X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fvnet%2Ftcp%2Ftcp_output.c;h=089f85a0ea0f6ce1e78f4d89fc9998b203fad831;hb=7ac053b27fee8f9e437cf7b61357943356381061;hp=e921a4a13eaf8830af75a253712cac8c447f3e7b;hpb=d3c008d108aa2187d1a2afe2833b4de25ca2c2ab;p=vpp.git

diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index e921a4a13ea..089f85a0ea0 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -24,16 +24,22 @@ typedef enum _tcp_output_next
 {
   TCP_OUTPUT_NEXT_DROP,
   TCP_OUTPUT_NEXT_IP_LOOKUP,
+  TCP_OUTPUT_NEXT_IP_REWRITE,
+  TCP_OUTPUT_NEXT_IP_ARP,
   TCP_OUTPUT_N_NEXT
 } tcp_output_next_t;
 
 #define foreach_tcp4_output_next              	\
   _ (DROP, "error-drop")                        \
-  _ (IP_LOOKUP, "ip4-lookup")
+  _ (IP_LOOKUP, "ip4-lookup")			\
+  _ (IP_REWRITE, "ip4-rewrite")			\
+  _ (IP_ARP, "ip4-arp")
 
 #define foreach_tcp6_output_next              	\
   _ (DROP, "error-drop")                        \
-  _ (IP_LOOKUP, "ip6-lookup")
+  _ (IP_LOOKUP, "ip6-lookup")			\
+  _ (IP_REWRITE, "ip6-rewrite")			\
+  _ (IP_ARP, "ip6-discover-neighbor")
 
 static char *tcp_error_strings[] = {
 #define tcp_error(n,s) s,
@@ -112,12 +118,13 @@ tcp_initial_wnd_unscaled (tcp_connection_t * tc)
 u32
 tcp_initial_window_to_advertise (tcp_connection_t * tc)
 {
+  tcp_main_t *tm = &tcp_main;
   u32 max_fifo;
 
   /* Initial wnd for SYN. Fifos are not allocated yet.
    * Use some predefined value. For SYN-ACK we still want the
    * scale to be computed in the same way */
-  max_fifo = TCP_MAX_RX_FIFO_SIZE;
+  max_fifo = tm->max_rx_fifo ? tm->max_rx_fifo : TCP_MAX_RX_FIFO_SIZE;
 
   tc->rcv_wscale = tcp_window_compute_scale (max_fifo);
   tc->rcv_wnd = tcp_initial_wnd_unscaled (tc);
@@ -125,30 +132,7 @@ tcp_initial_window_to_advertise (tcp_connection_t * tc)
   return clib_min (tc->rcv_wnd, TCP_WND_MAX);
 }
 
-/**
- * Compute and return window to advertise, scaled as per RFC1323
- */
-u32
-tcp_window_to_advertise (tcp_connection_t * tc, tcp_state_t state)
-{
-  if (state < TCP_STATE_ESTABLISHED)
-    return tcp_initial_window_to_advertise (tc);
-
-  tcp_update_rcv_wnd (tc);
-
-  if (tc->rcv_wnd == 0)
-    {
-      tc->flags |= TCP_CONN_SENT_RCV_WND0;
-    }
-  else
-    {
-      tc->flags &= ~TCP_CONN_SENT_RCV_WND0;
-    }
-
-  return tc->rcv_wnd >> tc->rcv_wscale;
-}
-
-void
+static void
 tcp_update_rcv_wnd (tcp_connection_t * tc)
 {
   i32 observed_wnd;
@@ -157,8 +141,8 @@ tcp_update_rcv_wnd (tcp_connection_t * tc)
   /*
    * Figure out how much space we have available
    */
-  available_space = stream_session_max_rx_enqueue (&tc->connection);
-  max_fifo = stream_session_rx_fifo_size (&tc->connection);
+  available_space = transport_max_rx_enqueue (&tc->connection);
+  max_fifo = transport_rx_fifo_size (&tc->connection);
 
   ASSERT (tc->rcv_opts.mss < max_fifo);
   if (available_space < tc->rcv_opts.mss && available_space < max_fifo >> 3)
@@ -194,10 +178,33 @@ tcp_update_rcv_wnd (tcp_connection_t * tc)
   tc->rcv_wnd = clib_min (wnd, TCP_WND_MAX << tc->rcv_wscale);
 }
 
+/**
+ * Compute and return window to advertise, scaled as per RFC1323
+ */
+static u32
+tcp_window_to_advertise (tcp_connection_t * tc, tcp_state_t state)
+{
+  if (state < TCP_STATE_ESTABLISHED)
+    return tcp_initial_window_to_advertise (tc);
+
+  tcp_update_rcv_wnd (tc);
+
+  if (tc->rcv_wnd == 0)
+    {
+      tc->flags |= TCP_CONN_SENT_RCV_WND0;
+    }
+  else
+    {
+      tc->flags &= ~TCP_CONN_SENT_RCV_WND0;
+    }
+
+  return tc->rcv_wnd >> tc->rcv_wscale;
+}
+
 /**
  * Write TCP options to segment.
  */
-u32
+static u32
 tcp_options_write (u8 * data, tcp_options_t * opts)
 {
   u32 opts_len = 0;
@@ -280,7 +287,7 @@ tcp_options_write (u8 * data, tcp_options_t * opts)
   return opts_len;
 }
 
-always_inline int
+static int
 tcp_make_syn_options (tcp_options_t * opts, u8 wnd_scale)
 {
   u8 len = 0;
@@ -309,7 +316,7 @@ tcp_make_syn_options (tcp_options_t * opts, u8 wnd_scale)
   return len;
 }
 
-always_inline int
+static int
 tcp_make_synack_options (tcp_connection_t * tc, tcp_options_t * opts)
 {
   u8 len = 0;
@@ -344,7 +351,7 @@ tcp_make_synack_options (tcp_connection_t * tc, tcp_options_t * opts)
   return len;
 }
 
-always_inline int
+static int
 tcp_make_established_options (tcp_connection_t * tc, tcp_options_t * opts)
 {
   u8 len = 0;
@@ -354,7 +361,7 @@ tcp_make_established_options (tcp_connection_t * tc, tcp_options_t * opts)
   if (tcp_opts_tstamp (&tc->rcv_opts))
     {
       opts->flags |= TCP_OPTS_FLAG_TSTAMP;
-      opts->tsval = tcp_time_now ();
+      opts->tsval = tcp_time_now_w_thread (tc->c_thread_index);
       opts->tsecr = tc->tsval_recent;
       len += TCP_OPTION_LEN_TIMESTAMP;
     }
@@ -383,32 +390,47 @@ tcp_make_options (tcp_connection_t * tc, tcp_options_t * opts,
     {
     case TCP_STATE_ESTABLISHED:
     case TCP_STATE_FIN_WAIT_1:
+    case TCP_STATE_CLOSED:
+    case TCP_STATE_CLOSE_WAIT:
       return tcp_make_established_options (tc, opts);
     case TCP_STATE_SYN_RCVD:
       return tcp_make_synack_options (tc, opts);
     case TCP_STATE_SYN_SENT:
       return tcp_make_syn_options (opts, tc->rcv_wscale);
     default:
-      clib_warning ("Not handled!");
+      clib_warning ("State not handled! %d", state);
       return 0;
     }
 }
 
 /**
- * Update snd_mss to reflect the effective segment size that we can send
- * by taking into account all TCP options, including SACKs
+ * Update burst send vars
+ *
+ * - Updates snd_mss to reflect the effective segment size that we can send
+ * by taking into account all TCP options, including SACKs.
+ * - Cache 'on the wire' options for reuse
+ * - Updates receive window which can be reused for a burst.
+ *
+ * This should *only* be called when doing bursts
  */
 void
-tcp_update_snd_mss (tcp_connection_t * tc)
+tcp_update_burst_snd_vars (tcp_connection_t * tc)
 {
+  tcp_main_t *tm = &tcp_main;
+
   /* Compute options to be used for connection. These may be reused when
    * sending data or to compute the effective mss (snd_mss) */
-  tc->snd_opts_len =
-    tcp_make_options (tc, &tc->snd_opts, TCP_STATE_ESTABLISHED);
+  tc->snd_opts_len = tcp_make_options (tc, &tc->snd_opts,
+				       TCP_STATE_ESTABLISHED);
 
   /* XXX check if MTU has been updated */
   tc->snd_mss = clib_min (tc->mss, tc->rcv_opts.mss) - tc->snd_opts_len;
   ASSERT (tc->snd_mss > 0);
+
+  tcp_options_write (tm->wrk_ctx[tc->c_thread_index].cached_opts,
+		     &tc->snd_opts);
+
+  tcp_update_rcv_wnd (tc);
 }
 
 void
@@ -436,51 +458,42 @@ tcp_init_mss (tcp_connection_t * tc)
     tc->snd_mss -= TCP_OPTION_LEN_TIMESTAMP;
 }
 
-always_inline int
-tcp_alloc_tx_buffers (tcp_main_t * tm, u8 thread_index, u32 n_free_buffers)
+static int
+tcp_alloc_tx_buffers (tcp_worker_ctx_t * wrk, u16 * n_bufs, u32 wanted)
 {
   vlib_main_t *vm = vlib_get_main ();
-  u32 current_length = vec_len (tm->tx_buffers[thread_index]);
-  u32 n_allocated;
-
-  vec_validate (tm->tx_buffers[thread_index],
-		current_length + n_free_buffers - 1);
-  n_allocated =
-    vlib_buffer_alloc (vm, &tm->tx_buffers[thread_index][current_length],
-		       n_free_buffers);
-  _vec_len (tm->tx_buffers[thread_index]) = current_length + n_allocated;
-  /* buffer shortage, report failure */
-  if (vec_len (tm->tx_buffers[thread_index]) == 0)
-    {
-      clib_warning ("out of buffers");
-      return -1;
-    }
-  return 0;
+  u32 n_alloc;
+
+  ASSERT (wanted > *n_bufs);
+  vec_validate_aligned (wrk->tx_buffers, wanted - 1, CLIB_CACHE_LINE_BYTES);
+  n_alloc = vlib_buffer_alloc (vm, &wrk->tx_buffers[*n_bufs],
+			       wanted - *n_bufs);
+  *n_bufs += n_alloc;
+  _vec_len (wrk->tx_buffers) = *n_bufs;
+  return n_alloc;
 }
 
 always_inline int
-tcp_get_free_buffer_index (tcp_main_t * tm, u32 * bidx)
+tcp_get_free_buffer_index (tcp_worker_ctx_t * wrk, u32 * bidx)
 {
-  u32 *my_tx_buffers;
-  u32 thread_index = vlib_get_thread_index ();
-  if (PREDICT_FALSE (vec_len (tm->tx_buffers[thread_index]) == 0))
+  u16 n_bufs = vec_len (wrk->tx_buffers);
+
+  TCP_DBG_BUFFER_ALLOC_MAYBE_FAIL (wrk->vm->thread_index);
+
+  if (PREDICT_FALSE (!n_bufs))
     {
-      if (tcp_alloc_tx_buffers (tm, thread_index, VLIB_FRAME_SIZE))
-	return -1;
+      if (!tcp_alloc_tx_buffers (wrk, &n_bufs, VLIB_FRAME_SIZE))
+	{
+	  *bidx = ~0;
+	  return -1;
+	}
     }
-  my_tx_buffers = tm->tx_buffers[thread_index];
-  *bidx = my_tx_buffers[vec_len (my_tx_buffers) - 1];
-  _vec_len (my_tx_buffers) -= 1;
+  *bidx = wrk->tx_buffers[--n_bufs];
+  _vec_len (wrk->tx_buffers) = n_bufs;
   return 0;
 }
 
-always_inline void
-tcp_return_buffer (tcp_main_t * tm)
-{
-  _vec_len (tm->tx_buffers[vlib_get_thread_index ()]) += 1;
-}
-
-always_inline void *
+static void *
 tcp_reuse_buffer (vlib_main_t * vm, vlib_buffer_t * b)
 {
   if (b->flags & VLIB_BUFFER_NEXT_PRESENT)
@@ -496,15 +509,16 @@ tcp_reuse_buffer (vlib_main_t * vm, vlib_buffer_t * b)
   return vlib_buffer_make_headroom (b, MAX_HDRS_LEN);
 }
 
-always_inline void *
+static void *
 tcp_init_buffer (vlib_main_t * vm, vlib_buffer_t * b)
 {
   ASSERT ((b->flags & VLIB_BUFFER_NEXT_PRESENT) == 0);
-  b->flags &= VLIB_BUFFER_FREE_LIST_INDEX_MASK;
+  b->flags &= VLIB_BUFFER_NON_DEFAULT_FREELIST;
   b->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;
   b->total_length_not_including_first_buffer = 0;
+  b->current_data = 0;
   vnet_buffer (b)->tcp.flags = 0;
-
+  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
   /* Leave enough space for headers */
   return vlib_buffer_make_headroom (b, MAX_HDRS_LEN);
 }
@@ -512,7 +526,7 @@ tcp_init_buffer (vlib_main_t * vm, vlib_buffer_t * b)
 /**
  * Prepare ACK
  */
-void
+static void
 tcp_make_ack_i (tcp_connection_t * tc, vlib_buffer_t * b, tcp_state_t state,
 		u8 flags)
 {
@@ -545,7 +559,6 @@ tcp_make_ack (tcp_connection_t * tc, vlib_buffer_t * b)
   tcp_reuse_buffer (vm, b);
   tcp_make_ack_i (tc, b, TCP_STATE_ESTABLISHED, TCP_FLAG_ACK);
   TCP_EVT_DBG (TCP_EVT_ACK_SENT, tc);
-  vnet_buffer (b)->tcp.flags = TCP_BUF_FLAG_ACK;
   tc->rcv_las = tc->rcv_nxt;
 }
 
@@ -581,7 +594,7 @@ tcp_make_syn (tcp_connection_t * tc, vlib_buffer_t * b)
   initial_wnd = tcp_initial_window_to_advertise (tc);
 
   /* Make and write options */
-  memset (&snd_opts, 0, sizeof (snd_opts));
+  clib_memset (&snd_opts, 0, sizeof (snd_opts));
   tcp_opts_len = tcp_make_syn_options (&snd_opts, tc->rcv_wscale);
   tcp_hdr_opts_len = tcp_opts_len + sizeof (tcp_header_t);
 
@@ -590,9 +603,6 @@ tcp_make_syn (tcp_connection_t * tc, vlib_buffer_t * b)
 			     initial_wnd);
   vnet_buffer (b)->tcp.connection_index = tc->c_c_index;
   tcp_options_write ((u8 *) (th + 1), &snd_opts);
-
-  tcp_timer_update (tc, TCP_TIMER_RETRANSMIT_SYN,
-		    tc->rto * TCP_TO_TIMER_TICK);
 }
 
 /**
@@ -607,7 +617,7 @@ tcp_make_synack (tcp_connection_t * tc, vlib_buffer_t * b)
   tcp_header_t *th;
   u16 initial_wnd;
 
-  memset (snd_opts, 0, sizeof (*snd_opts));
+  clib_memset (snd_opts, 0, sizeof (*snd_opts));
   tcp_reuse_buffer (vm, b);
 
   initial_wnd = tcp_initial_window_to_advertise (tc);
@@ -620,7 +630,6 @@ tcp_make_synack (tcp_connection_t * tc, vlib_buffer_t * b)
   tcp_options_write ((u8 *) (th + 1), snd_opts);
 
   vnet_buffer (b)->tcp.connection_index = tc->c_c_index;
-  vnet_buffer (b)->tcp.flags = TCP_BUF_FLAG_ACK;
 
   /* Init retransmit timer. Use update instead of set because of
    * retransmissions */
@@ -629,34 +638,29 @@ tcp_make_synack (tcp_connection_t * tc, vlib_buffer_t * b)
 }
 
 always_inline void
-tcp_enqueue_to_ip_lookup_i (vlib_main_t * vm, vlib_buffer_t * b, u32 bi,
-			    u8 is_ip4, u8 flush)
+tcp_enqueue_to_ip_lookup_i (tcp_worker_ctx_t * wrk, vlib_buffer_t * b, u32 bi,
+			    u8 is_ip4, u32 fib_index, u8 flush)
 {
-  tcp_main_t *tm = vnet_get_tcp_main ();
-  u32 thread_index = vlib_get_thread_index ();
+  vlib_main_t *vm = wrk->vm;
   u32 *to_next, next_index;
   vlib_frame_t *f;
 
   b->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;
   b->error = 0;
 
-  /* Default FIB for now */
-  vnet_buffer (b)->sw_if_index[VLIB_TX] = 0;
+  vnet_buffer (b)->sw_if_index[VLIB_TX] = fib_index;
+  vnet_buffer (b)->sw_if_index[VLIB_RX] = 0;
 
   /* Send to IP lookup */
   next_index = is_ip4 ? ip4_lookup_node.index : ip6_lookup_node.index;
-  if (VLIB_BUFFER_TRACE_TRAJECTORY > 0)
-    {
-      b->pre_data[0] = 2;
-      b->pre_data[1] = next_index;
-    }
+  tcp_trajectory_add_start (b, 1);
 
-  f = tm->ip_lookup_tx_frames[!is_ip4][thread_index];
+  f = wrk->ip_lookup_tx_frames[!is_ip4];
   if (!f)
     {
       f = vlib_get_frame_to_node (vm, next_index);
       ASSERT (f);
-      tm->ip_lookup_tx_frames[!is_ip4][thread_index] = f;
+      wrk->ip_lookup_tx_frames[!is_ip4] = f;
     }
 
   to_next = vlib_frame_vector_args (f);
@@ -665,30 +669,30 @@ tcp_enqueue_to_ip_lookup_i (vlib_main_t * vm, vlib_buffer_t * b, u32 bi,
   if (flush || f->n_vectors == VLIB_FRAME_SIZE)
     {
       vlib_put_frame_to_node (vm, next_index, f);
-      tm->ip_lookup_tx_frames[!is_ip4][thread_index] = 0;
+      wrk->ip_lookup_tx_frames[!is_ip4] = 0;
     }
 }
 
-always_inline void
-tcp_enqueue_to_ip_lookup_now (vlib_main_t * vm, vlib_buffer_t * b, u32 bi,
-			      u8 is_ip4)
+static void
+tcp_enqueue_to_ip_lookup_now (tcp_worker_ctx_t * wrk, vlib_buffer_t * b,
+			      u32 bi, u8 is_ip4, u32 fib_index)
 {
-  tcp_enqueue_to_ip_lookup_i (vm, b, bi, is_ip4, 1);
+  tcp_enqueue_to_ip_lookup_i (wrk, b, bi, is_ip4, fib_index, 1);
 }
 
-always_inline void
-tcp_enqueue_to_ip_lookup (vlib_main_t * vm, vlib_buffer_t * b, u32 bi,
-			  u8 is_ip4)
+static void
+tcp_enqueue_to_ip_lookup (tcp_worker_ctx_t * wrk, vlib_buffer_t * b, u32 bi,
+			  u8 is_ip4, u32 fib_index)
 {
-  tcp_enqueue_to_ip_lookup_i (vm, b, bi, is_ip4, 0);
+  tcp_enqueue_to_ip_lookup_i (wrk, b, bi, is_ip4, fib_index, 0);
+  if (wrk->vm->thread_index == 0 && vlib_num_workers ())
+    session_flush_frames_main_thread (wrk->vm);
 }
 
 always_inline void
-tcp_enqueue_to_output_i (vlib_main_t * vm, vlib_buffer_t * b, u32 bi,
+tcp_enqueue_to_output_i (tcp_worker_ctx_t * wrk, vlib_buffer_t * b, u32 bi,
 			 u8 is_ip4, u8 flush)
 {
-  tcp_main_t *tm = vnet_get_tcp_main ();
-  u32 thread_index = vlib_get_thread_index ();
   u32 *to_next, next_index;
   vlib_frame_t *f;
 
@@ -697,44 +701,41 @@ tcp_enqueue_to_output_i (vlib_main_t * vm, vlib_buffer_t * b, u32 bi,
 
   /* Decide where to send the packet */
   next_index = is_ip4 ? tcp4_output_node.index : tcp6_output_node.index;
-  if (VLIB_BUFFER_TRACE_TRAJECTORY > 0)
-    {
-      b->pre_data[0] = 1;
-      b->pre_data[1] = next_index;
-    }
+  tcp_trajectory_add_start (b, 2);
 
   /* Get frame to v4/6 output node */
-  f = tm->tx_frames[!is_ip4][thread_index];
+  f = wrk->tx_frames[!is_ip4];
   if (!f)
     {
-      f = vlib_get_frame_to_node (vm, next_index);
+      f = vlib_get_frame_to_node (wrk->vm, next_index);
       ASSERT (f);
-      tm->tx_frames[!is_ip4][thread_index] = f;
+      wrk->tx_frames[!is_ip4] = f;
     }
   to_next = vlib_frame_vector_args (f);
   to_next[f->n_vectors] = bi;
   f->n_vectors += 1;
   if (flush || f->n_vectors == VLIB_FRAME_SIZE)
     {
-      vlib_put_frame_to_node (vm, next_index, f);
-      tm->tx_frames[!is_ip4][thread_index] = 0;
+      vlib_put_frame_to_node (wrk->vm, next_index, f);
+      wrk->tx_frames[!is_ip4] = 0;
     }
 }
 
-always_inline void
-tcp_enqueue_to_output (vlib_main_t * vm, vlib_buffer_t * b, u32 bi, u8 is_ip4)
+static void
+tcp_enqueue_to_output (tcp_worker_ctx_t * wrk, vlib_buffer_t * b, u32 bi,
+		       u8 is_ip4)
 {
-  tcp_enqueue_to_output_i (vm, b, bi, is_ip4, 0);
+  tcp_enqueue_to_output_i (wrk, b, bi, is_ip4, 0);
 }
 
-always_inline void
-tcp_enqueue_to_output_now (vlib_main_t * vm, vlib_buffer_t * b, u32 bi,
+static void
+tcp_enqueue_to_output_now (tcp_worker_ctx_t * wrk, vlib_buffer_t * b, u32 bi,
 			   u8 is_ip4)
 {
-  tcp_enqueue_to_output_i (vm, b, bi, is_ip4, 1);
+  tcp_enqueue_to_output_i (wrk, b, bi, is_ip4, 1);
 }
 
-int
+static int
 tcp_make_reset_in_place (vlib_main_t * vm, vlib_buffer_t * b0,
 			 tcp_state_t state, u8 thread_index, u8 is_ip4)
 {
@@ -791,6 +792,7 @@ tcp_make_reset_in_place (vlib_main_t * vm, vlib_buffer_t * b0,
     }
 
   tcp_reuse_buffer (vm, b0);
+  tcp_trajectory_add_start (b0, 4);
   th0 = vlib_buffer_push_tcp_net_order (b0, dst_port, src_port, seq, ack,
 					sizeof (tcp_header_t), flags, 0);
 
@@ -820,20 +822,24 @@ tcp_make_reset_in_place (vlib_main_t * vm, vlib_buffer_t * b0,
 void
 tcp_send_reset_w_pkt (tcp_connection_t * tc, vlib_buffer_t * pkt, u8 is_ip4)
 {
+  tcp_worker_ctx_t *wrk = tcp_get_worker (tc->c_thread_index);
+  vlib_main_t *vm = wrk->vm;
   vlib_buffer_t *b;
-  u32 bi;
-  tcp_main_t *tm = vnet_get_tcp_main ();
-  vlib_main_t *vm = vlib_get_main ();
+  u32 bi, sw_if_index, fib_index;
   u8 tcp_hdr_len, flags = 0;
   tcp_header_t *th, *pkt_th;
   u32 seq, ack;
   ip4_header_t *ih4, *pkt_ih4;
   ip6_header_t *ih6, *pkt_ih6;
+  fib_protocol_t fib_proto;
 
-  if (PREDICT_FALSE (tcp_get_free_buffer_index (tm, &bi)))
+  if (PREDICT_FALSE (tcp_get_free_buffer_index (wrk, &bi)))
     return;
 
   b = vlib_get_buffer (vm, bi);
+  sw_if_index = vnet_buffer (pkt)->sw_if_index[VLIB_RX];
+  fib_proto = is_ip4 ? FIB_PROTOCOL_IP4 : FIB_PROTOCOL_IP6;
+  fib_index = fib_table_get_index_for_sw_if_index (fib_proto, sw_if_index);
   tcp_init_buffer (vm, b);
 
   /* Make and write options */
@@ -854,7 +860,7 @@ tcp_send_reset_w_pkt (tcp_connection_t * tc, vlib_buffer_t * pkt, u8 is_ip4)
     {
       flags = TCP_FLAG_RST;
       seq = pkt_th->ack_number;
-      ack = (tc && tc->state >= TCP_STATE_SYN_RCVD) ? tc->rcv_nxt : 0;
+      ack = (tc->state >= TCP_STATE_SYN_RCVD) ? tc->rcv_nxt : 0;
     }
   else
     {
@@ -885,7 +891,7 @@ tcp_send_reset_w_pkt (tcp_connection_t * tc, vlib_buffer_t * pkt, u8 is_ip4)
       ASSERT (!bogus);
     }
 
-  tcp_enqueue_to_ip_lookup_now (vm, b, bi, is_ip4);
+  tcp_enqueue_to_ip_lookup_now (wrk, b, bi, is_ip4, fib_index);
   TCP_EVT_DBG (TCP_EVT_RST_SENT, tc);
 }
 
@@ -895,15 +901,15 @@ tcp_send_reset_w_pkt (tcp_connection_t * tc, vlib_buffer_t * pkt, u8 is_ip4)
 void
 tcp_send_reset (tcp_connection_t * tc)
 {
-  vlib_main_t *vm = vlib_get_main ();
-  tcp_main_t *tm = vnet_get_tcp_main ();
+  tcp_worker_ctx_t *wrk = tcp_get_worker (tc->c_thread_index);
+  vlib_main_t *vm = wrk->vm;
   vlib_buffer_t *b;
   u32 bi;
   tcp_header_t *th;
   u16 tcp_hdr_opts_len, advertise_wnd, opts_write_len;
   u8 flags;
 
-  if (PREDICT_FALSE (tcp_get_free_buffer_index (tm, &bi)))
+  if (PREDICT_FALSE (tcp_get_free_buffer_index (wrk, &bi)))
     return;
   b = vlib_get_buffer (vm, bi);
   tcp_init_buffer (vm, b);
@@ -934,15 +940,16 @@ tcp_send_reset (tcp_connection_t * tc)
       th->checksum = ip6_tcp_udp_icmp_compute_checksum (vm, b, ih6, &bogus);
       ASSERT (!bogus);
     }
-  tcp_enqueue_to_ip_lookup_now (vm, b, bi, tc->c_is_ip4);
+  tcp_enqueue_to_ip_lookup_now (wrk, b, bi, tc->c_is_ip4, tc->c_fib_index);
   TCP_EVT_DBG (TCP_EVT_RST_SENT, tc);
 }
 
-void
-tcp_push_ip_hdr (tcp_main_t * tm, tcp_connection_t * tc, vlib_buffer_t * b)
+static void
+tcp_push_ip_hdr (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
+		 vlib_buffer_t * b)
 {
   tcp_header_t *th = vlib_buffer_get_current (b);
-  vlib_main_t *vm = vlib_get_main ();
+  vlib_main_t *vm = wrk->vm;
   if (tc->c_is_ip4)
     {
       ip4_header_t *ih;
@@ -972,12 +979,20 @@ tcp_push_ip_hdr (tcp_main_t * tm, tcp_connection_t * tc, vlib_buffer_t * b)
 void
 tcp_send_syn (tcp_connection_t * tc)
 {
+  tcp_worker_ctx_t *wrk = tcp_get_worker (tc->c_thread_index);
+  vlib_main_t *vm = wrk->vm;
   vlib_buffer_t *b;
   u32 bi;
-  tcp_main_t *tm = vnet_get_tcp_main ();
-  vlib_main_t *vm = vlib_get_main ();
 
-  if (PREDICT_FALSE (tcp_get_free_buffer_index (tm, &bi)))
+  /*
+   * Setup retransmit and establish timers before requesting buffer
+   * such that we can return if we've ran out.
+   */
+  tcp_timer_set (tc, TCP_TIMER_ESTABLISH, TCP_ESTABLISH_TIME);
+  tcp_timer_update (tc, TCP_TIMER_RETRANSMIT_SYN,
+		    tc->rto * TCP_TO_TIMER_TICK);
+
+  if (PREDICT_FALSE (tcp_get_free_buffer_index (wrk, &bi)))
     return;
 
   b = vlib_get_buffer (vm, bi);
@@ -989,44 +1004,56 @@ tcp_send_syn (tcp_connection_t * tc)
   tc->rtt_seq = tc->snd_nxt;
   tc->rto_boff = 0;
 
-  /* Set the connection establishment timer */
-  tcp_timer_set (tc, TCP_TIMER_ESTABLISH, TCP_ESTABLISH_TIME);
-
-  tcp_push_ip_hdr (tm, tc, b);
-  tcp_enqueue_to_ip_lookup (vm, b, bi, tc->c_is_ip4);
+  tcp_push_ip_hdr (wrk, tc, b);
+  tcp_enqueue_to_ip_lookup (wrk, b, bi, tc->c_is_ip4, tc->c_fib_index);
   TCP_EVT_DBG (TCP_EVT_SYN_SENT, tc);
 }
 
+void
+tcp_send_synack (tcp_connection_t * tc)
+{
+  tcp_worker_ctx_t *wrk = tcp_get_worker (tc->c_thread_index);
+  vlib_main_t *vm = wrk->vm;
+  vlib_buffer_t *b;
+  u32 bi;
+
+  /* Get buffer */
+  if (PREDICT_FALSE (tcp_get_free_buffer_index (wrk, &bi)))
+    return;
+
+  b = vlib_get_buffer (vm, bi);
+  tcp_make_synack (tc, b);
+  tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
+}
+
 /**
  * Flush tx frame populated by retransmits and timer pops
  */
 void
-tcp_flush_frame_to_output (vlib_main_t * vm, u8 thread_index, u8 is_ip4)
+tcp_flush_frame_to_output (tcp_worker_ctx_t * wrk, u8 is_ip4)
 {
-  if (tcp_main.tx_frames[!is_ip4][thread_index])
+  if (wrk->tx_frames[!is_ip4])
     {
       u32 next_index;
       next_index = is_ip4 ? tcp4_output_node.index : tcp6_output_node.index;
-      vlib_put_frame_to_node (vm, next_index,
-			      tcp_main.tx_frames[!is_ip4][thread_index]);
-      tcp_main.tx_frames[!is_ip4][thread_index] = 0;
+      vlib_put_frame_to_node (wrk->vm, next_index, wrk->tx_frames[!is_ip4]);
+      wrk->tx_frames[!is_ip4] = 0;
     }
 }
 
 /**
  * Flush ip lookup tx frames populated by timer pops
  */
-always_inline void
-tcp_flush_frame_to_ip_lookup (vlib_main_t * vm, u8 thread_index, u8 is_ip4)
+static void
+tcp_flush_frame_to_ip_lookup (tcp_worker_ctx_t * wrk, u8 is_ip4)
 {
-  if (tcp_main.ip_lookup_tx_frames[!is_ip4][thread_index])
+  if (wrk->ip_lookup_tx_frames[!is_ip4])
     {
       u32 next_index;
       next_index = is_ip4 ? ip4_lookup_node.index : ip6_lookup_node.index;
-      vlib_put_frame_to_node (vm, next_index,
-			      tcp_main.ip_lookup_tx_frames[!is_ip4]
-			      [thread_index]);
-      tcp_main.ip_lookup_tx_frames[!is_ip4][thread_index] = 0;
+      vlib_put_frame_to_node (wrk->vm, next_index,
+			      wrk->ip_lookup_tx_frames[!is_ip4]);
+      wrk->ip_lookup_tx_frames[!is_ip4] = 0;
     }
 }
 
@@ -1034,13 +1061,12 @@ tcp_flush_frame_to_ip_lookup (vlib_main_t * vm, u8 thread_index, u8 is_ip4)
  * Flush v4 and v6 tcp and ip-lookup tx frames for thread index
  */
 void
-tcp_flush_frames_to_output (u8 thread_index)
+tcp_flush_frames_to_output (tcp_worker_ctx_t * wrk)
 {
-  vlib_main_t *vm = vlib_get_main ();
-  tcp_flush_frame_to_output (vm, thread_index, 1);
-  tcp_flush_frame_to_output (vm, thread_index, 0);
-  tcp_flush_frame_to_ip_lookup (vm, thread_index, 1);
-  tcp_flush_frame_to_ip_lookup (vm, thread_index, 0);
+  tcp_flush_frame_to_output (wrk, 1);
+  tcp_flush_frame_to_output (wrk, 0);
+  tcp_flush_frame_to_ip_lookup (wrk, 1);
+  tcp_flush_frame_to_ip_lookup (wrk, 0);
 }
 
 /**
@@ -1049,20 +1075,31 @@ tcp_flush_frames_to_output (u8 thread_index)
 void
 tcp_send_fin (tcp_connection_t * tc)
 {
-  tcp_main_t *tm = vnet_get_tcp_main ();
-  vlib_main_t *vm = vlib_get_main ();
+  tcp_worker_ctx_t *wrk = tcp_get_worker (tc->c_thread_index);
+  vlib_main_t *vm = wrk->vm;
   vlib_buffer_t *b;
   u32 bi;
   u8 fin_snt = 0;
 
-  if (PREDICT_FALSE (tcp_get_free_buffer_index (tm, &bi)))
-    return;
-  b = vlib_get_buffer (vm, bi);
   fin_snt = tc->flags & TCP_CONN_FINSNT;
   if (fin_snt)
     tc->snd_nxt = tc->snd_una;
+
+  if (PREDICT_FALSE (tcp_get_free_buffer_index (wrk, &bi)))
+    {
+      /* Out of buffers so program fin retransmit ASAP */
+      tcp_timer_update (tc, TCP_TIMER_RETRANSMIT, 1);
+      goto post_enqueue;
+    }
+
+  tcp_retransmit_timer_force_update (tc);
+  b = vlib_get_buffer (vm, bi);
+  tcp_init_buffer (vm, b);
   tcp_make_fin (tc, b);
-  tcp_enqueue_to_output_now (vm, b, bi, tc->c_is_ip4);
+  tcp_enqueue_to_output_now (wrk, b, bi, tc->c_is_ip4);
+  TCP_EVT_DBG (TCP_EVT_FIN_SENT, tc);
+
+post_enqueue:
   if (!fin_snt)
     {
       tc->flags |= TCP_CONN_FINSNT;
@@ -1075,8 +1112,6 @@ tcp_send_fin (tcp_connection_t * tc)
     {
       tc->snd_nxt = tc->snd_una_max;
     }
-  tcp_retransmit_timer_force_update (tc);
-  TCP_EVT_DBG (TCP_EVT_FIN_SENT, tc);
 }
 
 always_inline u8
@@ -1085,6 +1120,7 @@ tcp_make_state_flags (tcp_connection_t * tc, tcp_state_t next_state)
   switch (next_state)
     {
     case TCP_STATE_ESTABLISHED:
+    case TCP_STATE_CLOSE_WAIT:
       return TCP_FLAG_ACK;
     case TCP_STATE_SYN_RCVD:
       return TCP_FLAG_SYN | TCP_FLAG_ACK;
@@ -1105,34 +1141,49 @@ tcp_make_state_flags (tcp_connection_t * tc, tcp_state_t next_state)
 /**
  * Push TCP header and update connection variables
  */
-static void
+always_inline void
 tcp_push_hdr_i (tcp_connection_t * tc, vlib_buffer_t * b,
-		tcp_state_t next_state, u8 compute_opts)
+		tcp_state_t next_state, u8 compute_opts, u8 maybe_burst)
 {
   u32 advertise_wnd, data_len;
-  u8 tcp_hdr_opts_len, opts_write_len, flags;
+  u8 tcp_hdr_opts_len, flags;
+  tcp_main_t *tm = &tcp_main;
   tcp_header_t *th;
 
-  data_len = b->current_length + b->total_length_not_including_first_buffer;
-  ASSERT (!b->total_length_not_including_first_buffer
-	  || (b->flags & VLIB_BUFFER_NEXT_PRESENT));
+  data_len = b->current_length;
+  if (PREDICT_FALSE (b->flags & VLIB_BUFFER_NEXT_PRESENT))
+    data_len += b->total_length_not_including_first_buffer;
+
   vnet_buffer (b)->tcp.flags = 0;
+  vnet_buffer (b)->tcp.connection_index = tc->c_c_index;
 
   if (compute_opts)
     tc->snd_opts_len = tcp_make_options (tc, &tc->snd_opts, tc->state);
 
   tcp_hdr_opts_len = tc->snd_opts_len + sizeof (tcp_header_t);
-  advertise_wnd = tcp_window_to_advertise (tc, next_state);
+
+  if (maybe_burst)
+    advertise_wnd = tc->rcv_wnd >> tc->rcv_wscale;
+  else
+    advertise_wnd = tcp_window_to_advertise (tc, next_state);
+
   flags = tcp_make_state_flags (tc, next_state);
 
-  /* Push header and options */
   th = vlib_buffer_push_tcp (b, tc->c_lcl_port, tc->c_rmt_port, tc->snd_nxt,
 			     tc->rcv_nxt, tcp_hdr_opts_len, flags,
 			     advertise_wnd);
-  opts_write_len = tcp_options_write ((u8 *) (th + 1), &tc->snd_opts);
 
-  ASSERT (opts_write_len == tc->snd_opts_len);
-  vnet_buffer (b)->tcp.connection_index = tc->c_c_index;
+  if (maybe_burst)
+    {
+      clib_memcpy ((u8 *) (th + 1),
+		   tm->wrk_ctx[tc->c_thread_index].cached_opts,
+		   tc->snd_opts_len);
+    }
+  else
+    {
+      u8 len = tcp_options_write ((u8 *) (th + 1), &tc->snd_opts);
+      ASSERT (len == tc->snd_opts_len);
+    }
 
   /*
    * Update connection variables
@@ -1141,33 +1192,100 @@ tcp_push_hdr_i (tcp_connection_t * tc, vlib_buffer_t * b,
   tc->snd_nxt += data_len;
   tc->rcv_las = tc->rcv_nxt;
 
-  /* TODO this is updated in output as well ... */
-  if (seq_gt (tc->snd_nxt, tc->snd_una_max))
+  TCP_EVT_DBG (TCP_EVT_PKTIZE, tc);
+}
+
+u32
+tcp_push_header (tcp_connection_t * tc, vlib_buffer_t * b)
+{
+  tcp_push_hdr_i (tc, b, TCP_STATE_ESTABLISHED, /* compute opts */ 0,
+		  /* burst */ 1);
+  tc->snd_una_max = tc->snd_nxt;
+  ASSERT (seq_leq (tc->snd_una_max, tc->snd_una + tc->snd_wnd
+		   + tcp_fastrecovery_sent_1_smss (tc) * tc->snd_mss));
+  tcp_validate_txf_size (tc, tc->snd_una_max - tc->snd_una);
+  /* If not tracking an ACK, start tracking */
+  if (tc->rtt_ts == 0 && !tcp_in_cong_recovery (tc))
     {
-      tc->snd_una_max = tc->snd_nxt;
-      tcp_validate_txf_size (tc, tc->snd_una_max - tc->snd_una);
+      tc->rtt_ts = tcp_time_now_us (tc->c_thread_index);
+      tc->rtt_seq = tc->snd_nxt;
     }
-
-  TCP_EVT_DBG (TCP_EVT_PKTIZE, tc);
+  if (PREDICT_FALSE (!tcp_timer_is_active (tc, TCP_TIMER_RETRANSMIT)))
+    {
+      tcp_retransmit_timer_set (tc);
+      tc->rto_boff = 0;
+    }
+  tcp_trajectory_add_start (b, 3);
+  return 0;
 }
 
 void
 tcp_send_ack (tcp_connection_t * tc)
 {
-  tcp_main_t *tm = vnet_get_tcp_main ();
-  vlib_main_t *vm = vlib_get_main ();
-
+  tcp_worker_ctx_t *wrk = tcp_get_worker (tc->c_thread_index);
+  vlib_main_t *vm = wrk->vm;
   vlib_buffer_t *b;
   u32 bi;
 
   /* Get buffer */
-  if (PREDICT_FALSE (tcp_get_free_buffer_index (tm, &bi)))
+  if (PREDICT_FALSE (tcp_get_free_buffer_index (wrk, &bi)))
     return;
   b = vlib_get_buffer (vm, bi);
+  tcp_init_buffer (vm, b);
 
   /* Fill in the ACK */
   tcp_make_ack (tc, b);
-  tcp_enqueue_to_output (vm, b, bi, tc->c_is_ip4);
+  tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
+}
+
+void
+tcp_program_ack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc)
+{
+  if (!(tc->flags & TCP_CONN_SNDACK))
+    {
+      vec_add1 (wrk->pending_acks, tc->c_c_index);
+      tc->flags |= TCP_CONN_SNDACK;
+    }
+}
+
+void
+tcp_program_dupack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc)
+{
+  if (!(tc->flags & TCP_CONN_SNDACK))
+    {
+      vec_add1 (wrk->pending_acks, tc->c_c_index);
+      tc->flags |= TCP_CONN_SNDACK;
+    }
+  if (tc->pending_dupacks < 255)
+    tc->pending_dupacks += 1;
+}
+
+void
+tcp_send_acks (tcp_worker_ctx_t * wrk)
+{
+  u32 thread_index, *pending_acks;
+  tcp_connection_t *tc;
+  int i, j, n_acks;
+
+  if (!vec_len (wrk->pending_acks))
+    return;
+
+  thread_index = wrk->vm->thread_index;
+  pending_acks = wrk->pending_acks;
+  for (i = 0; i < vec_len (pending_acks); i++)
+    {
+      tc = tcp_connection_get (pending_acks[i], thread_index);
+      tc->flags &= ~TCP_CONN_SNDACK;
+      n_acks = clib_max (1, tc->pending_dupacks);
+      /* If we're supposed to send dupacks but have no ooo data
+       * send only one ack */
+      if (tc->pending_dupacks && !vec_len (tc->snd_sacks))
+	n_acks = 1;
+      for (j = 0; j < n_acks; j++)
+	tcp_send_ack (tc);
+      tc->pending_dupacks = 0;
+    }
+  _vec_len (wrk->pending_acks) = 0;
 }
 
 /**
@@ -1187,48 +1305,27 @@ tcp_timer_delack_handler (u32 index)
 }
 
 /**
- * Build a retransmit segment
+ * Allocate a new buffer and build a new tcp segment
  *
- * @return the number of bytes in the segment or 0 if there's nothing to
- *         retransmit
+ * @param wrk		tcp worker
+ * @param tc		connection for which the segment will be allocated
+ * @param offset	offset of the first byte in the tx fifo
+ * @param max_deq_byte	segment size
+ * @param[out] b	pointer to buffer allocated
+ *
+ * @return 	the number of bytes in the segment or 0 if buffer cannot be
+ * 		allocated or no data available
  */
-u32
-tcp_prepare_retransmit_segment (tcp_connection_t * tc, u32 offset,
-				u32 max_deq_bytes, vlib_buffer_t ** b)
+static int
+tcp_prepare_segment (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
+		     u32 offset, u32 max_deq_bytes, vlib_buffer_t ** b)
 {
-  tcp_main_t *tm = vnet_get_tcp_main ();
-  vlib_main_t *vm = vlib_get_main ();
+  u32 bytes_per_buffer = vnet_get_tcp_main ()->bytes_per_buffer;
+  u32 bi, seg_size;
+  vlib_main_t *vm = wrk->vm;
   int n_bytes = 0;
-  u32 start, bi, available_bytes, seg_size;
   u8 *data;
 
-  ASSERT (tc->state >= TCP_STATE_ESTABLISHED);
-  ASSERT (max_deq_bytes != 0);
-
-  /*
-   * Make sure we can retransmit something
-   */
-  available_bytes = stream_session_tx_fifo_max_dequeue (&tc->connection);
-  ASSERT (available_bytes >= offset);
-  available_bytes -= offset;
-  if (!available_bytes)
-    return 0;
-  max_deq_bytes = clib_min (tc->snd_mss, max_deq_bytes);
-  max_deq_bytes = clib_min (available_bytes, max_deq_bytes);
-
-  /* Start is beyond snd_congestion */
-  start = tc->snd_una + offset;
-  if (seq_geq (start, tc->snd_congestion))
-    goto done;
-
-  /* Don't overshoot snd_congestion */
-  if (seq_gt (start + max_deq_bytes, tc->snd_congestion))
-    {
-      max_deq_bytes = tc->snd_congestion - start;
-      if (max_deq_bytes == 0)
-	goto done;
-    }
-
   seg_size = max_deq_bytes + MAX_HDRS_LEN;
 
   /*
@@ -1240,47 +1337,48 @@ tcp_prepare_retransmit_segment (tcp_connection_t * tc, u32 offset,
    * Allocate and fill in buffer(s)
    */
 
-  if (PREDICT_FALSE (tcp_get_free_buffer_index (tm, &bi)))
-    return 0;
-  *b = vlib_get_buffer (vm, bi);
-  data = tcp_init_buffer (vm, *b);
-
   /* Easy case, buffer size greater than mss */
-  if (PREDICT_TRUE (seg_size <= tm->bytes_per_buffer))
+  if (PREDICT_TRUE (seg_size <= bytes_per_buffer))
     {
+      if (PREDICT_FALSE (tcp_get_free_buffer_index (wrk, &bi)))
+	return 0;
+      *b = vlib_get_buffer (vm, bi);
+      data = tcp_init_buffer (vm, *b);
       n_bytes = stream_session_peek_bytes (&tc->connection, data, offset,
 					   max_deq_bytes);
       ASSERT (n_bytes == max_deq_bytes);
       b[0]->current_length = n_bytes;
-      tcp_push_hdr_i (tc, *b, tc->state, 0);
+      tcp_push_hdr_i (tc, *b, tc->state, /* compute opts */ 0, /* burst */ 0);
+      if (seq_gt (tc->snd_nxt, tc->snd_una_max))
+	tc->snd_una_max = tc->snd_nxt;
     }
   /* Split mss into multiple buffers */
   else
     {
       u32 chain_bi = ~0, n_bufs_per_seg;
-      u32 thread_index = vlib_get_thread_index ();
       u16 n_peeked, len_to_deq, available_bufs;
       vlib_buffer_t *chain_b, *prev_b;
       int i;
 
-      n_bufs_per_seg = ceil ((double) seg_size / tm->bytes_per_buffer);
-
       /* Make sure we have enough buffers */
-      available_bufs = vec_len (tm->tx_buffers[thread_index]);
+      n_bufs_per_seg = ceil ((double) seg_size / bytes_per_buffer);
+      available_bufs = vec_len (wrk->tx_buffers);
       if (n_bufs_per_seg > available_bufs)
 	{
-	  if (tcp_alloc_tx_buffers (tm, thread_index,
-				    VLIB_FRAME_SIZE - available_bufs))
+	  tcp_alloc_tx_buffers (wrk, &available_bufs, VLIB_FRAME_SIZE);
+	  if (n_bufs_per_seg > available_bufs)
 	    {
-	      tcp_return_buffer (tm);
 	      *b = 0;
 	      return 0;
 	    }
 	}
 
+      (void) tcp_get_free_buffer_index (wrk, &bi);
+      ASSERT (bi != (u32) ~ 0);
+      *b = vlib_get_buffer (vm, bi);
+      data = tcp_init_buffer (vm, *b);
       n_bytes = stream_session_peek_bytes (&tc->connection, data, offset,
-					   tm->bytes_per_buffer -
-					   MAX_HDRS_LEN);
+					   bytes_per_buffer - MAX_HDRS_LEN);
       b[0]->current_length = n_bytes;
       b[0]->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
       b[0]->total_length_not_including_first_buffer = 0;
@@ -1290,8 +1388,8 @@ tcp_prepare_retransmit_segment (tcp_connection_t * tc, u32 offset,
       for (i = 1; i < n_bufs_per_seg; i++)
 	{
 	  prev_b = chain_b;
-	  len_to_deq = clib_min (max_deq_bytes, tm->bytes_per_buffer);
-	  tcp_get_free_buffer_index (tm, &chain_bi);
+	  len_to_deq = clib_min (max_deq_bytes, bytes_per_buffer);
+	  tcp_get_free_buffer_index (wrk, &chain_bi);
 	  ASSERT (chain_bi != (u32) ~ 0);
 	  chain_b = vlib_get_buffer (vm, chain_bi);
 	  chain_b->current_data = 0;
@@ -1301,7 +1399,6 @@ tcp_prepare_retransmit_segment (tcp_connection_t * tc, u32 offset,
 	  ASSERT (n_peeked == len_to_deq);
 	  n_bytes += n_peeked;
 	  chain_b->current_length = n_peeked;
-	  chain_b->flags &= VLIB_BUFFER_FREE_LIST_INDEX_MASK;
 	  chain_b->next_buffer = 0;
 
 	  /* update previous buffer */
@@ -1312,12 +1409,62 @@ tcp_prepare_retransmit_segment (tcp_connection_t * tc, u32 offset,
 	  b[0]->total_length_not_including_first_buffer += n_peeked;
 	}
 
-      tcp_push_hdr_i (tc, *b, tc->state, 0);
+      tcp_push_hdr_i (tc, *b, tc->state, /* compute opts */ 0, /* burst */ 0);
+      if (seq_gt (tc->snd_nxt, tc->snd_una_max))
+	tc->snd_una_max = tc->snd_nxt;
     }
 
   ASSERT (n_bytes > 0);
-  ASSERT (((*b)->current_data + (*b)->current_length) <=
-	  tm->bytes_per_buffer);
+  ASSERT (((*b)->current_data + (*b)->current_length) <= bytes_per_buffer);
+
+  return n_bytes;
+}
+
+/**
+ * Build a retransmit segment
+ *
+ * @return the number of bytes in the segment or 0 if there's nothing to
+ *         retransmit
+ */
+static u32
+tcp_prepare_retransmit_segment (tcp_worker_ctx_t * wrk,
+				tcp_connection_t * tc, u32 offset,
+				u32 max_deq_bytes, vlib_buffer_t ** b)
+{
+  u32 start, available_bytes;
+  int n_bytes = 0;
+
+  ASSERT (tc->state >= TCP_STATE_ESTABLISHED);
+  ASSERT (max_deq_bytes != 0);
+
+  /*
+   * Make sure we can retransmit something
+   */
+  available_bytes = session_tx_fifo_max_dequeue (&tc->connection);
+  ASSERT (available_bytes >= offset);
+  available_bytes -= offset;
+  if (!available_bytes)
+    return 0;
+
+  max_deq_bytes = clib_min (tc->snd_mss, max_deq_bytes);
+  max_deq_bytes = clib_min (available_bytes, max_deq_bytes);
+
+  /* Start is beyond snd_congestion */
+  start = tc->snd_una + offset;
+  if (seq_geq (start, tc->snd_congestion))
+    goto done;
+
+  /* Don't overshoot snd_congestion */
+  if (seq_gt (start + max_deq_bytes, tc->snd_congestion))
+    {
+      max_deq_bytes = tc->snd_congestion - start;
+      if (max_deq_bytes == 0)
+	goto done;
+    }
+
+  n_bytes = tcp_prepare_segment (wrk, tc, offset, max_deq_bytes, b);
+  if (!n_bytes)
+    return 0;
 
   if (tcp_in_fastrecovery (tc))
     tc->snd_rxt_bytes += n_bytes;
@@ -1331,29 +1478,36 @@ done:
  * Reset congestion control, switch cwnd to loss window and try again.
  */
 static void
-tcp_rtx_timeout_cc (tcp_connection_t * tc)
+tcp_rxt_timeout_cc (tcp_connection_t * tc)
 {
+  TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 6);
   tc->prev_ssthresh = tc->ssthresh;
   tc->prev_cwnd = tc->cwnd;
 
   /* Cleanly recover cc (also clears up fast retransmit) */
   if (tcp_in_fastrecovery (tc))
-    tcp_cc_fastrecovery_exit (tc);
+    {
+      /* TODO be less aggressive about this */
+      scoreboard_clear (&tc->sack_sb);
+      tcp_cc_fastrecovery_exit (tc);
+    }
 
   /* Start again from the beginning */
-  tc->ssthresh = clib_max (tcp_flight_size (tc) / 2, 2 * tc->snd_mss);
+  tc->cc_algo->congestion (tc);
   tc->cwnd = tcp_loss_wnd (tc);
   tc->snd_congestion = tc->snd_una_max;
   tc->rtt_ts = 0;
+  tc->cwnd_acc_bytes = 0;
+  tcp_connection_tx_pacer_reset (tc, tc->cwnd, 2 * tc->snd_mss);
   tcp_recovery_on (tc);
 }
 
-static void
+static inline void
 tcp_timer_retransmit_handler_i (u32 index, u8 is_syn)
 {
-  tcp_main_t *tm = vnet_get_tcp_main ();
-  vlib_main_t *vm = vlib_get_main ();
   u32 thread_index = vlib_get_thread_index ();
+  tcp_worker_ctx_t *wrk = tcp_get_worker (thread_index);
+  vlib_main_t *vm = wrk->vm;
   tcp_connection_t *tc;
   vlib_buffer_t *b = 0;
   u32 bi, n_bytes;
@@ -1377,21 +1531,30 @@ tcp_timer_retransmit_handler_i (u32 index, u8 is_syn)
 
   if (tc->state >= TCP_STATE_ESTABLISHED)
     {
+      TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 2);
+
       /* Lost FIN, retransmit and return */
       if (tcp_is_lost_fin (tc))
 	{
 	  tcp_send_fin (tc);
+	  tc->rto_boff += 1;
+	  tc->rto = clib_min (tc->rto << 1, TCP_RTO_MAX);
 	  return;
 	}
 
-      /* Shouldn't be here */
-      if (tc->snd_una == tc->snd_una_max)
+      /* Shouldn't be here. This condition is tricky because it has to take
+       * into account boff > 0 due to persist timeout. */
+      if ((tc->rto_boff == 0 && tc->snd_una == tc->snd_una_max)
+	  || (tc->rto_boff > 0 && seq_geq (tc->snd_una, tc->snd_congestion)
+	      && !tcp_flight_size (tc)))
 	{
-	  tcp_recovery_off (tc);
+	  ASSERT (!tcp_in_recovery (tc));
+	  tc->rto_boff = 0;
 	  return;
 	}
 
-      /* We're not in recovery so make sure rto_boff is 0 */
+      /* We're not in recovery so make sure rto_boff is 0. Can be non 0 due
+       * to persist timer timeout */
       if (!tcp_in_recovery (tc) && tc->rto_boff > 0)
 	{
 	  tc->rto_boff = 0;
@@ -1404,28 +1567,24 @@ tcp_timer_retransmit_handler_i (u32 index, u8 is_syn)
 
       /* First retransmit timeout */
       if (tc->rto_boff == 1)
-	tcp_rtx_timeout_cc (tc);
-
-      tc->snd_nxt = tc->snd_una;
-      tc->rto = clib_min (tc->rto << 1, TCP_RTO_MAX);
+	tcp_rxt_timeout_cc (tc);
+      else
+	scoreboard_clear (&tc->sack_sb);
 
-      TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 1);
+      /* If we've sent beyond snd_congestion, update it */
+      if (seq_gt (tc->snd_una_max, tc->snd_congestion))
+	tc->snd_congestion = tc->snd_una_max;
 
-      /* Send one segment. Note that n_bytes may be zero due to buffer shortfall  */
-      n_bytes = tcp_prepare_retransmit_segment (tc, 0, tc->snd_mss, &b);
+      tc->snd_una_max = tc->snd_nxt = tc->snd_una;
+      tc->rto = clib_min (tc->rto << 1, TCP_RTO_MAX);
 
-      /* TODO be less aggressive about this */
-      scoreboard_clear (&tc->sack_sb);
+      /* Send one segment. Note that n_bytes may be zero due to buffer
+       * shortfall */
+      n_bytes = tcp_prepare_retransmit_segment (wrk, tc, 0, tc->snd_mss, &b);
 
       if (n_bytes == 0)
 	{
-	  ASSERT (!b);
-	  if (tc->snd_una == tc->snd_una_max)
-	    return;
-	  ASSERT (tc->rto_boff > 1 && tc->snd_una == tc->snd_congestion);
-	  clib_warning ("retransmit fail: %U", format_tcp_connection, tc, 2);
-	  /* Try again eventually */
-	  tcp_retransmit_timer_set (tc);
+	  tcp_retransmit_timer_force_update (tc);
 	  return;
 	}
 
@@ -1433,10 +1592,10 @@ tcp_timer_retransmit_handler_i (u32 index, u8 is_syn)
 
       /* For first retransmit, record timestamp (Eifel detection RFC3522) */
       if (tc->rto_boff == 1)
-	tc->snd_rxt_ts = tcp_time_now ();
+	tc->snd_rxt_ts = tcp_time_now_w_thread (tc->c_thread_index);
 
-      tcp_enqueue_to_output (vm, b, bi, tc->c_is_ip4);
-      tcp_retransmit_timer_update (tc);
+      tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
+      tcp_retransmit_timer_force_update (tc);
     }
   /* Retransmit for SYN */
   else if (tc->state == TCP_STATE_SYN_SENT)
@@ -1454,13 +1613,18 @@ tcp_timer_retransmit_handler_i (u32 index, u8 is_syn)
 	  return;
 	}
 
+      TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 2);
+
       /* Try without increasing RTO a number of times. If this fails,
        * start growing RTO exponentially */
       tc->rto_boff += 1;
       if (tc->rto_boff > TCP_RTO_SYN_RETRIES)
 	tc->rto = clib_min (tc->rto << 1, TCP_RTO_MAX);
 
-      if (PREDICT_FALSE (tcp_get_free_buffer_index (tm, &bi)))
+      tcp_timer_update (tc, TCP_TIMER_RETRANSMIT_SYN,
+			tc->rto * TCP_TO_TIMER_TICK);
+
+      if (PREDICT_FALSE (tcp_get_free_buffer_index (wrk, &bi)))
 	return;
 
       b = vlib_get_buffer (vm, bi);
@@ -1471,32 +1635,36 @@ tcp_timer_retransmit_handler_i (u32 index, u8 is_syn)
       TCP_EVT_DBG (TCP_EVT_SYN_RXT, tc, 0);
 
       /* This goes straight to ipx_lookup. Retransmit timer set already */
-      tcp_push_ip_hdr (tm, tc, b);
-      tcp_enqueue_to_ip_lookup (vm, b, bi, tc->c_is_ip4);
+      tcp_push_ip_hdr (wrk, tc, b);
+      tcp_enqueue_to_ip_lookup (wrk, b, bi, tc->c_is_ip4, tc->c_fib_index);
     }
   /* Retransmit SYN-ACK */
   else if (tc->state == TCP_STATE_SYN_RCVD)
     {
+      TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 2);
+
       tc->rto_boff += 1;
       if (tc->rto_boff > TCP_RTO_SYN_RETRIES)
 	tc->rto = clib_min (tc->rto << 1, TCP_RTO_MAX);
       tc->rtt_ts = 0;
 
-      if (PREDICT_FALSE (tcp_get_free_buffer_index (tm, &bi)))
-	return;
+      if (PREDICT_FALSE (tcp_get_free_buffer_index (wrk, &bi)))
+	{
+	  tcp_retransmit_timer_force_update (tc);
+	  return;
+	}
 
       b = vlib_get_buffer (vm, bi);
+      tcp_init_buffer (vm, b);
       tcp_make_synack (tc, b);
       TCP_EVT_DBG (TCP_EVT_SYN_RXT, tc, 1);
 
       /* Retransmit timer already updated, just enqueue to output */
-      tcp_enqueue_to_output (vm, b, bi, tc->c_is_ip4);
+      tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
     }
   else
     {
       ASSERT (tc->state == TCP_STATE_CLOSED);
-      if (CLIB_DEBUG)
-	TCP_DBG ("connection state: %U", format_tcp_connection, tc, 2);
       return;
     }
 }
@@ -1520,12 +1688,13 @@ tcp_timer_retransmit_syn_handler (u32 index)
 void
 tcp_timer_persist_handler (u32 index)
 {
-  tcp_main_t *tm = vnet_get_tcp_main ();
-  vlib_main_t *vm = vlib_get_main ();
   u32 thread_index = vlib_get_thread_index ();
+  tcp_worker_ctx_t *wrk = tcp_get_worker (thread_index);
+  u32 bi, max_snd_bytes, available_bytes, offset;
+  tcp_main_t *tm = vnet_get_tcp_main ();
+  vlib_main_t *vm = wrk->vm;
   tcp_connection_t *tc;
   vlib_buffer_t *b;
-  u32 bi, max_snd_bytes, available_bytes, offset;
   int n_bytes = 0;
   u8 *data;
 
@@ -1542,7 +1711,7 @@ tcp_timer_persist_handler (u32 index)
       || tc->snd_wnd > tc->snd_mss || tcp_in_recovery (tc))
     return;
 
-  available_bytes = stream_session_tx_fifo_max_dequeue (&tc->connection);
+  available_bytes = session_tx_fifo_max_dequeue (&tc->connection);
   offset = tc->snd_una_max - tc->snd_una;
 
   /* Reprogram persist if no new bytes available to send. We may have data
@@ -1566,8 +1735,11 @@ tcp_timer_persist_handler (u32 index)
   /*
    * Try to force the first unsent segment (or buffer)
    */
-  if (PREDICT_FALSE (tcp_get_free_buffer_index (tm, &bi)))
-    return;
+  if (PREDICT_FALSE (tcp_get_free_buffer_index (wrk, &bi)))
+    {
+      tcp_persist_timer_set (tc);
+      return;
+    }
   b = vlib_get_buffer (vm, bi);
   data = tcp_init_buffer (vm, b);
 
@@ -1581,8 +1753,10 @@ tcp_timer_persist_handler (u32 index)
 			   || tc->snd_nxt == tc->snd_una_max
 			   || tc->rto_boff > 1));
 
-  tcp_push_hdr_i (tc, b, tc->state, 0);
-  tcp_enqueue_to_output (vm, b, bi, tc->c_is_ip4);
+  tcp_push_hdr_i (tc, b, tc->state, /* compute opts */ 0, /* burst */ 0);
+  tc->snd_una_max = tc->snd_nxt;
+  tcp_validate_txf_size (tc, tc->snd_una_max - tc->snd_una);
+  tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
 
   /* Just sent new data, enable retransmit */
   tcp_retransmit_timer_update (tc);
@@ -1591,59 +1765,112 @@ tcp_timer_persist_handler (u32 index)
 /**
  * Retransmit first unacked segment
  */
-void
-tcp_retransmit_first_unacked (tcp_connection_t * tc)
+int
+tcp_retransmit_first_unacked (tcp_worker_ctx_t * wrk, tcp_connection_t * tc)
 {
-  vlib_main_t *vm = vlib_get_main ();
-  vlib_buffer_t *b;
   u32 bi, old_snd_nxt, n_bytes;
+  vlib_main_t *vm = wrk->vm;
+  vlib_buffer_t *b;
 
   old_snd_nxt = tc->snd_nxt;
   tc->snd_nxt = tc->snd_una;
 
-  TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 2);
-  n_bytes = tcp_prepare_retransmit_segment (tc, 0, tc->snd_mss, &b);
+  TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 1);
+
+  n_bytes = tcp_prepare_retransmit_segment (wrk, tc, 0, tc->snd_mss, &b);
   if (!n_bytes)
-    return;
-  bi = vlib_get_buffer_index (vm, b);
-  tcp_enqueue_to_output (vm, b, bi, tc->c_is_ip4);
+    return -1;
 
+  bi = vlib_get_buffer_index (vm, b);
+  tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
   tc->snd_nxt = old_snd_nxt;
+
+  return 0;
 }
 
+static int
+tcp_fast_retransmit_unsent (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
+			    u32 burst_size)
+{
+  u32 offset, n_segs = 0, n_written, bi;
+  vlib_main_t *vm = wrk->vm;
+  vlib_buffer_t *b = 0;
+
+  tc->snd_nxt = tc->snd_una_max;
+  offset = tc->snd_una_max - tc->snd_una;
+  while (n_segs < burst_size)
+    {
+      n_written = tcp_prepare_segment (wrk, tc, offset, tc->snd_mss, &b);
+      if (!n_written)
+	goto done;
+
+      bi = vlib_get_buffer_index (vm, b);
+      tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
+      offset += n_written;
+      n_segs += 1;
+    }
+
+done:
+  return n_segs;
+}
+
+#define scoreboard_rescue_rxt_valid(_sb, _tc)			\
+    (seq_geq (_sb->rescue_rxt, _tc->snd_una) 			\
+	&& seq_leq (_sb->rescue_rxt, _tc->snd_congestion))
+
 /**
  * Do fast retransmit with SACKs
  */
-void
-tcp_fast_retransmit_sack (tcp_connection_t * tc)
+int
+tcp_fast_retransmit_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
+			  u32 burst_size)
 {
-  vlib_main_t *vm = vlib_get_main ();
-  u32 n_written = 0, offset, max_bytes;
-  vlib_buffer_t *b = 0;
+  u32 n_written = 0, offset, max_bytes, n_segs = 0, n_segs_now;
   sack_scoreboard_hole_t *hole;
+  vlib_main_t *vm = wrk->vm;
+  vlib_buffer_t *b = 0;
   sack_scoreboard_t *sb;
   u32 bi, old_snd_nxt;
   int snd_space;
+  u32 max_deq;
   u8 snd_limited = 0, can_rescue = 0;
 
   ASSERT (tcp_in_fastrecovery (tc));
-  TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 0);
 
+  snd_space = tcp_available_cc_snd_space (tc);
+  if (snd_space < tc->snd_mss)
+    {
+      tcp_program_fastretransmit (wrk, tc);
+      return 0;
+    }
+
+  TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 0);
   old_snd_nxt = tc->snd_nxt;
   sb = &tc->sack_sb;
-  snd_space = tcp_available_snd_space (tc);
-
   hole = scoreboard_get_hole (sb, sb->cur_rxt_hole);
-  while (hole && snd_space > 0)
+
+  max_deq = session_tx_fifo_max_dequeue (&tc->connection);
+  max_deq -= tc->snd_una_max - tc->snd_una;
+
+  while (snd_space > 0 && n_segs < burst_size)
     {
-      hole = scoreboard_next_rxt_hole (sb, hole,
-				       tcp_fastrecovery_sent_1_smss (tc),
-				       &can_rescue, &snd_limited);
+      hole = scoreboard_next_rxt_hole (sb, hole, max_deq, &can_rescue,
+				       &snd_limited);
       if (!hole)
 	{
-	  if (!can_rescue || !(seq_lt (sb->rescue_rxt, tc->snd_una)
-			       || seq_gt (sb->rescue_rxt,
-					  tc->snd_congestion)))
+	  if (max_deq)
+	    {
+	      snd_space = clib_min (max_deq, snd_space);
+	      burst_size = clib_min (burst_size - n_segs,
+				     snd_space / tc->snd_mss);
+	      n_segs_now = tcp_fast_retransmit_unsent (wrk, tc, burst_size);
+	      if (max_deq > n_segs_now * tc->snd_mss)
+		tcp_program_fastretransmit (wrk, tc);
+	      n_segs += n_segs_now;
+	      goto done;
+	    }
+
+	  if (!can_rescue || scoreboard_rescue_rxt_valid (sb, tc))
 	    break;
 
 	  /* If rescue rxt undefined or less than snd_una then one segment of
@@ -1657,11 +1884,14 @@ tcp_fast_retransmit_sack (tcp_connection_t * tc)
 	  offset = tc->snd_congestion - tc->snd_una - max_bytes;
 	  sb->rescue_rxt = tc->snd_congestion;
 	  tc->snd_nxt = tc->snd_una + offset;
-	  n_written = tcp_prepare_retransmit_segment (tc, offset, max_bytes,
-						      &b);
-	  ASSERT (n_written);
+	  n_written = tcp_prepare_retransmit_segment (wrk, tc, offset,
+						      max_bytes, &b);
+	  if (!n_written)
+	    goto done;
+
 	  bi = vlib_get_buffer_index (vm, b);
-	  tcp_enqueue_to_output (vm, b, bi, tc->c_is_ip4);
+	  tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
+	  n_segs += 1;
 	  break;
 	}
 
@@ -1669,240 +1899,298 @@ tcp_fast_retransmit_sack (tcp_connection_t * tc)
       max_bytes = snd_limited ? clib_min (max_bytes, tc->snd_mss) : max_bytes;
       if (max_bytes == 0)
 	break;
+
       offset = sb->high_rxt - tc->snd_una;
       tc->snd_nxt = sb->high_rxt;
-      n_written = tcp_prepare_retransmit_segment (tc, offset, max_bytes, &b);
+      n_written = tcp_prepare_retransmit_segment (wrk, tc, offset, max_bytes,
+						  &b);
+      ASSERT (n_written <= snd_space);
 
       /* Nothing left to retransmit */
       if (n_written == 0)
 	break;
 
       bi = vlib_get_buffer_index (vm, b);
+      tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
+
       sb->high_rxt += n_written;
-      tcp_enqueue_to_output (vm, b, bi, tc->c_is_ip4);
-      ASSERT (n_written <= snd_space);
       snd_space -= n_written;
+      n_segs += 1;
     }
 
+  if (hole)
+    tcp_program_fastretransmit (wrk, tc);
+
+done:
   /* If window allows, send 1 SMSS of new data */
   tc->snd_nxt = old_snd_nxt;
+  return n_segs;
 }
 
 /**
  * Fast retransmit without SACK info
  */
-void
-tcp_fast_retransmit_no_sack (tcp_connection_t * tc)
+int
+tcp_fast_retransmit_no_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
+			     u32 burst_size)
 {
-  vlib_main_t *vm = vlib_get_main ();
-  u32 n_written = 0, offset = 0, bi, old_snd_nxt;
-  int snd_space;
+  u32 n_written = 0, offset = 0, bi, old_snd_nxt, max_deq, n_segs_now;
+  vlib_main_t *vm = wrk->vm;
+  int snd_space, n_segs = 0;
   vlib_buffer_t *b;
 
   ASSERT (tcp_in_fastrecovery (tc));
   TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 0);
-
-  /* Start resending from first un-acked segment */
   old_snd_nxt = tc->snd_nxt;
-  tc->snd_nxt = tc->snd_una;
-  snd_space = tcp_available_snd_space (tc);
 
-  while (snd_space > 0)
+  if (!tcp_fastrecovery_first (tc))
+    goto send_unsent;
+
+  /* RFC 6582: [If a partial ack], retransmit the first unacknowledged
+   * segment. */
+  snd_space = tc->sack_sb.last_bytes_delivered;
+  tc->snd_nxt = tc->snd_una;
+  while (snd_space > 0 && n_segs < burst_size)
     {
-      offset += n_written;
-      n_written = tcp_prepare_retransmit_segment (tc, offset, snd_space, &b);
+      n_written = tcp_prepare_retransmit_segment (wrk, tc, offset,
+						  tc->snd_mss, &b);
 
       /* Nothing left to retransmit */
       if (n_written == 0)
 	break;
 
       bi = vlib_get_buffer_index (vm, b);
-      tcp_enqueue_to_output (vm, b, bi, tc->c_is_ip4);
+      tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
       snd_space -= n_written;
+      offset += n_written;
+      n_segs += 1;
+    }
+
+  if (n_segs == burst_size)
+    goto done;
+
+send_unsent:
+
+  /* RFC 6582: Send a new segment if permitted by the new value of cwnd. */
+  snd_space = tcp_available_cc_snd_space (tc);
+  if (snd_space < tc->snd_mss || tc->snd_mss == 0)
+    goto done;
+
+  max_deq = session_tx_fifo_max_dequeue (&tc->connection);
+  max_deq -= tc->snd_una_max - tc->snd_una;
+  if (max_deq)
+    {
+      snd_space = clib_min (max_deq, snd_space);
+      burst_size = clib_min (burst_size - n_segs, snd_space / tc->snd_mss);
+      n_segs_now = tcp_fast_retransmit_unsent (wrk, tc, burst_size);
+      if (max_deq > n_segs_now * tc->snd_mss)
+	tcp_program_fastretransmit (wrk, tc);
+      n_segs += n_segs_now;
     }
 
-  /* Restore snd_nxt. If window allows, send 1 SMSS of new data */
+  /* Restore snd_nxt */
   tc->snd_nxt = old_snd_nxt;
+
+done:
+  tcp_fastrecovery_first_off (tc);
+  return n_segs;
 }
 
 /**
  * Do fast retransmit
  */
-void
-tcp_fast_retransmit (tcp_connection_t * tc)
+int
+tcp_fast_retransmit (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
+		     u32 burst_size)
 {
-  if (tcp_opts_sack_permitted (&tc->rcv_opts)
-      && scoreboard_first_hole (&tc->sack_sb))
-    tcp_fast_retransmit_sack (tc);
+  if (tcp_opts_sack_permitted (&tc->rcv_opts))
+    return tcp_fast_retransmit_sack (wrk, tc, burst_size);
   else
-    tcp_fast_retransmit_no_sack (tc);
+    return tcp_fast_retransmit_no_sack (wrk, tc, burst_size);
 }
 
-always_inline u32
-tcp_session_has_ooo_data (tcp_connection_t * tc)
+static void
+tcp_output_handle_link_local (tcp_connection_t * tc0, vlib_buffer_t * b0,
+			      u16 * next0, u32 * error0)
 {
-  stream_session_t *s =
-    stream_session_get (tc->c_s_index, tc->c_thread_index);
-  return svm_fifo_has_ooo_data (s->server_rx_fifo);
+  ip_adjacency_t *adj;
+  adj_index_t ai;
+
+  /* Not thread safe but as long as the connection exists the adj should
+   * not be removed */
+  ai = adj_nbr_find (FIB_PROTOCOL_IP6, VNET_LINK_IP6, &tc0->c_rmt_ip,
+		     tc0->sw_if_index);
+  if (ai == ADJ_INDEX_INVALID)
+    {
+      vnet_buffer (b0)->sw_if_index[VLIB_TX] = ~0;
+      *next0 = TCP_OUTPUT_NEXT_DROP;
+      *error0 = TCP_ERROR_LINK_LOCAL_RW;
+      return;
+    }
+
+  adj = adj_get (ai);
+  if (PREDICT_TRUE (adj->lookup_next_index == IP_LOOKUP_NEXT_REWRITE))
+    *next0 = TCP_OUTPUT_NEXT_IP_REWRITE;
+  else if (adj->lookup_next_index == IP_LOOKUP_NEXT_ARP)
+    *next0 = TCP_OUTPUT_NEXT_IP_ARP;
+  else
+    {
+      *next0 = TCP_OUTPUT_NEXT_DROP;
+      *error0 = TCP_ERROR_LINK_LOCAL_RW;
+    }
+  vnet_buffer (b0)->ip.adj_index[VLIB_TX] = ai;
 }
 
-always_inline uword
-tcp46_output_inline (vlib_main_t * vm,
-		     vlib_node_runtime_t * node,
-		     vlib_frame_t * from_frame, int is_ip4)
+static void
+tcp46_output_trace_frame (vlib_main_t * vm, vlib_node_runtime_t * node,
+			  u32 * to_next, u32 n_bufs)
 {
-  u32 n_left_from, next_index, *from, *to_next;
-  u32 my_thread_index = vm->thread_index;
+  u32 n_trace = vlib_get_trace_count (vm, node);
+  tcp_connection_t *tc;
+  tcp_tx_trace_t *t;
+  vlib_buffer_t *b;
+  tcp_header_t *th;
+  int i;
 
-  from = vlib_frame_vector_args (from_frame);
-  n_left_from = from_frame->n_vectors;
-  next_index = node->cached_next_index;
-  tcp_set_time_now (my_thread_index);
+  for (i = 0; i < clib_min (n_trace, n_bufs); i++)
+    {
+      b = vlib_get_buffer (vm, to_next[i]);
+      th = vlib_buffer_get_current (b);
+      tc = tcp_connection_get (vnet_buffer (b)->tcp.connection_index,
+			       vm->thread_index);
+      t = vlib_add_trace (vm, node, b, sizeof (*t));
+      clib_memcpy (&t->tcp_header, th, sizeof (t->tcp_header));
+      clib_memcpy (&t->tcp_connection, tc, sizeof (t->tcp_connection));
+    }
+}
 
-  while (n_left_from > 0)
+always_inline void
+tcp_output_push_ip (vlib_main_t * vm, vlib_buffer_t * b0,
+		    tcp_connection_t * tc0, u8 is_ip4)
+{
+  tcp_header_t *th0 = 0;
+
+  th0 = vlib_buffer_get_current (b0);
+  TCP_EVT_DBG (TCP_EVT_OUTPUT, tc0, th0->flags, b0->current_length);
+  if (is_ip4)
     {
-      u32 n_left_to_next;
+      vlib_buffer_push_ip4 (vm, b0, &tc0->c_lcl_ip4, &tc0->c_rmt_ip4,
+			    IP_PROTOCOL_TCP, 1);
+      b0->flags |= VNET_BUFFER_F_OFFLOAD_TCP_CKSUM;
+      vnet_buffer (b0)->l4_hdr_offset = (u8 *) th0 - b0->data;
+      th0->checksum = 0;
+    }
+  else
+    {
+      ip6_header_t *ih0;
+      ih0 = vlib_buffer_push_ip6 (vm, b0, &tc0->c_lcl_ip6,
+				  &tc0->c_rmt_ip6, IP_PROTOCOL_TCP);
+      b0->flags |= VNET_BUFFER_F_OFFLOAD_TCP_CKSUM;
+      vnet_buffer (b0)->l3_hdr_offset = (u8 *) ih0 - b0->data;
+      vnet_buffer (b0)->l4_hdr_offset = (u8 *) th0 - b0->data;
+      th0->checksum = 0;
+    }
+}
 
-      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
+always_inline void
+tcp_output_handle_packet (tcp_connection_t * tc0, vlib_buffer_t * b0,
+			  u32 * error0, u16 * next0, u8 is_ip4)
+{
 
-      while (n_left_from > 0 && n_left_to_next > 0)
-	{
-	  u32 bi0;
-	  vlib_buffer_t *b0;
-	  tcp_connection_t *tc0;
-	  tcp_tx_trace_t *t0;
-	  tcp_header_t *th0 = 0;
-	  u32 error0 = TCP_ERROR_PKTS_SENT, next0 = TCP_OUTPUT_NEXT_IP_LOOKUP;
+  if (PREDICT_FALSE (tc0->state == TCP_STATE_CLOSED))
+    {
+      *error0 = TCP_ERROR_INVALID_CONNECTION;
+      *next0 = TCP_OUTPUT_NEXT_DROP;
+      return;
+    }
 
-	  bi0 = from[0];
-	  to_next[0] = bi0;
-	  from += 1;
-	  to_next += 1;
-	  n_left_from -= 1;
-	  n_left_to_next -= 1;
+  vnet_buffer (b0)->sw_if_index[VLIB_TX] = tc0->c_fib_index;
+  vnet_buffer (b0)->sw_if_index[VLIB_RX] = 0;
 
-	  b0 = vlib_get_buffer (vm, bi0);
-	  tc0 = tcp_connection_get (vnet_buffer (b0)->tcp.connection_index,
-				    my_thread_index);
-	  if (PREDICT_FALSE (tc0 == 0 || tc0->state == TCP_STATE_CLOSED))
-	    {
-	      error0 = TCP_ERROR_INVALID_CONNECTION;
-	      next0 = TCP_OUTPUT_NEXT_DROP;
-	      goto done;
-	    }
+  if (!is_ip4)
+    {
+      if (PREDICT_FALSE (ip6_address_is_link_local_unicast (&tc0->c_rmt_ip6)))
+	tcp_output_handle_link_local (tc0, b0, next0, error0);
+    }
 
-	  th0 = vlib_buffer_get_current (b0);
-	  TCP_EVT_DBG (TCP_EVT_OUTPUT, tc0, th0->flags, b0->current_length);
+  if (!TCP_ALWAYS_ACK)
+    tcp_timer_reset (tc0, TCP_TIMER_DELACK);
+}
 
-	  if (is_ip4)
-	    {
-	      vlib_buffer_push_ip4 (vm, b0, &tc0->c_lcl_ip4, &tc0->c_rmt_ip4,
-				    IP_PROTOCOL_TCP, 1);
-	      b0->flags |= VNET_BUFFER_F_OFFLOAD_TCP_CKSUM;
-	      vnet_buffer (b0)->l4_hdr_offset = (u8 *) th0 - b0->data;
-	      th0->checksum = 0;
-	    }
-	  else
-	    {
-	      ip6_header_t *ih0;
-	      ih0 = vlib_buffer_push_ip6 (vm, b0, &tc0->c_lcl_ip6,
-					  &tc0->c_rmt_ip6, IP_PROTOCOL_TCP);
-	      b0->flags |= VNET_BUFFER_F_OFFLOAD_TCP_CKSUM;
-	      vnet_buffer (b0)->l3_hdr_offset = (u8 *) ih0 - b0->data;
-	      vnet_buffer (b0)->l4_hdr_offset = (u8 *) th0 - b0->data;
-	      th0->checksum = 0;
-	    }
+always_inline uword
+tcp46_output_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
+		     vlib_frame_t * frame, int is_ip4)
+{
+  u32 n_left_from, *from, thread_index = vm->thread_index;
+  vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
+  u16 nexts[VLIB_FRAME_SIZE], *next;
 
-	  /* Filter out DUPACKs if there are no OOO segments left */
-	  if (PREDICT_FALSE
-	      (vnet_buffer (b0)->tcp.flags & TCP_BUF_FLAG_DUPACK))
-	    {
-	      if (!tcp_session_has_ooo_data (tc0))
-		{
-		  error0 = TCP_ERROR_FILTERED_DUPACKS;
-		  next0 = TCP_OUTPUT_NEXT_DROP;
-		  goto done;
-		}
-	    }
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  tcp_set_time_now (tcp_get_worker (thread_index));
 
-	  /* Stop DELACK timer and fix flags */
-	  tc0->flags &= ~(TCP_CONN_SNDACK);
-	  tcp_timer_reset (tc0, TCP_TIMER_DELACK);
+  if (PREDICT_FALSE (node->flags & VLIB_NODE_FLAG_TRACE))
+    tcp46_output_trace_frame (vm, node, from, n_left_from);
 
-	  /* If not retransmitting
-	   * 1) update snd_una_max (SYN, SYNACK, FIN)
-	   * 2) If we're not tracking an ACK, start tracking */
-	  if (seq_lt (tc0->snd_una_max, tc0->snd_nxt))
-	    {
-	      tc0->snd_una_max = tc0->snd_nxt;
-	      if (tc0->rtt_ts == 0)
-		{
-		  tc0->rtt_ts = tcp_time_now ();
-		  tc0->rtt_seq = tc0->snd_nxt;
-		}
-	    }
+  vlib_get_buffers (vm, from, bufs, n_left_from);
+  b = bufs;
+  next = nexts;
 
-	  /* Set the retransmit timer if not set already and not
-	   * doing a pure ACK */
-	  if (!tcp_timer_is_active (tc0, TCP_TIMER_RETRANSMIT)
-	      && tc0->snd_nxt != tc0->snd_una)
-	    {
-	      tcp_retransmit_timer_set (tc0);
-	      tc0->rto_boff = 0;
-	    }
+  while (n_left_from >= 4)
+    {
+      u32 error0 = TCP_ERROR_PKTS_SENT, error1 = TCP_ERROR_PKTS_SENT;
+      tcp_connection_t *tc0, *tc1;
 
-#if 0
-	  /* Make sure we haven't lost route to our peer */
-	  if (PREDICT_FALSE (tc0->last_fib_check
-			     < tc0->snd_opts.tsval + TCP_FIB_RECHECK_PERIOD))
-	    {
-	      if (PREDICT_TRUE
-		  (tc0->c_rmt_fei == tcp_lookup_rmt_in_fib (tc0)))
-		{
-		  tc0->last_fib_check = tc0->snd_opts.tsval;
-		}
-	      else
-		{
-		  clib_warning ("lost connection to peer");
-		  tcp_connection_reset (tc0);
-		  goto done;
-		}
-	    }
+      {
+	vlib_prefetch_buffer_header (b[2], STORE);
+	CLIB_PREFETCH (b[2]->data, 2 * CLIB_CACHE_LINE_BYTES, STORE);
 
-	  /* Use pre-computed dpo to set next node */
-	  next0 = tc0->c_rmt_dpo.dpoi_next_node;
-	  vnet_buffer (b0)->ip.adj_index[VLIB_TX] = tc0->c_rmt_dpo.dpoi_index;
-#endif
+	vlib_prefetch_buffer_header (b[3], STORE);
+	CLIB_PREFETCH (b[3]->data, 2 * CLIB_CACHE_LINE_BYTES, STORE);
+      }
 
-	  vnet_buffer (b0)->sw_if_index[VLIB_RX] = 0;
-	  vnet_buffer (b0)->sw_if_index[VLIB_TX] = ~0;
+      next[0] = next[1] = TCP_OUTPUT_NEXT_IP_LOOKUP;
 
-	  b0->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;
-	done:
-	  b0->error = node->errors[error0];
-	  if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
-	    {
-	      t0 = vlib_add_trace (vm, node, b0, sizeof (*t0));
-	      if (th0)
-		{
-		  clib_memcpy (&t0->tcp_header, th0, sizeof (t0->tcp_header));
-		}
-	      else
-		{
-		  memset (&t0->tcp_header, 0, sizeof (t0->tcp_header));
-		}
-	      clib_memcpy (&t0->tcp_connection, tc0,
-			   sizeof (t0->tcp_connection));
-	    }
+      tc0 = tcp_connection_get (vnet_buffer (b[0])->tcp.connection_index,
+				thread_index);
+      tc1 = tcp_connection_get (vnet_buffer (b[1])->tcp.connection_index,
+				thread_index);
 
-	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
-					   n_left_to_next, bi0, next0);
+      tcp_output_push_ip (vm, b[0], tc0, is_ip4);
+      tcp_output_push_ip (vm, b[1], tc1, is_ip4);
+
+      tcp_output_handle_packet (tc0, b[0], &error0, &next[0], is_ip4);
+      tcp_output_handle_packet (tc1, b[1], &error1, &next[1], is_ip4);
+
+      b += 2;
+      next += 2;
+      n_left_from -= 2;
+    }
+  while (n_left_from > 0)
+    {
+      u32 error0 = TCP_ERROR_PKTS_SENT;
+      tcp_connection_t *tc0;
+
+      if (n_left_from > 1)
+	{
+	  vlib_prefetch_buffer_header (b[1], STORE);
+	  CLIB_PREFETCH (b[1]->data, 2 * CLIB_CACHE_LINE_BYTES, STORE);
 	}
 
-      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+      next[0] = TCP_OUTPUT_NEXT_IP_LOOKUP;
+      tc0 = tcp_connection_get (vnet_buffer (b[0])->tcp.connection_index,
+				thread_index);
+
+      tcp_output_push_ip (vm, b[0], tc0, is_ip4);
+      tcp_output_handle_packet (tc0, b[0], &error0, &next[0], is_ip4);
+
+      b += 1;
+      next += 1;
+      n_left_from -= 1;
     }
 
-  return from_frame->n_vectors;
+  vlib_buffer_enqueue_to_next (vm, node, from, nexts, frame->n_vectors);
+  return frame->n_vectors;
 }
 
 static uword
@@ -1962,23 +2250,6 @@ VLIB_REGISTER_NODE (tcp6_output_node) =
 
 VLIB_NODE_FUNCTION_MULTIARCH (tcp6_output_node, tcp6_output);
 
-u32
-tcp_push_header (transport_connection_t * tconn, vlib_buffer_t * b)
-{
-  tcp_connection_t *tc;
-
-  tc = (tcp_connection_t *) tconn;
-  tcp_push_hdr_i (tc, b, TCP_STATE_ESTABLISHED, 0);
-  ASSERT (seq_leq (tc->snd_una_max, tc->snd_una + tc->snd_wnd));
-
-  if (tc->rtt_ts == 0 && !tcp_in_cong_recovery (tc))
-    {
-      tc->rtt_ts = tcp_time_now ();
-      tc->rtt_seq = tc->snd_nxt;
-    }
-  return 0;
-}
-
 typedef enum _tcp_reset_next
 {
   TCP_RESET_NEXT_DROP,
@@ -2038,7 +2309,7 @@ tcp46_send_reset_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    }
 
 	  /* Prepare to send to IP lookup */
-	  vnet_buffer (b0)->sw_if_index[VLIB_TX] = 0;
+	  vnet_buffer (b0)->sw_if_index[VLIB_TX] = ~0;
 	  next0 = TCP_RESET_NEXT_IP_LOOKUP;
 
 	done: