2 * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 /* Based on sample implementation in 802.1D-1998. Above copyright and license
18 * applies to all modifications. */
23 #include <sys/types.h>
24 #include <netinet/in.h>
25 #include <arpa/inet.h>
28 #include "byte-order.h"
35 VLOG_DEFINE_THIS_MODULE(stp);
37 #define STP_PROTOCOL_ID 0x0000
38 #define STP_PROTOCOL_VERSION 0x00
39 #define STP_TYPE_CONFIG 0x00
40 #define STP_TYPE_TCN 0x80
43 struct stp_bpdu_header {
44 ovs_be16 protocol_id; /* STP_PROTOCOL_ID. */
45 uint8_t protocol_version; /* STP_PROTOCOL_VERSION. */
46 uint8_t bpdu_type; /* One of STP_TYPE_*. */
48 BUILD_ASSERT_DECL(sizeof(struct stp_bpdu_header) == 4);
50 enum stp_config_bpdu_flags {
51 STP_CONFIG_TOPOLOGY_CHANGE_ACK = 0x80,
52 STP_CONFIG_TOPOLOGY_CHANGE = 0x01
56 struct stp_config_bpdu {
57 struct stp_bpdu_header header; /* Type STP_TYPE_CONFIG. */
58 uint8_t flags; /* STP_CONFIG_* flags. */
59 ovs_be64 root_id; /* 8.5.1.1: Bridge believed to be root. */
60 ovs_be32 root_path_cost; /* 8.5.1.2: Cost of path to root. */
61 ovs_be64 bridge_id; /* 8.5.1.3: ID of transmitting bridge. */
62 ovs_be16 port_id; /* 8.5.1.4: Port transmitting the BPDU. */
63 ovs_be16 message_age; /* 8.5.1.5: Age of BPDU at tx time. */
64 ovs_be16 max_age; /* 8.5.1.6: Timeout for received data. */
65 ovs_be16 hello_time; /* 8.5.1.7: Time between BPDU generation. */
66 ovs_be16 forward_delay; /* 8.5.1.8: State progression delay. */
68 BUILD_ASSERT_DECL(sizeof(struct stp_config_bpdu) == 35);
72 struct stp_bpdu_header header; /* Type STP_TYPE_TCN. */
74 BUILD_ASSERT_DECL(sizeof(struct stp_tcn_bpdu) == 4);
77 bool active; /* Timer in use? */
78 int value; /* Current value of timer, counting up. */
83 void *aux; /* Auxiliary data the user may retrieve. */
84 int port_id; /* 8.5.5.1: Unique port identifier. */
85 enum stp_state state; /* 8.5.5.2: Current state. */
86 int path_cost; /* 8.5.5.3: Cost of tx/rx on this port. */
87 stp_identifier designated_root; /* 8.5.5.4. */
88 int designated_cost; /* 8.5.5.5: Path cost to root on port. */
89 stp_identifier designated_bridge; /* 8.5.5.6. */
90 int designated_port; /* 8.5.5.7: Port to send config msgs on. */
91 bool topology_change_ack; /* 8.5.5.8: Flag for next config BPDU. */
92 bool config_pending; /* 8.5.5.9: Send BPDU when hold expires? */
93 bool change_detection_enabled; /* 8.5.5.10: Detect topology changes? */
95 struct stp_timer message_age_timer; /* 8.5.6.1: Age of received info. */
96 struct stp_timer forward_delay_timer; /* 8.5.6.2: State change timer. */
97 struct stp_timer hold_timer; /* 8.5.6.3: BPDU rate limit timer. */
99 int tx_count; /* Number of BPDUs transmitted. */
100 int rx_count; /* Number of valid BPDUs received. */
101 int error_count; /* Number of bad BPDUs received. */
107 struct list node; /* Node in all_stps list. */
109 /* Static bridge data. */
110 char *name; /* Human-readable name for log messages. */
111 stp_identifier bridge_id; /* 8.5.3.7: This bridge. */
112 int max_age; /* 8.5.3.4: Time to drop received data. */
113 int hello_time; /* 8.5.3.5: Time between sending BPDUs. */
114 int forward_delay; /* 8.5.3.6: Delay between state changes. */
115 int bridge_max_age; /* 8.5.3.8: max_age when we're root. */
116 int bridge_hello_time; /* 8.5.3.9: hello_time as root. */
117 int bridge_forward_delay; /* 8.5.3.10: forward_delay as root. */
118 int rq_max_age; /* User-requested max age, in ms. */
119 int rq_hello_time; /* User-requested hello time, in ms. */
120 int rq_forward_delay; /* User-requested forward delay, in ms. */
121 int elapsed_remainder; /* Left-over msecs from last stp_tick(). */
123 /* Dynamic bridge data. */
124 stp_identifier designated_root; /* 8.5.3.1: Bridge believed to be root. */
125 unsigned int root_path_cost; /* 8.5.3.2: Cost of path to root. */
126 struct stp_port *root_port; /* 8.5.3.3: Lowest cost port to root. */
127 bool topology_change_detected; /* 8.5.3.11: Detected a topology change? */
128 bool topology_change; /* 8.5.3.12: Received topology change? */
131 struct stp_timer hello_timer; /* 8.5.4.1: Hello timer. */
132 struct stp_timer tcn_timer; /* 8.5.4.2: Topology change timer. */
133 struct stp_timer topology_change_timer; /* 8.5.4.3. */
136 struct stp_port ports[STP_MAX_PORTS];
138 /* Interface to client. */
139 bool fdb_needs_flush; /* MAC learning tables needs flushing. */
140 struct stp_port *first_changed_port;
141 void (*send_bpdu)(struct ofpbuf *bpdu, int port_no, void *aux);
145 static struct list all_stps = LIST_INITIALIZER(&all_stps);
147 #define FOR_EACH_ENABLED_PORT(PORT, STP) \
148 for ((PORT) = stp_next_enabled_port((STP), (STP)->ports); \
150 (PORT) = stp_next_enabled_port((STP), (PORT) + 1))
151 static struct stp_port *
152 stp_next_enabled_port(const struct stp *stp, const struct stp_port *port)
154 for (; port < &stp->ports[ARRAY_SIZE(stp->ports)]; port++) {
155 if (port->state != STP_DISABLED) {
156 return CONST_CAST(struct stp_port *, port);
162 #define MESSAGE_AGE_INCREMENT 1
164 static void stp_transmit_config(struct stp_port *);
165 static bool stp_supersedes_port_info(const struct stp_port *,
166 const struct stp_config_bpdu *);
167 static void stp_record_config_information(struct stp_port *,
168 const struct stp_config_bpdu *);
169 static void stp_record_config_timeout_values(struct stp *,
170 const struct stp_config_bpdu *);
171 static bool stp_is_designated_port(const struct stp_port *);
172 static void stp_config_bpdu_generation(struct stp *);
173 static void stp_transmit_tcn(struct stp *);
174 static void stp_configuration_update(struct stp *);
175 static bool stp_supersedes_root(const struct stp_port *root,
176 const struct stp_port *);
177 static void stp_root_selection(struct stp *);
178 static void stp_designated_port_selection(struct stp *);
179 static void stp_become_designated_port(struct stp_port *);
180 static void stp_port_state_selection(struct stp *);
181 static void stp_make_forwarding(struct stp_port *);
182 static void stp_make_blocking(struct stp_port *);
183 static void stp_set_port_state(struct stp_port *, enum stp_state);
184 static void stp_topology_change_detection(struct stp *);
185 static void stp_topology_change_acknowledged(struct stp *);
186 static void stp_acknowledge_topology_change(struct stp_port *);
187 static void stp_received_config_bpdu(struct stp *, struct stp_port *,
188 const struct stp_config_bpdu *);
189 static void stp_received_tcn_bpdu(struct stp *, struct stp_port *);
190 static void stp_hello_timer_expiry(struct stp *);
191 static void stp_message_age_timer_expiry(struct stp_port *);
192 static bool stp_is_designated_for_some_port(const struct stp *);
193 static void stp_forward_delay_timer_expiry(struct stp_port *);
194 static void stp_tcn_timer_expiry(struct stp *);
195 static void stp_topology_change_timer_expiry(struct stp *);
196 static void stp_hold_timer_expiry(struct stp_port *);
197 static void stp_initialize_port(struct stp_port *, enum stp_state);
198 static void stp_become_root_bridge(struct stp *);
199 static void stp_update_bridge_timers(struct stp *);
201 static int clamp(int x, int min, int max);
202 static int ms_to_timer(int ms);
203 static int timer_to_ms(int timer);
204 static void stp_start_timer(struct stp_timer *, int value);
205 static void stp_stop_timer(struct stp_timer *);
206 static bool stp_timer_expired(struct stp_timer *, int elapsed, int timeout);
208 static void stp_send_bpdu(struct stp_port *, const void *, size_t);
209 static void stp_unixctl_tcn(struct unixctl_conn *, int argc,
210 const char *argv[], void *aux);
215 unixctl_command_register("stp/tcn", "[bridge]", 0, 1, stp_unixctl_tcn,
219 /* Creates and returns a new STP instance that initially has no ports enabled.
221 * 'bridge_id' should be a 48-bit MAC address as returned by
222 * eth_addr_to_uint64(). 'bridge_id' may also have a priority value in its top
223 * 16 bits; if those bits are set to 0, STP_DEFAULT_BRIDGE_PRIORITY is used.
224 * (This priority may be changed with stp_set_bridge_priority().)
226 * When the bridge needs to send out a BPDU, it calls 'send_bpdu'. This
227 * callback may be called from stp_tick() or stp_received_bpdu(). The
228 * arguments to 'send_bpdu' are an STP BPDU encapsulated in 'bpdu',
229 * the spanning tree port number 'port_no' that should transmit the
230 * packet, and auxiliary data to be passed to the callback in 'aux'.
233 stp_create(const char *name, stp_identifier bridge_id,
234 void (*send_bpdu)(struct ofpbuf *bpdu, int port_no, void *aux),
240 stp = xzalloc(sizeof *stp);
241 stp->name = xstrdup(name);
242 stp->bridge_id = bridge_id;
243 if (!(stp->bridge_id >> 48)) {
244 stp->bridge_id |= (uint64_t) STP_DEFAULT_BRIDGE_PRIORITY << 48;
247 stp->rq_max_age = STP_DEFAULT_MAX_AGE;
248 stp->rq_hello_time = STP_DEFAULT_HELLO_TIME;
249 stp->rq_forward_delay = STP_DEFAULT_FWD_DELAY;
250 stp_update_bridge_timers(stp);
251 stp->max_age = stp->bridge_max_age;
252 stp->hello_time = stp->bridge_hello_time;
253 stp->forward_delay = stp->bridge_forward_delay;
255 stp->designated_root = stp->bridge_id;
256 stp->root_path_cost = 0;
257 stp->root_port = NULL;
258 stp->topology_change_detected = false;
259 stp->topology_change = false;
261 stp_stop_timer(&stp->tcn_timer);
262 stp_stop_timer(&stp->topology_change_timer);
263 stp_start_timer(&stp->hello_timer, 0);
265 stp->send_bpdu = send_bpdu;
268 stp->first_changed_port = &stp->ports[ARRAY_SIZE(stp->ports)];
269 for (p = stp->ports; p < &stp->ports[ARRAY_SIZE(stp->ports)]; p++) {
271 p->port_id = (stp_port_no(p) + 1) | (STP_DEFAULT_PORT_PRIORITY << 8);
272 p->path_cost = 19; /* Recommended default for 100 Mb/s link. */
273 stp_initialize_port(p, STP_DISABLED);
275 list_push_back(&all_stps, &stp->node);
279 /* Destroys 'stp'. */
281 stp_destroy(struct stp *stp)
284 list_remove(&stp->node);
290 /* Runs 'stp' given that 'ms' milliseconds have passed. */
292 stp_tick(struct stp *stp, int ms)
297 /* Convert 'ms' to STP timer ticks. Preserve any leftover milliseconds
298 * from previous stp_tick() calls so that we don't lose STP ticks when we
299 * are called too frequently. */
300 ms = clamp(ms, 0, INT_MAX - 1000) + stp->elapsed_remainder;
301 elapsed = ms_to_timer(ms);
302 stp->elapsed_remainder = ms - timer_to_ms(elapsed);
307 if (stp_timer_expired(&stp->hello_timer, elapsed, stp->hello_time)) {
308 stp_hello_timer_expiry(stp);
310 if (stp_timer_expired(&stp->tcn_timer, elapsed, stp->bridge_hello_time)) {
311 stp_tcn_timer_expiry(stp);
313 if (stp_timer_expired(&stp->topology_change_timer, elapsed,
314 stp->max_age + stp->forward_delay)) {
315 stp_topology_change_timer_expiry(stp);
317 FOR_EACH_ENABLED_PORT (p, stp) {
318 if (stp_timer_expired(&p->message_age_timer, elapsed, stp->max_age)) {
319 stp_message_age_timer_expiry(p);
322 FOR_EACH_ENABLED_PORT (p, stp) {
323 if (stp_timer_expired(&p->forward_delay_timer, elapsed,
324 stp->forward_delay)) {
325 stp_forward_delay_timer_expiry(p);
327 if (stp_timer_expired(&p->hold_timer, elapsed, ms_to_timer(1000))) {
328 stp_hold_timer_expiry(p);
334 set_bridge_id(struct stp *stp, stp_identifier new_bridge_id)
336 if (new_bridge_id != stp->bridge_id) {
340 root = stp_is_root_bridge(stp);
341 FOR_EACH_ENABLED_PORT (p, stp) {
342 if (stp_is_designated_port(p)) {
343 p->designated_bridge = new_bridge_id;
346 stp->bridge_id = new_bridge_id;
347 stp_configuration_update(stp);
348 stp_port_state_selection(stp);
349 if (stp_is_root_bridge(stp) && !root) {
350 stp_become_root_bridge(stp);
356 stp_set_bridge_id(struct stp *stp, stp_identifier bridge_id)
358 const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
359 const uint64_t pri_bits = ~mac_bits;
360 set_bridge_id(stp, (stp->bridge_id & pri_bits) | (bridge_id & mac_bits));
364 stp_set_bridge_priority(struct stp *stp, uint16_t new_priority)
366 const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
367 set_bridge_id(stp, ((stp->bridge_id & mac_bits)
368 | ((uint64_t) new_priority << 48)));
371 /* Sets the desired hello time for 'stp' to 'ms', in milliseconds. The actual
372 * hello time is clamped to the range of 1 to 10 seconds and subject to the
373 * relationship (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge
374 * hello time is only used when 'stp' is the root bridge. */
376 stp_set_hello_time(struct stp *stp, int ms)
378 stp->rq_hello_time = ms;
379 stp_update_bridge_timers(stp);
382 /* Sets the desired max age for 'stp' to 'ms', in milliseconds. The actual max
383 * age is clamped to the range of 6 to 40 seconds and subject to the
384 * relationships (2 * (bridge_forward_delay - 1 s) >= bridge_max_age) and
385 * (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge max age is
386 * only used when 'stp' is the root bridge. */
388 stp_set_max_age(struct stp *stp, int ms)
390 stp->rq_max_age = ms;
391 stp_update_bridge_timers(stp);
394 /* Sets the desired forward delay for 'stp' to 'ms', in milliseconds. The
395 * actual forward delay is clamped to the range of 4 to 30 seconds and subject
396 * to the relationship (2 * (bridge_forward_delay - 1 s) >= bridge_max_age).
397 * The bridge forward delay is only used when 'stp' is the root bridge. */
399 stp_set_forward_delay(struct stp *stp, int ms)
401 stp->rq_forward_delay = ms;
402 stp_update_bridge_timers(stp);
405 /* Returns the name given to 'stp' in the call to stp_create(). */
407 stp_get_name(const struct stp *stp)
412 /* Returns the bridge ID for 'stp'. */
414 stp_get_bridge_id(const struct stp *stp)
416 return stp->bridge_id;
419 /* Returns the bridge ID of the bridge currently believed to be the root. */
421 stp_get_designated_root(const struct stp *stp)
423 return stp->designated_root;
426 /* Returns true if 'stp' believes itself to the be root of the spanning tree,
427 * false otherwise. */
429 stp_is_root_bridge(const struct stp *stp)
431 return stp->bridge_id == stp->designated_root;
434 /* Returns the cost of the path from 'stp' to the root of the spanning tree. */
436 stp_get_root_path_cost(const struct stp *stp)
438 return stp->root_path_cost;
441 /* Returns the bridge hello time, in ms. The returned value is not necessarily
442 * the value passed to stp_set_hello_time(): it is clamped to the valid range
443 * and quantized to the STP timer resolution. */
445 stp_get_hello_time(const struct stp *stp)
447 return timer_to_ms(stp->bridge_hello_time);
450 /* Returns the bridge max age, in ms. The returned value is not necessarily
451 * the value passed to stp_set_max_age(): it is clamped to the valid range,
452 * quantized to the STP timer resolution, and adjusted to match the constraints
453 * due to the hello time. */
455 stp_get_max_age(const struct stp *stp)
457 return timer_to_ms(stp->bridge_max_age);
460 /* Returns the bridge forward delay, in ms. The returned value is not
461 * necessarily the value passed to stp_set_forward_delay(): it is clamped to
462 * the valid range, quantized to the STP timer resolution, and adjusted to
463 * match the constraints due to the forward delay. */
465 stp_get_forward_delay(const struct stp *stp)
467 return timer_to_ms(stp->bridge_forward_delay);
470 /* Returns true if something has happened to 'stp' which necessitates flushing
471 * the client's MAC learning table. Calling this function resets 'stp' so that
472 * future calls will return false until flushing is required again. */
474 stp_check_and_reset_fdb_flush(struct stp *stp)
476 bool needs_flush = stp->fdb_needs_flush;
477 stp->fdb_needs_flush = false;
481 /* Returns the port in 'stp' with index 'port_no', which must be between 0 and
484 stp_get_port(struct stp *stp, int port_no)
486 ovs_assert(port_no >= 0 && port_no < ARRAY_SIZE(stp->ports));
487 return &stp->ports[port_no];
490 /* Returns the port connecting 'stp' to the root bridge, or a null pointer if
491 * there is no such port. */
493 stp_get_root_port(struct stp *stp)
495 return stp->root_port;
498 /* Finds a port whose state has changed. If successful, stores the port whose
499 * state changed in '*portp' and returns true. If no port has changed, stores
500 * NULL in '*portp' and returns false. */
502 stp_get_changed_port(struct stp *stp, struct stp_port **portp)
504 struct stp_port *end = &stp->ports[ARRAY_SIZE(stp->ports)];
507 for (p = stp->first_changed_port; p < end; p++) {
508 if (p->state_changed) {
509 p->state_changed = false;
510 stp->first_changed_port = p + 1;
515 stp->first_changed_port = end;
520 /* Returns the name for the given 'state' (for use in debugging and log
523 stp_state_name(enum stp_state state)
541 /* Returns true if 'state' is one in which packets received on a port should
542 * be forwarded, false otherwise.
544 * Returns true if 'state' is STP_DISABLED, since presumably in that case the
545 * port should still work, just not have STP applied to it. */
547 stp_forward_in_state(enum stp_state state)
549 return (state & (STP_DISABLED | STP_FORWARDING)) != 0;
552 /* Returns true if 'state' is one in which MAC learning should be done on
553 * packets received on a port, false otherwise.
555 * Returns true if 'state' is STP_DISABLED, since presumably in that case the
556 * port should still work, just not have STP applied to it. */
558 stp_learn_in_state(enum stp_state state)
560 return (state & (STP_DISABLED | STP_LEARNING | STP_FORWARDING)) != 0;
563 /* Returns the name for the given 'role' (for use in debugging and log
566 stp_role_name(enum stp_role role)
571 case STP_ROLE_DESIGNATED:
573 case STP_ROLE_ALTERNATE:
575 case STP_ROLE_DISABLED:
582 /* Notifies the STP entity that bridge protocol data unit 'bpdu', which is
583 * 'bpdu_size' bytes in length, was received on port 'p'.
585 * This function may call the 'send_bpdu' function provided to stp_create(). */
587 stp_received_bpdu(struct stp_port *p, const void *bpdu, size_t bpdu_size)
589 struct stp *stp = p->stp;
590 const struct stp_bpdu_header *header;
592 if (p->state == STP_DISABLED) {
596 if (bpdu_size < sizeof(struct stp_bpdu_header)) {
597 VLOG_WARN("%s: received runt %zu-byte BPDU", stp->name, bpdu_size);
603 if (header->protocol_id != htons(STP_PROTOCOL_ID)) {
604 VLOG_WARN("%s: received BPDU with unexpected protocol ID %"PRIu16,
605 stp->name, ntohs(header->protocol_id));
609 if (header->protocol_version != STP_PROTOCOL_VERSION) {
610 VLOG_DBG("%s: received BPDU with unexpected protocol version %"PRIu8,
611 stp->name, header->protocol_version);
614 switch (header->bpdu_type) {
615 case STP_TYPE_CONFIG:
616 if (bpdu_size < sizeof(struct stp_config_bpdu)) {
617 VLOG_WARN("%s: received config BPDU with invalid size %zu",
618 stp->name, bpdu_size);
622 stp_received_config_bpdu(stp, p, bpdu);
626 if (bpdu_size != sizeof(struct stp_tcn_bpdu)) {
627 VLOG_WARN("%s: received TCN BPDU with invalid size %zu",
628 stp->name, bpdu_size);
632 stp_received_tcn_bpdu(stp, p);
636 VLOG_WARN("%s: received BPDU of unexpected type %"PRIu8,
637 stp->name, header->bpdu_type);
644 /* Returns the STP entity in which 'p' is nested. */
646 stp_port_get_stp(struct stp_port *p)
651 /* Sets the 'aux' member of 'p'.
653 * The 'aux' member will be reset to NULL when stp_port_disable() is
654 * called or stp_port_enable() is called when the port is in a Disabled
657 stp_port_set_aux(struct stp_port *p, void *aux)
662 /* Returns the 'aux' member of 'p'. */
664 stp_port_get_aux(struct stp_port *p)
669 /* Returns the index of port 'p' within its bridge. */
671 stp_port_no(const struct stp_port *p)
673 struct stp *stp = p->stp;
674 ovs_assert(p >= stp->ports && p < &stp->ports[ARRAY_SIZE(stp->ports)]);
675 return p - stp->ports;
678 /* Returns the port ID for 'p'. */
680 stp_port_get_id(const struct stp_port *p)
685 /* Returns the state of port 'p'. */
687 stp_port_get_state(const struct stp_port *p)
692 /* Returns the role of port 'p'. */
694 stp_port_get_role(const struct stp_port *p)
696 struct stp_port *root_port = stp_get_root_port(p->stp);
698 if (root_port && root_port->port_id == p->port_id) {
699 return STP_ROLE_ROOT;
700 } else if (stp_is_designated_port(p)) {
701 return STP_ROLE_DESIGNATED;
702 } else if (p->state == STP_DISABLED) {
703 return STP_ROLE_DISABLED;
705 return STP_ROLE_ALTERNATE;
709 /* Retrieves BPDU transmit and receive counts for 'p'. */
710 void stp_port_get_counts(const struct stp_port *p,
711 int *tx_count, int *rx_count, int *error_count)
713 *tx_count = p->tx_count;
714 *rx_count = p->rx_count;
715 *error_count = p->error_count;
718 /* Disables STP on port 'p'. */
720 stp_port_disable(struct stp_port *p)
722 struct stp *stp = p->stp;
723 if (p->state != STP_DISABLED) {
724 bool root = stp_is_root_bridge(stp);
725 stp_become_designated_port(p);
726 stp_set_port_state(p, STP_DISABLED);
727 p->topology_change_ack = false;
728 p->config_pending = false;
729 stp_stop_timer(&p->message_age_timer);
730 stp_stop_timer(&p->forward_delay_timer);
731 stp_configuration_update(stp);
732 stp_port_state_selection(stp);
733 if (stp_is_root_bridge(stp) && !root) {
734 stp_become_root_bridge(stp);
740 /* Enables STP on port 'p'. The port will initially be in "blocking" state. */
742 stp_port_enable(struct stp_port *p)
744 if (p->state == STP_DISABLED) {
745 stp_initialize_port(p, STP_BLOCKING);
746 stp_port_state_selection(p->stp);
750 /* Sets the priority of port 'p' to 'new_priority'. Lower numerical values
751 * are interpreted as higher priorities. */
753 stp_port_set_priority(struct stp_port *p, uint8_t new_priority)
755 uint16_t new_port_id = (p->port_id & 0xff) | (new_priority << 8);
756 if (p->port_id != new_port_id) {
757 struct stp *stp = p->stp;
758 if (stp_is_designated_port(p)) {
759 p->designated_port = new_port_id;
761 p->port_id = new_port_id;
762 if (stp->bridge_id == p->designated_bridge
763 && p->port_id < p->designated_port) {
764 stp_become_designated_port(p);
765 stp_port_state_selection(stp);
770 /* Convert 'speed' (measured in Mb/s) into the path cost. */
772 stp_convert_speed_to_cost(unsigned int speed)
774 return speed >= 10000 ? 2 /* 10 Gb/s. */
775 : speed >= 1000 ? 4 /* 1 Gb/s. */
776 : speed >= 100 ? 19 /* 100 Mb/s. */
777 : speed >= 16 ? 62 /* 16 Mb/s. */
778 : speed >= 10 ? 100 /* 10 Mb/s. */
779 : speed >= 4 ? 250 /* 4 Mb/s. */
780 : 19; /* 100 Mb/s (guess). */
783 /* Sets the path cost of port 'p' to 'path_cost'. Lower values are generally
784 * used to indicate faster links. Use stp_port_set_speed() to automatically
785 * generate a default path cost from a link speed. */
787 stp_port_set_path_cost(struct stp_port *p, uint16_t path_cost)
789 if (p->path_cost != path_cost) {
790 struct stp *stp = p->stp;
791 p->path_cost = path_cost;
792 stp_configuration_update(stp);
793 stp_port_state_selection(stp);
797 /* Sets the path cost of port 'p' based on 'speed' (measured in Mb/s). */
799 stp_port_set_speed(struct stp_port *p, unsigned int speed)
801 stp_port_set_path_cost(p, stp_convert_speed_to_cost(speed));
804 /* Enables topology change detection on port 'p'. */
806 stp_port_enable_change_detection(struct stp_port *p)
808 p->change_detection_enabled = true;
811 /* Disables topology change detection on port 'p'. */
813 stp_port_disable_change_detection(struct stp_port *p)
815 p->change_detection_enabled = false;
819 stp_transmit_config(struct stp_port *p)
821 struct stp *stp = p->stp;
822 bool root = stp_is_root_bridge(stp);
823 if (!root && !stp->root_port) {
826 if (p->hold_timer.active) {
827 p->config_pending = true;
829 struct stp_config_bpdu config;
830 memset(&config, 0, sizeof config);
831 config.header.protocol_id = htons(STP_PROTOCOL_ID);
832 config.header.protocol_version = STP_PROTOCOL_VERSION;
833 config.header.bpdu_type = STP_TYPE_CONFIG;
835 if (p->topology_change_ack) {
836 config.flags |= STP_CONFIG_TOPOLOGY_CHANGE_ACK;
838 if (stp->topology_change) {
839 config.flags |= STP_CONFIG_TOPOLOGY_CHANGE;
841 config.root_id = htonll(stp->designated_root);
842 config.root_path_cost = htonl(stp->root_path_cost);
843 config.bridge_id = htonll(stp->bridge_id);
844 config.port_id = htons(p->port_id);
846 config.message_age = htons(0);
848 config.message_age = htons(stp->root_port->message_age_timer.value
849 + MESSAGE_AGE_INCREMENT);
851 config.max_age = htons(stp->max_age);
852 config.hello_time = htons(stp->hello_time);
853 config.forward_delay = htons(stp->forward_delay);
854 if (ntohs(config.message_age) < stp->max_age) {
855 p->topology_change_ack = false;
856 p->config_pending = false;
857 stp_send_bpdu(p, &config, sizeof config);
858 stp_start_timer(&p->hold_timer, 0);
864 stp_supersedes_port_info(const struct stp_port *p,
865 const struct stp_config_bpdu *config)
867 if (ntohll(config->root_id) != p->designated_root) {
868 return ntohll(config->root_id) < p->designated_root;
869 } else if (ntohl(config->root_path_cost) != p->designated_cost) {
870 return ntohl(config->root_path_cost) < p->designated_cost;
871 } else if (ntohll(config->bridge_id) != p->designated_bridge) {
872 return ntohll(config->bridge_id) < p->designated_bridge;
874 return (ntohll(config->bridge_id) != p->stp->bridge_id
875 || ntohs(config->port_id) <= p->designated_port);
880 stp_record_config_information(struct stp_port *p,
881 const struct stp_config_bpdu *config)
883 p->designated_root = ntohll(config->root_id);
884 p->designated_cost = ntohl(config->root_path_cost);
885 p->designated_bridge = ntohll(config->bridge_id);
886 p->designated_port = ntohs(config->port_id);
887 stp_start_timer(&p->message_age_timer, ntohs(config->message_age));
891 stp_record_config_timeout_values(struct stp *stp,
892 const struct stp_config_bpdu *config)
894 stp->max_age = ntohs(config->max_age);
895 stp->hello_time = ntohs(config->hello_time);
896 stp->forward_delay = ntohs(config->forward_delay);
897 stp->topology_change = config->flags & STP_CONFIG_TOPOLOGY_CHANGE;
901 stp_is_designated_port(const struct stp_port *p)
903 return (p->designated_bridge == p->stp->bridge_id
904 && p->designated_port == p->port_id);
908 stp_config_bpdu_generation(struct stp *stp)
912 FOR_EACH_ENABLED_PORT (p, stp) {
913 if (stp_is_designated_port(p)) {
914 stp_transmit_config(p);
920 stp_transmit_tcn(struct stp *stp)
922 struct stp_port *p = stp->root_port;
923 struct stp_tcn_bpdu tcn_bpdu;
927 tcn_bpdu.header.protocol_id = htons(STP_PROTOCOL_ID);
928 tcn_bpdu.header.protocol_version = STP_PROTOCOL_VERSION;
929 tcn_bpdu.header.bpdu_type = STP_TYPE_TCN;
930 stp_send_bpdu(p, &tcn_bpdu, sizeof tcn_bpdu);
934 stp_configuration_update(struct stp *stp)
936 stp_root_selection(stp);
937 stp_designated_port_selection(stp);
941 stp_supersedes_root(const struct stp_port *root, const struct stp_port *p)
943 int p_cost = p->designated_cost + p->path_cost;
944 int root_cost = root->designated_cost + root->path_cost;
946 if (p->designated_root != root->designated_root) {
947 return p->designated_root < root->designated_root;
948 } else if (p_cost != root_cost) {
949 return p_cost < root_cost;
950 } else if (p->designated_bridge != root->designated_bridge) {
951 return p->designated_bridge < root->designated_bridge;
952 } else if (p->designated_port != root->designated_port) {
953 return p->designated_port < root->designated_port;
955 return p->port_id < root->port_id;
960 stp_root_selection(struct stp *stp)
962 struct stp_port *p, *root;
965 FOR_EACH_ENABLED_PORT (p, stp) {
966 if (stp_is_designated_port(p)
967 || p->designated_root >= stp->bridge_id) {
970 if (root && !stp_supersedes_root(root, p)) {
975 stp->root_port = root;
977 stp->designated_root = stp->bridge_id;
978 stp->root_path_cost = 0;
980 stp->designated_root = root->designated_root;
981 stp->root_path_cost = root->designated_cost + root->path_cost;
986 stp_designated_port_selection(struct stp *stp)
990 FOR_EACH_ENABLED_PORT (p, stp) {
991 if (stp_is_designated_port(p)
992 || p->designated_root != stp->designated_root
993 || stp->root_path_cost < p->designated_cost
994 || (stp->root_path_cost == p->designated_cost
995 && (stp->bridge_id < p->designated_bridge
996 || (stp->bridge_id == p->designated_bridge
997 && p->port_id <= p->designated_port))))
999 stp_become_designated_port(p);
1005 stp_become_designated_port(struct stp_port *p)
1007 struct stp *stp = p->stp;
1008 p->designated_root = stp->designated_root;
1009 p->designated_cost = stp->root_path_cost;
1010 p->designated_bridge = stp->bridge_id;
1011 p->designated_port = p->port_id;
1015 stp_port_state_selection(struct stp *stp)
1019 FOR_EACH_ENABLED_PORT (p, stp) {
1020 if (p == stp->root_port) {
1021 p->config_pending = false;
1022 p->topology_change_ack = false;
1023 stp_make_forwarding(p);
1024 } else if (stp_is_designated_port(p)) {
1025 stp_stop_timer(&p->message_age_timer);
1026 stp_make_forwarding(p);
1028 p->config_pending = false;
1029 p->topology_change_ack = false;
1030 stp_make_blocking(p);
1036 stp_make_forwarding(struct stp_port *p)
1038 if (p->state == STP_BLOCKING) {
1039 stp_set_port_state(p, STP_LISTENING);
1040 stp_start_timer(&p->forward_delay_timer, 0);
1045 stp_make_blocking(struct stp_port *p)
1047 if (!(p->state & (STP_DISABLED | STP_BLOCKING))) {
1048 if (p->state & (STP_FORWARDING | STP_LEARNING)) {
1049 if (p->change_detection_enabled) {
1050 stp_topology_change_detection(p->stp);
1053 stp_set_port_state(p, STP_BLOCKING);
1054 stp_stop_timer(&p->forward_delay_timer);
1059 stp_set_port_state(struct stp_port *p, enum stp_state state)
1061 if (state != p->state && !p->state_changed) {
1062 p->state_changed = true;
1063 if (p < p->stp->first_changed_port) {
1064 p->stp->first_changed_port = p;
1071 stp_topology_change_detection(struct stp *stp)
1073 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
1075 if (stp_is_root_bridge(stp)) {
1076 stp->topology_change = true;
1077 stp_start_timer(&stp->topology_change_timer, 0);
1078 } else if (!stp->topology_change_detected) {
1079 stp_transmit_tcn(stp);
1080 stp_start_timer(&stp->tcn_timer, 0);
1082 stp->fdb_needs_flush = true;
1083 stp->topology_change_detected = true;
1084 VLOG_INFO_RL(&rl, "%s: detected topology change.", stp->name);
1088 stp_topology_change_acknowledged(struct stp *stp)
1090 stp->topology_change_detected = false;
1091 stp_stop_timer(&stp->tcn_timer);
1095 stp_acknowledge_topology_change(struct stp_port *p)
1097 p->topology_change_ack = true;
1098 stp_transmit_config(p);
1102 stp_received_config_bpdu(struct stp *stp, struct stp_port *p,
1103 const struct stp_config_bpdu *config)
1105 if (ntohs(config->message_age) >= ntohs(config->max_age)) {
1106 VLOG_WARN("%s: received config BPDU with message age (%u) greater "
1107 "than max age (%u)",
1109 ntohs(config->message_age), ntohs(config->max_age));
1112 if (p->state != STP_DISABLED) {
1113 bool root = stp_is_root_bridge(stp);
1114 if (stp_supersedes_port_info(p, config)) {
1115 stp_record_config_information(p, config);
1116 stp_configuration_update(stp);
1117 stp_port_state_selection(stp);
1118 if (!stp_is_root_bridge(stp) && root) {
1119 stp_stop_timer(&stp->hello_timer);
1120 if (stp->topology_change_detected) {
1121 stp_stop_timer(&stp->topology_change_timer);
1122 stp_transmit_tcn(stp);
1123 stp_start_timer(&stp->tcn_timer, 0);
1126 if (p == stp->root_port) {
1127 stp_record_config_timeout_values(stp, config);
1128 stp_config_bpdu_generation(stp);
1129 if (config->flags & STP_CONFIG_TOPOLOGY_CHANGE_ACK) {
1130 stp_topology_change_acknowledged(stp);
1132 if (config->flags & STP_CONFIG_TOPOLOGY_CHANGE) {
1133 stp->fdb_needs_flush = true;
1136 } else if (stp_is_designated_port(p)) {
1137 stp_transmit_config(p);
1143 stp_received_tcn_bpdu(struct stp *stp, struct stp_port *p)
1145 if (p->state != STP_DISABLED) {
1146 if (stp_is_designated_port(p)) {
1147 stp_topology_change_detection(stp);
1148 stp_acknowledge_topology_change(p);
1154 stp_hello_timer_expiry(struct stp *stp)
1156 stp_config_bpdu_generation(stp);
1157 stp_start_timer(&stp->hello_timer, 0);
1161 stp_message_age_timer_expiry(struct stp_port *p)
1163 struct stp *stp = p->stp;
1164 bool root = stp_is_root_bridge(stp);
1165 stp_become_designated_port(p);
1166 stp_configuration_update(stp);
1167 stp_port_state_selection(stp);
1168 if (stp_is_root_bridge(stp) && !root) {
1169 stp->max_age = stp->bridge_max_age;
1170 stp->hello_time = stp->bridge_hello_time;
1171 stp->forward_delay = stp->bridge_forward_delay;
1172 stp_topology_change_detection(stp);
1173 stp_stop_timer(&stp->tcn_timer);
1174 stp_config_bpdu_generation(stp);
1175 stp_start_timer(&stp->hello_timer, 0);
1180 stp_is_designated_for_some_port(const struct stp *stp)
1182 const struct stp_port *p;
1184 FOR_EACH_ENABLED_PORT (p, stp) {
1185 if (p->designated_bridge == stp->bridge_id) {
1193 stp_forward_delay_timer_expiry(struct stp_port *p)
1195 if (p->state == STP_LISTENING) {
1196 stp_set_port_state(p, STP_LEARNING);
1197 stp_start_timer(&p->forward_delay_timer, 0);
1198 } else if (p->state == STP_LEARNING) {
1199 stp_set_port_state(p, STP_FORWARDING);
1200 if (stp_is_designated_for_some_port(p->stp)) {
1201 if (p->change_detection_enabled) {
1202 stp_topology_change_detection(p->stp);
1209 stp_tcn_timer_expiry(struct stp *stp)
1211 stp_transmit_tcn(stp);
1212 stp_start_timer(&stp->tcn_timer, 0);
1216 stp_topology_change_timer_expiry(struct stp *stp)
1218 stp->topology_change_detected = false;
1219 stp->topology_change = false;
1223 stp_hold_timer_expiry(struct stp_port *p)
1225 if (p->config_pending) {
1226 stp_transmit_config(p);
1231 stp_initialize_port(struct stp_port *p, enum stp_state state)
1233 ovs_assert(state & (STP_DISABLED | STP_BLOCKING));
1234 stp_become_designated_port(p);
1235 stp_set_port_state(p, state);
1236 p->topology_change_ack = false;
1237 p->config_pending = false;
1238 p->change_detection_enabled = true;
1240 stp_stop_timer(&p->message_age_timer);
1241 stp_stop_timer(&p->forward_delay_timer);
1242 stp_stop_timer(&p->hold_timer);
1243 p->tx_count = p->rx_count = p->error_count = 0;
1247 stp_become_root_bridge(struct stp *stp)
1249 stp->max_age = stp->bridge_max_age;
1250 stp->hello_time = stp->bridge_hello_time;
1251 stp->forward_delay = stp->bridge_forward_delay;
1252 stp_topology_change_detection(stp);
1253 stp_stop_timer(&stp->tcn_timer);
1254 stp_config_bpdu_generation(stp);
1255 stp_start_timer(&stp->hello_timer, 0);
1259 stp_start_timer(struct stp_timer *timer, int value)
1261 timer->value = value;
1262 timer->active = true;
1266 stp_stop_timer(struct stp_timer *timer)
1268 timer->active = false;
1272 stp_timer_expired(struct stp_timer *timer, int elapsed, int timeout)
1274 if (timer->active) {
1275 timer->value += elapsed;
1276 if (timer->value >= timeout) {
1277 timer->active = false;
1284 /* Returns the number of whole STP timer ticks in 'ms' milliseconds. There
1285 * are 256 STP timer ticks per second. */
1289 return ms * 0x100 / 1000;
1292 /* Returns the number of whole milliseconds in 'timer' STP timer ticks. There
1293 * are 256 STP timer ticks per second. */
1295 timer_to_ms(int timer)
1297 return timer * 1000 / 0x100;
1301 clamp(int x, int min, int max)
1303 return x < min ? min : x > max ? max : x;
1307 stp_update_bridge_timers(struct stp *stp)
1311 ht = clamp(stp->rq_hello_time, 1000, 10000);
1312 ma = clamp(stp->rq_max_age, MAX(2 * (ht + 1000), 6000), 40000);
1313 fd = clamp(stp->rq_forward_delay, ma / 2 + 1000, 30000);
1315 stp->bridge_hello_time = ms_to_timer(ht);
1316 stp->bridge_max_age = ms_to_timer(ma);
1317 stp->bridge_forward_delay = ms_to_timer(fd);
1319 if (stp_is_root_bridge(stp)) {
1320 stp->max_age = stp->bridge_max_age;
1321 stp->hello_time = stp->bridge_hello_time;
1322 stp->forward_delay = stp->bridge_forward_delay;
1327 stp_send_bpdu(struct stp_port *p, const void *bpdu, size_t bpdu_size)
1329 struct eth_header *eth;
1330 struct llc_header *llc;
1334 pkt = ofpbuf_new(ETH_HEADER_LEN + LLC_HEADER_LEN + bpdu_size);
1335 pkt->l2 = eth = ofpbuf_put_zeros(pkt, sizeof *eth);
1336 llc = ofpbuf_put_zeros(pkt, sizeof *llc);
1337 pkt->l3 = ofpbuf_put(pkt, bpdu, bpdu_size);
1340 memcpy(eth->eth_dst, eth_addr_stp, ETH_ADDR_LEN);
1341 /* p->stp->send_bpdu() must fill in source address. */
1342 eth->eth_type = htons(pkt->size - ETH_HEADER_LEN);
1345 llc->llc_dsap = STP_LLC_DSAP;
1346 llc->llc_ssap = STP_LLC_SSAP;
1347 llc->llc_cntl = STP_LLC_CNTL;
1349 p->stp->send_bpdu(pkt, stp_port_no(p), p->stp->aux);
1356 stp_find(const char *name)
1360 LIST_FOR_EACH (stp, node, &all_stps) {
1361 if (!strcmp(stp->name, name)) {
1369 stp_unixctl_tcn(struct unixctl_conn *conn, int argc,
1370 const char *argv[], void *aux OVS_UNUSED)
1373 struct stp *stp = stp_find(argv[1]);
1376 unixctl_command_reply_error(conn, "no such stp object");
1379 stp_topology_change_detection(stp);
1383 LIST_FOR_EACH (stp, node, &all_stps) {
1384 stp_topology_change_detection(stp);
1388 unixctl_command_reply(conn, "OK");