL);
-      return;
-    }
+  rv = vce_generate_event (&vcm->event_thread, ev_idx);
+  ASSERT (rv == 0);
 
-  pool_get (vcm->sessions, session);
-  memset (session, 0, sizeof (*session));
-  session_index = session - vcm->sessions;
+  VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: client accept request from %s"
+       " address %U port %d queue %p!", getpid (), mp->handle, session_index,
+       mp->is_ip4 ? "IPv4" : "IPv6", format_ip46_address, &mp->ip,
+       mp->is_ip4 ? IP46_TYPE_IP4 : IP46_TYPE_IP6,
+       clib_net_to_host_u16 (mp->port), session->vpp_evt_q);
 
-  session->client_context = mp->context;
-  session->vpp_handle = session_index;
-  session->client_queue_address = mp->client_queue_address;
-  session->is_cut_thru = 1;
-  session->is_server = 1;
-  session->peer_port = mp->port;
-  session->peer_addr.is_ip4 = mp->is_ip4;
-  clib_memcpy (&session->peer_addr.ip46, mp->ip,
-              sizeof (session->peer_addr.ip46));
-
-  session->state = STATE_ACCEPT;
-  clib_fifo_add1 (vcm->client_session_index_fifo, session_index);
-  if (VPPCOM_DEBUG > 1)
-    clib_warning
-      ("[%d] Got a cut-thru connect request to client: "
-       "sid %d, clib_fifo_elts %u!\n", getpid (), session_index,
-       clib_fifo_elts (vcm->client_session_index_fifo));
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  vcl_evt (VCL_EVT_ACCEPT, session, listen_session, session_index);
+  VCL_SESSION_UNLOCK ();
 }
 
+/* VPP combines bind and listen as one operation. VCL manages the separation
+ * of bind and listen locally via vppcom_session_bind() and
+ * vppcom_session_listen() */
 static void
-vppcom_send_bind_sock (session_t * session)
+vppcom_send_bind_sock (vcl_session_t * session, u32 session_index)
 {
   vl_api_bind_sock_t *bmp;
 
   /* Assumes caller has acquired spinlock: vcm->sessions_lockp */
-  session->is_server = 1;
   bmp = vl_msg_api_alloc (sizeof (*bmp));
   memset (bmp, 0, sizeof (*bmp));
 
   bmp->_vl_msg_id = ntohs (VL_API_BIND_SOCK);
   bmp->client_index = vcm->my_client_index;
-  bmp->context = htonl (0xfeedface);
-  bmp->vrf = session->vrf;
-  bmp->is_ip4 = session->lcl_addr.is_ip4;
-  clib_memcpy (bmp->ip, &session->lcl_addr.ip46, sizeof (bmp->ip));
-  bmp->port = session->lcl_port;
-  bmp->proto = session->proto;
+  bmp->context = session_index;
+  bmp->is_ip4 = session->transport.is_ip4;
+  clib_memcpy (bmp->ip, &session->transport.lcl_ip, sizeof (bmp->ip));
+  bmp->port = session->transport.lcl_port;
+  bmp->proto = session->session_type;
   clib_memcpy (bmp->options, session->options, sizeof (bmp->options));
   vl_msg_api_send_shmem (vcm->vl_input_queue, (u8 *) & bmp);
 }
 
 static void
-vppcom_send_unbind_sock (u32 session_index)
+vppcom_send_unbind_sock (u64 vpp_handle)
 {
   vl_api_unbind_sock_t *ump;
-  session_t *session = 0;
-  int rv;
-
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  rv = vppcom_session_at_index (session_index, &session);
-  if (PREDICT_FALSE (rv))
-    {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                     getpid (), session_index);
-      return;
-    }
 
   ump = vl_msg_api_alloc (sizeof (*ump));
   memset (ump, 0, sizeof (*ump));
 
   ump->_vl_msg_id = ntohs (VL_API_UNBIND_SOCK);
   ump->client_index = vcm->my_client_index;
-  ump->handle = session->vpp_handle;
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  ump->handle = vpp_handle;
   vl_msg_api_send_shmem (vcm->vl_input_queue, (u8 *) & ump);
 }
 
 static int
-vppcom_session_unbind_cut_thru (session_t * session, u32 session_index)
+vppcom_session_unbind (u32 session_index)
 {
-  svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
-  svm_fifo_segment_private_t *seg;
-  int rv = VPPCOM_OK;
+  vcl_session_t *session = 0;
+  int rv;
+  u64 vpp_handle;
+
+  VCL_SESSION_LOCK_AND_GET (session_index, &session);
+
+  vpp_handle = session->vpp_handle;
+  vppcom_session_table_del_listener (vpp_handle);
+  session->vpp_handle = ~0;
+  session->session_state = STATE_DISCONNECT;
+
+  VCL_SESSION_UNLOCK ();
 
-  if (VPPCOM_DEBUG > 1)
-    clib_warning ("[%d] sid %d, seg_nxd %d:\n"
-                 "  server_rx_fifo %p, refcnt = %d\n"
-                 "  server_tx_fifo %p, refcnt = %d",
-                 getpid (), session_index, session->sm_seg_index,
-                 session->server_rx_fifo, session->server_rx_fifo->refcnt,
-                 session->server_tx_fifo, session->server_tx_fifo->refcnt);
-
-  seg = vec_elt_at_index (sm->segments, session->sm_seg_index);
-  svm_fifo_segment_free_fifo (seg, session->server_rx_fifo,
-                             FIFO_SEGMENT_RX_FREELIST);
-  svm_fifo_segment_free_fifo (seg, session->server_tx_fifo,
-                             FIFO_SEGMENT_TX_FREELIST);
-  svm_fifo_segment_delete (seg);
+  VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: sending unbind msg! new state"
+       " 0x%x (%s)", getpid (), vpp_handle, session_index, STATE_DISCONNECT,
+       vppcom_session_state_str (STATE_DISCONNECT));
+  vcl_evt (VCL_EVT_UNBIND, session);
+  vppcom_send_unbind_sock (vpp_handle);
 
+done:
   return rv;
 }
 
-static int
-vppcom_session_unbind (u32 session_index)
+static inline int
+vppcom_session_disconnect (u32 session_index)
 {
   int rv;
+  vcl_session_t *session;
+  u64 vpp_handle;
+  session_state_t state;
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  if (PREDICT_FALSE (pool_is_free_index (vcm->sessions, session_index)))
-    {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 1)
-       clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                     getpid (), session_index);
-      return VPPCOM_EBADFD;
-    }
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  VCL_SESSION_LOCK_AND_GET (session_index, &session);
 
-  if (vcm->bind_session_index != session_index)
-    clib_warning ("[%d] ERROR: unbinding a not bound listener %u (%u)",
-                 session_index, vcm->bind_session_index);
-  vcm->bind_session_index = session_index;
-  vppcom_send_unbind_sock (session_index);
-  rv = vppcom_wait_for_session_state_change (session_index, STATE_START,
-                                            vcm->cfg.session_timeout);
-  if (PREDICT_FALSE (rv))
-    {
-      vcm->bind_session_index = ~0;
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] server unbind timed out, rv = %s (%d)",
-                     getpid (), vppcom_retval_str (rv), rv);
-      return rv;
-    }
-  return VPPCOM_OK;
-}
+  vpp_handle = session->vpp_handle;
+  state = session->session_state;
+  VCL_SESSION_UNLOCK ();
 
-static inline int
-vppcom_session_disconnect (u32 session_index)
-{
-  int rv;
-  session_t *session;
+  VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u state 0x%x (%s)", getpid (),
+       vpp_handle, session_index, state, vppcom_session_state_str (state));
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  rv = vppcom_session_at_index (session_index, &session);
-  if (PREDICT_FALSE (rv))
+  if (PREDICT_FALSE (state & STATE_LISTEN))
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 1)
-       clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                     getpid (), session_index);
-      return rv;
+      clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx, sid %u: "
+                   "Cannot disconnect a listen socket!",
+                   getpid (), vpp_handle, session_index);
+      rv = VPPCOM_EBADFD;
+      goto done;
     }
 
-  if (!session->is_cut_thru)
+  /* The peer has already initiated the close,
+   * so send the disconnect session reply.
+   */
+  if (state & STATE_CLOSE_ON_EMPTY)
     {
-      if (VPPCOM_DEBUG > 1)
-       clib_warning ("[%d] disconnecting sid (%u)", getpid (),
-                     session_index);
-      vppcom_send_disconnect (session);
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-
-      rv = vppcom_wait_for_session_state_change (session_index,
-                                                STATE_DISCONNECT, 1.0);
-      /* TBD: Force clean up on error/timeout since there is no other
-       *      way to recover from a failed disconnect.
-       */
-      if ((VPPCOM_DEBUG > 0) && (rv < 0))
-       clib_warning ("[%d] disconnect (session %d) failed, rv = %s (%d)",
-                     getpid (), session_index, vppcom_retval_str (rv), rv);
+      //XXX alagalah - Check and drain here?
+      vppcom_send_disconnect_session_reply (vpp_handle,
+                                           session_index, 0 /* rv */ );
+      VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: sending disconnect "
+           "REPLY...", getpid (), vpp_handle, session_index);
     }
+
+  /* Otherwise, send a disconnect session msg...
+   */
   else
     {
-      /* TBD: Handle cut-thru disconnect */
-      clib_spinlock_unlock (&vcm->sessions_lockp);
+      VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: sending disconnect...",
+           getpid (), vpp_handle, session_index);
+
+      vppcom_send_disconnect_session (vpp_handle, session_index);
     }
 
-  return VPPCOM_OK;
+done:
+  return rv;
 }
 
 #define foreach_sock_msg                                        \
@@ -1378,19 +1332,19 @@ _(SESSION_ENABLE_DISABLE_REPLY, session_enable_disable_reply)   \
 _(BIND_SOCK_REPLY, bind_sock_reply)                             \
 _(UNBIND_SOCK_REPLY, unbind_sock_reply)                         \
 _(ACCEPT_SESSION, accept_session)                               \
-_(CONNECT_SOCK, connect_sock)                                   \
 _(CONNECT_SESSION_REPLY, connect_session_reply)                 \
 _(DISCONNECT_SESSION, disconnect_session)                       \
 _(DISCONNECT_SESSION_REPLY, disconnect_session_reply)           \
 _(RESET_SESSION, reset_session)                                 \
 _(APPLICATION_ATTACH_REPLY, application_attach_reply)           \
 _(APPLICATION_DETACH_REPLY, application_detach_reply)           \
-_(MAP_ANOTHER_SEGMENT, map_another_segment)
+_(MAP_ANOTHER_SEGMENT, map_another_segment)                     \
+_(UNMAP_SEGMENT, unmap_segment)
 
 static void
 vppcom_api_hookup (void)
 {
-#define _(N,n)                                                  \
+#define _(N, n)                                                  \
     vl_msg_api_set_handlers(VL_API_##N, #n,                     \
                            vl_api_##n##_t_handler,              \
                            vl_noop_handler,                     \
@@ -1407,6 +1361,7 @@ vppcom_cfg_init (vppcom_cfg_t * vcl_cfg)
   ASSERT (vcl_cfg);
 
   vcl_cfg->heapsize = (256ULL << 20);
+  vcl_cfg->vpp_api_q_length = 1024;
   vcl_cfg->segment_baseva = 0x200000000ULL;
   vcl_cfg->segment_size = (256 << 20);
   vcl_cfg->add_segment_size = (128 << 20);
@@ -1418,6 +1373,8 @@ vppcom_cfg_init (vppcom_cfg_t * vcl_cfg)
   vcl_cfg->app_timeout = 10 * 60.0;
   vcl_cfg->session_timeout = 10 * 60.0;
   vcl_cfg->accept_timeout = 60.0;
+  vcl_cfg->event_ring_size = (128 << 10);
+  vcl_cfg->event_log_path = "/dev/shm";
 }
 
 static void
@@ -1439,13 +1396,18 @@ vppcom_cfg_heapsize (char *conf_fname)
   fp = fopen (conf_fname, "r");
   if (fp == NULL)
     {
-      if (VPPCOM_DEBUG > 0)
-       fprintf (stderr, "open configuration file '%s' failed\n", conf_fname);
+      VDBG (0, "VCL<%d>: using default heapsize %lld (0x%llx)", getpid (),
+           vcl_cfg->heapsize, vcl_cfg->heapsize);
       goto defaulted;
     }
+
   argv = calloc (1, sizeof (char *));
   if (argv == NULL)
-    goto defaulted;
+    {
+      VDBG (0, "VCL<%d>: calloc failed, using default heapsize %lld (0x%llx)",
+           getpid (), vcl_cfg->heapsize, vcl_cfg->heapsize);
+      goto defaulted;
+    }
 
   while (1)
     {
@@ -1459,11 +1421,21 @@ vppcom_cfg_heapsize (char *conf_fname)
          argc++;
          char **tmp = realloc (argv, argc * sizeof (char *));
          if (tmp == NULL)
-           goto defaulted;
+           {
+             VDBG (0, "VCL<%d>: realloc failed, using default heapsize %lld "
+                   "(0x%llx)", getpid (), vcl_cfg->heapsize,
+                   vcl_cfg->heapsize);
+             goto defaulted;
+           }
          argv = tmp;
          arg = strndup (p, 1024);
          if (arg == NULL)
-           goto defaulted;
+           {
+             VDBG (0, "VCL<%d>: strndup failed, using default heapsize %lld "
+                   "(0x%llx)", getpid (), vcl_cfg->heapsize,
+                   vcl_cfg->heapsize);
+             goto defaulted;
+           }
          argv[argc - 1] = arg;
          p = strtok (NULL, " \t\n");
        }
@@ -1474,7 +1446,11 @@ vppcom_cfg_heapsize (char *conf_fname)
 
   char **tmp = realloc (argv, (argc + 1) * sizeof (char *));
   if (tmp == NULL)
-    goto defaulted;
+    {
+      VDBG (0, "VCL<%d>: realloc failed, using default heapsize %lld "
+           "(0x%llx)", getpid (), vcl_cfg->heapsize, vcl_cfg->heapsize);
+      goto defaulted;
+    }
   argv = tmp;
   argv[argc] = NULL;
 
@@ -1498,11 +1474,9 @@ vppcom_cfg_heapsize (char *conf_fname)
            }
          if (size == 0)
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] parse error '%s %s', "
-                             "using default heapsize %lld (0x%llx)",
-                             getpid (), argv[i], argv[i + 1],
-                             vcl_cfg->heapsize, vcl_cfg->heapsize);
+             VDBG (0, "VCL<%d>: parse error '%s %s', using default "
+                   "heapsize %lld (0x%llx)", getpid (), argv[i], argv[i + 1],
+                   vcl_cfg->heapsize, vcl_cfg->heapsize);
              goto defaulted;
            }
 
@@ -1512,11 +1486,9 @@ vppcom_cfg_heapsize (char *conf_fname)
            vcl_cfg->heapsize = size << 20;
          else
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] parse error '%s %s', "
-                             "using default heapsize %lld (0x%llx)",
-                             getpid (), argv[i], argv[i + 1],
-                             vcl_cfg->heapsize, vcl_cfg->heapsize);
+             VDBG (0, "VCL<%d>: parse error '%s %s', using default "
+                   "heapsize %lld (0x%llx)", getpid (), argv[i], argv[i + 1],
+                   vcl_cfg->heapsize, vcl_cfg->heapsize);
              goto defaulted;
            }
        }
@@ -1532,31 +1504,33 @@ defaulted:
                  MAP_SHARED | MAP_ANONYMOUS, -1, 0);
   if (vcl_mem == MAP_FAILED)
     {
-      clib_unix_error ("[%d] ERROR: mmap(0, %lld == 0x%llx, "
+      clib_unix_error ("VCL<%d>: ERROR: mmap(0, %lld == 0x%llx, "
                       "PROT_READ | PROT_WRITE,MAP_SHARED | MAP_ANONYMOUS, "
                       "-1, 0) failed!",
                       getpid (), vcl_cfg->heapsize, vcl_cfg->heapsize);
+      ASSERT (vcl_mem != MAP_FAILED);
       return;
     }
   heap = clib_mem_init (vcl_mem, vcl_cfg->heapsize);
   if (!heap)
     {
-      clib_warning ("[%d] ERROR: clib_mem_init() failed!", getpid ());
+      clib_warning ("VCL<%d>: ERROR: clib_mem_init() failed!", getpid ());
+      ASSERT (heap);
       return;
     }
   vcl_mem = clib_mem_alloc (sizeof (_vppcom_main));
   if (!vcl_mem)
     {
-      clib_warning ("[%d] ERROR: clib_mem_alloc() failed!", getpid ());
+      clib_warning ("VCL<%d>: ERROR: clib_mem_alloc() failed!", getpid ());
+      ASSERT (vcl_mem);
       return;
     }
 
   clib_memcpy (vcl_mem, &_vppcom_main, sizeof (_vppcom_main));
   vcm = vcl_mem;
 
-  if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] allocated VCL heap = %p, size %lld (0x%llx)",
-                 getpid (), heap, vcl_cfg->heapsize, vcl_cfg->heapsize);
+  VDBG (0, "VCL<%d>: allocated VCL heap = %p, size %lld (0x%llx)", getpid (),
+       heap, vcl_cfg->heapsize, vcl_cfg->heapsize);
 }
 
 static void
@@ -1569,28 +1543,27 @@ vppcom_cfg_read (char *conf_fname)
   u8 vc_cfg_input = 0;
   u8 *chroot_path;
   struct stat s;
-  u32 uid, gid;
+  u32 uid, gid, q_len;
 
   fd = open (conf_fname, O_RDONLY);
   if (fd < 0)
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] open configuration file '%s' failed!",
-                     getpid (), conf_fname);
+      VDBG (0, "VCL<%d>: using default configuration.", getpid (),
+           conf_fname);
       goto file_done;
     }
 
   if (fstat (fd, &s) < 0)
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] failed to stat `%s'", getpid (), conf_fname);
+      VDBG (0, "VCL<%d>: failed to stat `%s', using default configuration",
+           getpid (), conf_fname);
       goto file_done;
     }
 
   if (!(S_ISREG (s.st_mode) || S_ISLNK (s.st_mode)))
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] not a regular file `%s'", getpid (), conf_fname);
+      VDBG (0, "VCL<%d>: not a regular file `%s', using default "
+           "configuration", getpid (), conf_fname);
       goto file_done;
     }
 
@@ -1612,205 +1585,190 @@ vppcom_cfg_read (char *conf_fname)
          if (unformat (line_input, "heapsize %s", &chroot_path))
            {
              vec_terminate_c_string (chroot_path);
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured heapsize %s, "
-                             "actual heapsize %lld (0x%llx)",
-                             getpid (), chroot_path, vcl_cfg->heapsize,
-                             vcl_cfg->heapsize);
+             VDBG (0, "VCL<%d>: configured heapsize %s, actual heapsize %lld"
+                   " (0x%llx)", getpid (), chroot_path, vcl_cfg->heapsize,
+                   vcl_cfg->heapsize);
              vec_free (chroot_path);
            }
          else if (unformat (line_input, "api-prefix %s", &chroot_path))
            {
              vec_terminate_c_string (chroot_path);
+             if (vcl_cfg->vpp_api_filename)
+               vec_free (vcl_cfg->vpp_api_filename);
+             vcl_cfg->vpp_api_filename = format (0, "/%s-vpe-api%c",
+                                                 chroot_path, 0);
              vl_set_memory_root_path ((char *) chroot_path);
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured api-prefix %s",
-                             getpid (), chroot_path);
+
+             VDBG (0, "VCL<%d>: configured api-prefix (%s) and api filename"
+                   " (%s)", getpid (), chroot_path,
+                   vcl_cfg->vpp_api_filename);
              chroot_path = 0;  /* Don't vec_free() it! */
            }
+         else if (unformat (line_input, "vpp-api-q-length %d", &q_len))
+           {
+             if (q_len < vcl_cfg->vpp_api_q_length)
+               {
+                 clib_warning ("VCL<%d>: ERROR: configured vpp-api-q-length "
+                               "(%u) is too small! Using default: %u ",
+                               getpid (), q_len, vcl_cfg->vpp_api_q_length);
+               }
+             else
+               {
+                 vcl_cfg->vpp_api_q_length = q_len;
+
+                 VDBG (0, "VCL<%d>: configured vpp-api-q-length %u",
+                       getpid (), vcl_cfg->vpp_api_q_length);
+               }
+           }
          else if (unformat (line_input, "uid %d", &uid))
            {
              vl_set_memory_uid (uid);
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured uid %d", getpid (), uid);
+             VDBG (0, "VCL<%d>: configured uid %d", getpid (), uid);
            }
          else if (unformat (line_input, "gid %d", &gid))
            {
              vl_set_memory_gid (gid);
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured gid %d", getpid (), gid);
+             VDBG (0, "VCL<%d>: configured gid %d", getpid (), gid);
            }
          else if (unformat (line_input, "segment-baseva 0x%lx",
                             &vcl_cfg->segment_baseva))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured segment_baseva 0x%lx",
-                             getpid (), vcl_cfg->segment_baseva);
+             VDBG (0, "VCL<%d>: configured segment_baseva 0x%lx", getpid (),
+                   vcl_cfg->segment_baseva);
            }
          else if (unformat (line_input, "segment-size 0x%lx",
                             &vcl_cfg->segment_size))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured segment_size 0x%lx (%ld)",
-                             getpid (), vcl_cfg->segment_size,
-                             vcl_cfg->segment_size);
+             VDBG (0, "VCL<%d>: configured segment_size 0x%lx (%ld)",
+                   getpid (), vcl_cfg->segment_size, vcl_cfg->segment_size);
            }
          else if (unformat (line_input, "segment-size %ld",
                             &vcl_cfg->segment_size))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured segment_size %ld (0x%lx)",
-                             getpid (), vcl_cfg->segment_size,
-                             vcl_cfg->segment_size);
+             VDBG (0, "VCL<%d>: configured segment_size %ld (0x%lx)",
+                   getpid (), vcl_cfg->segment_size, vcl_cfg->segment_size);
            }
          else if (unformat (line_input, "add-segment-size 0x%lx",
                             &vcl_cfg->add_segment_size))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning
-                 ("[%d] configured add_segment_size 0x%lx (%ld)",
-                  getpid (), vcl_cfg->add_segment_size,
-                  vcl_cfg->add_segment_size);
+             VDBG (0, "VCL<%d>: configured add_segment_size 0x%lx (%ld)",
+                   getpid (), vcl_cfg->add_segment_size,
+                   vcl_cfg->add_segment_size);
            }
          else if (unformat (line_input, "add-segment-size %ld",
                             &vcl_cfg->add_segment_size))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning
-                 ("[%d] configured add_segment_size %ld (0x%lx)",
-                  getpid (), vcl_cfg->add_segment_size,
-                  vcl_cfg->add_segment_size);
+             VDBG (0, "VCL<%d>: configured add_segment_size %ld (0x%lx)",
+                   getpid (), vcl_cfg->add_segment_size,
+                   vcl_cfg->add_segment_size);
            }
          else if (unformat (line_input, "preallocated-fifo-pairs %d",
                             &vcl_cfg->preallocated_fifo_pairs))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured preallocated_fifo_pairs "
-                             "%d (0x%x)", getpid (),
-                             vcl_cfg->preallocated_fifo_pairs,
-                             vcl_cfg->preallocated_fifo_pairs);
+             VDBG (0, "VCL<%d>: configured preallocated_fifo_pairs %d "
+                   "(0x%x)", getpid (), vcl_cfg->preallocated_fifo_pairs,
+                   vcl_cfg->preallocated_fifo_pairs);
            }
          else if (unformat (line_input, "rx-fifo-size 0x%lx",
                             &vcl_cfg->rx_fifo_size))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured rx_fifo_size 0x%lx (%ld)",
-                             getpid (), vcl_cfg->rx_fifo_size,
-                             vcl_cfg->rx_fifo_size);
+             VDBG (0, "VCL<%d>: configured rx_fifo_size 0x%lx (%ld)",
+                   getpid (), vcl_cfg->rx_fifo_size, vcl_cfg->rx_fifo_size);
            }
          else if (unformat (line_input, "rx-fifo-size %ld",
                             &vcl_cfg->rx_fifo_size))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured rx_fifo_size %ld (0x%lx)",
-                             getpid (), vcl_cfg->rx_fifo_size,
-                             vcl_cfg->rx_fifo_size);
+             VDBG (0, "VCL<%d>: configured rx_fifo_size %ld (0x%lx)",
+                   getpid (), vcl_cfg->rx_fifo_size, vcl_cfg->rx_fifo_size);
            }
          else if (unformat (line_input, "tx-fifo-size 0x%lx",
                             &vcl_cfg->tx_fifo_size))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured tx_fifo_size 0x%lx (%ld)",
-                             getpid (), vcl_cfg->tx_fifo_size,
-                             vcl_cfg->tx_fifo_size);
+             VDBG (0, "VCL<%d>: configured tx_fifo_size 0x%lx (%ld)",
+                   getpid (), vcl_cfg->tx_fifo_size, vcl_cfg->tx_fifo_size);
            }
          else if (unformat (line_input, "tx-fifo-size %ld",
                             &vcl_cfg->tx_fifo_size))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured tx_fifo_size %ld (0x%lx)",
-                             getpid (), vcl_cfg->tx_fifo_size,
-                             vcl_cfg->tx_fifo_size);
+             VDBG (0, "VCL<%d>: configured tx_fifo_size %ld (0x%lx)",
+                   getpid (), vcl_cfg->tx_fifo_size, vcl_cfg->tx_fifo_size);
            }
          else if (unformat (line_input, "event-queue-size 0x%lx",
                             &vcl_cfg->event_queue_size))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured event_queue_size 0x%lx (%ld)",
-                             getpid (), vcl_cfg->event_queue_size,
-                             vcl_cfg->event_queue_size);
+             VDBG (0, "VCL<%d>: configured event_queue_size 0x%lx (%ld)",
+                   getpid (), vcl_cfg->event_queue_size,
+                   vcl_cfg->event_queue_size);
            }
          else if (unformat (line_input, "event-queue-size %ld",
                             &vcl_cfg->event_queue_size))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured event_queue_size %ld (0x%lx)",
-                             getpid (), vcl_cfg->event_queue_size,
-                             vcl_cfg->event_queue_size);
+             VDBG (0, "VCL<%d>: configured event_queue_size %ld (0x%lx)",
+                   getpid (), vcl_cfg->event_queue_size,
+                   vcl_cfg->event_queue_size);
            }
          else if (unformat (line_input, "listen-queue-size 0x%lx",
                             &vcl_cfg->listen_queue_size))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured listen_queue_size 0x%lx (%ld)",
-                             getpid (), vcl_cfg->listen_queue_size,
-                             vcl_cfg->listen_queue_size);
+             VDBG (0, "VCL<%d>: configured listen_queue_size 0x%lx (%ld)",
+                   getpid (), vcl_cfg->listen_queue_size,
+                   vcl_cfg->listen_queue_size);
            }
          else if (unformat (line_input, "listen-queue-size %ld",
                             &vcl_cfg->listen_queue_size))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured listen_queue_size %ld (0x%lx)",
-                             getpid (), vcl_cfg->listen_queue_size,
-                             vcl_cfg->listen_queue_size);
+             VDBG (0, "VCL<%d>: configured listen_queue_size %ld (0x%lx)",
+                   getpid (), vcl_cfg->listen_queue_size,
+                   vcl_cfg->listen_queue_size);
            }
          else if (unformat (line_input, "app-timeout %f",
                             &vcl_cfg->app_timeout))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured app_timeout %f",
-                             getpid (), vcl_cfg->app_timeout);
+             VDBG (0, "VCL<%d>: configured app_timeout %f",
+                   getpid (), vcl_cfg->app_timeout);
            }
          else if (unformat (line_input, "session-timeout %f",
                             &vcl_cfg->session_timeout))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured session_timeout %f",
-                             getpid (), vcl_cfg->session_timeout);
+             VDBG (0, "VCL<%d>: configured session_timeout %f",
+                   getpid (), vcl_cfg->session_timeout);
            }
          else if (unformat (line_input, "accept-timeout %f",
                             &vcl_cfg->accept_timeout))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured accept_timeout %f",
-                             getpid (), vcl_cfg->accept_timeout);
+             VDBG (0, "VCL<%d>: configured accept_timeout %f",
+                   getpid (), vcl_cfg->accept_timeout);
            }
          else if (unformat (line_input, "app-proxy-transport-tcp"))
            {
              vcl_cfg->app_proxy_transport_tcp = 1;
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured app_proxy_transport_tcp (%d)",
-                             getpid (), vcl_cfg->app_proxy_transport_tcp);
+             VDBG (0, "VCL<%d>: configured app_proxy_transport_tcp (%d)",
+                   getpid (), vcl_cfg->app_proxy_transport_tcp);
            }
          else if (unformat (line_input, "app-proxy-transport-udp"))
            {
              vcl_cfg->app_proxy_transport_udp = 1;
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured app_proxy_transport_udp (%d)",
-                             getpid (), vcl_cfg->app_proxy_transport_udp);
+             VDBG (0, "VCL<%d>: configured app_proxy_transport_udp (%d)",
+                   getpid (), vcl_cfg->app_proxy_transport_udp);
            }
          else if (unformat (line_input, "app-scope-local"))
            {
              vcl_cfg->app_scope_local = 1;
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured app_scope_local (%d)",
-                             getpid (), vcl_cfg->app_scope_local);
+             VDBG (0, "VCL<%d>: configured app_scope_local (%d)",
+                   getpid (), vcl_cfg->app_scope_local);
            }
          else if (unformat (line_input, "app-scope-global"))
            {
              vcl_cfg->app_scope_global = 1;
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured app_scope_global (%d)",
-                             getpid (), vcl_cfg->app_scope_global);
+             VDBG (0, "VCL<%d>: configured app_scope_global (%d)",
+                   getpid (), vcl_cfg->app_scope_global);
            }
          else if (unformat (line_input, "namespace-secret %lu",
                             &vcl_cfg->namespace_secret))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning
-                 ("[%d] configured namespace_secret %lu (0x%lx)",
-                  getpid (), vcl_cfg->namespace_secret,
-                  vcl_cfg->namespace_secret);
+             VDBG (0, "VCL<%d>: configured namespace_secret %lu (0x%lx)",
+                   getpid (), vcl_cfg->namespace_secret,
+                   vcl_cfg->namespace_secret);
            }
          else if (unformat (line_input, "namespace-id %v",
                             &vcl_cfg->namespace_id))
@@ -1821,29 +1779,26 @@ vppcom_cfg_read (char *conf_fname)
              if (nsid_vec_len > max_nsid_vec_len)
                {
                  _vec_len (vcl_cfg->namespace_id) = max_nsid_vec_len;
-                 if (VPPCOM_DEBUG > 0)
-                   clib_warning ("[%d] configured namespace_id is too long,"
-                                 " truncated to %d characters!", getpid (),
-                                 max_nsid_vec_len);
+                 VDBG (0, "VCL<%d>: configured namespace_id is too long,"
+                       " truncated to %d characters!",
+                       getpid (), max_nsid_vec_len);
                }
 
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured namespace_id %v",
-                             getpid (), vcl_cfg->namespace_id);
+             VDBG (0, "VCL<%d>: configured namespace_id %v",
+                   getpid (), vcl_cfg->namespace_id);
            }
          else if (unformat (line_input, "}"))
            {
              vc_cfg_input = 0;
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] completed parsing vppcom config!",
-                             getpid ());
+             VDBG (0, "VCL<%d>: completed parsing vppcom config!",
+                   getpid ());
              goto input_done;
            }
          else
            {
              if (line_input->buffer[line_input->index] != '#')
                {
-                 clib_warning ("[%d] Unknown vppcom config option: '%s'",
+                 clib_warning ("VCL<%d>: Unknown vppcom config option: '%s'",
                                getpid (), (char *)
                                &line_input->buffer[line_input->index]);
                }
@@ -1882,29 +1837,40 @@ vppcom_app_create (char *app_name)
        {
          u32 tmp;
          if (sscanf (env_var_str, "%u", &tmp) != 1)
-           clib_warning ("[%d] Invalid debug level specified in "
-                         "the environment variable "
-                         VPPCOM_ENV_DEBUG
+           clib_warning ("VCL<%d>: WARNING: Invalid debug level specified "
+                         "in the environment variable " VPPCOM_ENV_DEBUG
                          " (%s)!\n", getpid (), env_var_str);
          else
            {
              vcm->debug = tmp;
-             clib_warning ("[%d] configured debug level (%u) from "
-                           VPPCOM_ENV_DEBUG "!", getpid (), vcm->debug);
+             VDBG (0, "VCL<%d>: configured VCL debug level (%u) from "
+                   VPPCOM_ENV_DEBUG "!", getpid (), vcm->debug);
            }
        }
       conf_fname = getenv (VPPCOM_ENV_CONF);
       if (!conf_fname)
-       {
-         conf_fname = VPPCOM_CONF_DEFAULT;
-         if (VPPCOM_DEBUG > 0)
-           clib_warning ("[%d] getenv '%s' failed!", getpid (),
-                         VPPCOM_ENV_CONF);
-       }
+       conf_fname = VPPCOM_CONF_DEFAULT;
       vppcom_cfg_heapsize (conf_fname);
+      vcl_cfg = &vcm->cfg;
+      clib_spinlock_init (&vcm->session_fifo_lockp);
       clib_fifo_validate (vcm->client_session_index_fifo,
                          vcm->cfg.listen_queue_size);
       vppcom_cfg_read (conf_fname);
+
+
+      env_var_str = getenv (VPPCOM_ENV_API_PREFIX);
+      if (env_var_str)
+       {
+         if (vcl_cfg->vpp_api_filename)
+           vec_free (vcl_cfg->vpp_api_filename);
+         vcl_cfg->vpp_api_filename = format (0, "/%s-vpe-api%c",
+                                             env_var_str, 0);
+         vl_set_memory_root_path ((char *) env_var_str);
+
+         VDBG (0, "VCL<%d>: configured api prefix (%s) and filename (%s) "
+               "from " VPPCOM_ENV_API_PREFIX "!",
+               getpid (), env_var_str, vcl_cfg->vpp_api_filename);
+       }
       env_var_str = getenv (VPPCOM_ENV_APP_NAMESPACE_ID);
       if (env_var_str)
        {
@@ -1914,63 +1880,56 @@ vppcom_app_create (char *app_name)
          vec_validate (vcm->cfg.namespace_id, ns_id_vec_len - 1);
          clib_memcpy (vcm->cfg.namespace_id, env_var_str, ns_id_vec_len);
 
-         if (VPPCOM_DEBUG > 0)
-           clib_warning ("[%d] configured namespace_id (%v) from "
-                         VPPCOM_ENV_APP_NAMESPACE_ID "!", getpid (),
-                         vcm->cfg.namespace_id);
+         VDBG (0, "VCL<%d>: configured namespace_id (%v) from "
+               VPPCOM_ENV_APP_NAMESPACE_ID "!", getpid (),
+               vcm->cfg.namespace_id);
        }
       env_var_str = getenv (VPPCOM_ENV_APP_NAMESPACE_SECRET);
       if (env_var_str)
        {
          u64 tmp;
          if (sscanf (env_var_str, "%lu", &tmp) != 1)
-           clib_warning ("[%d] Invalid namespace secret specified in "
-                         "the environment variable "
+           clib_warning ("VCL<%d>: WARNING: Invalid namespace secret "
+                         "specified in the environment variable "
                          VPPCOM_ENV_APP_NAMESPACE_SECRET
                          " (%s)!\n", getpid (), env_var_str);
          else
            {
              vcm->cfg.namespace_secret = tmp;
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] configured namespace secret (%lu) from "
-                             VPPCOM_ENV_APP_NAMESPACE_ID "!", getpid (),
-                             vcm->cfg.namespace_secret);
+             VDBG (0, "VCL<%d>: configured namespace secret (%lu) from "
+                   VPPCOM_ENV_APP_NAMESPACE_SECRET "!", getpid (),
+                   vcm->cfg.namespace_secret);
            }
        }
       if (getenv (VPPCOM_ENV_APP_PROXY_TRANSPORT_TCP))
        {
          vcm->cfg.app_proxy_transport_tcp = 1;
-         if (VPPCOM_DEBUG > 0)
-           clib_warning ("[%d] configured app_proxy_transport_tcp (%u) from "
-                         VPPCOM_ENV_APP_PROXY_TRANSPORT_TCP "!", getpid (),
-                         vcm->cfg.app_proxy_transport_tcp);
+         VDBG (0, "VCL<%d>: configured app_proxy_transport_tcp (%u) from "
+               VPPCOM_ENV_APP_PROXY_TRANSPORT_TCP "!", getpid (),
+               vcm->cfg.app_proxy_transport_tcp);
        }
       if (getenv (VPPCOM_ENV_APP_PROXY_TRANSPORT_UDP))
        {
          vcm->cfg.app_proxy_transport_udp = 1;
-         if (VPPCOM_DEBUG > 0)
-           clib_warning ("[%d] configured app_proxy_transport_udp (%u) from "
-                         VPPCOM_ENV_APP_PROXY_TRANSPORT_UDP "!", getpid (),
-                         vcm->cfg.app_proxy_transport_udp);
+         VDBG (0, "VCL<%d>: configured app_proxy_transport_udp (%u) from "
+               VPPCOM_ENV_APP_PROXY_TRANSPORT_UDP "!", getpid (),
+               vcm->cfg.app_proxy_transport_udp);
        }
       if (getenv (VPPCOM_ENV_APP_SCOPE_LOCAL))
        {
          vcm->cfg.app_scope_local = 1;
-         if (VPPCOM_DEBUG > 0)
-           clib_warning ("[%d] configured app_scope_local (%u) from "
-                         VPPCOM_ENV_APP_SCOPE_LOCAL "!", getpid (),
-                         vcm->cfg.app_scope_local);
+         VDBG (0, "VCL<%d>: configured app_scope_local (%u) from "
+               VPPCOM_ENV_APP_SCOPE_LOCAL "!", getpid (),
+               vcm->cfg.app_scope_local);
        }
       if (getenv (VPPCOM_ENV_APP_SCOPE_GLOBAL))
        {
          vcm->cfg.app_scope_global = 1;
-         if (VPPCOM_DEBUG > 0)
-           clib_warning ("[%d] configured app_scope_global (%u) from "
-                         VPPCOM_ENV_APP_SCOPE_GLOBAL "!", getpid (),
-                         vcm->cfg.app_scope_global);
+         VDBG (0, "VCL<%d>: configured app_scope_global (%u) from "
+               VPPCOM_ENV_APP_SCOPE_GLOBAL "!", getpid (),
+               vcm->cfg.app_scope_global);
        }
 
-      vcm->bind_session_index = ~0;
       vcm->main_cpu = os_get_thread_index ();
       heap = clib_mem_get_per_cpu_heap ();
       h = mheap_header (heap);
@@ -1982,47 +1941,52 @@ vppcom_app_create (char *app_name)
 
       clib_time_init (&vcm->clib_time);
       vppcom_init_error_string_table ();
-      svm_fifo_segment_init (vcl_cfg->segment_baseva,
-                            20 /* timeout in secs */ );
+      svm_fifo_segment_main_init (vcl_cfg->segment_baseva,
+                                 20 /* timeout in secs */ );
       clib_spinlock_init (&vcm->sessions_lockp);
-      vppcom_api_hookup ();
     }
 
   if (vcm->my_client_index == ~0)
     {
+
+      /* API hookup and connect to VPP */
+      vppcom_api_hookup ();
+      vcl_elog_init (vcm);
       vcm->app_state = STATE_APP_START;
       rv = vppcom_connect_to_vpp (app_name);
       if (rv)
        {
-         clib_warning ("[%d] couldn't connect to VPP.", getpid ());
+         clib_warning ("VCL<%d>: ERROR: couldn't connect to VPP!",
+                       getpid ());
          return rv;
        }
 
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] sending session enable", getpid ());
+      /* State event handling thread */
+
+      rv = vce_start_event_thread (&(vcm->event_thread), 20);
+
+      VDBG (0, "VCL<%d>: sending session enable", getpid ());
 
       rv = vppcom_app_session_enable ();
       if (rv)
        {
-         clib_warning ("[%d] vppcom_app_session_enable() failed!",
-                       getpid ());
+         clib_warning ("VCL<%d>: ERROR: vppcom_app_session_enable() "
+                       "failed!", getpid ());
          return rv;
        }
 
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] sending app attach", getpid ());
+      VDBG (0, "VCL<%d>: sending app attach", getpid ());
 
       rv = vppcom_app_attach ();
       if (rv)
        {
-         clib_warning ("[%d] vppcom_app_attach() failed!", getpid ());
+         clib_warning ("VCL<%d>: ERROR: vppcom_app_attach() failed!",
+                       getpid ());
          return rv;
        }
 
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] app_name '%s', my_client_index %d (0x%x)",
-                     getpid (), app_name, vcm->my_client_index,
-                     vcm->my_client_index);
+      VDBG (0, "VCL<%d>: app_name '%s', my_client_index %d (0x%x)",
+           getpid (), app_name, vcm->my_client_index, vcm->my_client_index);
     }
 
   return VPPCOM_OK;
@@ -2032,46 +1996,56 @@ void
 vppcom_app_destroy (void)
 {
   int rv;
+  f64 orig_app_timeout;
 
   if (vcm->my_client_index == ~0)
     return;
 
-  if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] detaching from VPP, my_client_index %d (0x%x)",
-                 getpid (), vcm->my_client_index, vcm->my_client_index);
+  VDBG (0, "VCL<%d>: detaching from VPP, my_client_index %d (0x%x)",
+       getpid (), vcm->my_client_index, vcm->my_client_index);
+  vcl_evt (VCL_EVT_DETACH, vcm);
 
   vppcom_app_detach ();
+  orig_app_timeout = vcm->cfg.app_timeout;
+  vcm->cfg.app_timeout = 2.0;
   rv = vppcom_wait_for_app_state_change (STATE_APP_ENABLED);
+  vcm->cfg.app_timeout = orig_app_timeout;
   if (PREDICT_FALSE (rv))
-    {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] application detach timed out, rv = %s (%d)",
-                     getpid (), vppcom_retval_str (rv), rv);
-    }
+    VDBG (0, "VCL<%d>: application detach timed out! returning %d (%s)",
+         getpid (), rv, vppcom_retval_str (rv));
+
+  vcl_elog_stop (vcm);
   vl_client_disconnect_from_vlib ();
   vcm->my_client_index = ~0;
   vcm->app_state = STATE_APP_START;
 }
 
 int
-vppcom_session_create (u32 vrf, u8 proto, u8 is_nonblocking)
+vppcom_session_create (u8 proto, u8 is_nonblocking)
 {
-  session_t *session;
+  vcl_session_t *session;
   u32 session_index;
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
+  VCL_SESSION_LOCK ();
   pool_get (vcm->sessions, session);
   memset (session, 0, sizeof (*session));
   session_index = session - vcm->sessions;
 
-  session->vrf = vrf;
-  session->proto = proto;
-  session->state = STATE_START;
-  session->is_nonblocking = is_nonblocking ? 1 : 0;
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  session->session_type = proto;
+  session->session_state = STATE_START;
+  session->vpp_handle = ~0;
 
-  if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] sid %d", getpid (), session_index);
+  if (is_nonblocking)
+    VCL_SESS_ATTR_SET (session->attr, VCL_SESS_ATTR_NONBLOCK);
+  else
+    VCL_SESS_ATTR_CLR (session->attr, VCL_SESS_ATTR_NONBLOCK);
+
+  vcl_evt (VCL_EVT_CREATE, session, session_type, session->session_state,
+          is_nonblocking, session_index);
+
+  VCL_SESSION_UNLOCK ();
+
+  VDBG (0, "VCL<%d>: sid %u", getpid (), session_index);
 
   return (int) session_index;
 }
@@ -2079,63 +2053,51 @@ vppcom_session_create (u32 vrf, u8 proto, u8 is_nonblocking)
 int
 vppcom_session_close (uint32_t session_index)
 {
-  session_t *session = 0;
+  vcl_session_t *session = 0;
   int rv;
-  u8 is_server;
-  u8 is_listen;
-  u8 is_cut_thru;
   u8 is_vep;
   u8 is_vep_session;
   u32 next_sid;
   u32 vep_idx;
+  u64 vpp_handle;
+  uword *p;
   session_state_t state;
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  rv = vppcom_session_at_index (session_index, &session);
-  if (PREDICT_FALSE (rv))
-    {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                     getpid (), session_index);
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      goto done;
-    }
-  is_server = session->is_server;
-  is_listen = session->is_listen;
-  is_cut_thru = session->is_cut_thru;
+  VCL_SESSION_LOCK_AND_GET (session_index, &session);
   is_vep = session->is_vep;
   is_vep_session = session->is_vep_session;
   next_sid = session->vep.next_sid;
   vep_idx = session->vep.vep_idx;
-  state = session->state;
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  state = session->session_state;
+  vpp_handle = session->vpp_handle;
+  VCL_SESSION_UNLOCK ();
 
   if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] sid %d", getpid (), session_index);
+    {
+      if (is_vep)
+       clib_warning ("VCL<%d>: vep_idx %u / sid %u: "
+                     "closing epoll session...",
+                     getpid (), session_index, session_index);
+      else
+       clib_warning ("VCL<%d>: vpp handle 0x%llx, sid %d: "
+                     "closing session...",
+                     getpid (), vpp_handle, session_index);
+    }
 
   if (is_vep)
     {
       while (next_sid != ~0)
        {
          rv = vppcom_epoll_ctl (session_index, EPOLL_CTL_DEL, next_sid, 0);
-         if ((VPPCOM_DEBUG > 0) && (rv < 0))
-           clib_warning ("[%d] EPOLL_CTL_DEL vep_idx %u, sid %u failed, "
-                         "rv = %s (%d)", getpid (), vep_idx, next_sid,
-                         vppcom_retval_str (rv), rv);
+         if (PREDICT_FALSE (rv < 0))
+           VDBG (0, "VCL<%d>: vpp handle 0x%llx, sid %u: EPOLL_CTL_DEL "
+                 "vep_idx %u failed! rv %d (%s)",
+                 getpid (), vpp_handle, next_sid, vep_idx,
+                 rv, vppcom_retval_str (rv));
 
-         clib_spinlock_lock (&vcm->sessions_lockp);
-         rv = vppcom_session_at_index (session_index, &session);
-         if (PREDICT_FALSE (rv))
-           {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning
-                 ("[%d] invalid session, sid (%u) has been closed!",
-                  getpid (), session_index);
-             clib_spinlock_unlock (&vcm->sessions_lockp);
-             goto done;
-           }
+         VCL_SESSION_LOCK_AND_GET (session_index, &session);
          next_sid = session->vep.next_sid;
-         clib_spinlock_unlock (&vcm->sessions_lockp);
+         VCL_SESSION_UNLOCK ();
        }
     }
   else
@@ -2143,475 +2105,481 @@ vppcom_session_close (uint32_t session_index)
       if (is_vep_session)
        {
          rv = vppcom_epoll_ctl (vep_idx, EPOLL_CTL_DEL, session_index, 0);
-         if ((VPPCOM_DEBUG > 0) && (rv < 0))
-           clib_warning ("[%d] EPOLL_CTL_DEL vep_idx %u, sid %u failed, "
-                         "rv = %s (%d)", getpid (), vep_idx, session_index,
-                         vppcom_retval_str (rv), rv);
+         if (rv < 0)
+           VDBG (0, "VCL<%d>: vpp handle 0x%llx, sid %u: EPOLL_CTL_DEL "
+                 "vep_idx %u failed! rv %d (%s)",
+                 getpid (), vpp_handle, session_index,
+                 vep_idx, rv, vppcom_retval_str (rv));
        }
 
-      if (is_cut_thru && is_server && (state == STATE_ACCEPT))
+      if (state & STATE_LISTEN)
        {
-         rv = vppcom_session_unbind_cut_thru (session, session_index);
-         if ((VPPCOM_DEBUG > 0) && (rv < 0))
-           clib_warning ("[%d] unbind cut-thru (session %d) failed, "
-                         "rv = %s (%d)",
-                         getpid (), session_index,
-                         vppcom_retval_str (rv), rv);
+         rv = vppcom_session_unbind (session_index);
+         if (PREDICT_FALSE (rv < 0))
+           VDBG (0, "VCL<%d>: vpp handle 0x%llx, sid %u: listener unbind "
+                 "failed! rv %d (%s)",
+                 getpid (), vpp_handle, session_index,
+                 rv, vppcom_retval_str (rv));
        }
-      else if (is_server && is_listen)
+
+      else if (state & (CLIENT_STATE_OPEN | SERVER_STATE_OPEN))
        {
-         rv = vppcom_session_unbind (session_index);
-         if ((VPPCOM_DEBUG > 0) && (rv < 0))
-           clib_warning ("[%d] unbind (session %d) failed, rv = %s (%d)",
-                         getpid (), session_index,
-                         vppcom_retval_str (rv), rv);
+         rv = vppcom_session_disconnect (session_index);
+         if (PREDICT_FALSE (rv < 0))
+           clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx, sid %u: "
+                         "session disconnect failed! rv %d (%s)",
+                         getpid (), vpp_handle, session_index,
+                         rv, vppcom_retval_str (rv));
        }
-      else if (state == STATE_CONNECT)
-       if (vppcom_session_disconnect (session_index))
-         goto done;
     }
-  clib_spinlock_lock (&vcm->sessions_lockp);
+
+  VCL_SESSION_LOCK_AND_GET (session_index, &session);
+  vpp_handle = session->vpp_handle;
+  if (vpp_handle != ~0)
+    {
+      p = hash_get (vcm->session_index_by_vpp_handles, vpp_handle);
+      if (p)
+       hash_unset (vcm->session_index_by_vpp_handles, vpp_handle);
+    }
   pool_put_index (vcm->sessions, session_index);
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+
+  VCL_SESSION_UNLOCK ();
+
+  if (VPPCOM_DEBUG > 0)
+    {
+      if (is_vep)
+       clib_warning ("VCL<%d>: vep_idx %u / sid %u: epoll session removed.",
+                     getpid (), session_index, session_index);
+      else
+       clib_warning ("VCL<%d>: vpp handle 0x%llx, sid %u: session removed.",
+                     getpid (), vpp_handle, session_index);
+    }
 done:
+
+  vcl_evt (VCL_EVT_CLOSE, session, rv);
+
   return rv;
 }
 
 int
 vppcom_session_bind (uint32_t session_index, vppcom_endpt_t * ep)
 {
-  session_t *session = 0;
+  vcl_session_t *session = 0;
   int rv;
 
   if (!ep || !ep->ip)
     return VPPCOM_EINVAL;
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  rv = vppcom_session_at_index (session_index, &session);
-  if (PREDICT_FALSE (rv))
-    {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                     getpid (), session_index);
-      return rv;
-    }
+  VCL_SESSION_LOCK_AND_GET (session_index, &session);
 
   if (session->is_vep)
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) is an epoll session!",
-                     getpid (), session_index);
-      return VPPCOM_EBADFD;
+      VCL_SESSION_UNLOCK ();
+      clib_warning ("VCL<%d>: ERROR: sid %u: cannot "
+                   "bind to an epoll session!", getpid (), session_index);
+      rv = VPPCOM_EBADFD;
+      goto done;
     }
 
-  session->vrf = ep->vrf;
-  session->lcl_addr.is_ip4 = ep->is_ip4;
-  session->lcl_addr.ip46 = to_ip46 (!ep->is_ip4, ep->ip);
-  session->lcl_port = ep->port;
-
-  if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] sid %d, bound to lcl address %U lcl port %u",
-                 getpid (), session_index, format_ip46_address,
-                 &session->lcl_addr.ip46, session->lcl_addr.is_ip4,
-                 clib_net_to_host_u16 (session->lcl_port));
-
-  clib_spinlock_unlock (&vcm->sessions_lockp);
-  return VPPCOM_OK;
+  session->transport.is_ip4 = ep->is_ip4;
+  session->transport.lcl_ip = to_ip46 (ep->is_ip4 ? IP46_TYPE_IP4 :
+                                      IP46_TYPE_IP6, ep->ip);
+  session->transport.lcl_port = ep->port;
+
+  VDBG (0, "VCL<%d>: sid %u: binding to local %s address %U port %u, "
+       "proto %s", getpid (), session_index,
+       session->transport.is_ip4 ? "IPv4" : "IPv6",
+       format_ip46_address, &session->transport.lcl_ip,
+       session->transport.is_ip4 ? IP46_TYPE_IP4 : IP46_TYPE_IP6,
+       clib_net_to_host_u16 (session->transport.lcl_port),
+       session->session_type ? "UDP" : "TCP");
+  vcl_evt (VCL_EVT_BIND, session);
+  VCL_SESSION_UNLOCK ();
+done:
+  return rv;
 }
 
 int
 vppcom_session_listen (uint32_t listen_session_index, uint32_t q_len)
 {
-  session_t *listen_session = 0;
-  int rv;
+  vcl_session_t *listen_session = 0;
+  u64 listen_vpp_handle;
+  int rv, retval;
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  rv = vppcom_session_at_index (listen_session_index, &listen_session);
-  if (PREDICT_FALSE (rv))
-    {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                     getpid (), listen_session_index);
-      return rv;
-    }
+  if (q_len == 0 || q_len == ~0)
+    q_len = vcm->cfg.listen_queue_size;
+
+  VCL_SESSION_LOCK_AND_GET (listen_session_index, &listen_session);
 
   if (listen_session->is_vep)
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) is an epoll session!",
-                     getpid (), listen_session_index);
-      return VPPCOM_EBADFD;
+      VCL_SESSION_UNLOCK ();
+      clib_warning ("VCL<%d>: ERROR: sid %u: cannot listen on an "
+                   "epoll session!", getpid (), listen_session_index);
+      rv = VPPCOM_EBADFD;
+      goto done;
     }
 
-  if (listen_session->is_listen)
+  listen_vpp_handle = listen_session->vpp_handle;
+  if (listen_session->session_state & STATE_LISTEN)
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] sid (%u) is already in listen state!",
-                     getpid (), listen_session_index);
-      return VPPCOM_OK;
+      VCL_SESSION_UNLOCK ();
+      VDBG (0, "VCL<%d>: vpp handle 0x%llx, sid %u: already in listen state!",
+           getpid (), listen_vpp_handle, listen_session_index);
+      rv = VPPCOM_OK;
+      goto done;
     }
 
-  if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] sid %d", getpid (), listen_session_index);
+  VDBG (0, "VCL<%d>: vpp handle 0x%llx, sid %u: sending VPP bind+listen "
+       "request...", getpid (), listen_vpp_handle, listen_session_index);
 
-  ASSERT (vcm->bind_session_index == ~0);
-  vcm->bind_session_index = listen_session_index;
-  vppcom_send_bind_sock (listen_session);
-  clib_spinlock_unlock (&vcm->sessions_lockp);
-  rv =
+  vppcom_send_bind_sock (listen_session, listen_session_index);
+  VCL_SESSION_UNLOCK ();
+  retval =
     vppcom_wait_for_session_state_change (listen_session_index, STATE_LISTEN,
                                          vcm->cfg.session_timeout);
-  if (PREDICT_FALSE (rv))
-    {
-      vcm->bind_session_index = ~0;
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] server listen timed out, rv = %d (%d)",
-                     getpid (), vppcom_retval_str (rv), rv);
-      return rv;
-    }
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  rv = vppcom_session_at_index (listen_session_index, &listen_session);
-  if (PREDICT_FALSE (rv))
+  VCL_SESSION_LOCK_AND_GET (listen_session_index, &listen_session);
+  if (PREDICT_FALSE (retval))
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                     getpid (), listen_session_index);
-      return rv;
+      VDBG (0, "VCL<%d>: vpp handle 0x%llx, sid %u: bind+listen failed! "
+           "returning %d (%s)", getpid (), listen_session->vpp_handle,
+           listen_session_index, retval, vppcom_retval_str (retval));
+      VCL_SESSION_UNLOCK ();
+      rv = retval;
+      goto done;
     }
-  listen_session->is_listen = 1;
+
+  VCL_ACCEPT_FIFO_LOCK ();
   clib_fifo_validate (vcm->client_session_index_fifo, q_len);
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  VCL_ACCEPT_FIFO_UNLOCK ();
 
-  return VPPCOM_OK;
+  VCL_SESSION_UNLOCK ();
+
+done:
+  return rv;
 }
 
 int
-vppcom_session_accept (uint32_t listen_session_index, vppcom_endpt_t * ep,
-                      uint32_t flags, double wait_for_time)
+validate_args_session_accept_ (vcl_session_t * listen_session)
 {
-  session_t *listen_session = 0;
-  session_t *client_session = 0;
-  u32 client_session_index = ~0;
-  int rv;
-  f64 wait_for;
-  char *cut_thru_str;
-
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  rv = vppcom_session_at_index (listen_session_index, &listen_session);
-  if (PREDICT_FALSE (rv))
-    {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                     getpid (), listen_session_index);
-      return rv;
-    }
+  u32 listen_session_index = listen_session - vcm->sessions;
 
+  /* Input validation - expects spinlock on sessions_lockp */
   if (listen_session->is_vep)
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) is an epoll session!",
-                     getpid (), listen_session_index);
+      clib_warning ("VCL<%d>: ERROR: sid %u: cannot accept on an "
+                   "epoll session!", getpid (), listen_session_index);
       return VPPCOM_EBADFD;
     }
 
-  if (listen_session->state != STATE_LISTEN)
+  if (listen_session->session_state != STATE_LISTEN)
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] session not in listen state, state = %s",
-                     getpid (),
-                     vppcom_session_state_str (listen_session->state));
+      clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx, sid %u: "
+                   "not in listen state! state 0x%x (%s)", getpid (),
+                   listen_session->vpp_handle, listen_session_index,
+                   listen_session->session_state,
+                   vppcom_session_state_str (listen_session->session_state));
       return VPPCOM_EBADFD;
     }
-  wait_for = listen_session->is_nonblocking ? 0 :
-    (wait_for_time < 0) ? vcm->cfg.accept_timeout : wait_for_time;
+  return VPPCOM_OK;
+}
 
-  if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] sid %d: %s (%d)", getpid (),
-                 listen_session_index,
-                 vppcom_session_state_str (listen_session->state),
-                 listen_session->state);
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+int
+vppcom_session_accept (uint32_t listen_session_index, vppcom_endpt_t * ep,
+                      uint32_t flags)
+{
+  vcl_session_t *listen_session = 0;
+  vcl_session_t *client_session = 0;
+  u32 client_session_index = ~0;
+  int rv;
+  u64 listen_vpp_handle;
+  vce_event_handler_reg_t *reg;
+  vce_event_t *ev;
+  vce_event_connect_request_t *result;
+  struct timespec ts;
+  struct timeval tv;
+  int millisecond_timeout = 1;
+  int hours_timeout = 20 * 60 * 60;
+
+  VCL_SESSION_LOCK_AND_GET (listen_session_index, &listen_session);
+  listen_vpp_handle = listen_session->vpp_handle;      // For debugging
+
+  rv = validate_args_session_accept_ (listen_session);
+  if (rv)
+    {
+      VCL_SESSION_UNLOCK ();
+      goto done;
+    }
 
-  while (1)
+  /* Using an aggressive timer of 1ms and a generous timer of
+   * 20 hours, we can implement a blocking and non-blocking listener
+   * as both event and time driven */
+  gettimeofday (&tv, NULL);
+  ts.tv_nsec = (tv.tv_usec * 1000) + (1000 * millisecond_timeout);
+  ts.tv_sec = tv.tv_sec;
+
+  /* Predict that the Listener is blocking more often than not */
+  if (PREDICT_TRUE (!VCL_SESS_ATTR_TEST (listen_session->attr,
+                                        VCL_SESS_ATTR_NONBLOCK)))
+    ts.tv_sec += hours_timeout;
+
+  VCL_SESSION_UNLOCK ();
+
+  /* Register handler for connect_request event on listen_session_index */
+  vce_event_key_t evk;
+  evk.session_index = listen_session_index;
+  evk.eid = VCL_EVENT_CONNECT_REQ_ACCEPTED;
+  reg = vce_register_handler (&vcm->event_thread, &evk,
+                             vce_connect_request_handler_fn, 0);
+  VCL_EVENTS_LOCK ();
+  ev = vce_get_event_from_index (&vcm->event_thread, reg->ev_idx);
+  pthread_mutex_lock (&reg->handler_lock);
+  while (!ev)
     {
-      rv = vppcom_wait_for_client_session_index (wait_for);
-      if (rv)
+      VCL_EVENTS_UNLOCK ();
+      rv = pthread_cond_timedwait (&reg->handler_cond,
+                                  &reg->handler_lock, &ts);
+      if (rv == ETIMEDOUT)
        {
-         if ((VPPCOM_DEBUG > 0))
-           clib_warning ("[%d] sid %d, accept timed out, rv = %s (%d)",
-                         getpid (), listen_session_index,
-                         vppcom_retval_str (rv), rv);
-         if ((wait_for == 0) || (wait_for_time > 0))
-           return rv;
+         rv = VPPCOM_EAGAIN;
+         goto cleanup;
        }
-      else
-       break;
+      VCL_EVENTS_LOCK ();
+      ev = vce_get_event_from_index (&vcm->event_thread, reg->ev_idx);
     }
+  result = vce_get_event_data (ev, sizeof (*result));
+  client_session_index = result->accepted_session_index;
+  VCL_EVENTS_UNLOCK ();
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  clib_fifo_sub1 (vcm->client_session_index_fifo, client_session_index);
-  rv = vppcom_session_at_index (client_session_index, &client_session);
-  ASSERT (rv == VPPCOM_OK);
-  ASSERT (client_session->peer_addr.is_ip4 ==
-         listen_session->lcl_addr.is_ip4);
+  /* Remove from the FIFO used to service epoll */
+  VCL_ACCEPT_FIFO_LOCK ();
+  if (clib_fifo_elts (vcm->client_session_index_fifo))
+    {
+      u32 tmp_client_session_index;
+      clib_fifo_sub1 (vcm->client_session_index_fifo,
+                     tmp_client_session_index);
+      /* It wasn't ours... put it back ... */
+      if (tmp_client_session_index != client_session_index)
+       clib_fifo_add1 (vcm->client_session_index_fifo,
+                       tmp_client_session_index);
+    }
+  VCL_ACCEPT_FIFO_UNLOCK ();
 
-  client_session->is_nonblocking = (flags & O_NONBLOCK) ? 1 : 0;
-  if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] Got a request: client sid %d, flags %d, "
-                 " is_nonblocking %u", getpid (), client_session_index,
-                 flags, client_session->is_nonblocking);
-
-  ep->vrf = client_session->vrf;
-  ep->is_cut_thru = client_session->is_cut_thru;
-  ep->is_ip4 = client_session->peer_addr.is_ip4;
-  ep->port = client_session->peer_port;
-  if (client_session->peer_addr.is_ip4)
-    clib_memcpy (ep->ip, &client_session->peer_addr.ip46.ip4,
-                sizeof (ip4_address_t));
-  else
-    clib_memcpy (ep->ip, &client_session->peer_addr.ip46.ip6,
-                sizeof (ip6_address_t));
+  VCL_SESSION_LOCK ();
 
-  if (client_session->is_server && client_session->is_cut_thru)
+  rv = vppcom_session_at_index (client_session_index, &client_session);
+  if (PREDICT_FALSE (rv))
     {
-      static svm_fifo_segment_create_args_t _a;
-      svm_fifo_segment_create_args_t *a = &_a;
-      svm_fifo_segment_private_t *seg;
+      rv = VPPCOM_ECONNABORTED;
+      clib_warning ("VCL<%d>: vpp handle 0x%llx, sid %u: client sid %u "
+                   "lookup failed! returning %d (%s)", getpid (),
+                   listen_vpp_handle, listen_session_index,
+                   client_session_index, rv, vppcom_retval_str (rv));
+      goto cleanup;
+    }
 
-      cut_thru_str = "cut-thru ";
+  if (flags & O_NONBLOCK)
+    VCL_SESS_ATTR_SET (client_session->attr, VCL_SESS_ATTR_NONBLOCK);
+  else
+    VCL_SESS_ATTR_CLR (client_session->attr, VCL_SESS_ATTR_NONBLOCK);
 
-      /* Create the segment */
-      memset (a, 0, sizeof (*a));
-      a->segment_name = (char *)
-       format ((u8 *) a->segment_name, "%d:segment%d%c",
-               getpid (), vcm->unique_segment_index++, 0);
-      a->segment_size = vcm->cfg.segment_size;
-      a->preallocated_fifo_pairs = vcm->cfg.preallocated_fifo_pairs;
-      a->rx_fifo_size = vcm->cfg.rx_fifo_size;
-      a->tx_fifo_size = vcm->cfg.tx_fifo_size;
+  VDBG (0, "VCL<%d>: vpp handle 0x%llx, sid %u: Got a client request! "
+       "vpp handle 0x%llx, sid %u, flags %d, is_nonblocking %u",
+       getpid (), listen_vpp_handle, listen_session_index,
+       client_session->vpp_handle, client_session_index,
+       flags, VCL_SESS_ATTR_TEST (client_session->attr,
+                                  VCL_SESS_ATTR_NONBLOCK));
 
-      rv = svm_fifo_segment_create (a);
-      if (PREDICT_FALSE (rv))
-       {
-         if (VPPCOM_DEBUG > 1)
-           clib_warning ("[%d] svm_fifo_segment_create ('%s') failed",
-                         getpid (), a->segment_name);
-         vec_reset_length (a->new_segment_indices);
-         rv = VNET_API_ERROR_URI_FIFO_CREATE_FAILED;
-         vppcom_send_connect_session_reply (client_session, rv);
-         clib_spinlock_unlock (&vcm->sessions_lockp);
-         return VPPCOM_ENOMEM;
-       }
-
-      client_session->segment_name = vec_dup ((u8 *) a->segment_name);
-      client_session->sm_seg_index = a->new_segment_indices[0];
-      vec_free (a->new_segment_indices);
-
-      seg = svm_fifo_segment_get_segment (client_session->sm_seg_index);
-      client_session->server_rx_fifo =
-       svm_fifo_segment_alloc_fifo (seg, vcm->cfg.rx_fifo_size,
-                                    FIFO_SEGMENT_RX_FREELIST);
-      if (PREDICT_FALSE (!client_session->server_rx_fifo))
-       {
-         svm_fifo_segment_delete (seg);
-         clib_warning ("[%d] rx fifo alloc failed, size %ld (0x%lx)",
-                       getpid (), vcm->cfg.rx_fifo_size,
-                       vcm->cfg.rx_fifo_size);
-         rv = VNET_API_ERROR_URI_FIFO_CREATE_FAILED;
-         vppcom_send_connect_session_reply (client_session, rv);
-         clib_spinlock_unlock (&vcm->sessions_lockp);
-         return VPPCOM_ENOMEM;
-       }
-      client_session->server_rx_fifo->master_session_index =
-       client_session_index;
-
-      client_session->server_tx_fifo =
-       svm_fifo_segment_alloc_fifo (seg, vcm->cfg.tx_fifo_size,
-                                    FIFO_SEGMENT_TX_FREELIST);
-      if (PREDICT_FALSE (!client_session->server_tx_fifo))
-       {
-         svm_fifo_segment_delete (seg);
-         if (VPPCOM_DEBUG > 1)
-           clib_warning ("[%d] tx fifo alloc failed, size %ld (0x%lx)",
-                         getpid (), vcm->cfg.tx_fifo_size,
-                         vcm->cfg.tx_fifo_size);
-         rv = VNET_API_ERROR_URI_FIFO_CREATE_FAILED;
-         vppcom_send_connect_session_reply (client_session, rv);
-         clib_spinlock_unlock (&vcm->sessions_lockp);
-         return VPPCOM_ENOMEM;
-       }
-      client_session->server_tx_fifo->master_session_index =
-       client_session_index;
-
-      if (VPPCOM_DEBUG > 1)
-       clib_warning ("[%d] created segment '%s': rx_fifo %p, tx_fifo %p",
-                     getpid (), client_session->segment_name,
-                     client_session->server_rx_fifo,
-                     client_session->server_tx_fifo);
-
-#ifdef CUT_THRU_EVENT_QUEUE    /* TBD */
-      {
-       void *oldheap;
-       ssvm_shared_header_t *sh = seg->ssvm.sh;
-
-       ssvm_lock_non_recursive (sh, 1);
-       oldheap = ssvm_push_heap (sh);
-       event_q = client_session->vpp_event_queue =
-         unix_shared_memory_queue_init (vcm->cfg.event_queue_size,
-                                        sizeof (session_fifo_event_t),
-                                        getpid (), 0 /* signal not sent */ );
-       ssvm_pop_heap (oldheap);
-       ssvm_unlock_non_recursive (sh);
-      }
-#endif
-      vppcom_send_connect_session_reply (client_session, 0);
-    }
-  else
+  if (ep)
     {
-      cut_thru_str = " ";
-      vppcom_send_accept_session_reply (client_session->vpp_handle, 0);
+      ep->is_ip4 = client_session->transport.is_ip4;
+      ep->port = client_session->transport.rmt_port;
+      if (client_session->transport.is_ip4)
+       clib_memcpy (ep->ip, &client_session->transport.rmt_ip.ip4,
+                    sizeof (ip4_address_t));
+      else
+       clib_memcpy (ep->ip, &client_session->transport.rmt_ip.ip6,
+                    sizeof (ip6_address_t));
     }
 
-  if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] sid %d, accepted %sconnection to peer address "
-                 "%U peer port %u",
-                 getpid (), client_session_index, cut_thru_str,
-                 format_ip46_address, &client_session->peer_addr.ip46,
-                 client_session->peer_addr.is_ip4,
-                 clib_net_to_host_u16 (client_session->peer_port));
+  vppcom_send_accept_session_reply (client_session->vpp_handle,
+                                   client_session->client_context,
+                                   0 /* retval OK */ );
+
+  VDBG (0, "VCL<%d>: vpp handle 0x%llx, sid %u: accepted vpp handle 0x%llx,"
+       " sid %u connection from peer %s address %U port %u to local %s address"
+       " %U port %u",
+       getpid (), listen_vpp_handle,
+       listen_session_index, client_session->vpp_handle,
+       client_session_index,
+       client_session->transport.is_ip4 ? "IPv4" : "IPv6",
+       format_ip46_address, &client_session->transport.rmt_ip,
+       client_session->transport.is_ip4 ?
+       IP46_TYPE_IP4 : IP46_TYPE_IP6,
+       clib_net_to_host_u16 (client_session->transport.rmt_port),
+       client_session->transport.is_ip4 ? "IPv4" : "IPv6",
+       format_ip46_address, &client_session->transport.lcl_ip,
+       client_session->transport.is_ip4 ?
+       IP46_TYPE_IP4 : IP46_TYPE_IP6,
+       clib_net_to_host_u16 (client_session->transport.lcl_port));
+  vcl_evt (VCL_EVT_ACCEPT, client_session, listen_session,
+          client_session_index);
+  VCL_SESSION_UNLOCK ();
+
+  rv = (int) client_session_index;
+  vce_clear_event (&vcm->event_thread, reg->ev_idx);
+  if (vcm->session_io_thread.io_sessions_lockp)
+    {
+      /* Throw this new accepted session index into the rx poll thread pool */
+      VCL_IO_SESSIONS_LOCK ();
+      u32 *active_session_index;
+      pool_get (vcm->session_io_thread.active_session_indexes,
+               active_session_index);
+      *active_session_index = client_session_index;
+      VCL_IO_SESSIONS_UNLOCK ();
+    }
+cleanup:
+  vce_unregister_handler (&vcm->event_thread, reg);
+  pthread_mutex_unlock (&reg->handler_lock);
 
-  clib_spinlock_unlock (&vcm->sessions_lockp);
-  return (int) client_session_index;
+done:
+  return rv;
 }
 
 int
 vppcom_session_connect (uint32_t session_index, vppcom_endpt_t * server_ep)
 {
-  session_t *session = 0;
-  int rv;
+  vcl_session_t *session = 0;
+  u64 vpp_handle = 0;
+  int rv, retval = VPPCOM_OK;
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  rv = vppcom_session_at_index (session_index, &session);
-  if (PREDICT_FALSE (rv))
-    {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                     getpid (), session_index);
-      return rv;
-    }
+  VCL_SESSION_LOCK_AND_GET (session_index, &session);
 
-  if (session->is_vep)
+  if (PREDICT_FALSE (session->is_vep))
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) is an epoll session!",
-                     getpid (), session_index);
-      return VPPCOM_EBADFD;
+      VCL_SESSION_UNLOCK ();
+      clib_warning ("VCL<%d>: ERROR: sid %u: cannot "
+                   "connect on an epoll session!", getpid (), session_index);
+      rv = VPPCOM_EBADFD;
+      goto done;
     }
 
-  if (session->state == STATE_CONNECT)
+  if (PREDICT_FALSE (session->session_state & CLIENT_STATE_OPEN))
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] session, sid (%u) already connected!",
-                     getpid (), session_index);
-      return VPPCOM_OK;
+      VDBG (0, "VCL<%d>: vpp handle 0x%llx, sid %u: session already "
+           "connected to %s %U port %d proto %s, state 0x%x (%s)",
+           getpid (), session->vpp_handle, session_index,
+           session->transport.is_ip4 ? "IPv4" : "IPv6",
+           format_ip46_address,
+           &session->transport.rmt_ip, session->transport.is_ip4 ?
+           IP46_TYPE_IP4 : IP46_TYPE_IP6,
+           clib_net_to_host_u16 (session->transport.rmt_port),
+           session->session_type ? "UDP" : "TCP", session->session_state,
+           vppcom_session_state_str (session->session_state));
+
+      VCL_SESSION_UNLOCK ();
+      goto done;
     }
 
-  session->vrf = server_ep->vrf;
-  session->peer_addr.is_ip4 = server_ep->is_ip4;
-  session->peer_addr.ip46 = to_ip46 (!server_ep->is_ip4, server_ep->ip);
-  session->peer_port = server_ep->port;
-
-  if (VPPCOM_DEBUG > 0)
-    {
-      u8 *ip_str = format (0, "%U", format_ip46_address,
-                          &session->peer_addr.ip46,
-                          session->peer_addr.is_ip4);
-      clib_warning ("[%d] connect sid %d to %s server port %d proto %s",
-                   getpid (), session_index, ip_str,
-                   clib_net_to_host_u16 (session->peer_port),
-                   session->proto ? "UDP" : "TCP");
-      vec_free (ip_str);
-    }
+  session->transport.is_ip4 = server_ep->is_ip4;
+  if (session->transport.is_ip4)
+    clib_memcpy (&session->transport.rmt_ip.ip4, server_ep->ip,
+                sizeof (ip4_address_t));
+  else
+    clib_memcpy (&session->transport.rmt_ip.ip6, server_ep->ip,
+                sizeof (ip6_address_t));
+  session->transport.rmt_port = server_ep->port;
+
+  VDBG (0, "VCL<%d>: vpp handle 0x%llx, sid %u: connecting to server %s %U "
+       "port %d proto %s",
+       getpid (), session->vpp_handle, session_index,
+       session->transport.is_ip4 ? "IPv4" : "IPv6",
+       format_ip46_address,
+       &session->transport.rmt_ip, session->transport.is_ip4 ?
+       IP46_TYPE_IP4 : IP46_TYPE_IP6,
+       clib_net_to_host_u16 (session->transport.rmt_port),
+       session->session_type ? "UDP" : "TCP");
 
   vppcom_send_connect_sock (session, session_index);
-  clib_spinlock_unlock (&vcm->sessions_lockp);
-  rv = vppcom_wait_for_session_state_change (session_index, STATE_CONNECT,
-                                            vcm->cfg.session_timeout);
-  if (PREDICT_FALSE (rv))
+  VCL_SESSION_UNLOCK ();
+
+  retval =
+    vppcom_wait_for_session_state_change (session_index, STATE_CONNECT,
+                                         vcm->cfg.session_timeout);
+
+  VCL_SESSION_LOCK_AND_GET (session_index, &session);
+  vpp_handle = session->vpp_handle;
+  VCL_SESSION_UNLOCK ();
+
+done:
+  if (PREDICT_FALSE (retval))
     {
+      rv = retval;
       if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] connect timed out, rv = %s (%d)",
-                     getpid (), vppcom_retval_str (rv), rv);
-      return rv;
+       {
+         if (session)
+           clib_warning ("VCL<%d>: vpp handle 0x%llx, sid %u: connect "
+                         "failed! returning %d (%s)", getpid (), vpp_handle,
+                         session_index, rv, vppcom_retval_str (rv));
+         else
+           clib_warning ("VCL<%d>: no session for sid %u: connect failed! "
+                         "returning %d (%s)", getpid (),
+                         session_index, rv, vppcom_retval_str (rv));
+       }
     }
-  if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] sid %d connected!", getpid (), session_index);
+  else
+    VDBG (0, "VCL<%d>: vpp handle 0x%llx, sid %u: connected!",
+         getpid (), vpp_handle, session_index);
 
-  return VPPCOM_OK;
+  return rv;
 }
 
 static inline int
 vppcom_session_read_internal (uint32_t session_index, void *buf, int n,
                              u8 peek)
 {
-  session_t *session = 0;
+  vcl_session_t *session = 0;
   svm_fifo_t *rx_fifo;
   int n_read = 0;
   int rv;
-  char *fifo_str;
+  int is_nonblocking;
+
+  u64 vpp_handle;
   u32 poll_et;
+  session_state_t state;
 
   ASSERT (buf);
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  rv = vppcom_session_at_index (session_index, &session);
-  if (PREDICT_FALSE (rv))
-    {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                     getpid (), session_index);
-      return rv;
-    }
+  VCL_SESSION_LOCK_AND_GET (session_index, &session);
 
-  if (session->is_vep)
+  is_nonblocking = VCL_SESS_ATTR_TEST (session->attr, VCL_SESS_ATTR_NONBLOCK);
+  rx_fifo = session->rx_fifo;
+  state = session->session_state;
+  vpp_handle = session->vpp_handle;
+
+  if (PREDICT_FALSE (session->is_vep))
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) is an epoll session!",
-                     getpid (), session_index);
-      return VPPCOM_EBADFD;
+      VCL_SESSION_UNLOCK ();
+      clib_warning ("VCL<%d>: ERROR: sid %u: cannot "
+                   "read from an epoll session!", getpid (), session_index);
+      rv = VPPCOM_EBADFD;
+      goto done;
     }
 
-  if (session->state == STATE_DISCONNECT)
+  if (PREDICT_FALSE (!(state & (SERVER_STATE_OPEN | CLIENT_STATE_OPEN))))
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] sid (%u) has been closed by remote peer!",
-                     getpid (), session_index);
-      return VPPCOM_ECONNRESET;
+      VCL_SESSION_UNLOCK ();
+      rv = ((state & STATE_DISCONNECT) ? VPPCOM_ECONNRESET : VPPCOM_ENOTCONN);
+
+      VDBG (0, "VCL<%d>: vpp handle 0x%llx, sid %u: %s session is not open! "
+           "state 0x%x (%s), returning %d (%s)",
+           getpid (), vpp_handle, session_index, state,
+           vppcom_session_state_str (state), rv, vppcom_retval_str (rv));
+      goto done;
     }
 
-  rx_fifo = ((!session->is_cut_thru || session->is_server) ?
-            session->server_rx_fifo : session->server_tx_fifo);
-  fifo_str = ((!session->is_cut_thru || session->is_server) ?
-             "server_rx_fifo" : "server_tx_fifo");
-  poll_et =
-    ((EPOLLET | EPOLLIN) & session->vep.ev.events) == (EPOLLET | EPOLLIN);
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  VCL_SESSION_UNLOCK ();
 
   do
     {
@@ -2620,24 +2588,57 @@ vppcom_session_read_internal (uint32_t session_index, void *buf, int n,
       else
        n_read = svm_fifo_dequeue_nowait (rx_fifo, n, buf);
     }
-  while (!session->is_nonblocking && (n_read <= 0));
+  while (!is_nonblocking && (n_read <= 0));
 
-  if (poll_et && (n_read <= 0))
+  if (n_read <= 0)
     {
-      clib_spinlock_lock (&vcm->sessions_lockp);
-      session->vep.et_mask |= EPOLLIN;
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-    }
+      VCL_SESSION_LOCK_AND_GET (session_index, &session);
+
+      poll_et = (((EPOLLET | EPOLLIN) & session->vep.ev.events) ==
+                (EPOLLET | EPOLLIN));
+      if (poll_et)
+       session->vep.et_mask |= EPOLLIN;
+
+      if (state & STATE_CLOSE_ON_EMPTY)
+       {
+         rv = VPPCOM_ECONNRESET;
+
+         VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: Empty fifo with "
+               "session state 0x%x (%s)! Setting state to 0x%x (%s), "
+               "returning %d (%s)",
+               getpid (), session->vpp_handle, session_index,
+               state, vppcom_session_state_str (state),
+               STATE_DISCONNECT,
+               vppcom_session_state_str (STATE_DISCONNECT), rv,
+               vppcom_retval_str (rv));
+
+         session->session_state = STATE_DISCONNECT;
+       }
+      else
+       rv = VPPCOM_EAGAIN;
 
-  if ((VPPCOM_DEBUG > 2) && (n_read > 0))
-    clib_warning ("[%d] sid %d, read %d bytes from %s (%p)", getpid (),
-                 session_index, n_read, fifo_str, rx_fifo);
+      VCL_SESSION_UNLOCK ();
+    }
+  else
+    rv = n_read;
 
-  return (n_read <= 0) ? VPPCOM_EAGAIN : n_read;
+  if (VPPCOM_DEBUG > 2)
+    {
+      if (rv > 0)
+       clib_warning ("VCL<%d>: vpp handle 0x%llx, sid %u: read %d bytes "
+                     "from (%p)", getpid (), vpp_handle,
+                     session_index, n_read, rx_fifo);
+      else
+       clib_warning ("VCL<%d>: vpp handle 0x%llx, sid %u: nothing read! "
+                     "returning %d (%s)", getpid (), vpp_handle,
+                     session_index, rv, vppcom_retval_str (rv));
+    }
+done:
+  return rv;
 }
 
 int
-vppcom_session_read (uint32_t session_index, void *buf, int n)
+vppcom_session_read (uint32_t session_index, void *buf, size_t n)
 {
   return (vppcom_session_read_internal (session_index, buf, n, 0));
 }
@@ -2649,202 +2650,287 @@ vppcom_session_peek (uint32_t session_index, void *buf, int n)
 }
 
 static inline int
-vppcom_session_read_ready (session_t * session, u32 session_index)
+vppcom_session_read_ready (vcl_session_t * session, u32 session_index)
 {
-  svm_fifo_t *rx_fifo = 0;
   int ready = 0;
   u32 poll_et;
+  int rv;
+  session_state_t state = session->session_state;
+  u64 vpp_handle = session->vpp_handle;
 
   /* Assumes caller has acquired spinlock: vcm->sessions_lockp */
-  if (session->is_vep)
+  if (PREDICT_FALSE (session->is_vep))
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) is an epoll session!",
-                     getpid (), session_index);
-      return VPPCOM_EBADFD;
+      clib_warning ("VCL<%d>: ERROR: sid %u: cannot read from an "
+                   "epoll session!", getpid (), session_index);
+      rv = VPPCOM_EBADFD;
+      goto done;
     }
 
-  if (session->state == STATE_DISCONNECT)
+  if (session->session_state & STATE_LISTEN)
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] sid (%u) has been closed by remote peer!",
-                     getpid (), session_index);
-      return VPPCOM_ECONNRESET;
+      VCL_ACCEPT_FIFO_LOCK ();
+      ready = clib_fifo_elts (vcm->client_session_index_fifo);
+      VCL_ACCEPT_FIFO_UNLOCK ();
     }
-
-  if (session->is_listen)
-    ready = clib_fifo_elts (vcm->client_session_index_fifo);
   else
     {
-      rx_fifo = ((!session->is_cut_thru || session->is_server) ?
-                session->server_rx_fifo : session->server_tx_fifo);
+      if (!(state & (SERVER_STATE_OPEN | CLIENT_STATE_OPEN | STATE_LISTEN)))
+       {
+         rv = ((state & STATE_DISCONNECT) ? VPPCOM_ECONNRESET :
+               VPPCOM_ENOTCONN);
+
+         VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: session is not open!"
+               " state 0x%x (%s), returning %d (%s)",
+               getpid (), vpp_handle, session_index,
+               state, vppcom_session_state_str (state),
+               rv, vppcom_retval_str (rv));
+         goto done;
+       }
 
-      ready = svm_fifo_max_dequeue (rx_fifo);
+      ready = svm_fifo_max_dequeue (session->rx_fifo);
     }
 
-  poll_et =
-    ((EPOLLET | EPOLLIN) & session->vep.ev.events) == (EPOLLET | EPOLLIN);
-  if (poll_et && (ready == 0))
+  if (ready == 0)
     {
-      if (VPPCOM_DEBUG > 11)
-       clib_warning ("[%d] sid %d: current vep.et_mask = 0x%x", getpid (),
-                     session_index, session->vep.et_mask);
-      session->vep.et_mask |= EPOLLIN;
-      if (VPPCOM_DEBUG > 11)
-       clib_warning ("[%d] sid %d: updated vep.et_mask = 0x%x", getpid (),
-                     session_index, session->vep.et_mask);
+      poll_et =
+       ((EPOLLET | EPOLLIN) & session->vep.ev.events) == (EPOLLET | EPOLLIN);
+      if (poll_et)
+       session->vep.et_mask |= EPOLLIN;
+
+      if (state & STATE_CLOSE_ON_EMPTY)
+       {
+         rv = VPPCOM_ECONNRESET;
+
+         VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: Empty fifo with "
+               "session state 0x%x (%s)! Setting state to 0x%x (%s), "
+               "returning %d (%s)",
+               getpid (), session_index, vpp_handle,
+               state, vppcom_session_state_str (state),
+               STATE_DISCONNECT,
+               vppcom_session_state_str (STATE_DISCONNECT), rv,
+               vppcom_retval_str (rv));
+         session->session_state = STATE_DISCONNECT;
+         goto done;
+       }
     }
+  rv = ready;
+
+  if (vcm->app_event_queue->cursize &&
+      !pthread_mutex_trylock (&vcm->app_event_queue->mutex))
+    {
+      u32 i, n_to_dequeue = vcm->app_event_queue->cursize;
+      session_fifo_event_t e;
+
+      for (i = 0; i < n_to_dequeue; i++)
+       svm_queue_sub_raw (vcm->app_event_queue, (u8 *) & e);
 
-  if (session->vep.et_mask && (VPPCOM_DEBUG > 11))
-    clib_warning ("[%d] sid %d, is_listen %u, peek %s (%p), ready = %d, "
-                 "et_mask 0x%x",
-                 getpid (), session_index, session->is_listen,
-                 session->is_server ? "server_rx_fifo" : "server_tx_fifo",
-                 rx_fifo, ready, session->vep.et_mask);
-  return ready;
+      pthread_mutex_unlock (&vcm->app_event_queue->mutex);
+    }
+done:
+  return rv;
 }
 
 int
-vppcom_session_write (uint32_t session_index, void *buf, int n)
+vppcom_session_write (uint32_t session_index, void *buf, size_t n)
 {
-  session_t *session = 0;
-  svm_fifo_t *tx_fifo;
-  unix_shared_memory_queue_t *q;
+  vcl_session_t *session = 0;
+  svm_fifo_t *tx_fifo = 0;
+  svm_queue_t *q;
   session_fifo_event_t evt;
-  int rv, n_write;
-  char *fifo_str;
+  session_state_t state;
+  int rv, n_write, is_nonblocking;
   u32 poll_et;
+  u64 vpp_handle;
 
   ASSERT (buf);
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
-  rv = vppcom_session_at_index (session_index, &session);
-  if (PREDICT_FALSE (rv))
-    {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                     getpid (), session_index);
-      return rv;
-    }
+  VCL_SESSION_LOCK_AND_GET (session_index, &session);
 
-  if (session->is_vep)
+  tx_fifo = session->tx_fifo;
+  is_nonblocking = VCL_SESS_ATTR_TEST (session->attr, VCL_SESS_ATTR_NONBLOCK);
+  vpp_handle = session->vpp_handle;
+  state = session->session_state;
+
+  if (PREDICT_FALSE (session->is_vep))
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) is an epoll session!",
-                     getpid (), session_index);
-      return VPPCOM_EBADFD;
+      VCL_SESSION_UNLOCK ();
+      clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx, sid %u: "
+                   "cannot write to an epoll session!",
+                   getpid (), vpp_handle, session_index);
+
+      rv = VPPCOM_EBADFD;
+      goto done;
     }
 
-  if (session->state == STATE_DISCONNECT)
+  if (!(session->session_state & (SERVER_STATE_OPEN | CLIENT_STATE_OPEN)))
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] sid (%u) has been closed by remote peer!",
-                     getpid (), session_index);
-      return VPPCOM_ECONNRESET;
+      rv =
+       ((session->session_state & STATE_DISCONNECT) ? VPPCOM_ECONNRESET :
+        VPPCOM_ENOTCONN);
+
+      VCL_SESSION_UNLOCK ();
+      VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: session is not open! "
+           "state 0x%x (%s)",
+           getpid (), vpp_handle, session_index,
+           state, vppcom_session_state_str (state));
+      goto done;
     }
 
-  tx_fifo = ((!session->is_cut_thru || session->is_server) ?
-            session->server_tx_fifo : session->server_rx_fifo);
-  fifo_str = ((!session->is_cut_thru || session->is_server) ?
-             "server_tx_fifo" : "server_rx_fifo");
-  q = session->vpp_event_queue;
-  poll_et = (((EPOLLET | EPOLLOUT) & session->vep.ev.events) ==
-            (EPOLLET | EPOLLOUT));
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  VCL_SESSION_UNLOCK ();
 
   do
     {
-      n_write = svm_fifo_enqueue_nowait (tx_fifo, n, buf);
+      n_write = svm_fifo_enqueue_nowait (tx_fifo, n, (void *) buf);
     }
-  while (!session->is_nonblocking && (n_write <= 0));
+  while (!is_nonblocking && (n_write <= 0));
 
-  /* If event wasn't set, add one */
-  if (!session->is_cut_thru && (n_write > 0) && svm_fifo_set_event (tx_fifo))
-    {
-      int rval;
+  /* If event wasn't set, add one
+   *
+   * To reduce context switching, can check if an
+   * event is already there for this event_key, but for now
+   * this will suffice. */
 
+  if ((n_write > 0) && svm_fifo_set_event (tx_fifo))
+    {
       /* Fabricate TX event, send to vpp */
       evt.fifo = tx_fifo;
       evt.event_type = FIFO_EVENT_APP_TX;
 
-      rval = vppcom_session_at_index (session_index, &session);
-      if (PREDICT_FALSE (rval))
-       {
-         if (VPPCOM_DEBUG > 1)
-           clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                         getpid (), session_index);
-         return rval;
-       }
+      VCL_SESSION_LOCK_AND_GET (session_index, &session);
+      q = session->vpp_evt_q;
       ASSERT (q);
-      unix_shared_memory_queue_add (q, (u8 *) & evt,
-                                   0 /* do wait for mutex */ );
+      svm_queue_add (q, (u8 *) & evt, 0 /* do wait for mutex */ );
+      VCL_SESSION_UNLOCK ();
+      VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: added FIFO_EVENT_APP_TX "
+           "to vpp_event_q %p, n_write %d", getpid (),
+           vpp_handle, session_index, q, n_write);
     }
 
-  if (poll_et && (n_write <= 0))
+  if (n_write <= 0)
     {
-      clib_spinlock_lock (&vcm->sessions_lockp);
-      session->vep.et_mask |= EPOLLOUT;
-      clib_spinlock_unlock (&vcm->sessions_lockp);
+      VCL_SESSION_LOCK_AND_GET (session_index, &session);
+
+      poll_et = (((EPOLLET | EPOLLOUT) & session->vep.ev.events) ==
+                (EPOLLET | EPOLLOUT));
+      if (poll_et)
+       session->vep.et_mask |= EPOLLOUT;
+
+      if (session->session_state & STATE_CLOSE_ON_EMPTY)
+       {
+         rv = VPPCOM_ECONNRESET;
+
+         VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: Empty fifo with "
+               "session state 0x%x (%s)! Setting state to 0x%x (%s), "
+               "returning %d (%s)",
+               getpid (), session->vpp_handle, session_index,
+               session->session_state,
+               vppcom_session_state_str (session->session_state),
+               STATE_DISCONNECT,
+               vppcom_session_state_str (STATE_DISCONNECT), rv,
+               vppcom_retval_str (rv));
+
+         session->session_state = STATE_DISCONNECT;
+       }
+      else
+       rv = VPPCOM_EAGAIN;
+
+      VCL_SESSION_UNLOCK ();
     }
+  else
+    rv = n_write;
 
   if (VPPCOM_DEBUG > 2)
     {
-      if (n_write == -2)
-       clib_warning ("[%d] sid %d, FIFO-FULL %s (%p)", getpid (),
-                     session_index, fifo_str, tx_fifo);
+      if (n_write <= 0)
+       clib_warning ("VCL<%d>: vpp handle 0x%llx, sid %u: "
+                     "FIFO-FULL (%p)", getpid (), vpp_handle,
+                     session_index, tx_fifo);
       else
-       clib_warning ("[%d] sid %d, wrote %d bytes to %s (%p)", getpid (),
-                     session_index, n_write, fifo_str, tx_fifo);
+       clib_warning ("VCL<%d>: vpp handle 0x%llx, sid %u: "
+                     "wrote %d bytes tx-fifo: (%p)", getpid (),
+                     vpp_handle, session_index, n_write, tx_fifo);
     }
-  return (n_write < 0) ? VPPCOM_EAGAIN : n_write;
+done:
+  return rv;
 }
 
 static inline int
-vppcom_session_write_ready (session_t * session, u32 session_index)
+vppcom_session_write_ready (vcl_session_t * session, u32 session_index)
 {
-  svm_fifo_t *tx_fifo;
-  char *fifo_str;
   int ready;
   u32 poll_et;
+  int rv;
+
+  ASSERT (session);
 
   /* Assumes caller has acquired spinlock: vcm->sessions_lockp */
-  if (session->is_vep)
+  if (PREDICT_FALSE (session->is_vep))
     {
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] invalid session, sid (%u) is an epoll session!",
-                     getpid (), session_index);
-      return VPPCOM_EBADFD;
+      clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx, sid %u: "
+                   "cannot write to an epoll session!",
+                   getpid (), session->vpp_handle, session_index);
+      rv = VPPCOM_EBADFD;
+      goto done;
     }
 
-  if (session->state == STATE_DISCONNECT)
+  if (PREDICT_FALSE (session->session_state & STATE_LISTEN))
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] sid (%u) has been closed by remote peer!",
-                     getpid (), session_index);
-      return VPPCOM_ECONNRESET;
+      clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx, sid %u: "
+                   "cannot write to a listen session!",
+                   getpid (), session->vpp_handle, session_index);
+      rv = VPPCOM_EBADFD;
+      goto done;
     }
 
-  tx_fifo = ((!session->is_cut_thru || session->is_server) ?
-            session->server_tx_fifo : session->server_rx_fifo);
-  fifo_str = ((!session->is_cut_thru || session->is_server) ?
-             "server_tx_fifo" : "server_rx_fifo");
+  if (!(session->session_state & (SERVER_STATE_OPEN | CLIENT_STATE_OPEN)))
+    {
+      session_state_t state = session->session_state;
 
-  ready = svm_fifo_max_enqueue (tx_fifo);
+      rv = ((state & STATE_DISCONNECT) ? VPPCOM_ECONNRESET : VPPCOM_ENOTCONN);
 
-  if (VPPCOM_DEBUG > 3)
-    clib_warning ("[%d] sid %d, peek %s (%p), ready = %d", getpid (),
-                 session_index, fifo_str, tx_fifo, ready);
-  poll_et = (((EPOLLET | EPOLLOUT) & session->vep.ev.events) ==
-            (EPOLLET | EPOLLOUT));
-  if (poll_et && (ready == 0))
-    session->vep.et_mask |= EPOLLOUT;
+      clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx, sid %u: "
+                   "session is not open! state 0x%x (%s), "
+                   "returning %d (%s)", getpid (), session->vpp_handle,
+                   session_index,
+                   state, vppcom_session_state_str (state),
+                   rv, vppcom_retval_str (rv));
+      goto done;
+    }
+
+  ready = svm_fifo_max_enqueue (session->tx_fifo);
+
+  VDBG (3, "VCL<%d>: vpp handle 0x%llx, sid %u: peek %s (%p), ready = %d",
+       getpid (), session->vpp_handle, session_index, session->tx_fifo,
+       ready);
 
-  return ready;
+  if (ready == 0)
+    {
+      poll_et = (((EPOLLET | EPOLLOUT) & session->vep.ev.events) ==
+                (EPOLLET | EPOLLOUT));
+      if (poll_et)
+       session->vep.et_mask |= EPOLLOUT;
+
+      if (session->session_state & STATE_CLOSE_ON_EMPTY)
+       {
+         rv = VPPCOM_ECONNRESET;
+
+         VDBG (1, "VCL<%d>: vpp handle 0x%llx, sid %u: Empty fifo with "
+               "session state 0x%x (%s)! Setting state to 0x%x (%s), "
+               "returning %d (%s)", getpid (),
+               session->vpp_handle, session_index,
+               session->session_state,
+               vppcom_session_state_str (session->session_state),
+               STATE_DISCONNECT,
+               vppcom_session_state_str (STATE_DISCONNECT), rv,
+               vppcom_retval_str (rv));
+         session->session_state = STATE_DISCONNECT;
+         goto done;
+       }
+    }
+  rv = ready;
+done:
+  return rv;
 }
 
 int
@@ -2853,7 +2939,7 @@ vppcom_select (unsigned long n_bits, unsigned long *read_map,
               double time_to_wait)
 {
   u32 session_index;
-  session_t *session = 0;
+  vcl_session_t *session = 0;
   int rv, bits_set = 0;
   f64 timeout = clib_time_now (&vcm->clib_time) + time_to_wait;
   u32 minbits = clib_max (n_bits, BITS (uword));
@@ -2863,20 +2949,25 @@ vppcom_select (unsigned long n_bits, unsigned long *read_map,
   if (n_bits && read_map)
     {
       clib_bitmap_validate (vcm->rd_bitmap, minbits);
-      clib_memcpy (vcm->rd_bitmap, read_map, vec_len (vcm->rd_bitmap));
-      memset (read_map, 0, vec_len (vcm->rd_bitmap));
+      clib_memcpy (vcm->rd_bitmap, read_map,
+                  vec_len (vcm->rd_bitmap) * sizeof (clib_bitmap_t));
+      memset (read_map, 0, vec_len (vcm->rd_bitmap) * sizeof (clib_bitmap_t));
     }
   if (n_bits && write_map)
     {
       clib_bitmap_validate (vcm->wr_bitmap, minbits);
-      clib_memcpy (vcm->wr_bitmap, write_map, vec_len (vcm->wr_bitmap));
-      memset (write_map, 0, vec_len (vcm->wr_bitmap));
+      clib_memcpy (vcm->wr_bitmap, write_map,
+                  vec_len (vcm->wr_bitmap) * sizeof (clib_bitmap_t));
+      memset (write_map, 0,
+             vec_len (vcm->wr_bitmap) * sizeof (clib_bitmap_t));
     }
   if (n_bits && except_map)
     {
       clib_bitmap_validate (vcm->ex_bitmap, minbits);
-      clib_memcpy (vcm->ex_bitmap, except_map, vec_len (vcm->ex_bitmap));
-      memset (except_map, 0, vec_len (vcm->ex_bitmap));
+      clib_memcpy (vcm->ex_bitmap, except_map,
+                  vec_len (vcm->ex_bitmap) * sizeof (clib_bitmap_t));
+      memset (except_map, 0,
+             vec_len (vcm->ex_bitmap) * sizeof (clib_bitmap_t));
     }
 
   do
@@ -2888,32 +2979,52 @@ vppcom_select (unsigned long n_bits, unsigned long *read_map,
             {
               clib_bitmap_foreach (session_index, vcm->rd_bitmap,
                 ({
-                  clib_spinlock_lock (&vcm->sessions_lockp);
+                  VCL_SESSION_LOCK();
                   rv = vppcom_session_at_index (session_index, &session);
                   if (rv < 0)
                     {
-                      clib_spinlock_unlock (&vcm->sessions_lockp);
-                      if (VPPCOM_DEBUG > 1)
-                        clib_warning ("[%d] session %d specified in "
-                                      "read_map is closed.", getpid (),
+                      VCL_SESSION_UNLOCK();
+                      VDBG (1, "VCL<%d>: session %d specified in read_map is"
+                         " closed.", getpid (),
                                       session_index);
                       bits_set = VPPCOM_EBADFD;
                       goto select_done;
                     }
-
-                  rv = vppcom_session_read_ready (session, session_index);
-                  clib_spinlock_unlock (&vcm->sessions_lockp);
+                  if (session->session_state & STATE_LISTEN)
+                    {
+                      vce_event_handler_reg_t *reg = 0;
+                      vce_event_key_t evk;
+
+                      /* Check if handler already registered for this
+                       * event.
+                       * If not, register handler for connect_request event
+                       * on listen_session_index
+                       */
+                      evk.session_index = session_index;
+                      evk.eid = VCL_EVENT_CONNECT_REQ_ACCEPTED;
+                      reg = vce_get_event_handler (&vcm->event_thread, &evk);
+                      if (!reg)
+                        reg = vce_register_handler (&vcm->event_thread, &evk,
+                                    vce_poll_wait_connect_request_handler_fn,
+                                                   0 /* No callback args */);
+                      rv = vppcom_session_read_ready (session, session_index);
+                      if (rv > 0)
+                        {
+                          vce_unregister_handler (&vcm->event_thread, reg);
+                        }
+                    }
+                  else
+                    rv = vppcom_session_read_ready (session, session_index);
+                  VCL_SESSION_UNLOCK();
                   if (except_map && vcm->ex_bitmap &&
                       clib_bitmap_get (vcm->ex_bitmap, session_index) &&
                       (rv < 0))
                     {
-                      // TBD: clib_warning
                       clib_bitmap_set_no_check (except_map, session_index, 1);
                       bits_set++;
                     }
                   else if (rv > 0)
                     {
-                      // TBD: clib_warning
                       clib_bitmap_set_no_check (read_map, session_index, 1);
                       bits_set++;
                     }
@@ -2924,13 +3035,12 @@ vppcom_select (unsigned long n_bits, unsigned long *read_map,
             {
               clib_bitmap_foreach (session_index, vcm->wr_bitmap,
                 ({
-                  clib_spinlock_lock (&vcm->sessions_lockp);
+                  VCL_SESSION_LOCK();
                   rv = vppcom_session_at_index (session_index, &session);
                   if (rv < 0)
                     {
-                      clib_spinlock_unlock (&vcm->sessions_lockp);
-                      if (VPPCOM_DEBUG > 0)
-                        clib_warning ("[%d] session %d specified in "
+                      VCL_SESSION_UNLOCK();
+                      VDBG (0, "VCL<%d>: session %d specified in "
                                       "write_map is closed.", getpid (),
                                       session_index);
                       bits_set = VPPCOM_EBADFD;
@@ -2938,10 +3048,9 @@ vppcom_select (unsigned long n_bits, unsigned long *read_map,
                     }
 
                   rv = vppcom_session_write_ready (session, session_index);
-                  clib_spinlock_unlock (&vcm->sessions_lockp);
+                  VCL_SESSION_UNLOCK();
                   if (write_map && (rv > 0))
                     {
-                      // TBD: clib_warning
                       clib_bitmap_set_no_check (write_map, session_index, 1);
                       bits_set++;
                     }
@@ -2952,24 +3061,22 @@ vppcom_select (unsigned long n_bits, unsigned long *read_map,
             {
               clib_bitmap_foreach (session_index, vcm->ex_bitmap,
                 ({
-                  clib_spinlock_lock (&vcm->sessions_lockp);
+                  VCL_SESSION_LOCK();
                   rv = vppcom_session_at_index (session_index, &session);
                   if (rv < 0)
                     {
-                      clib_spinlock_unlock (&vcm->sessions_lockp);
-                      if (VPPCOM_DEBUG > 1)
-                        clib_warning ("[%d] session %d specified in "
-                                      "except_map is closed.", getpid (),
+                      VCL_SESSION_UNLOCK();
+                      VDBG (1, "VCL<%d>: session %d specified in except_map "
+                         "is closed.", getpid (),
                                       session_index);
                       bits_set = VPPCOM_EBADFD;
                       goto select_done;
                     }
 
                   rv = vppcom_session_read_ready (session, session_index);
-                  clib_spinlock_unlock (&vcm->sessions_lockp);
+                  VCL_SESSION_UNLOCK();
                   if (rv < 0)
                     {
-                      // TBD: clib_warning
                       clib_bitmap_set_no_check (except_map, session_index, 1);
                       bits_set++;
                     }
@@ -2978,7 +3085,7 @@ vppcom_select (unsigned long n_bits, unsigned long *read_map,
         }
       /* *INDENT-ON* */
     }
-  while (clib_time_now (&vcm->clib_time) < timeout);
+  while ((time_to_wait == -1) || (clib_time_now (&vcm->clib_time) < timeout));
 
 select_done:
   return (bits_set);
@@ -2987,7 +3094,7 @@ select_done:
 static inline void
 vep_verify_epoll_chain (u32 vep_idx)
 {
-  session_t *session;
+  vcl_session_t *session;
   vppcom_epoll_t *vep;
   int rv;
   u32 sid = vep_idx;
@@ -2999,80 +3106,81 @@ vep_verify_epoll_chain (u32 vep_idx)
   rv = vppcom_session_at_index (vep_idx, &session);
   if (PREDICT_FALSE (rv))
     {
-      clib_warning ("[%d] ERROR: Invalid vep_idx (%u)!", getpid (), vep_idx);
+      clib_warning ("VCL<%d>: ERROR: Invalid vep_idx (%u)!",
+                   getpid (), vep_idx);
       goto done;
     }
   if (PREDICT_FALSE (!session->is_vep))
     {
-      clib_warning ("[%d] ERROR: vep_idx (%u) is not a vep!", getpid (),
-                   vep_idx);
+      clib_warning ("VCL<%d>: ERROR: vep_idx (%u) is not a vep!",
+                   getpid (), vep_idx);
       goto done;
     }
-  clib_warning ("[%d] vep_idx (%u): Dumping epoll chain\n"
+  vep = &session->vep;
+  clib_warning ("VCL<%d>: vep_idx (%u): Dumping epoll chain\n"
                "{\n"
                "   is_vep         = %u\n"
                "   is_vep_session = %u\n"
+               "   next_sid       = 0x%x (%u)\n"
                "   wait_cont_idx  = 0x%x (%u)\n"
-               "}\n", getpid (),
-               vep_idx, session->is_vep, session->is_vep_session,
+               "}\n", getpid (), vep_idx,
+               session->is_vep, session->is_vep_session,
+               vep->next_sid, vep->next_sid,
                session->wait_cont_idx, session->wait_cont_idx);
-  do
+
+  for (sid = vep->next_sid; sid != ~0; sid = vep->next_sid)
     {
+      rv = vppcom_session_at_index (sid, &session);
+      if (PREDICT_FALSE (rv))
+       {
+         clib_warning ("VCL<%d>: ERROR: Invalid sid (%u)!", getpid (), sid);
+         goto done;
+       }
+      if (PREDICT_FALSE (session->is_vep))
+       clib_warning ("VCL<%d>: ERROR: sid (%u) is a vep!",
+                     getpid (), vep_idx);
+      else if (PREDICT_FALSE (!session->is_vep_session))
+       {
+         clib_warning ("VCL<%d>: ERROR: session (%u) "
+                       "is not a vep session!", getpid (), sid);
+         goto done;
+       }
       vep = &session->vep;
-      sid = vep->next_sid;
-      if (sid != ~0)
+      if (PREDICT_FALSE (vep->vep_idx != vep_idx))
+       clib_warning ("VCL<%d>: ERROR: session (%u) vep_idx (%u) != "
+                     "vep_idx (%u)!", getpid (),
+                     sid, session->vep.vep_idx, vep_idx);
+      if (session->is_vep_session)
        {
-         rv = vppcom_session_at_index (sid, &session);
-         if (PREDICT_FALSE (rv))
-           {
-             clib_warning ("[%d] ERROR: Invalid sid (%u)!", getpid (), sid);
-             goto done;
-           }
-         if (PREDICT_FALSE (session->is_vep))
-           clib_warning ("[%d] ERROR: sid (%u) is a vep!",
-                         getpid (), vep_idx);
-         else if (PREDICT_FALSE (!session->is_vep_session))
-           {
-             clib_warning ("[%d] ERROR: session (%u) is not a vep session!",
-                           getpid (), sid);
-             goto done;
-           }
-         if (PREDICT_FALSE (session->vep.vep_idx != vep_idx))
-           clib_warning ("[%d] ERROR: session (%u) vep_idx (%u) != "
-                         "vep_idx (%u)!", getpid (),
-                         sid, session->vep.vep_idx, vep_idx);
-         if (session->is_vep_session)
-           {
-             clib_warning ("vep_idx[%u]: sid 0x%x (%u)\n"
-                           "{\n"
-                           "   next_sid       = 0x%x (%u)\n"
-                           "   prev_sid       = 0x%x (%u)\n"
-                           "   vep_idx        = 0x%x (%u)\n"
-                           "   ev.events      = 0x%x\n"
-                           "   ev.data.u64    = 0x%llx\n"
-                           "   et_mask        = 0x%x\n"
-                           "}\n",
-                           vep_idx, sid, sid,
-                           vep->next_sid, vep->next_sid,
-                           vep->prev_sid, vep->prev_sid,
-                           vep->vep_idx, vep->vep_idx,
-                           vep->ev.events, vep->ev.data.u64, vep->et_mask);
-           }
+         clib_warning ("vep_idx[%u]: sid 0x%x (%u)\n"
+                       "{\n"
+                       "   next_sid       = 0x%x (%u)\n"
+                       "   prev_sid       = 0x%x (%u)\n"
+                       "   vep_idx        = 0x%x (%u)\n"
+                       "   ev.events      = 0x%x\n"
+                       "   ev.data.u64    = 0x%llx\n"
+                       "   et_mask        = 0x%x\n"
+                       "}\n",
+                       vep_idx, sid, sid,
+                       vep->next_sid, vep->next_sid,
+                       vep->prev_sid, vep->prev_sid,
+                       vep->vep_idx, vep->vep_idx,
+                       vep->ev.events, vep->ev.data.u64, vep->et_mask);
        }
     }
-  while (sid != ~0);
 
 done:
-  clib_warning ("[%d] vep_idx (%u): Dump complete!\n", getpid (), vep_idx);
+  clib_warning ("VCL<%d>: vep_idx (%u): Dump complete!\n",
+               getpid (), vep_idx);
 }
 
 int
 vppcom_epoll_create (void)
 {
-  session_t *vep_session;
+  vcl_session_t *vep_session;
   u32 vep_idx;
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
+  VCL_SESSION_LOCK ();
   pool_get (vcm->sessions, vep_session);
   memset (vep_session, 0, sizeof (*vep_session));
   vep_idx = vep_session - vcm->sessions;
@@ -3082,10 +3190,14 @@ vppcom_epoll_create (void)
   vep_session->vep.next_sid = ~0;
   vep_session->vep.prev_sid = ~0;
   vep_session->wait_cont_idx = ~0;
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  vep_session->vpp_handle = ~0;
+  vep_session->poll_reg = 0;
 
-  if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] Created vep_idx %u!", getpid (), vep_idx);
+  vcl_evt (VCL_EVT_EPOLL_CREATE, vep_session, vep_idx);
+  VCL_SESSION_UNLOCK ();
+
+  VDBG (0, "VCL<%d>: Created vep_idx %u / sid %u!",
+       getpid (), vep_idx, vep_idx);
 
   return (vep_idx);
 }
@@ -3094,31 +3206,28 @@ int
 vppcom_epoll_ctl (uint32_t vep_idx, int op, uint32_t session_index,
                  struct epoll_event *event)
 {
-  session_t *vep_session;
-  session_t *session;
+  vcl_session_t *vep_session;
+  vcl_session_t *session;
   int rv;
 
   if (vep_idx == session_index)
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] ERROR: vep_idx == session_index (%u)!",
-                     getpid (), vep_idx);
+      clib_warning ("VCL<%d>: ERROR: vep_idx == session_index (%u)!",
+                   getpid (), vep_idx);
       return VPPCOM_EINVAL;
     }
 
-  clib_spinlock_lock (&vcm->sessions_lockp);
+  VCL_SESSION_LOCK ();
   rv = vppcom_session_at_index (vep_idx, &vep_session);
   if (PREDICT_FALSE (rv))
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] ERROR: Invalid vep_idx (%u)!", vep_idx);
+      clib_warning ("VCL<%d>: ERROR: Invalid vep_idx (%u)!", vep_idx);
       goto done;
     }
   if (PREDICT_FALSE (!vep_session->is_vep))
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] ERROR: vep_idx (%u) is not a vep!",
-                     getpid (), vep_idx);
+      clib_warning ("VCL<%d>: ERROR: vep_idx (%u) is not a vep!",
+                   getpid (), vep_idx);
       rv = VPPCOM_EINVAL;
       goto done;
     }
@@ -3129,15 +3238,13 @@ vppcom_epoll_ctl (uint32_t vep_idx, int op, uint32_t session_index,
   rv = vppcom_session_at_index (session_index, &session);
   if (PREDICT_FALSE (rv))
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] ERROR: Invalid session_index (%u)!",
-                     getpid (), session_index);
+      VDBG (0, "VCL<%d>: ERROR: Invalid session_index (%u)!",
+           getpid (), session_index);
       goto done;
     }
   if (PREDICT_FALSE (session->is_vep))
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("ERROR: session_index (%u) is a vep!", vep_idx);
+      clib_warning ("ERROR: session_index (%u) is a vep!", vep_idx);
       rv = VPPCOM_EINVAL;
       goto done;
     }
@@ -3147,22 +3254,21 @@ vppcom_epoll_ctl (uint32_t vep_idx, int op, uint32_t session_index,
     case EPOLL_CTL_ADD:
       if (PREDICT_FALSE (!event))
        {
-         clib_warning ("[%d] ERROR: EPOLL_CTL_ADD: NULL pointer to "
+         clib_warning ("VCL<%d>: ERROR: EPOLL_CTL_ADD: NULL pointer to "
                        "epoll_event structure!", getpid ());
          rv = VPPCOM_EINVAL;
          goto done;
        }
       if (vep_session->vep.next_sid != ~0)
        {
-         session_t *next_session;
+         vcl_session_t *next_session;
          rv = vppcom_session_at_index (vep_session->vep.next_sid,
                                        &next_session);
          if (PREDICT_FALSE (rv))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] ERROR: EPOLL_CTL_ADD: Invalid "
-                             "vep.next_sid (%u) on vep_idx (%u)!",
-                             getpid (), vep_session->vep.next_sid, vep_idx);
+             clib_warning ("VCL<%d>: ERROR: EPOLL_CTL_ADD: Invalid "
+                           "vep.next_sid (%u) on vep_idx (%u)!",
+                           getpid (), vep_session->vep.next_sid, vep_idx);
              goto done;
            }
          ASSERT (next_session->vep.prev_sid == vep_idx);
@@ -3173,68 +3279,85 @@ vppcom_epoll_ctl (uint32_t vep_idx, int op, uint32_t session_index,
       session->vep.vep_idx = vep_idx;
       session->vep.et_mask = VEP_DEFAULT_ET_MASK;
       session->vep.ev = *event;
+      session->is_vep = 0;
       session->is_vep_session = 1;
       vep_session->vep.next_sid = session_index;
-      if (VPPCOM_DEBUG > 1)
-       clib_warning ("[%d] EPOLL_CTL_ADD: vep_idx %u, sid %u, events 0x%x,"
-                     " data 0x%llx!", getpid (), vep_idx, session_index,
-                     event->events, event->data.u64);
+
+      /* VCL Event Register handler */
+      if (session->session_state & STATE_LISTEN)
+       {
+         /* Register handler for connect_request event on listen_session_index */
+         vce_event_key_t evk;
+         evk.session_index = session_index;
+         evk.eid = VCL_EVENT_CONNECT_REQ_ACCEPTED;
+         vep_session->poll_reg =
+           vce_register_handler (&vcm->event_thread, &evk,
+                                 vce_poll_wait_connect_request_handler_fn,
+                                 0 /* No callback args */ );
+       }
+      VDBG (1, "VCL<%d>: EPOLL_CTL_ADD: vep_idx %u, "
+           "sid %u, events 0x%x, data 0x%llx!",
+           getpid (), vep_idx, session_index,
+           event->events, event->data.u64);
+      vcl_evt (VCL_EVT_EPOLL_CTLADD, session, event->events, event->data.u64);
       break;
 
     case EPOLL_CTL_MOD:
       if (PREDICT_FALSE (!event))
        {
-         clib_warning ("[%d] ERROR: EPOLL_CTL_MOD: NULL pointer to "
+         clib_warning ("VCL<%d>: ERROR: EPOLL_CTL_MOD: NULL pointer to "
                        "epoll_event structure!", getpid ());
          rv = VPPCOM_EINVAL;
          goto done;
        }
-      if (PREDICT_FALSE (!session->is_vep_session &&
-                        (session->vep.vep_idx != vep_idx)))
+      else if (PREDICT_FALSE (!session->is_vep_session))
        {
-         if (VPPCOM_DEBUG > 0)
-           {
-             if (!session->is_vep_session)
-               clib_warning ("[%d] ERROR: EPOLL_CTL_MOD: session (%u) "
-                             "is not a vep session!",
-                             getpid (), session_index);
-             else
-               clib_warning ("[%d] ERROR: EPOLL_CTL_MOD: session (%u) "
-                             "vep_idx (%u) != vep_idx (%u)!",
-                             getpid (), session_index,
-                             session->vep.vep_idx, vep_idx);
-           }
+         clib_warning ("VCL<%d>: ERROR: sid %u EPOLL_CTL_MOD: "
+                       "not a vep session!", getpid (), session_index);
+         rv = VPPCOM_EINVAL;
+         goto done;
+       }
+      else if (PREDICT_FALSE (session->vep.vep_idx != vep_idx))
+       {
+         clib_warning ("VCL<%d>: ERROR: sid %u EPOLL_CTL_MOD: "
+                       "vep_idx (%u) != vep_idx (%u)!",
+                       getpid (), session_index,
+                       session->vep.vep_idx, vep_idx);
          rv = VPPCOM_EINVAL;
          goto done;
        }
       session->vep.et_mask = VEP_DEFAULT_ET_MASK;
       session->vep.ev = *event;
-      if (VPPCOM_DEBUG > 1)
-       clib_warning ("[%d] EPOLL_CTL_MOD: vep_idx %u, sid %u, events 0x%x,"
-                     " data 0x%llx!", getpid (), vep_idx, session_index,
-                     event->events, event->data.u64);
+      VDBG (1, "VCL<%d>: EPOLL_CTL_MOD: vep_idx %u, sid %u, events 0x%x,"
+           " data 0x%llx!", getpid (), vep_idx, session_index, event->events,
+           event->data.u64);
       break;
 
     case EPOLL_CTL_DEL:
-      if (PREDICT_FALSE (!session->is_vep_session &&
-                        (session->vep.vep_idx != vep_idx)))
+      if (PREDICT_FALSE (!session->is_vep_session))
        {
-         if (VPPCOM_DEBUG > 0)
-           {
-             if (!session->is_vep_session)
-               clib_warning ("[%d] ERROR: EPOLL_CTL_DEL: session (%u) "
-                             "is not a vep session!",
-                             getpid (), session_index);
-             else
-               clib_warning ("[%d] ERROR: EPOLL_CTL_DEL: session (%u) "
-                             "vep_idx (%u) != vep_idx (%u)!",
-                             getpid (), session_index,
-                             session->vep.vep_idx, vep_idx);
-           }
+         clib_warning ("VCL<%d>: ERROR: sid %u EPOLL_CTL_DEL: "
+                       "not a vep session!", getpid (), session_index);
+         rv = VPPCOM_EINVAL;
+         goto done;
+       }
+      else if (PREDICT_FALSE (session->vep.vep_idx != vep_idx))
+       {
+         clib_warning ("VCL<%d>: ERROR: sid %u EPOLL_CTL_DEL: "
+                       "vep_idx (%u) != vep_idx (%u)!",
+                       getpid (), session_index,
+                       session->vep.vep_idx, vep_idx);
          rv = VPPCOM_EINVAL;
          goto done;
        }
 
+      /* VCL Event Un-register handler */
+      if ((session->session_state & STATE_LISTEN) && vep_session->poll_reg)
+       {
+         (void) vce_unregister_handler (&vcm->event_thread,
+                                        vep_session->poll_reg);
+       }
+
       vep_session->wait_cont_idx =
        (vep_session->wait_cont_idx == session_index) ?
        session->vep.next_sid : vep_session->wait_cont_idx;
@@ -3243,15 +3366,13 @@ vppcom_epoll_ctl (uint32_t vep_idx, int op, uint32_t session_index,
        vep_session->vep.next_sid = session->vep.next_sid;
       else
        {
-         session_t *prev_session;
+         vcl_session_t *prev_session;
          rv = vppcom_session_at_index (session->vep.prev_sid, &prev_session);
          if (PREDICT_FALSE (rv))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] ERROR: EPOLL_CTL_DEL: Invalid "
-                             "vep.prev_sid (%u) on sid (%u)!",
-                             getpid (), session->vep.prev_sid,
-                             session_index);
+             clib_warning ("VCL<%d>: ERROR: EPOLL_CTL_DEL: Invalid "
+                           "vep.prev_sid (%u) on sid (%u)!",
+                           getpid (), session->vep.prev_sid, session_index);
              goto done;
            }
          ASSERT (prev_session->vep.next_sid == session_index);
@@ -3259,15 +3380,13 @@ vppcom_epoll_ctl (uint32_t vep_idx, int op, uint32_t session_index,
        }
       if (session->vep.next_sid != ~0)
        {
-         session_t *next_session;
+         vcl_session_t *next_session;
          rv = vppcom_session_at_index (session->vep.next_sid, &next_session);
          if (PREDICT_FALSE (rv))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] ERROR: EPOLL_CTL_DEL: Invalid "
-                             "vep.next_sid (%u) on sid (%u)!",
-                             getpid (), session->vep.next_sid,
-                             session_index);
+             clib_warning ("VCL<%d>: ERROR: EPOLL_CTL_DEL: Invalid "
+                           "vep.next_sid (%u) on sid (%u)!",
+                           getpid (), session->vep.next_sid, session_index);
              goto done;
            }
          ASSERT (next_session->vep.prev_sid == session_index);
@@ -3279,20 +3398,20 @@ vppcom_epoll_ctl (uint32_t vep_idx, int op, uint32_t session_index,
       session->vep.prev_sid = ~0;
       session->vep.vep_idx = ~0;
       session->is_vep_session = 0;
-      if (VPPCOM_DEBUG > 1)
-       clib_warning ("[%d] EPOLL_CTL_DEL: vep_idx %u, sid %u!",
-                     getpid (), vep_idx, session_index);
+      VDBG (1, "VCL<%d>: EPOLL_CTL_DEL: vep_idx %u, sid %u!",
+           getpid (), vep_idx, session_index);
+      vcl_evt (VCL_EVT_EPOLL_CTLDEL, session, vep_idx);
       break;
 
     default:
-      clib_warning ("[%d] ERROR: Invalid operation (%d)!", getpid (), op);
+      clib_warning ("VCL<%d>: ERROR: Invalid operation (%d)!", getpid (), op);
       rv = VPPCOM_EINVAL;
     }
 
   vep_verify_epoll_chain (vep_idx);
 
 done:
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  VCL_SESSION_UNLOCK ();
   return rv;
 }
 
@@ -3300,7 +3419,7 @@ int
 vppcom_epoll_wait (uint32_t vep_idx, struct epoll_event *events,
                   int maxevents, double wait_for_time)
 {
-  session_t *vep_session;
+  vcl_session_t *vep_session;
   int rv;
   f64 timeout = clib_time_now (&vcm->clib_time) + wait_for_time;
   u32 keep_trying = 1;
@@ -3310,32 +3429,29 @@ vppcom_epoll_wait (uint32_t vep_idx, struct epoll_event *events,
 
   if (PREDICT_FALSE (maxevents <= 0))
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] ERROR: Invalid maxevents (%d)!",
-                     getpid (), maxevents);
+      clib_warning ("VCL<%d>: ERROR: Invalid maxevents (%d)!",
+                   getpid (), maxevents);
       return VPPCOM_EINVAL;
     }
   memset (events, 0, sizeof (*events) * maxevents);
 
-  VCL_LOCK_AND_GET_SESSION (vep_idx, &vep_session);
+  VCL_SESSION_LOCK_AND_GET (vep_idx, &vep_session);
   vep_next_sid = vep_session->vep.next_sid;
   is_vep = vep_session->is_vep;
   wait_cont_idx = vep_session->wait_cont_idx;
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  VCL_SESSION_UNLOCK ();
 
   if (PREDICT_FALSE (!is_vep))
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] ERROR: vep_idx (%u) is not a vep!",
-                     getpid (), vep_idx);
+      clib_warning ("VCL<%d>: ERROR: vep_idx (%u) is not a vep!",
+                   getpid (), vep_idx);
       rv = VPPCOM_EINVAL;
       goto done;
     }
   if (PREDICT_FALSE (vep_next_sid == ~0))
     {
-      if (VPPCOM_DEBUG > 0)
-       clib_warning ("[%d] WARNING: vep_idx (%u) is empty!",
-                     getpid (), vep_idx);
+      VDBG (1, "VCL<%d>: WARNING: vep_idx (%u) is empty!",
+           getpid (), vep_idx);
       goto done;
     }
 
@@ -3343,7 +3459,7 @@ vppcom_epoll_wait (uint32_t vep_idx, struct epoll_event *events,
     {
       u32 sid;
       u32 next_sid = ~0;
-      session_t *session;
+      vcl_session_t *session;
 
       for (sid = (wait_cont_idx == ~0) ? vep_next_sid : wait_cont_idx;
           sid != ~0; sid = next_sid)
@@ -3353,7 +3469,7 @@ vppcom_epoll_wait (uint32_t vep_idx, struct epoll_event *events,
          int ready;
          u64 session_ev_data;
 
-         VCL_LOCK_AND_GET_SESSION (sid, &session);
+         VCL_SESSION_LOCK_AND_GET (sid, &session);
          next_sid = session->vep.next_sid;
          session_events = session->vep.ev.events;
          et_mask = session->vep.et_mask;
@@ -3361,29 +3477,28 @@ vppcom_epoll_wait (uint32_t vep_idx, struct epoll_event *events,
          is_vep_session = session->is_vep_session;
          session_vep_idx = session->vep.vep_idx;
          session_ev_data = session->vep.ev.data.u64;
-         clib_spinlock_unlock (&vcm->sessions_lockp);
+
+         VCL_SESSION_UNLOCK ();
 
          if (PREDICT_FALSE (is_vep))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] ERROR: sid (%u) is a vep!",
-                             getpid (), vep_idx);
+             VDBG (0, "VCL<%d>: ERROR: sid (%u) is a vep!",
+                   getpid (), vep_idx);
              rv = VPPCOM_EINVAL;
              goto done;
            }
          if (PREDICT_FALSE (!is_vep_session))
            {
-             if (VPPCOM_DEBUG > 0)
-               clib_warning ("[%d] ERROR: session (%u) is not "
-                             "a vep session!", getpid (), sid);
+             VDBG (0, "VCL<%d>: ERROR: session (%u) is not "
+                   "a vep session!", getpid (), sid);
              rv = VPPCOM_EINVAL;
              goto done;
            }
          if (PREDICT_FALSE (session_vep_idx != vep_idx))
            {
-             clib_warning ("[%d] ERROR: session (%u) "
+             clib_warning ("VCL<%d>: ERROR: session (%u) "
                            "vep_idx (%u) != vep_idx (%u)!",
-                           getpid (), sid, session->vep.vep_idx, vep_idx);
+                           getpid (), sid, session_vep_idx, vep_idx);
              rv = VPPCOM_EINVAL;
              goto done;
            }
@@ -3392,9 +3507,9 @@ vppcom_epoll_wait (uint32_t vep_idx, struct epoll_event *events,
 
          if (EPOLLIN & session_events)
            {
-             VCL_LOCK_AND_GET_SESSION (sid, &session);
+             VCL_SESSION_LOCK_AND_GET (sid, &session);
              ready = vppcom_session_read_ready (session, sid);
-             clib_spinlock_unlock (&vcm->sessions_lockp);
+             VCL_SESSION_UNLOCK ();
              if ((ready > 0) && (EPOLLIN & et_mask))
                {
                  add_event = 1;
@@ -3421,9 +3536,9 @@ vppcom_epoll_wait (uint32_t vep_idx, struct epoll_event *events,
 
          if (EPOLLOUT & session_events)
            {
-             VCL_LOCK_AND_GET_SESSION (sid, &session);
+             VCL_SESSION_LOCK_AND_GET (sid, &session);
              ready = vppcom_session_write_ready (session, sid);
-             clib_spinlock_unlock (&vcm->sessions_lockp);
+             VCL_SESSION_UNLOCK ();
              if ((ready > 0) && (EPOLLOUT & et_mask))
                {
                  add_event = 1;
@@ -3453,16 +3568,16 @@ vppcom_epoll_wait (uint32_t vep_idx, struct epoll_event *events,
              events[num_ev].data.u64 = session_ev_data;
              if (EPOLLONESHOT & session_events)
                {
-                 VCL_LOCK_AND_GET_SESSION (sid, &session);
+                 VCL_SESSION_LOCK_AND_GET (sid, &session);
                  session->vep.ev.events = 0;
-                 clib_spinlock_unlock (&vcm->sessions_lockp);
+                 VCL_SESSION_UNLOCK ();
                }
              num_ev++;
              if (num_ev == maxevents)
                {
-                 VCL_LOCK_AND_GET_SESSION (vep_idx, &vep_session);
+                 VCL_SESSION_LOCK_AND_GET (vep_idx, &vep_session);
                  vep_session->wait_cont_idx = next_sid;
-                 clib_spinlock_unlock (&vcm->sessions_lockp);
+                 VCL_SESSION_UNLOCK ();
                  goto done;
                }
            }
@@ -3481,9 +3596,9 @@ vppcom_epoll_wait (uint32_t vep_idx, struct epoll_event *events,
 
   if (wait_cont_idx != ~0)
     {
-      VCL_LOCK_AND_GET_SESSION (vep_idx, &vep_session);
+      VCL_SESSION_LOCK_AND_GET (vep_idx, &vep_session);
       vep_session->wait_cont_idx = ~0;
-      clib_spinlock_unlock (&vcm->sessions_lockp);
+      VCL_SESSION_UNLOCK ();
     }
 done:
   return (rv != VPPCOM_OK) ? rv : num_ev;
@@ -3493,121 +3608,523 @@ int
 vppcom_session_attr (uint32_t session_index, uint32_t op,
                     void *buffer, uint32_t * buflen)
 {
-  session_t *session;
+  vcl_session_t *session;
   int rv = VPPCOM_OK;
   u32 *flags = buffer;
   vppcom_endpt_t *ep = buffer;
 
-  VCL_LOCK_AND_GET_SESSION (session_index, &session);
+  VCL_SESSION_LOCK_AND_GET (session_index, &session);
+
+  ASSERT (session);
+
   switch (op)
     {
     case VPPCOM_ATTR_GET_NREAD:
       rv = vppcom_session_read_ready (session, session_index);
-      if (VPPCOM_DEBUG > 2)
-       clib_warning ("[%d] VPPCOM_ATTR_GET_NREAD: sid %u, nread = %d",
-                     getpid (), rv);
-
+      VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_NREAD: sid %u, nread = %d",
+           getpid (), rv);
       break;
 
     case VPPCOM_ATTR_GET_NWRITE:
       rv = vppcom_session_write_ready (session, session_index);
-      if (VPPCOM_DEBUG > 2)
-       clib_warning ("[%d] VPPCOM_ATTR_GET_NWRITE: sid %u, nwrite = %d",
-                     getpid (), session_index, rv);
-
+      VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_NWRITE: sid %u, nwrite = %d",
+           getpid (), session_index, rv);
       break;
 
     case VPPCOM_ATTR_GET_FLAGS:
-      if (buffer && buflen && (*buflen >= sizeof (*flags)))
+      if (PREDICT_TRUE (buffer && buflen && (*buflen >= sizeof (*flags))))
        {
-         *flags = O_RDWR | ((session->is_nonblocking) ? O_NONBLOCK : 0);
+         *flags = O_RDWR | (VCL_SESS_ATTR_TEST (session->attr,
+                                                VCL_SESS_ATTR_NONBLOCK));
          *buflen = sizeof (*flags);
-         if (VPPCOM_DEBUG > 2)
-           clib_warning ("[%d] VPPCOM_ATTR_GET_FLAGS: sid %u, "
-                         "flags = 0x%08x, is_nonblocking = %u", getpid (),
-                         session_index, *flags, session->is_nonblocking);
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_FLAGS: sid %u, flags = 0x%08x, "
+               "is_nonblocking = %u", getpid (),
+               session_index, *flags,
+               VCL_SESS_ATTR_TEST (session->attr, VCL_SESS_ATTR_NONBLOCK));
        }
       else
        rv = VPPCOM_EINVAL;
       break;
 
     case VPPCOM_ATTR_SET_FLAGS:
-      if (buffer && buflen && (*buflen >= sizeof (*flags)))
+      if (PREDICT_TRUE (buffer && buflen && (*buflen == sizeof (*flags))))
        {
-         session->is_nonblocking = (*flags & O_NONBLOCK) ? 1 : 0;
-         if (VPPCOM_DEBUG > 2)
-           clib_warning ("[%d] VPPCOM_ATTR_SET_FLAGS: sid %u, "
-                         "flags = 0x%08x, is_nonblocking = %u",
-                         getpid (), *flags, session->is_nonblocking);
+         if (*flags & O_NONBLOCK)
+           VCL_SESS_ATTR_SET (session->attr, VCL_SESS_ATTR_NONBLOCK);
+         else
+           VCL_SESS_ATTR_CLR (session->attr, VCL_SESS_ATTR_NONBLOCK);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_SET_FLAGS: sid %u, flags = 0x%08x,"
+               " is_nonblocking = %u",
+               getpid (), session_index, *flags,
+               VCL_SESS_ATTR_TEST (session->attr, VCL_SESS_ATTR_NONBLOCK));
        }
       else
        rv = VPPCOM_EINVAL;
       break;
 
     case VPPCOM_ATTR_GET_PEER_ADDR:
-      if (buffer && buflen && (*buflen >= sizeof (*ep)))
+      if (PREDICT_TRUE (buffer && buflen &&
+                       (*buflen >= sizeof (*ep)) && ep->ip))
        {
-         ep->vrf = session->vrf;
-         ep->is_ip4 = session->peer_addr.is_ip4;
-         ep->port = session->peer_port;
-         if (session->peer_addr.is_ip4)
-           clib_memcpy (ep->ip, &session->peer_addr.ip46.ip4,
+         ep->is_ip4 = session->transport.is_ip4;
+         ep->port = session->transport.rmt_port;
+         if (session->transport.is_ip4)
+           clib_memcpy (ep->ip, &session->transport.rmt_ip.ip4,
                         sizeof (ip4_address_t));
          else
-           clib_memcpy (ep->ip, &session->peer_addr.ip46.ip6,
+           clib_memcpy (ep->ip, &session->transport.rmt_ip.ip6,
                         sizeof (ip6_address_t));
          *buflen = sizeof (*ep);
-         if (VPPCOM_DEBUG > 1)
-           clib_warning ("[%d] VPPCOM_ATTR_GET_PEER_ADDR: sid %u, is_ip4 = "
-                         "%u, addr = %U, port %u", getpid (),
-                         session_index, ep->is_ip4, format_ip46_address,
-                         &session->peer_addr.ip46, ep->is_ip4,
-                         clib_net_to_host_u16 (ep->port));
+         VDBG (1, "VCL<%d>: VPPCOM_ATTR_GET_PEER_ADDR: sid %u, is_ip4 = %u, "
+               "addr = %U, port %u", getpid (),
+               session_index, ep->is_ip4, format_ip46_address,
+               &session->transport.rmt_ip,
+               ep->is_ip4 ? IP46_TYPE_IP4 : IP46_TYPE_IP6,
+               clib_net_to_host_u16 (ep->port));
        }
       else
        rv = VPPCOM_EINVAL;
       break;
 
     case VPPCOM_ATTR_GET_LCL_ADDR:
-      if (buffer && buflen && (*buflen >= sizeof (*ep)))
+      if (PREDICT_TRUE (buffer && buflen &&
+                       (*buflen >= sizeof (*ep)) && ep->ip))
        {
-         ep->vrf = session->vrf;
-         ep->is_ip4 = session->lcl_addr.is_ip4;
-         ep->port = session->lcl_port;
-         if (session->lcl_addr.is_ip4)
-           clib_memcpy (ep->ip, &session->lcl_addr.ip46.ip4,
+         ep->is_ip4 = session->transport.is_ip4;
+         ep->port = session->transport.lcl_port;
+         if (session->transport.is_ip4)
+           clib_memcpy (ep->ip, &session->transport.lcl_ip.ip4,
                         sizeof (ip4_address_t));
          else
-           clib_memcpy (ep->ip, &session->lcl_addr.ip46.ip6,
+           clib_memcpy (ep->ip, &session->transport.lcl_ip.ip6,
                         sizeof (ip6_address_t));
          *buflen = sizeof (*ep);
-         if (VPPCOM_DEBUG > 1)
-           clib_warning ("[%d] VPPCOM_ATTR_GET_LCL_ADDR: sid %u, is_ip4 = "
-                         "%u, addr = %U port %d", getpid (),
-                         session_index, ep->is_ip4, format_ip46_address,
-                         &session->lcl_addr.ip46, ep->is_ip4,
-                         clib_net_to_host_u16 (ep->port));
+         VDBG (1, "VCL<%d>: VPPCOM_ATTR_GET_LCL_ADDR: sid %u, is_ip4 = %u,"
+               " addr = %U port %d", getpid (),
+               session_index, ep->is_ip4, format_ip46_address,
+               &session->transport.lcl_ip,
+               ep->is_ip4 ? IP46_TYPE_IP4 : IP46_TYPE_IP6,
+               clib_net_to_host_u16 (ep->port));
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_LIBC_EPFD:
+      rv = session->libc_epfd;
+      VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_LIBC_EPFD: libc_epfd %d",
+           getpid (), rv);
+      break;
+
+    case VPPCOM_ATTR_SET_LIBC_EPFD:
+      if (PREDICT_TRUE (buffer && buflen &&
+                       (*buflen == sizeof (session->libc_epfd))))
+       {
+         session->libc_epfd = *(int *) buffer;
+         *buflen = sizeof (session->libc_epfd);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_SET_LIBC_EPFD: libc_epfd %d, "
+               "buflen %d", getpid (), session->libc_epfd, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_PROTOCOL:
+      if (buffer && buflen && (*buflen >= sizeof (int)))
+       {
+         *(int *) buffer = session->session_type;
+         *buflen = sizeof (int);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_PROTOCOL: %d (%s), buflen %d",
+               getpid (), *(int *) buffer, *(int *) buffer ? "UDP" : "TCP",
+               *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_LISTEN:
+      if (buffer && buflen && (*buflen >= sizeof (int)))
+       {
+         *(int *) buffer = VCL_SESS_ATTR_TEST (session->attr,
+                                               VCL_SESS_ATTR_LISTEN);
+         *buflen = sizeof (int);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_LISTEN: %d, buflen %d",
+               getpid (), *(int *) buffer, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_ERROR:
+      if (buffer && buflen && (*buflen >= sizeof (int)))
+       {
+         *(int *) buffer = 0;
+         *buflen = sizeof (int);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_ERROR: %d, buflen %d, #VPP-TBD#",
+               getpid (), *(int *) buffer, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_TX_FIFO_LEN:
+      if (buffer && buflen && (*buflen >= sizeof (u32)))
+       {
+
+         /* VPP-TBD */
+         *(size_t *) buffer = (session->sndbuf_size ? session->sndbuf_size :
+                               session->tx_fifo ? session->tx_fifo->nitems :
+                               vcm->cfg.tx_fifo_size);
+         *buflen = sizeof (u32);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_TX_FIFO_LEN: %u (0x%x), "
+               "buflen %d, #VPP-TBD#", getpid (),
+               *(size_t *) buffer, *(size_t *) buffer, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_SET_TX_FIFO_LEN:
+      if (buffer && buflen && (*buflen == sizeof (u32)))
+       {
+         /* VPP-TBD */
+         session->sndbuf_size = *(u32 *) buffer;
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_SET_TX_FIFO_LEN: %u (0x%x), "
+               "buflen %d, #VPP-TBD#", getpid (),
+               session->sndbuf_size, session->sndbuf_size, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_RX_FIFO_LEN:
+      if (buffer && buflen && (*buflen >= sizeof (u32)))
+       {
+
+         /* VPP-TBD */
+         *(size_t *) buffer = (session->rcvbuf_size ? session->rcvbuf_size :
+                               session->rx_fifo ? session->rx_fifo->nitems :
+                               vcm->cfg.rx_fifo_size);
+         *buflen = sizeof (u32);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_RX_FIFO_LEN: %u (0x%x), "
+               "buflen %d, #VPP-TBD#", getpid (),
+               *(size_t *) buffer, *(size_t *) buffer, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_SET_RX_FIFO_LEN:
+      if (buffer && buflen && (*buflen == sizeof (u32)))
+       {
+         /* VPP-TBD */
+         session->rcvbuf_size = *(u32 *) buffer;
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_SET_RX_FIFO_LEN: %u (0x%x), "
+               "buflen %d, #VPP-TBD#", getpid (),
+               session->sndbuf_size, session->sndbuf_size, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_REUSEADDR:
+      if (buffer && buflen && (*buflen >= sizeof (int)))
+       {
+         /* VPP-TBD */
+         *(int *) buffer = VCL_SESS_ATTR_TEST (session->attr,
+                                               VCL_SESS_ATTR_REUSEADDR);
+         *buflen = sizeof (int);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_REUSEADDR: %d, "
+               "buflen %d, #VPP-TBD#", getpid (), *(int *) buffer, *buflen);
        }
       else
        rv = VPPCOM_EINVAL;
       break;
 
     case VPPCOM_ATTR_SET_REUSEADDR:
+      if (buffer && buflen && (*buflen == sizeof (int)) &&
+         !VCL_SESS_ATTR_TEST (session->attr, VCL_SESS_ATTR_LISTEN))
+       {
+         /* VPP-TBD */
+         if (*(int *) buffer)
+           VCL_SESS_ATTR_SET (session->attr, VCL_SESS_ATTR_REUSEADDR);
+         else
+           VCL_SESS_ATTR_CLR (session->attr, VCL_SESS_ATTR_REUSEADDR);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_SET_REUSEADDR: %d, buflen %d,"
+               " #VPP-TBD#", getpid (),
+               VCL_SESS_ATTR_TEST (session->attr,
+                                   VCL_SESS_ATTR_REUSEADDR), *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_REUSEPORT:
+      if (buffer && buflen && (*buflen >= sizeof (int)))
+       {
+         /* VPP-TBD */
+         *(int *) buffer = VCL_SESS_ATTR_TEST (session->attr,
+                                               VCL_SESS_ATTR_REUSEPORT);
+         *buflen = sizeof (int);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_REUSEPORT: %d, buflen %d,"
+               " #VPP-TBD#", getpid (), *(int *) buffer, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_SET_REUSEPORT:
+      if (buffer && buflen && (*buflen == sizeof (int)) &&
+         !VCL_SESS_ATTR_TEST (session->attr, VCL_SESS_ATTR_LISTEN))
+       {
+         /* VPP-TBD */
+         if (*(int *) buffer)
+           VCL_SESS_ATTR_SET (session->attr, VCL_SESS_ATTR_REUSEPORT);
+         else
+           VCL_SESS_ATTR_CLR (session->attr, VCL_SESS_ATTR_REUSEPORT);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_SET_REUSEPORT: %d, buflen %d,"
+               " #VPP-TBD#", getpid (),
+               VCL_SESS_ATTR_TEST (session->attr,
+                                   VCL_SESS_ATTR_REUSEPORT), *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_BROADCAST:
+      if (buffer && buflen && (*buflen >= sizeof (int)))
+       {
+         /* VPP-TBD */
+         *(int *) buffer = VCL_SESS_ATTR_TEST (session->attr,
+                                               VCL_SESS_ATTR_BROADCAST);
+         *buflen = sizeof (int);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_BROADCAST: %d, buflen %d,"
+               " #VPP-TBD#", getpid (), *(int *) buffer, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
       break;
 
     case VPPCOM_ATTR_SET_BROADCAST:
+      if (buffer && buflen && (*buflen == sizeof (int)))
+       {
+         /* VPP-TBD */
+         if (*(int *) buffer)
+           VCL_SESS_ATTR_SET (session->attr, VCL_SESS_ATTR_BROADCAST);
+         else
+           VCL_SESS_ATTR_CLR (session->attr, VCL_SESS_ATTR_BROADCAST);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_SET_BROADCAST: %d, buflen %d, "
+               "#VPP-TBD#", getpid (),
+               VCL_SESS_ATTR_TEST (session->attr,
+                                   VCL_SESS_ATTR_BROADCAST), *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_V6ONLY:
+      if (buffer && buflen && (*buflen >= sizeof (int)))
+       {
+         /* VPP-TBD */
+         *(int *) buffer = VCL_SESS_ATTR_TEST (session->attr,
+                                               VCL_SESS_ATTR_V6ONLY);
+         *buflen = sizeof (int);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_V6ONLY: %d, buflen %d, "
+               "#VPP-TBD#", getpid (), *(int *) buffer, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
       break;
 
     case VPPCOM_ATTR_SET_V6ONLY:
+      if (buffer && buflen && (*buflen == sizeof (int)))
+       {
+         /* VPP-TBD */
+         if (*(int *) buffer)
+           VCL_SESS_ATTR_SET (session->attr, VCL_SESS_ATTR_V6ONLY);
+         else
+           VCL_SESS_ATTR_CLR (session->attr, VCL_SESS_ATTR_V6ONLY);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_SET_V6ONLY: %d, buflen %d, "
+               "#VPP-TBD#", getpid (),
+               VCL_SESS_ATTR_TEST (session->attr,
+                                   VCL_SESS_ATTR_V6ONLY), *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_KEEPALIVE:
+      if (buffer && buflen && (*buflen >= sizeof (int)))
+       {
+         /* VPP-TBD */
+         *(int *) buffer = VCL_SESS_ATTR_TEST (session->attr,
+                                               VCL_SESS_ATTR_KEEPALIVE);
+         *buflen = sizeof (int);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_KEEPALIVE: %d, buflen %d, "
+               "#VPP-TBD#", getpid (), *(int *) buffer, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
       break;
 
     case VPPCOM_ATTR_SET_KEEPALIVE:
+      if (buffer && buflen && (*buflen == sizeof (int)))
+       {
+         /* VPP-TBD */
+         if (*(int *) buffer)
+           VCL_SESS_ATTR_SET (session->attr, VCL_SESS_ATTR_KEEPALIVE);
+         else
+           VCL_SESS_ATTR_CLR (session->attr, VCL_SESS_ATTR_KEEPALIVE);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_SET_KEEPALIVE: %d, buflen %d, "
+               "#VPP-TBD#", getpid (),
+               VCL_SESS_ATTR_TEST (session->attr,
+                                   VCL_SESS_ATTR_KEEPALIVE), *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_TCP_NODELAY:
+      if (buffer && buflen && (*buflen >= sizeof (int)))
+       {
+         /* VPP-TBD */
+         *(int *) buffer = VCL_SESS_ATTR_TEST (session->attr,
+                                               VCL_SESS_ATTR_TCP_NODELAY);
+         *buflen = sizeof (int);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_TCP_NODELAY: %d, buflen %d, "
+               "#VPP-TBD#", getpid (), *(int *) buffer, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_SET_TCP_NODELAY:
+      if (buffer && buflen && (*buflen == sizeof (int)))
+       {
+         /* VPP-TBD */
+         if (*(int *) buffer)
+           VCL_SESS_ATTR_SET (session->attr, VCL_SESS_ATTR_TCP_NODELAY);
+         else
+           VCL_SESS_ATTR_CLR (session->attr, VCL_SESS_ATTR_TCP_NODELAY);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_SET_TCP_NODELAY: %d, buflen %d, "
+               "#VPP-TBD#", getpid (),
+               VCL_SESS_ATTR_TEST (session->attr,
+                                   VCL_SESS_ATTR_TCP_NODELAY), *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_TCP_KEEPIDLE:
+      if (buffer && buflen && (*buflen >= sizeof (int)))
+       {
+         /* VPP-TBD */
+         *(int *) buffer = VCL_SESS_ATTR_TEST (session->attr,
+                                               VCL_SESS_ATTR_TCP_KEEPIDLE);
+         *buflen = sizeof (int);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_TCP_KEEPIDLE: %d, buflen %d, "
+               "#VPP-TBD#", getpid (), *(int *) buffer, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
       break;
 
     case VPPCOM_ATTR_SET_TCP_KEEPIDLE:
+      if (buffer && buflen && (*buflen == sizeof (int)))
+       {
+         /* VPP-TBD */
+         if (*(int *) buffer)
+           VCL_SESS_ATTR_SET (session->attr, VCL_SESS_ATTR_TCP_KEEPIDLE);
+         else
+           VCL_SESS_ATTR_CLR (session->attr, VCL_SESS_ATTR_TCP_KEEPIDLE);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_SET_TCP_KEEPIDLE: %d, buflen %d, "
+               "#VPP-TBD#", getpid (),
+               VCL_SESS_ATTR_TEST (session->attr,
+                                   VCL_SESS_ATTR_TCP_KEEPIDLE), *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_TCP_KEEPINTVL:
+      if (buffer && buflen && (*buflen >= sizeof (int)))
+       {
+         /* VPP-TBD */
+         *(int *) buffer = VCL_SESS_ATTR_TEST (session->attr,
+                                               VCL_SESS_ATTR_TCP_KEEPINTVL);
+         *buflen = sizeof (int);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_TCP_KEEPINTVL: %d, buflen %d, "
+               "#VPP-TBD#", getpid (), *(int *) buffer, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
       break;
 
     case VPPCOM_ATTR_SET_TCP_KEEPINTVL:
+      if (buffer && buflen && (*buflen == sizeof (int)))
+       {
+         /* VPP-TBD */
+         if (*(int *) buffer)
+           VCL_SESS_ATTR_SET (session->attr, VCL_SESS_ATTR_TCP_KEEPINTVL);
+         else
+           VCL_SESS_ATTR_CLR (session->attr, VCL_SESS_ATTR_TCP_KEEPINTVL);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_SET_TCP_KEEPINTVL: %d, buflen %d, "
+               "#VPP-TBD#", getpid (),
+               VCL_SESS_ATTR_TEST (session->attr,
+                                   VCL_SESS_ATTR_TCP_KEEPINTVL), *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_GET_TCP_USER_MSS:
+      if (buffer && buflen && (*buflen >= sizeof (u32)))
+       {
+         /* VPP-TBD */
+         *(u32 *) buffer = session->user_mss;
+         *buflen = sizeof (int);
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_GET_TCP_USER_MSS: %d, buflen %d,"
+               " #VPP-TBD#", getpid (), *(int *) buffer, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
+      break;
+
+    case VPPCOM_ATTR_SET_TCP_USER_MSS:
+      if (buffer && buflen && (*buflen == sizeof (u32)))
+       {
+         /* VPP-TBD */
+         session->user_mss = *(u32 *) buffer;
+
+         VDBG (2, "VCL<%d>: VPPCOM_ATTR_SET_TCP_USER_MSS: %u, buflen %d, "
+               "#VPP-TBD#", getpid (), session->user_mss, *buflen);
+       }
+      else
+       rv = VPPCOM_EINVAL;
       break;
 
     default:
@@ -3616,7 +4133,7 @@ vppcom_session_attr (uint32_t session_index, uint32_t op,
     }
 
 done:
-  clib_spinlock_unlock (&vcm->sessions_lockp);
+  VCL_SESSION_UNLOCK ();
   return rv;
 }
 
@@ -3625,32 +4142,30 @@ vppcom_session_recvfrom (uint32_t session_index, void *buffer,
                         uint32_t buflen, int flags, vppcom_endpt_t * ep)
 {
   int rv = VPPCOM_OK;
-  session_t *session = 0;
+  vcl_session_t *session = 0;
 
   if (ep)
     {
-      clib_spinlock_lock (&vcm->sessions_lockp);
+      VCL_SESSION_LOCK ();
       rv = vppcom_session_at_index (session_index, &session);
       if (PREDICT_FALSE (rv))
        {
-         clib_spinlock_unlock (&vcm->sessions_lockp);
-         if (VPPCOM_DEBUG > 0)
-           clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-                         getpid (), session_index);
+         VCL_SESSION_UNLOCK ();
+         VDBG (0, "VCL<%d>: invalid session, sid (%u) has been closed!",
+               getpid (), session_index);
          rv = VPPCOM_EBADFD;
-         clib_spinlock_unlock (&vcm->sessions_lockp);
+         VCL_SESSION_UNLOCK ();
          goto done;
        }
-      ep->vrf = session->vrf;
-      ep->is_ip4 = session->peer_addr.is_ip4;
-      ep->port = session->peer_port;
-      if (session->peer_addr.is_ip4)
-       clib_memcpy (ep->ip, &session->peer_addr.ip46.ip4,
+      ep->is_ip4 = session->transport.is_ip4;
+      ep->port = session->transport.rmt_port;
+      if (session->transport.is_ip4)
+       clib_memcpy (ep->ip, &session->transport.rmt_ip.ip4,
                     sizeof (ip4_address_t));
       else
-       clib_memcpy (ep->ip, &session->peer_addr.ip46.ip6,
+       clib_memcpy (ep->ip, &session->transport.rmt_ip.ip6,
                     sizeof (ip6_address_t));
-      clib_spinlock_unlock (&vcm->sessions_lockp);
+      VCL_SESSION_UNLOCK ();
     }
 
   if (flags == 0)
@@ -3659,7 +4174,8 @@ vppcom_session_recvfrom (uint32_t session_index, void *buffer,
     rv = vppcom_session_peek (session_index, buffer, buflen);
   else
     {
-      clib_warning ("[%d] Unsupport flags for recvfrom %d", getpid (), flags);
+      clib_warning ("VCL<%d>: Unsupport flags for recvfrom %d",
+                   getpid (), flags);
       rv = VPPCOM_EAFNOSUPPORT;
     }
 
@@ -3683,14 +4199,381 @@ vppcom_session_sendto (uint32_t session_index, void *buffer,
   if (flags)
     {
       // TBD check the flags and do the right thing
-      if (VPPCOM_DEBUG > 2)
-       clib_warning ("[%d] handling flags 0x%u (%d) not implemented yet.",
-                     getpid (), flags, flags);
+      VDBG (2, "VCL<%d>: handling flags 0x%u (%d) not implemented yet.",
+           getpid (), flags, flags);
     }
 
   return (vppcom_session_write (session_index, buffer, buflen));
 }
 
+int
+vppcom_poll (vcl_poll_t * vp, uint32_t n_sids, double wait_for_time)
+{
+  f64 timeout = clib_time_now (&vcm->clib_time) + wait_for_time;
+  u32 i, keep_trying = 1;
+  int rv, num_ev = 0;
+
+  VDBG (3, "VCL<%d>: vp %p, nsids %u, wait_for_time %f",
+       getpid (), vp, n_sids, wait_for_time);
+
+  if (!vp)
+    return VPPCOM_EFAULT;
+
+  do
+    {
+      vcl_session_t *session;
+
+      for (i = 0; i < n_sids; i++)
+       {
+         ASSERT (vp[i].revents);
+
+         VCL_SESSION_LOCK_AND_GET (vp[i].sid, &session);
+         VCL_SESSION_UNLOCK ();
+
+         if (*vp[i].revents)
+           *vp[i].revents = 0;
+
+         if (POLLIN & vp[i].events)
+           {
+             VCL_SESSION_LOCK_AND_GET (vp[i].sid, &session);
+             rv = vppcom_session_read_ready (session, vp[i].sid);
+             VCL_SESSION_UNLOCK ();
+             if (rv > 0)
+               {
+                 *vp[i].revents |= POLLIN;
+                 num_ev++;
+               }
+             else if (rv < 0)
+               {
+                 switch (rv)
+                   {
+                   case VPPCOM_ECONNRESET:
+                     *vp[i].revents = POLLHUP;
+                     break;
+
+                   default:
+                     *vp[i].revents = POLLERR;
+                     break;
+                   }
+                 num_ev++;
+               }
+           }
+
+         if (POLLOUT & vp[i].events)
+           {
+             VCL_SESSION_LOCK_AND_GET (vp[i].sid, &session);
+             rv = vppcom_session_write_ready (session, vp[i].sid);
+             VCL_SESSION_UNLOCK ();
+             if (rv > 0)
+               {
+                 *vp[i].revents |= POLLOUT;
+                 num_ev++;
+               }
+             else if (rv < 0)
+               {
+                 switch (rv)
+                   {
+                   case VPPCOM_ECONNRESET:
+                     *vp[i].revents = POLLHUP;
+                     break;
+
+                   default:
+                     *vp[i].revents = POLLERR;
+                     break;
+                   }
+                 num_ev++;
+               }
+           }
+
+         if (0)                // Note "done:" label used by VCL_SESSION_LOCK_AND_GET()
+           {
+           done:
+             *vp[i].revents = POLLNVAL;
+             num_ev++;
+           }
+       }
+      if (wait_for_time != -1)
+       keep_trying = (clib_time_now (&vcm->clib_time) <= timeout) ? 1 : 0;
+    }
+  while ((num_ev == 0) && keep_trying);
+
+  if (VPPCOM_DEBUG > 3)
+    {
+      clib_warning ("VCL<%d>: returning %d", getpid (), num_ev);
+      for (i = 0; i < n_sids; i++)
+       {
+         clib_warning ("VCL<%d>: vp[%d].sid %d (0x%x), .events 0x%x, "
+                       ".revents 0x%x", getpid (), i, vp[i].sid, vp[i].sid,
+                       vp[i].events, *vp[i].revents);
+       }
+    }
+  return num_ev;
+}
+
+/*
+ * VPPCOM Event Functions
+ */
+
+void *
+vppcom_session_io_thread_fn (void *arg)
+{
+  vppcom_session_io_thread_t *evt = (vppcom_session_io_thread_t *) arg;
+  u32 *session_indexes = 0, *session_index;
+  int i, rv;
+  u32 bytes = 0;
+  vcl_session_t *session;
+
+  while (1)
+    {
+      vec_reset_length (session_indexes);
+      VCE_IO_SESSIONS_LOCK ();
+      pool_foreach (session_index, evt->active_session_indexes, (
+                                                                 {
+                                                                 vec_add1
+                                                                 (session_indexes,
+                                                                  *session_index);
+                                                                 }
+                   ));
+      VCE_IO_SESSIONS_UNLOCK ();
+      if (session_indexes)
+       {
+         for (i = 0; i < vec_len (session_indexes); ++i)
+           {
+             VCL_SESSION_LOCK_AND_GET (session_indexes[i], &session);
+             bytes = svm_fifo_max_dequeue (session->rx_fifo);
+             VCL_SESSION_UNLOCK ();
+
+             if (bytes)
+               {
+                 vppcom_ioevent_t *eio;
+                 vce_event_t *ev;
+                 u32 ev_idx;
+
+                 VCL_EVENTS_LOCK ();
+
+                 pool_get (vcm->event_thread.vce_events, ev);
+                 ev_idx = (u32) (ev - vcm->event_thread.vce_events);
+                 eio = vce_get_event_data (ev, sizeof (*eio));
+                 ev->evk.eid = VCL_EVENT_IOEVENT_RX_FIFO;
+                 ev->evk.session_index = session_indexes[i];
+                 eio->bytes = bytes;
+                 eio->session_index = session_indexes[i];
+
+                 VCL_EVENTS_UNLOCK ();
+
+                 rv = vce_generate_event (&vcm->event_thread, ev_idx);
+               }
+           }
+       }
+      struct timespec ts;
+      ts.tv_sec = 0;
+      ts.tv_nsec = 1000000;    /* 1 millisecond */
+      nanosleep (&ts, NULL);
+    }
+done:
+  VCL_SESSION_UNLOCK ();
+  return NULL;
+}
+
+int
+vppcom_start_io_event_thread (vppcom_session_io_thread_t * evt,
+                             u8 max_sessions)
+{
+  pthread_cond_init (&(evt->vce_io_cond), NULL);
+  pthread_mutex_init (&(evt->vce_io_lock), NULL);
+
+  clib_spinlock_init (&(evt->io_sessions_lockp));
+
+  return pthread_create (&(evt->thread), NULL /* attr */ ,
+                        vppcom_session_io_thread_fn, evt);
+}
+
+void
+vce_registered_ioevent_handler_fn (void *arg)
+{
+  vce_event_handler_reg_t *reg = (vce_event_handler_reg_t *) arg;
+  vppcom_ioevent_t *eio;
+  vce_event_t *ev;
+  u32 ioevt_ndx = (u64) (reg->handler_fn_args);
+  vppcom_session_ioevent_t *ioevent, ioevent_;
+
+  VCL_EVENTS_LOCK ();
+  ev = vce_get_event_from_index (&vcm->event_thread, reg->ev_idx);
+  eio = vce_get_event_data (ev, sizeof (*eio));
+  VCL_EVENTS_UNLOCK ();
+
+  VCL_IO_SESSIONS_LOCK ();
+  ioevent = pool_elt_at_index (vcm->session_io_thread.ioevents, ioevt_ndx);
+  ioevent_ = *ioevent;
+  VCL_IO_SESSIONS_UNLOCK ();
+  (ioevent_.user_cb) (eio, ioevent_.user_cb_data);
+  vce_clear_event (&vcm->event_thread, reg->ev_idx);
+  return;
+
+  /*TODO - Unregister check in close for this listener */
+
+}
+
+void
+vce_registered_listener_connect_handler_fn (void *arg)
+{
+  vce_event_handler_reg_t *reg = (vce_event_handler_reg_t *) arg;
+  vce_event_connect_request_t *ecr;
+  vce_event_t *ev;
+  vppcom_endpt_t ep;
+
+  vcl_session_t *new_session;
+  int rv;
+
+  vppcom_session_listener_t *session_listener =
+    (vppcom_session_listener_t *) reg->handler_fn_args;
+
+  VCL_EVENTS_LOCK ();
+  ev = vce_get_event_from_index (&vcm->event_thread, reg->ev_idx);
+  ecr = vce_get_event_data (ev, sizeof (*ecr));
+  VCL_EVENTS_UNLOCK ();
+  VCL_SESSION_LOCK_AND_GET (ecr->accepted_session_index, &new_session);
+
+  ep.is_ip4 = new_session->transport.is_ip4;
+  ep.port = new_session->transport.rmt_port;
+  if (new_session->transport.is_ip4)
+    clib_memcpy (&ep.ip, &new_session->transport.rmt_ip.ip4,
+                sizeof (ip4_address_t));
+  else
+    clib_memcpy (&ep.ip, &new_session->transport.rmt_ip.ip6,
+                sizeof (ip6_address_t));
+
+  vppcom_send_accept_session_reply (new_session->vpp_handle,
+                                   new_session->client_context,
+                                   0 /* retval OK */ );
+  VCL_SESSION_UNLOCK ();
+
+  (session_listener->user_cb) (ecr->accepted_session_index, &ep,
+                              session_listener->user_cb_data);
+
+  if (vcm->session_io_thread.io_sessions_lockp)
+    {
+      /* Throw this new accepted session index into the rx poll thread pool */
+      VCL_IO_SESSIONS_LOCK ();
+      u32 *active_session_index;
+      pool_get (vcm->session_io_thread.active_session_indexes,
+               active_session_index);
+      *active_session_index = ecr->accepted_session_index;
+      VCL_IO_SESSIONS_UNLOCK ();
+    }
+
+  /*TODO - Unregister check in close for this listener */
+  return;
+
+done:
+  ASSERT (0);                  // If we can't get a lock or accepted session fails, lets blow up.
+}
+
+/**
+ * @brief vce_poll_wait_connect_request_handler_fn
+ * - used by vppcom_epoll_xxxx() for listener sessions
+ * - when a vl_api_accept_session_t_handler() generates an event
+ *   this callback is alerted and sets the fields that vppcom_epoll_wait()
+ *   expects to see.
+ *
+ * @param arg - void* to be cast to vce_event_handler_reg_t*
+ */
+void
+vce_poll_wait_connect_request_handler_fn (void *arg)
+{
+  vce_event_handler_reg_t *reg = (vce_event_handler_reg_t *) arg;
+  vce_event_t *ev;
+  /* Retrieve the VCL_EVENT_CONNECT_REQ_ACCEPTED event */
+  ev = vce_get_event_from_index (&vcm->event_thread, reg->ev_idx);
+  vce_event_connect_request_t *ecr = vce_get_event_data (ev, sizeof (*ecr));
+
+  /* Add the accepted_session_index to the FIFO */
+  VCL_ACCEPT_FIFO_LOCK ();
+  clib_fifo_add1 (vcm->client_session_index_fifo,
+                 ecr->accepted_session_index);
+  VCL_ACCEPT_FIFO_UNLOCK ();
+
+  /* Recycling the event. */
+  VCL_EVENTS_LOCK ();
+  ev->recycle = 1;
+  clib_fifo_add1 (vcm->event_thread.event_index_fifo, reg->ev_idx);
+  VCL_EVENTS_UNLOCK ();
+}
+
+int
+vppcom_session_register_ioevent_cb (uint32_t session_index,
+                                   vppcom_session_ioevent_cb cb,
+                                   uint8_t rx, void *ptr)
+{
+  int rv = VPPCOM_OK;
+  vce_event_key_t evk;
+  vppcom_session_ioevent_t *ioevent;
+
+  if (!vcm->session_io_thread.io_sessions_lockp)
+    rv = vppcom_start_io_event_thread (&vcm->session_io_thread, 100    /* DAW_TODO: ??? hard-coded value */
+      );
+
+  if (rv == VPPCOM_OK)
+    {
+      void *io_evt_ndx;
+
+      /* Register handler for ioevent on session_index */
+      VCL_IO_SESSIONS_LOCK ();
+      pool_get (vcm->session_io_thread.ioevents, ioevent);
+      io_evt_ndx = (void *) (ioevent - vcm->session_io_thread.ioevents);
+      ioevent->user_cb = cb;
+      ioevent->user_cb_data = ptr;
+      VCL_IO_SESSIONS_UNLOCK ();
+
+      evk.session_index = session_index;
+      evk.eid = rx ? VCL_EVENT_IOEVENT_RX_FIFO : VCL_EVENT_IOEVENT_TX_FIFO;
+
+      (void) vce_register_handler (&vcm->event_thread, &evk,
+                                  vce_registered_ioevent_handler_fn,
+                                  io_evt_ndx);
+    }
+  return rv;
+}
+
+int
+vppcom_session_register_listener (uint32_t session_index,
+                                 vppcom_session_listener_cb cb,
+                                 vppcom_session_listener_errcb
+                                 errcb, uint8_t flags, int q_len, void *ptr)
+{
+  int rv = VPPCOM_OK;
+  vce_event_key_t evk;
+  vppcom_session_listener_t *listener_args;
+
+  if (!vcm->session_io_thread.io_sessions_lockp)
+    rv = vppcom_start_io_event_thread (&vcm->session_io_thread, 100    /* DAW_TODO: ??? hard-coded value */
+      );
+  if (rv)
+    {
+      goto done;
+    }
+  rv = vppcom_session_listen (session_index, q_len);
+  if (rv)
+    {
+      goto done;
+    }
+
+  /* Register handler for connect_request event on listen_session_index */
+  listener_args = clib_mem_alloc (sizeof (vppcom_session_listener_t)); // DAW_TODO: Use a pool instead of thrashing the memory allocator!
+  listener_args->user_cb = cb;
+  listener_args->user_cb_data = ptr;
+  listener_args->user_errcb = errcb;
+
+  evk.session_index = session_index;
+  evk.eid = VCL_EVENT_CONNECT_REQ_ACCEPTED;
+  (void) vce_register_handler (&vcm->event_thread, &evk,
+                              vce_registered_listener_connect_handler_fn,
+                              listener_args);
+
+done:
+  return rv;
+}
+
 /*
  * fd.io coding-style-patch-verification: ON
  *