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>
34 * @brief Ethernet Bridge Learning.
36 * Populate the mac table with entries mapping the packet's source mac + bridge
37 * domain ID to the input sw_if_index.
39 * Note that learning and forwarding are separate graph nodes. This means that
40 * for a set of packets, all learning is performed first, then all nodes are
41 * forwarded. The forwarding is done based on the end-state of the mac table,
42 * instead of the state after each packet. Thus the forwarding results could
43 * differ in certain cases (mac move tests), but this not expected to cause
44 * problems in real-world networks. It is much simpler to separate learning
45 * and forwarding into separate nodes.
58 /* packet trace format function */
60 format_l2learn_trace (u8 * s, va_list * args)
62 CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
63 CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
64 l2learn_trace_t *t = va_arg (*args, l2learn_trace_t *);
66 s = format (s, "l2-learn: sw_if_index %d dst %U src %U bd_index %d",
68 format_ethernet_address, t->dst,
69 format_ethernet_address, t->src, t->bd_index);
73 static vlib_node_registration_t l2learn_node;
75 #define foreach_l2learn_error \
76 _(L2LEARN, "L2 learn packets") \
77 _(MISS, "L2 learn misses") \
78 _(MAC_MOVE, "L2 mac moves") \
79 _(MAC_MOVE_VIOLATE, "L2 mac move violations") \
80 _(LIMIT, "L2 not learned due to limit") \
81 _(HIT_UPDATE, "L2 learn hit updates") \
82 _(FILTER_DROP, "L2 filter mac drops")
86 #define _(sym,str) L2LEARN_ERROR_##sym,
92 static char *l2learn_error_strings[] = {
93 #define _(sym,string) string,
106 /** Perform learning on one packet based on the mac table lookup result. */
108 static_always_inline void
109 l2learn_process (vlib_node_runtime_t * node,
110 l2learn_main_t * msm,
114 l2fib_entry_key_t * key0,
115 l2fib_entry_key_t * cached_key,
117 l2fib_entry_result_t * result0, u32 * next0, u8 timestamp)
119 /* Set up the default next node (typically L2FWD) */
120 *next0 = vnet_l2_feature_next (b0, msm->feat_next_node_index,
123 /* Check mac table lookup result */
124 if (PREDICT_TRUE (result0->fields.sw_if_index == sw_if_index0))
126 /* Entry in L2FIB with matching sw_if_index matched - normal fast path */
127 u32 dtime = timestamp - result0->fields.timestamp;
128 u32 dsn = result0->fields.sn.as_u16 - vnet_buffer (b0)->l2.l2fib_sn;
129 u32 check = (dtime && vnet_buffer (b0)->l2.bd_age) || dsn;
131 if (PREDICT_TRUE (check == 0))
132 return; /* MAC entry up to date */
133 if (result0->fields.age_not)
134 return; /* Static MAC always age_not */
135 if (msm->global_learn_count > msm->global_learn_limit)
136 return; /* Above learn limit - do not update */
138 /* Limit updates per l2-learn node call to avoid prolonged update burst
139 * as dtime advance over 1 minute mark, unless more than 1 min behind
141 if ((*count > 2) && (dtime == 1) && (dsn == 0))
144 counter_base[L2LEARN_ERROR_HIT_UPDATE] += 1;
147 else if (result0->raw == ~0)
149 /* Entry not in L2FIB - add it */
150 counter_base[L2LEARN_ERROR_MISS] += 1;
152 if (msm->global_learn_count >= msm->global_learn_limit)
155 * Global limit reached. Do not learn the mac but forward the packet.
156 * In the future, limits could also be per-interface or bridge-domain.
158 counter_base[L2LEARN_ERROR_LIMIT] += 1;
162 /* Do not learn if mac is 0 */
163 l2fib_entry_key_t key = *key0;
164 key.fields.bd_index = 0;
168 /* It is ok to learn */
169 msm->global_learn_count++;
170 result0->raw = 0; /* clear all fields */
171 result0->fields.sw_if_index = sw_if_index0;
172 result0->fields.lrn_evt = (msm->client_pid != 0);
176 /* Entry in L2FIB with different sw_if_index - mac move or filter */
177 if (result0->fields.filter)
179 ASSERT (result0->fields.sw_if_index == ~0);
180 /* drop packet because lookup matched a filter mac entry */
181 b0->error = node->errors[L2LEARN_ERROR_FILTER_DROP];
182 *next0 = L2LEARN_NEXT_DROP;
186 if (result0->fields.static_mac)
189 * Don't overwrite a static mac
190 * TODO: Check violation policy. For now drop the packet
192 b0->error = node->errors[L2LEARN_ERROR_MAC_MOVE_VIOLATE];
193 *next0 = L2LEARN_NEXT_DROP;
198 * TODO: may want to rate limit mac moves
199 * TODO: check global/bridge domain/interface learn limits
201 result0->fields.sw_if_index = sw_if_index0;
202 if (result0->fields.age_not) /* The mac was provisioned */
204 msm->global_learn_count++;
205 result0->fields.age_not = 0;
207 result0->fields.lrn_evt = (msm->client_pid != 0);
208 counter_base[L2LEARN_ERROR_MAC_MOVE] += 1;
211 /* Update the entry */
212 result0->fields.timestamp = timestamp;
213 result0->fields.sn.as_u16 = vnet_buffer (b0)->l2.l2fib_sn;
215 BVT (clib_bihash_kv) kv;
217 kv.value = result0->raw;
218 BV (clib_bihash_add_del) (msm->mac_table, &kv, 1 /* is_add */ );
220 /* Invalidate the cache */
221 cached_key->raw = ~0;
225 static_always_inline uword
226 l2learn_node_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
227 vlib_frame_t * frame, int do_trace)
229 u32 n_left_from, *from, *to_next;
230 l2learn_next_t next_index;
231 l2learn_main_t *msm = &l2learn_main;
232 vlib_node_t *n = vlib_get_node (vm, l2learn_node.index);
233 u32 node_counter_base_index = n->error_heap_index;
234 vlib_error_main_t *em = &vm->error_main;
235 l2fib_entry_key_t cached_key;
236 l2fib_entry_result_t cached_result;
237 u8 timestamp = (u8) (vlib_time_now (vm) / 60);
240 from = vlib_frame_vector_args (frame);
241 n_left_from = frame->n_vectors; /* number of packets to process */
242 next_index = node->cached_next_index;
244 /* Clear the one-entry cache in case mac table was updated */
246 cached_result.raw = ~0; /* warning be gone */
248 while (n_left_from > 0)
252 /* get space to enqueue frame to graph node "next_index" */
253 vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
255 while (n_left_from >= 8 && n_left_to_next >= 4)
257 u32 bi0, bi1, bi2, bi3;
258 vlib_buffer_t *b0, *b1, *b2, *b3;
259 u32 next0, next1, next2, next3;
260 u32 sw_if_index0, sw_if_index1, sw_if_index2, sw_if_index3;
261 ethernet_header_t *h0, *h1, *h2, *h3;
262 l2fib_entry_key_t key0, key1, key2, key3;
263 l2fib_entry_result_t result0, result1, result2, result3;
264 u32 bucket0, bucket1, bucket2, bucket3;
266 /* Prefetch next iteration. */
268 vlib_buffer_t *p4, *p5, *p6, *p7;;
270 p4 = vlib_get_buffer (vm, from[4]);
271 p5 = vlib_get_buffer (vm, from[5]);
272 p6 = vlib_get_buffer (vm, from[6]);
273 p7 = vlib_get_buffer (vm, from[7]);
275 vlib_prefetch_buffer_header (p4, LOAD);
276 vlib_prefetch_buffer_header (p5, LOAD);
277 vlib_prefetch_buffer_header (p6, LOAD);
278 vlib_prefetch_buffer_header (p7, LOAD);
280 CLIB_PREFETCH (p4->data, CLIB_CACHE_LINE_BYTES, STORE);
281 CLIB_PREFETCH (p5->data, CLIB_CACHE_LINE_BYTES, STORE);
282 CLIB_PREFETCH (p6->data, CLIB_CACHE_LINE_BYTES, STORE);
283 CLIB_PREFETCH (p7->data, CLIB_CACHE_LINE_BYTES, STORE);
286 /* speculatively enqueue b0 and b1 to the current next frame */
287 /* bi is "buffer index", b is pointer to the buffer */
288 to_next[0] = bi0 = from[0];
289 to_next[1] = bi1 = from[1];
290 to_next[2] = bi2 = from[2];
291 to_next[3] = bi3 = from[3];
297 b0 = vlib_get_buffer (vm, bi0);
298 b1 = vlib_get_buffer (vm, bi1);
299 b2 = vlib_get_buffer (vm, bi2);
300 b3 = vlib_get_buffer (vm, bi3);
302 /* RX interface handles */
303 sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
304 sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
305 sw_if_index2 = vnet_buffer (b2)->sw_if_index[VLIB_RX];
306 sw_if_index3 = vnet_buffer (b3)->sw_if_index[VLIB_RX];
308 /* Process 4 x pkts */
310 h0 = vlib_buffer_get_current (b0);
311 h1 = vlib_buffer_get_current (b1);
312 h2 = vlib_buffer_get_current (b2);
313 h3 = vlib_buffer_get_current (b3);
317 if (b0->flags & VLIB_BUFFER_IS_TRACED)
320 vlib_add_trace (vm, node, b0, sizeof (*t));
321 t->sw_if_index = sw_if_index0;
322 t->bd_index = vnet_buffer (b0)->l2.bd_index;
323 clib_memcpy (t->src, h0->src_address, 6);
324 clib_memcpy (t->dst, h0->dst_address, 6);
326 if (b1->flags & VLIB_BUFFER_IS_TRACED)
329 vlib_add_trace (vm, node, b1, sizeof (*t));
330 t->sw_if_index = sw_if_index1;
331 t->bd_index = vnet_buffer (b1)->l2.bd_index;
332 clib_memcpy (t->src, h1->src_address, 6);
333 clib_memcpy (t->dst, h1->dst_address, 6);
335 if (b2->flags & VLIB_BUFFER_IS_TRACED)
338 vlib_add_trace (vm, node, b2, sizeof (*t));
339 t->sw_if_index = sw_if_index2;
340 t->bd_index = vnet_buffer (b2)->l2.bd_index;
341 clib_memcpy (t->src, h2->src_address, 6);
342 clib_memcpy (t->dst, h2->dst_address, 6);
344 if (b3->flags & VLIB_BUFFER_IS_TRACED)
347 vlib_add_trace (vm, node, b3, sizeof (*t));
348 t->sw_if_index = sw_if_index3;
349 t->bd_index = vnet_buffer (b3)->l2.bd_index;
350 clib_memcpy (t->src, h3->src_address, 6);
351 clib_memcpy (t->dst, h3->dst_address, 6);
356 vlib_node_increment_counter (vm, l2learn_node.index,
357 L2LEARN_ERROR_L2LEARN, 4);
359 l2fib_lookup_4 (msm->mac_table, &cached_key, &cached_result,
364 vnet_buffer (b0)->l2.bd_index,
365 vnet_buffer (b1)->l2.bd_index,
366 vnet_buffer (b2)->l2.bd_index,
367 vnet_buffer (b3)->l2.bd_index,
368 &key0, &key1, &key2, &key3,
369 &bucket0, &bucket1, &bucket2, &bucket3,
370 &result0, &result1, &result2, &result3);
372 l2learn_process (node, msm, &em->counters[node_counter_base_index],
373 b0, sw_if_index0, &key0, &cached_key,
374 &count, &result0, &next0, timestamp);
376 l2learn_process (node, msm, &em->counters[node_counter_base_index],
377 b1, sw_if_index1, &key1, &cached_key,
378 &count, &result1, &next1, timestamp);
380 l2learn_process (node, msm, &em->counters[node_counter_base_index],
381 b2, sw_if_index2, &key2, &cached_key,
382 &count, &result2, &next2, timestamp);
384 l2learn_process (node, msm, &em->counters[node_counter_base_index],
385 b3, sw_if_index3, &key3, &cached_key,
386 &count, &result3, &next3, timestamp);
388 /* verify speculative enqueues, maybe switch current next frame */
389 /* if next0==next1==next_index then nothing special needs to be done */
390 vlib_validate_buffer_enqueue_x4 (vm, node, next_index,
391 to_next, n_left_to_next,
393 next0, next1, next2, next3);
396 while (n_left_from > 0 && n_left_to_next > 0)
402 ethernet_header_t *h0;
403 l2fib_entry_key_t key0;
404 l2fib_entry_result_t result0;
407 /* speculatively enqueue b0 to the current next frame */
415 b0 = vlib_get_buffer (vm, bi0);
417 sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
419 h0 = vlib_buffer_get_current (b0);
421 if (do_trace && PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
423 l2learn_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
424 t->sw_if_index = sw_if_index0;
425 t->bd_index = vnet_buffer (b0)->l2.bd_index;
426 clib_memcpy (t->src, h0->src_address, 6);
427 clib_memcpy (t->dst, h0->dst_address, 6);
431 vlib_node_increment_counter (vm, l2learn_node.index,
432 L2LEARN_ERROR_L2LEARN, 1);
435 l2fib_lookup_1 (msm->mac_table, &cached_key, &cached_result,
436 h0->src_address, vnet_buffer (b0)->l2.bd_index,
437 &key0, &bucket0, &result0);
439 l2learn_process (node, msm, &em->counters[node_counter_base_index],
440 b0, sw_if_index0, &key0, &cached_key,
441 &count, &result0, &next0, timestamp);
443 /* verify speculative enqueue, maybe switch current next frame */
444 vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
445 to_next, n_left_to_next,
449 vlib_put_next_frame (vm, node, next_index, n_left_to_next);
452 return frame->n_vectors;
456 l2learn_node_fn (vlib_main_t * vm,
457 vlib_node_runtime_t * node, vlib_frame_t * frame)
459 if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
460 return l2learn_node_inline (vm, node, frame, 1 /* do_trace */ );
461 return l2learn_node_inline (vm, node, frame, 0 /* do_trace */ );
465 VLIB_REGISTER_NODE (l2learn_node,static) = {
466 .function = l2learn_node_fn,
468 .vector_size = sizeof (u32),
469 .format_trace = format_l2learn_trace,
470 .type = VLIB_NODE_TYPE_INTERNAL,
472 .n_errors = ARRAY_LEN(l2learn_error_strings),
473 .error_strings = l2learn_error_strings,
475 .n_next_nodes = L2LEARN_N_NEXT,
477 /* edit / add dispositions here */
479 [L2LEARN_NEXT_DROP] = "error-drop",
480 [L2LEARN_NEXT_L2FWD] = "l2-fwd",
485 VLIB_NODE_FUNCTION_MULTIARCH (l2learn_node, l2learn_node_fn)
486 clib_error_t *l2learn_init (vlib_main_t * vm)
488 l2learn_main_t *mp = &l2learn_main;
491 mp->vnet_main = vnet_get_main ();
493 /* Initialize the feature next-node indexes */
494 feat_bitmap_init_next_nodes (vm,
497 l2input_get_feat_names (),
498 mp->feat_next_node_index);
500 /* init the hash table ptr */
501 mp->mac_table = get_mac_table ();
504 * Set the default number of dynamically learned macs to the number
507 mp->global_learn_limit = L2LEARN_DEFAULT_LIMIT;
512 VLIB_INIT_FUNCTION (l2learn_init);
516 * Set subinterface learn enable/disable.
518 * set interface l2 learn <interface> [disable]
520 static clib_error_t *
521 int_learn (vlib_main_t * vm,
522 unformat_input_t * input, vlib_cli_command_t * cmd)
524 vnet_main_t *vnm = vnet_get_main ();
525 clib_error_t *error = 0;
529 if (!unformat_user (input, unformat_vnet_sw_interface, vnm, &sw_if_index))
531 error = clib_error_return (0, "unknown interface `%U'",
532 format_unformat_error, input);
537 if (unformat (input, "disable"))
542 /* set the interface flag */
543 l2input_intf_bitmap_enable (sw_if_index, L2INPUT_FEAT_LEARN, enable);
550 * Layer 2 learning can be enabled and disabled on each
551 * interface and on each bridge-domain. Use this command to
552 * manage interfaces. It is enabled by default.
555 * Example of how to enable learning:
556 * @cliexcmd{set interface l2 learn GigabitEthernet0/8/0}
557 * Example of how to disable learning:
558 * @cliexcmd{set interface l2 learn GigabitEthernet0/8/0 disable}
561 VLIB_CLI_COMMAND (int_learn_cli, static) = {
562 .path = "set interface l2 learn",
563 .short_help = "set interface l2 learn <interface> [disable]",
564 .function = int_learn,
569 static clib_error_t *
570 l2learn_config (vlib_main_t * vm, unformat_input_t * input)
572 l2learn_main_t *mp = &l2learn_main;
574 while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
576 if (unformat (input, "limit %d", &mp->global_learn_limit))
580 return clib_error_return (0, "unknown input `%U'",
581 format_unformat_error, input);
587 VLIB_CONFIG_FUNCTION (l2learn_config, "l2learn");
591 * fd.io coding-style-patch-verification: ON
594 * eval: (c-set-style "gnu")