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 l2learn_main_t l2learn_main;
36 * @brief Ethernet Bridge Learning.
38 * Populate the mac table with entries mapping the packet's source mac + bridge
39 * domain ID to the input sw_if_index.
41 * Note that learning and forwarding are separate graph nodes. This means that
42 * for a set of packets, all learning is performed first, then all nodes are
43 * forwarded. The forwarding is done based on the end-state of the mac table,
44 * instead of the state after each packet. Thus the forwarding results could
45 * differ in certain cases (mac move tests), but this not expected to cause
46 * problems in real-world networks. It is much simpler to separate learning
47 * and forwarding into separate nodes.
60 /* packet trace format function */
62 format_l2learn_trace (u8 * s, va_list * args)
64 CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
65 CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
66 l2learn_trace_t *t = va_arg (*args, l2learn_trace_t *);
68 s = format (s, "l2-learn: sw_if_index %d dst %U src %U bd_index %d",
70 format_ethernet_address, t->dst,
71 format_ethernet_address, t->src, t->bd_index);
75 static vlib_node_registration_t l2learn_node;
77 #define foreach_l2learn_error \
78 _(L2LEARN, "L2 learn packets") \
79 _(MISS, "L2 learn misses") \
80 _(MAC_MOVE, "L2 mac moves") \
81 _(MAC_MOVE_VIOLATE, "L2 mac move violations") \
82 _(LIMIT, "L2 not learned due to limit") \
83 _(HIT_UPDATE, "L2 learn hit updates") \
84 _(FILTER_DROP, "L2 filter mac drops")
88 #define _(sym,str) L2LEARN_ERROR_##sym,
94 static char *l2learn_error_strings[] = {
95 #define _(sym,string) string,
108 /** Perform learning on one packet based on the mac table lookup result. */
110 static_always_inline void
111 l2learn_process (vlib_node_runtime_t * node,
112 l2learn_main_t * msm,
116 l2fib_entry_key_t * key0,
117 l2fib_entry_key_t * cached_key,
119 l2fib_entry_result_t * result0, u32 * next0, u8 timestamp)
121 /* Set up the default next node (typically L2FWD) */
122 *next0 = vnet_l2_feature_next (b0, msm->feat_next_node_index,
125 /* Check mac table lookup result */
126 if (PREDICT_TRUE (result0->fields.sw_if_index == sw_if_index0))
128 /* Entry in L2FIB with matching sw_if_index matched - normal fast path */
129 u32 dtime = timestamp - result0->fields.timestamp;
130 u32 dsn = result0->fields.sn.as_u16 - vnet_buffer (b0)->l2.l2fib_sn;
131 u32 check = (dtime && vnet_buffer (b0)->l2.bd_age) || dsn;
133 if (PREDICT_TRUE (check == 0))
134 return; /* MAC entry up to date */
135 if (l2fib_entry_result_is_set_AGE_NOT (result0))
136 return; /* Static MAC always age_not */
137 if (msm->global_learn_count > msm->global_learn_limit)
138 return; /* Above learn limit - do not update */
140 /* Limit updates per l2-learn node call to avoid prolonged update burst
141 * as dtime advance over 1 minute mark, unless more than 1 min behind
143 if ((*count > 2) && (dtime == 1) && (dsn == 0))
146 counter_base[L2LEARN_ERROR_HIT_UPDATE] += 1;
149 else if (result0->raw == ~0)
151 /* Entry not in L2FIB - add it */
152 counter_base[L2LEARN_ERROR_MISS] += 1;
154 if (msm->global_learn_count >= msm->global_learn_limit)
157 * Global limit reached. Do not learn the mac but forward the packet.
158 * In the future, limits could also be per-interface or bridge-domain.
160 counter_base[L2LEARN_ERROR_LIMIT] += 1;
164 /* Do not learn if mac is 0 */
165 l2fib_entry_key_t key = *key0;
166 key.fields.bd_index = 0;
170 /* It is ok to learn */
171 msm->global_learn_count++;
172 result0->raw = 0; /* clear all fields */
173 result0->fields.sw_if_index = sw_if_index0;
174 if (msm->client_pid != 0)
175 l2fib_entry_result_set_LRN_EVT (result0);
177 l2fib_entry_result_clear_LRN_EVT (result0);
181 /* Entry in L2FIB with different sw_if_index - mac move or filter */
182 if (l2fib_entry_result_is_set_FILTER (result0))
184 ASSERT (result0->fields.sw_if_index == ~0);
185 /* drop packet because lookup matched a filter mac entry */
186 b0->error = node->errors[L2LEARN_ERROR_FILTER_DROP];
187 *next0 = L2LEARN_NEXT_DROP;
191 if (l2fib_entry_result_is_set_STATIC (result0))
194 * Don't overwrite a static mac
195 * TODO: Check violation policy. For now drop the packet
197 b0->error = node->errors[L2LEARN_ERROR_MAC_MOVE_VIOLATE];
198 *next0 = L2LEARN_NEXT_DROP;
203 * TODO: may want to rate limit mac moves
204 * TODO: check global/bridge domain/interface learn limits
206 result0->fields.sw_if_index = sw_if_index0;
207 if (l2fib_entry_result_is_set_AGE_NOT (result0))
209 /* The mac was provisioned */
210 msm->global_learn_count++;
211 l2fib_entry_result_clear_AGE_NOT (result0);
213 if (msm->client_pid != 0)
214 l2fib_entry_result_set_bits (result0,
215 (L2FIB_ENTRY_RESULT_FLAG_LRN_EVT |
216 L2FIB_ENTRY_RESULT_FLAG_LRN_MOV));
218 l2fib_entry_result_clear_bits (result0,
219 (L2FIB_ENTRY_RESULT_FLAG_LRN_EVT |
220 L2FIB_ENTRY_RESULT_FLAG_LRN_MOV));
221 counter_base[L2LEARN_ERROR_MAC_MOVE] += 1;
224 /* Update the entry */
225 result0->fields.timestamp = timestamp;
226 result0->fields.sn.as_u16 = vnet_buffer (b0)->l2.l2fib_sn;
228 BVT (clib_bihash_kv) kv;
230 kv.value = result0->raw;
231 BV (clib_bihash_add_del) (msm->mac_table, &kv, 1 /* is_add */ );
233 /* Invalidate the cache */
234 cached_key->raw = ~0;
238 static_always_inline uword
239 l2learn_node_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
240 vlib_frame_t * frame, int do_trace)
242 u32 n_left_from, *from, *to_next;
243 l2learn_next_t next_index;
244 l2learn_main_t *msm = &l2learn_main;
245 vlib_node_t *n = vlib_get_node (vm, l2learn_node.index);
246 u32 node_counter_base_index = n->error_heap_index;
247 vlib_error_main_t *em = &vm->error_main;
248 l2fib_entry_key_t cached_key;
249 l2fib_entry_result_t cached_result;
250 u8 timestamp = (u8) (vlib_time_now (vm) / 60);
253 from = vlib_frame_vector_args (frame);
254 n_left_from = frame->n_vectors; /* number of packets to process */
255 next_index = node->cached_next_index;
257 /* Clear the one-entry cache in case mac table was updated */
259 cached_result.raw = ~0; /* warning be gone */
261 while (n_left_from > 0)
265 /* get space to enqueue frame to graph node "next_index" */
266 vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
268 while (n_left_from >= 8 && n_left_to_next >= 4)
270 u32 bi0, bi1, bi2, bi3;
271 vlib_buffer_t *b0, *b1, *b2, *b3;
272 u32 next0, next1, next2, next3;
273 u32 sw_if_index0, sw_if_index1, sw_if_index2, sw_if_index3;
274 ethernet_header_t *h0, *h1, *h2, *h3;
275 l2fib_entry_key_t key0, key1, key2, key3;
276 l2fib_entry_result_t result0, result1, result2, result3;
277 u32 bucket0, bucket1, bucket2, bucket3;
279 /* Prefetch next iteration. */
281 vlib_buffer_t *p4, *p5, *p6, *p7;;
283 p4 = vlib_get_buffer (vm, from[4]);
284 p5 = vlib_get_buffer (vm, from[5]);
285 p6 = vlib_get_buffer (vm, from[6]);
286 p7 = vlib_get_buffer (vm, from[7]);
288 vlib_prefetch_buffer_header (p4, LOAD);
289 vlib_prefetch_buffer_header (p5, LOAD);
290 vlib_prefetch_buffer_header (p6, LOAD);
291 vlib_prefetch_buffer_header (p7, LOAD);
293 CLIB_PREFETCH (p4->data, CLIB_CACHE_LINE_BYTES, STORE);
294 CLIB_PREFETCH (p5->data, CLIB_CACHE_LINE_BYTES, STORE);
295 CLIB_PREFETCH (p6->data, CLIB_CACHE_LINE_BYTES, STORE);
296 CLIB_PREFETCH (p7->data, CLIB_CACHE_LINE_BYTES, STORE);
299 /* speculatively enqueue b0 and b1 to the current next frame */
300 /* bi is "buffer index", b is pointer to the buffer */
301 to_next[0] = bi0 = from[0];
302 to_next[1] = bi1 = from[1];
303 to_next[2] = bi2 = from[2];
304 to_next[3] = bi3 = from[3];
310 b0 = vlib_get_buffer (vm, bi0);
311 b1 = vlib_get_buffer (vm, bi1);
312 b2 = vlib_get_buffer (vm, bi2);
313 b3 = vlib_get_buffer (vm, bi3);
315 /* RX interface handles */
316 sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
317 sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
318 sw_if_index2 = vnet_buffer (b2)->sw_if_index[VLIB_RX];
319 sw_if_index3 = vnet_buffer (b3)->sw_if_index[VLIB_RX];
321 /* Process 4 x pkts */
323 h0 = vlib_buffer_get_current (b0);
324 h1 = vlib_buffer_get_current (b1);
325 h2 = vlib_buffer_get_current (b2);
326 h3 = vlib_buffer_get_current (b3);
330 if (b0->flags & VLIB_BUFFER_IS_TRACED)
333 vlib_add_trace (vm, node, b0, sizeof (*t));
334 t->sw_if_index = sw_if_index0;
335 t->bd_index = vnet_buffer (b0)->l2.bd_index;
336 clib_memcpy (t->src, h0->src_address, 6);
337 clib_memcpy (t->dst, h0->dst_address, 6);
339 if (b1->flags & VLIB_BUFFER_IS_TRACED)
342 vlib_add_trace (vm, node, b1, sizeof (*t));
343 t->sw_if_index = sw_if_index1;
344 t->bd_index = vnet_buffer (b1)->l2.bd_index;
345 clib_memcpy (t->src, h1->src_address, 6);
346 clib_memcpy (t->dst, h1->dst_address, 6);
348 if (b2->flags & VLIB_BUFFER_IS_TRACED)
351 vlib_add_trace (vm, node, b2, sizeof (*t));
352 t->sw_if_index = sw_if_index2;
353 t->bd_index = vnet_buffer (b2)->l2.bd_index;
354 clib_memcpy (t->src, h2->src_address, 6);
355 clib_memcpy (t->dst, h2->dst_address, 6);
357 if (b3->flags & VLIB_BUFFER_IS_TRACED)
360 vlib_add_trace (vm, node, b3, sizeof (*t));
361 t->sw_if_index = sw_if_index3;
362 t->bd_index = vnet_buffer (b3)->l2.bd_index;
363 clib_memcpy (t->src, h3->src_address, 6);
364 clib_memcpy (t->dst, h3->dst_address, 6);
369 vlib_node_increment_counter (vm, l2learn_node.index,
370 L2LEARN_ERROR_L2LEARN, 4);
372 l2fib_lookup_4 (msm->mac_table, &cached_key, &cached_result,
377 vnet_buffer (b0)->l2.bd_index,
378 vnet_buffer (b1)->l2.bd_index,
379 vnet_buffer (b2)->l2.bd_index,
380 vnet_buffer (b3)->l2.bd_index,
381 &key0, &key1, &key2, &key3,
382 &bucket0, &bucket1, &bucket2, &bucket3,
383 &result0, &result1, &result2, &result3);
385 l2learn_process (node, msm, &em->counters[node_counter_base_index],
386 b0, sw_if_index0, &key0, &cached_key,
387 &count, &result0, &next0, timestamp);
389 l2learn_process (node, msm, &em->counters[node_counter_base_index],
390 b1, sw_if_index1, &key1, &cached_key,
391 &count, &result1, &next1, timestamp);
393 l2learn_process (node, msm, &em->counters[node_counter_base_index],
394 b2, sw_if_index2, &key2, &cached_key,
395 &count, &result2, &next2, timestamp);
397 l2learn_process (node, msm, &em->counters[node_counter_base_index],
398 b3, sw_if_index3, &key3, &cached_key,
399 &count, &result3, &next3, timestamp);
401 /* verify speculative enqueues, maybe switch current next frame */
402 /* if next0==next1==next_index then nothing special needs to be done */
403 vlib_validate_buffer_enqueue_x4 (vm, node, next_index,
404 to_next, n_left_to_next,
406 next0, next1, next2, next3);
409 while (n_left_from > 0 && n_left_to_next > 0)
415 ethernet_header_t *h0;
416 l2fib_entry_key_t key0;
417 l2fib_entry_result_t result0;
420 /* speculatively enqueue b0 to the current next frame */
428 b0 = vlib_get_buffer (vm, bi0);
430 sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
432 h0 = vlib_buffer_get_current (b0);
434 if (do_trace && PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
436 l2learn_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
437 t->sw_if_index = sw_if_index0;
438 t->bd_index = vnet_buffer (b0)->l2.bd_index;
439 clib_memcpy (t->src, h0->src_address, 6);
440 clib_memcpy (t->dst, h0->dst_address, 6);
444 vlib_node_increment_counter (vm, l2learn_node.index,
445 L2LEARN_ERROR_L2LEARN, 1);
448 l2fib_lookup_1 (msm->mac_table, &cached_key, &cached_result,
449 h0->src_address, vnet_buffer (b0)->l2.bd_index,
450 &key0, &bucket0, &result0);
452 l2learn_process (node, msm, &em->counters[node_counter_base_index],
453 b0, sw_if_index0, &key0, &cached_key,
454 &count, &result0, &next0, timestamp);
456 /* verify speculative enqueue, maybe switch current next frame */
457 vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
458 to_next, n_left_to_next,
462 vlib_put_next_frame (vm, node, next_index, n_left_to_next);
465 return frame->n_vectors;
469 l2learn_node_fn (vlib_main_t * vm,
470 vlib_node_runtime_t * node, vlib_frame_t * frame)
472 if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
473 return l2learn_node_inline (vm, node, frame, 1 /* do_trace */ );
474 return l2learn_node_inline (vm, node, frame, 0 /* do_trace */ );
478 VLIB_REGISTER_NODE (l2learn_node,static) = {
479 .function = l2learn_node_fn,
481 .vector_size = sizeof (u32),
482 .format_trace = format_l2learn_trace,
483 .type = VLIB_NODE_TYPE_INTERNAL,
485 .n_errors = ARRAY_LEN(l2learn_error_strings),
486 .error_strings = l2learn_error_strings,
488 .n_next_nodes = L2LEARN_N_NEXT,
490 /* edit / add dispositions here */
492 [L2LEARN_NEXT_DROP] = "error-drop",
493 [L2LEARN_NEXT_L2FWD] = "l2-fwd",
498 VLIB_NODE_FUNCTION_MULTIARCH (l2learn_node, l2learn_node_fn)
499 clib_error_t *l2learn_init (vlib_main_t * vm)
501 l2learn_main_t *mp = &l2learn_main;
504 mp->vnet_main = vnet_get_main ();
506 /* Initialize the feature next-node indexes */
507 feat_bitmap_init_next_nodes (vm,
510 l2input_get_feat_names (),
511 mp->feat_next_node_index);
513 /* init the hash table ptr */
514 mp->mac_table = get_mac_table ();
517 * Set the default number of dynamically learned macs to the number
520 mp->global_learn_limit = L2LEARN_DEFAULT_LIMIT;
525 VLIB_INIT_FUNCTION (l2learn_init);
529 * Set subinterface learn enable/disable.
531 * set interface l2 learn <interface> [disable]
533 static clib_error_t *
534 int_learn (vlib_main_t * vm,
535 unformat_input_t * input, vlib_cli_command_t * cmd)
537 vnet_main_t *vnm = vnet_get_main ();
538 clib_error_t *error = 0;
542 if (!unformat_user (input, unformat_vnet_sw_interface, vnm, &sw_if_index))
544 error = clib_error_return (0, "unknown interface `%U'",
545 format_unformat_error, input);
550 if (unformat (input, "disable"))
555 /* set the interface flag */
556 l2input_intf_bitmap_enable (sw_if_index, L2INPUT_FEAT_LEARN, enable);
563 * Layer 2 learning can be enabled and disabled on each
564 * interface and on each bridge-domain. Use this command to
565 * manage interfaces. It is enabled by default.
568 * Example of how to enable learning:
569 * @cliexcmd{set interface l2 learn GigabitEthernet0/8/0}
570 * Example of how to disable learning:
571 * @cliexcmd{set interface l2 learn GigabitEthernet0/8/0 disable}
574 VLIB_CLI_COMMAND (int_learn_cli, static) = {
575 .path = "set interface l2 learn",
576 .short_help = "set interface l2 learn <interface> [disable]",
577 .function = int_learn,
582 static clib_error_t *
583 l2learn_config (vlib_main_t * vm, unformat_input_t * input)
585 l2learn_main_t *mp = &l2learn_main;
587 while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
589 if (unformat (input, "limit %d", &mp->global_learn_limit))
593 return clib_error_return (0, "unknown input `%U'",
594 format_unformat_error, input);
600 VLIB_CONFIG_FUNCTION (l2learn_config, "l2learn");
604 * fd.io coding-style-patch-verification: ON
607 * eval: (c-set-style "gnu")