2 * l2_learn.c : layer 2 learning using l2fib
4 * Copyright (c) 2013 Cisco and/or its affiliates.
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at:
9 * http://www.apache.org/licenses/LICENSE-2.0
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
18 #include <vlib/vlib.h>
19 #include <vnet/vnet.h>
20 #include <vnet/pg/pg.h>
21 #include <vnet/ethernet/ethernet.h>
24 #include <vnet/l2/l2_input.h>
25 #include <vnet/l2/feat_bitmap.h>
26 #include <vnet/l2/l2_fib.h>
27 #include <vnet/l2/l2_learn.h>
29 #include <vppinfra/error.h>
30 #include <vppinfra/hash.h>
32 #ifndef CLIB_MARCH_VARIANT
33 l2learn_main_t l2learn_main;
38 * @brief Ethernet Bridge Learning.
40 * Populate the mac table with entries mapping the packet's source mac + bridge
41 * domain ID to the input sw_if_index.
43 * Note that learning and forwarding are separate graph nodes. This means that
44 * for a set of packets, all learning is performed first, then all nodes are
45 * forwarded. The forwarding is done based on the end-state of the mac table,
46 * instead of the state after each packet. Thus the forwarding results could
47 * differ in certain cases (mac move tests), but this not expected to cause
48 * problems in real-world networks. It is much simpler to separate learning
49 * and forwarding into separate nodes.
62 /* packet trace format function */
64 format_l2learn_trace (u8 * s, va_list * args)
66 CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
67 CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
68 l2learn_trace_t *t = va_arg (*args, l2learn_trace_t *);
70 s = format (s, "l2-learn: sw_if_index %d dst %U src %U bd_index %d",
72 format_ethernet_address, t->dst,
73 format_ethernet_address, t->src, t->bd_index);
77 extern vlib_node_registration_t l2learn_node;
79 #define foreach_l2learn_error \
80 _(L2LEARN, "L2 learn packets") \
81 _(MISS, "L2 learn misses") \
82 _(MAC_MOVE, "L2 mac moves") \
83 _(MAC_MOVE_VIOLATE, "L2 mac move violations") \
84 _(LIMIT, "L2 not learned due to limit") \
85 _(HIT_UPDATE, "L2 learn hit updates") \
86 _(FILTER_DROP, "L2 filter mac drops")
90 #define _(sym,str) L2LEARN_ERROR_##sym,
96 static char *l2learn_error_strings[] = {
97 #define _(sym,string) string,
110 /** Perform learning on one packet based on the mac table lookup result. */
112 static_always_inline void
113 l2learn_process (vlib_node_runtime_t * node,
114 l2learn_main_t * msm,
118 l2fib_entry_key_t * key0,
119 l2fib_entry_key_t * cached_key,
121 l2fib_entry_result_t * result0, u16 * next0, u8 timestamp)
123 /* Set up the default next node (typically L2FWD) */
124 *next0 = vnet_l2_feature_next (b0, msm->feat_next_node_index,
127 /* Check mac table lookup result */
128 if (PREDICT_TRUE (result0->fields.sw_if_index == sw_if_index0))
130 /* Entry in L2FIB with matching sw_if_index matched - normal fast path */
131 u32 dtime = timestamp - result0->fields.timestamp;
132 u32 dsn = result0->fields.sn.as_u16 - vnet_buffer (b0)->l2.l2fib_sn;
133 u32 check = (dtime && vnet_buffer (b0)->l2.bd_age) || dsn;
135 if (PREDICT_TRUE (check == 0))
136 return; /* MAC entry up to date */
137 if (l2fib_entry_result_is_set_AGE_NOT (result0))
138 return; /* Static MAC always age_not */
139 if (msm->global_learn_count > msm->global_learn_limit)
140 return; /* Above learn limit - do not update */
142 /* Limit updates per l2-learn node call to avoid prolonged update burst
143 * as dtime advance over 1 minute mark, unless more than 1 min behind
145 if ((*count > 2) && (dtime == 1) && (dsn == 0))
148 counter_base[L2LEARN_ERROR_HIT_UPDATE] += 1;
151 else if (result0->raw == ~0)
153 /* Entry not in L2FIB - add it */
154 counter_base[L2LEARN_ERROR_MISS] += 1;
156 if (msm->global_learn_count >= msm->global_learn_limit)
159 * Global limit reached. Do not learn the mac but forward the packet.
160 * In the future, limits could also be per-interface or bridge-domain.
162 counter_base[L2LEARN_ERROR_LIMIT] += 1;
166 /* Do not learn if mac is 0 */
167 l2fib_entry_key_t key = *key0;
168 key.fields.bd_index = 0;
172 /* It is ok to learn */
173 msm->global_learn_count++;
174 result0->raw = 0; /* clear all fields */
175 result0->fields.sw_if_index = sw_if_index0;
176 if (msm->client_pid != 0)
177 l2fib_entry_result_set_LRN_EVT (result0);
179 l2fib_entry_result_clear_LRN_EVT (result0);
183 /* Entry in L2FIB with different sw_if_index - mac move or filter */
184 if (l2fib_entry_result_is_set_FILTER (result0))
186 ASSERT (result0->fields.sw_if_index == ~0);
187 /* drop packet because lookup matched a filter mac entry */
188 b0->error = node->errors[L2LEARN_ERROR_FILTER_DROP];
189 *next0 = L2LEARN_NEXT_DROP;
193 if (l2fib_entry_result_is_set_STATIC (result0))
196 * Don't overwrite a static mac
197 * TODO: Check violation policy. For now drop the packet
199 b0->error = node->errors[L2LEARN_ERROR_MAC_MOVE_VIOLATE];
200 *next0 = L2LEARN_NEXT_DROP;
205 * TODO: may want to rate limit mac moves
206 * TODO: check global/bridge domain/interface learn limits
208 result0->fields.sw_if_index = sw_if_index0;
209 if (l2fib_entry_result_is_set_AGE_NOT (result0))
211 /* The mac was provisioned */
212 msm->global_learn_count++;
213 l2fib_entry_result_clear_AGE_NOT (result0);
215 if (msm->client_pid != 0)
216 l2fib_entry_result_set_bits (result0,
217 (L2FIB_ENTRY_RESULT_FLAG_LRN_EVT |
218 L2FIB_ENTRY_RESULT_FLAG_LRN_MOV));
220 l2fib_entry_result_clear_bits (result0,
221 (L2FIB_ENTRY_RESULT_FLAG_LRN_EVT |
222 L2FIB_ENTRY_RESULT_FLAG_LRN_MOV));
223 counter_base[L2LEARN_ERROR_MAC_MOVE] += 1;
226 /* Update the entry */
227 result0->fields.timestamp = timestamp;
228 result0->fields.sn.as_u16 = vnet_buffer (b0)->l2.l2fib_sn;
230 BVT (clib_bihash_kv) kv;
232 kv.value = result0->raw;
233 BV (clib_bihash_add_del) (msm->mac_table, &kv, 1 /* is_add */ );
235 /* Invalidate the cache */
236 cached_key->raw = ~0;
240 static_always_inline uword
241 l2learn_node_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
242 vlib_frame_t * frame, int do_trace)
245 l2learn_main_t *msm = &l2learn_main;
246 vlib_node_t *n = vlib_get_node (vm, l2learn_node.index);
247 u32 node_counter_base_index = n->error_heap_index;
248 vlib_error_main_t *em = &vm->error_main;
249 l2fib_entry_key_t cached_key;
250 l2fib_entry_result_t cached_result;
251 u8 timestamp = (u8) (vlib_time_now (vm) / 60);
253 vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
254 u16 nexts[VLIB_FRAME_SIZE], *next;
256 from = vlib_frame_vector_args (frame);
257 n_left = frame->n_vectors; /* number of packets to process */
258 vlib_get_buffers (vm, from, bufs, n_left);
262 /* Clear the one-entry cache in case mac table was updated */
264 cached_result.raw = ~0; /* warning be gone */
268 u32 sw_if_index0, sw_if_index1, sw_if_index2, sw_if_index3;
269 const ethernet_header_t *h0, *h1, *h2, *h3;
270 l2fib_entry_key_t key0, key1, key2, key3;
271 l2fib_entry_result_t result0, result1, result2, result3;
273 /* Prefetch next iteration. */
275 /* buffer header is read and written, so use LOAD
277 vlib_prefetch_buffer_header (b[4], LOAD);
278 vlib_prefetch_buffer_header (b[5], LOAD);
279 vlib_prefetch_buffer_header (b[6], LOAD);
280 vlib_prefetch_buffer_header (b[7], LOAD);
282 CLIB_PREFETCH (b[4]->data, CLIB_CACHE_LINE_BYTES, LOAD);
283 CLIB_PREFETCH (b[5]->data, CLIB_CACHE_LINE_BYTES, LOAD);
284 CLIB_PREFETCH (b[6]->data, CLIB_CACHE_LINE_BYTES, LOAD);
285 CLIB_PREFETCH (b[7]->data, CLIB_CACHE_LINE_BYTES, LOAD);
288 /* RX interface handles */
289 sw_if_index0 = vnet_buffer (b[0])->sw_if_index[VLIB_RX];
290 sw_if_index1 = vnet_buffer (b[1])->sw_if_index[VLIB_RX];
291 sw_if_index2 = vnet_buffer (b[2])->sw_if_index[VLIB_RX];
292 sw_if_index3 = vnet_buffer (b[3])->sw_if_index[VLIB_RX];
294 /* Process 4 x pkts */
296 h0 = vlib_buffer_get_current (b[0]);
297 h1 = vlib_buffer_get_current (b[1]);
298 h2 = vlib_buffer_get_current (b[2]);
299 h3 = vlib_buffer_get_current (b[3]);
303 if (b[0]->flags & VLIB_BUFFER_IS_TRACED)
306 vlib_add_trace (vm, node, b[0], sizeof (*t));
307 t->sw_if_index = sw_if_index0;
308 t->bd_index = vnet_buffer (b[0])->l2.bd_index;
309 clib_memcpy_fast (t->src, h0->src_address, 6);
310 clib_memcpy_fast (t->dst, h0->dst_address, 6);
312 if (b[1]->flags & VLIB_BUFFER_IS_TRACED)
315 vlib_add_trace (vm, node, b[1], sizeof (*t));
316 t->sw_if_index = sw_if_index1;
317 t->bd_index = vnet_buffer (b[1])->l2.bd_index;
318 clib_memcpy_fast (t->src, h1->src_address, 6);
319 clib_memcpy_fast (t->dst, h1->dst_address, 6);
321 if (b[2]->flags & VLIB_BUFFER_IS_TRACED)
324 vlib_add_trace (vm, node, b[2], sizeof (*t));
325 t->sw_if_index = sw_if_index2;
326 t->bd_index = vnet_buffer (b[2])->l2.bd_index;
327 clib_memcpy_fast (t->src, h2->src_address, 6);
328 clib_memcpy_fast (t->dst, h2->dst_address, 6);
330 if (b[3]->flags & VLIB_BUFFER_IS_TRACED)
333 vlib_add_trace (vm, node, b[3], sizeof (*t));
334 t->sw_if_index = sw_if_index3;
335 t->bd_index = vnet_buffer (b[3])->l2.bd_index;
336 clib_memcpy_fast (t->src, h3->src_address, 6);
337 clib_memcpy_fast (t->dst, h3->dst_address, 6);
342 vlib_node_increment_counter (vm, l2learn_node.index,
343 L2LEARN_ERROR_L2LEARN, 4);
345 l2fib_lookup_4 (msm->mac_table, &cached_key, &cached_result,
350 vnet_buffer (b[0])->l2.bd_index,
351 vnet_buffer (b[1])->l2.bd_index,
352 vnet_buffer (b[2])->l2.bd_index,
353 vnet_buffer (b[3])->l2.bd_index,
354 &key0, &key1, &key2, &key3,
355 &result0, &result1, &result2, &result3);
357 l2learn_process (node, msm, &em->counters[node_counter_base_index],
358 b[0], sw_if_index0, &key0, &cached_key,
359 &count, &result0, next, timestamp);
361 l2learn_process (node, msm, &em->counters[node_counter_base_index],
362 b[1], sw_if_index1, &key1, &cached_key,
363 &count, &result1, next + 1, timestamp);
365 l2learn_process (node, msm, &em->counters[node_counter_base_index],
366 b[2], sw_if_index2, &key2, &cached_key,
367 &count, &result2, next + 2, timestamp);
369 l2learn_process (node, msm, &em->counters[node_counter_base_index],
370 b[3], sw_if_index3, &key3, &cached_key,
371 &count, &result3, next + 3, timestamp);
381 ethernet_header_t *h0;
382 l2fib_entry_key_t key0;
383 l2fib_entry_result_t result0;
385 sw_if_index0 = vnet_buffer (b[0])->sw_if_index[VLIB_RX];
387 h0 = vlib_buffer_get_current (b[0]);
389 if (do_trace && PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
391 l2learn_trace_t *t = vlib_add_trace (vm, node, b[0], sizeof (*t));
392 t->sw_if_index = sw_if_index0;
393 t->bd_index = vnet_buffer (b[0])->l2.bd_index;
394 clib_memcpy_fast (t->src, h0->src_address, 6);
395 clib_memcpy_fast (t->dst, h0->dst_address, 6);
399 vlib_node_increment_counter (vm, l2learn_node.index,
400 L2LEARN_ERROR_L2LEARN, 1);
403 l2fib_lookup_1 (msm->mac_table, &cached_key, &cached_result,
404 h0->src_address, vnet_buffer (b[0])->l2.bd_index,
407 l2learn_process (node, msm, &em->counters[node_counter_base_index],
408 b[0], sw_if_index0, &key0, &cached_key,
409 &count, &result0, next, timestamp);
416 vlib_buffer_enqueue_to_next (vm, node, from, nexts, frame->n_vectors);
418 return frame->n_vectors;
421 VLIB_NODE_FN (l2learn_node) (vlib_main_t * vm,
422 vlib_node_runtime_t * node, vlib_frame_t * frame)
424 if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
425 return l2learn_node_inline (vm, node, frame, 1 /* do_trace */ );
426 return l2learn_node_inline (vm, node, frame, 0 /* do_trace */ );
430 VLIB_REGISTER_NODE (l2learn_node) = {
432 .vector_size = sizeof (u32),
433 .format_trace = format_l2learn_trace,
434 .type = VLIB_NODE_TYPE_INTERNAL,
436 .n_errors = ARRAY_LEN(l2learn_error_strings),
437 .error_strings = l2learn_error_strings,
439 .n_next_nodes = L2LEARN_N_NEXT,
441 /* edit / add dispositions here */
443 [L2LEARN_NEXT_DROP] = "error-drop",
444 [L2LEARN_NEXT_L2FWD] = "l2-fwd",
449 #ifndef CLIB_MARCH_VARIANT
451 l2learn_init (vlib_main_t * vm)
453 l2learn_main_t *mp = &l2learn_main;
456 mp->vnet_main = vnet_get_main ();
458 /* Initialize the feature next-node indexes */
459 feat_bitmap_init_next_nodes (vm,
462 l2input_get_feat_names (),
463 mp->feat_next_node_index);
465 /* init the hash table ptr */
466 mp->mac_table = get_mac_table ();
469 * Set the default number of dynamically learned macs to the number
472 mp->global_learn_limit = L2LEARN_DEFAULT_LIMIT;
477 VLIB_INIT_FUNCTION (l2learn_init);
481 * Set subinterface learn enable/disable.
483 * set interface l2 learn <interface> [disable]
485 static clib_error_t *
486 int_learn (vlib_main_t * vm,
487 unformat_input_t * input, vlib_cli_command_t * cmd)
489 vnet_main_t *vnm = vnet_get_main ();
490 clib_error_t *error = 0;
494 if (!unformat_user (input, unformat_vnet_sw_interface, vnm, &sw_if_index))
496 error = clib_error_return (0, "unknown interface `%U'",
497 format_unformat_error, input);
502 if (unformat (input, "disable"))
507 /* set the interface flag */
508 l2input_intf_bitmap_enable (sw_if_index, L2INPUT_FEAT_LEARN, enable);
515 * Layer 2 learning can be enabled and disabled on each
516 * interface and on each bridge-domain. Use this command to
517 * manage interfaces. It is enabled by default.
520 * Example of how to enable learning:
521 * @cliexcmd{set interface l2 learn GigabitEthernet0/8/0}
522 * Example of how to disable learning:
523 * @cliexcmd{set interface l2 learn GigabitEthernet0/8/0 disable}
526 VLIB_CLI_COMMAND (int_learn_cli, static) = {
527 .path = "set interface l2 learn",
528 .short_help = "set interface l2 learn <interface> [disable]",
529 .function = int_learn,
534 static clib_error_t *
535 l2learn_config (vlib_main_t * vm, unformat_input_t * input)
537 l2learn_main_t *mp = &l2learn_main;
539 while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
541 if (unformat (input, "limit %d", &mp->global_learn_limit))
545 return clib_error_return (0, "unknown input `%U'",
546 format_unformat_error, input);
552 VLIB_CONFIG_FUNCTION (l2learn_config, "l2learn");
558 * fd.io coding-style-patch-verification: ON
561 * eval: (c-set-style "gnu")