1 /* Copyright (c) 2008 The Board of Trustees of The Leland Stanford
4 * We are making the OpenFlow specification and associated documentation
5 * (Software) available for public use and benefit with the expectation
6 * that others will use, modify and enhance the Software and contribute
7 * those enhancements back to the community. However, since we would
8 * like to make the Software available for broadest use, with as few
9 * restrictions as possible permission is hereby granted, free of
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11 * the Software under the copyrights without restriction, including
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13 * distribute, sublicense, and/or sell copies of the Software, and to
14 * permit persons to whom the Software is furnished to do so, subject to
15 * the following conditions:
17 * The above copyright notice and this permission notice shall be
18 * included in all copies or substantial portions of the Software.
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
23 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
24 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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29 * The name and trademarks of copyright holder(s) may NOT be used in
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31 * derivatives without specific, written prior permission.
34 /* Based on sample implementation in 802.1D-1998. Above copyright and license
35 * applies to all modifications. */
38 #include <arpa/inet.h>
47 #define THIS_MODULE VLM_stp
49 /* Ethernet address used as the destination for STP frames. */
50 const uint8_t stp_eth_addr[ETH_ADDR_LEN]
51 = { 0x01, 0x80, 0xC2, 0x00, 0x00, 0x01 };
53 #define STP_PROTOCOL_ID 0x0000
54 #define STP_PROTOCOL_VERSION 0x00
55 #define STP_TYPE_CONFIG 0x00
56 #define STP_TYPE_TCN 0x80
58 struct stp_bpdu_header {
59 uint16_t protocol_id; /* STP_PROTOCOL_ID. */
60 uint8_t protocol_version; /* STP_PROTOCOL_VERSION. */
61 uint8_t bpdu_type; /* One of STP_TYPE_*. */
62 } __attribute__((packed));
63 BUILD_ASSERT_DECL(sizeof(struct stp_bpdu_header) == 4);
65 enum stp_config_bpdu_flags {
66 STP_CONFIG_TOPOLOGY_CHANGE_ACK = 0x80,
67 STP_CONFIG_TOPOLOGY_CHANGE = 0x01
70 struct stp_config_bpdu {
71 struct stp_bpdu_header header; /* Type STP_TYPE_CONFIG. */
72 uint8_t flags; /* STP_CONFIG_* flags. */
73 uint64_t root_id; /* 8.5.1.1: Bridge believed to be root. */
74 uint32_t root_path_cost; /* 8.5.1.2: Cost of path to root. */
75 uint64_t bridge_id; /* 8.5.1.3: ID of transmitting bridge. */
76 uint16_t port_id; /* 8.5.1.4: Port transmitting the BPDU. */
77 uint16_t message_age; /* 8.5.1.5: Age of BPDU at tx time. */
78 uint16_t max_age; /* 8.5.1.6: Timeout for received data. */
79 uint16_t hello_time; /* 8.5.1.7: Time between BPDU generation. */
80 uint16_t forward_delay; /* 8.5.1.8: State progression delay. */
81 } __attribute__((packed));
82 BUILD_ASSERT_DECL(sizeof(struct stp_config_bpdu) == 35);
85 struct stp_bpdu_header header; /* Type STP_TYPE_TCN. */
86 } __attribute__((packed));
87 BUILD_ASSERT_DECL(sizeof(struct stp_tcn_bpdu) == 4);
90 bool active; /* Timer in use? */
91 int value; /* Current value of timer, counting up. */
96 int port_id; /* 8.5.5.1: Unique port identifier. */
97 enum stp_state state; /* 8.5.5.2: Current state. */
98 int path_cost; /* 8.5.5.3: Cost of tx/rx on this port. */
99 stp_identifier designated_root; /* 8.5.5.4. */
100 int designated_cost; /* 8.5.5.5: Path cost to root on port. */
101 stp_identifier designated_bridge; /* 8.5.5.6. */
102 int designated_port; /* 8.5.5.7: Port to send config msgs on. */
103 bool topology_change_ack; /* 8.5.5.8: Flag for next config BPDU. */
104 bool config_pending; /* 8.5.5.9: Send BPDU when hold expires? */
105 bool change_detection_enabled; /* 8.5.5.10: Detect topology changes? */
107 struct stp_timer message_age_timer; /* 8.5.6.1: Age of received info. */
108 struct stp_timer forward_delay_timer; /* 8.5.6.2: State change timer. */
109 struct stp_timer hold_timer; /* 8.5.6.3: BPDU rate limit timer. */
115 /* Static bridge data. */
116 char *name; /* Human-readable name for log messages. */
117 stp_identifier bridge_id; /* 8.5.3.7: This bridge. */
118 int max_age; /* 8.5.3.4: Time to drop received data. */
119 int hello_time; /* 8.5.3.5: Time between sending BPDUs. */
120 int forward_delay; /* 8.5.3.6: Delay between state changes. */
121 int bridge_max_age; /* 8.5.3.8: max_age when we're root. */
122 int bridge_hello_time; /* 8.5.3.9: hello_time as root. */
123 int bridge_forward_delay; /* 8.5.3.10: forward_delay as root. */
125 /* Dynamic bridge data. */
126 stp_identifier designated_root; /* 8.5.3.1: Bridge believed to be root. */
127 unsigned int root_path_cost; /* 8.5.3.2: Cost of path to root. */
128 struct stp_port *root_port; /* 8.5.3.3: Lowest cost port to root. */
129 bool topology_change_detected; /* 8.5.3.11: Detected a topology change? */
130 bool topology_change; /* 8.5.3.12: Received topology change? */
133 struct stp_timer hello_timer; /* 8.5.4.1: Hello timer. */
134 struct stp_timer tcn_timer; /* 8.5.4.2: Topology change timer. */
135 struct stp_timer topology_change_timer; /* 8.5.4.3. */
138 struct stp_port ports[STP_MAX_PORTS];
140 /* Interface to client. */
141 struct stp_port *first_changed_port;
142 void (*send_bpdu)(const void *bpdu, size_t bpdu_size,
143 int port_no, void *aux);
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 (struct stp_port *) port;
162 #define SECONDS_TO_TIMER(SECS) ((SECS) * 0x100)
164 #define MESSAGE_AGE_INCREMENT 1
166 static void stp_transmit_config(struct stp_port *);
167 static bool stp_supersedes_port_info(const struct stp_port *,
168 const struct stp_config_bpdu *);
169 static void stp_record_config_information(struct stp_port *,
170 const struct stp_config_bpdu *);
171 static void stp_record_config_timeout_values(struct stp *,
172 const struct stp_config_bpdu *);
173 static bool stp_is_designated_port(const struct stp_port *);
174 static void stp_config_bpdu_generation(struct stp *);
175 static void stp_transmit_tcn(struct stp *);
176 static void stp_configuration_update(struct stp *);
177 static bool stp_supersedes_root(const struct stp_port *root,
178 const struct stp_port *);
179 static void stp_root_selection(struct stp *);
180 static void stp_designated_port_selection(struct stp *);
181 static void stp_become_designated_port(struct stp_port *);
182 static void stp_port_state_selection(struct stp *);
183 static void stp_make_forwarding(struct stp_port *);
184 static void stp_make_blocking(struct stp_port *);
185 static void stp_set_port_state(struct stp_port *, enum stp_state);
186 static void stp_topology_change_detection(struct stp *);
187 static void stp_topology_change_acknowledged(struct stp *);
188 static void stp_acknowledge_topology_change(struct stp_port *);
189 static void stp_received_config_bpdu(struct stp *, struct stp_port *,
190 const struct stp_config_bpdu *);
191 static void stp_received_tcn_bpdu(struct stp *, struct stp_port *,
192 const struct stp_tcn_bpdu *);
193 static void stp_hello_timer_expiry(struct stp *);
194 static void stp_message_age_timer_expiry(struct stp_port *);
195 static bool stp_is_designated_for_some_port(const struct stp *);
196 static void stp_forward_delay_timer_expiry(struct stp_port *);
197 static void stp_tcn_timer_expiry(struct stp *);
198 static void stp_topology_change_timer_expiry(struct stp *);
199 static void stp_hold_timer_expiry(struct stp_port *);
200 static void stp_initialize_port(struct stp_port *, enum stp_state);
201 static void stp_become_root_bridge(struct stp *stp);
203 static void stp_start_timer(struct stp_timer *, int value);
204 static void stp_stop_timer(struct stp_timer *);
205 static bool stp_timer_expired(struct stp_timer *, int elapsed, int timeout);
207 /* Creates and returns a new STP instance that initially has no port enabled.
209 * 'bridge_id' should be a 48-bit MAC address as returned by
210 * eth_addr_to_uint64(). 'bridge_id' may also have a priority value in its top
211 * 16 bits; if those bits are set to 0, the default bridge priority of 32768 is
212 * used. (This priority may be changed with stp_set_bridge_priority().)
214 * When the bridge needs to send out a BPDU, it calls 'send_bpdu', passing
215 * 'aux' as auxiliary data. This callback may be called from stp_tick() or
216 * stp_received_bpdu().
219 stp_create(const char *name, stp_identifier bridge_id,
220 void (*send_bpdu)(const void *bpdu, size_t bpdu_size,
221 int port_no, void *aux),
227 stp = xcalloc(1, sizeof *stp);
228 stp->name = xstrdup(name);
229 stp->bridge_id = bridge_id;
230 if (!(stp->bridge_id >> 48)) {
231 stp->bridge_id |= UINT64_C(32768) << 48;
233 stp->max_age = SECONDS_TO_TIMER(6);
234 stp->hello_time = SECONDS_TO_TIMER(2);
235 stp->forward_delay = SECONDS_TO_TIMER(4);
236 stp->bridge_max_age = stp->max_age;
237 stp->bridge_hello_time = stp->hello_time;
238 stp->bridge_forward_delay = stp->forward_delay;
240 /* Verify constraints stated by 802.1D. */
241 assert(2 * (stp->forward_delay - SECONDS_TO_TIMER(1)) >= stp->max_age);
242 assert(stp->max_age >= 2 * (stp->hello_time + SECONDS_TO_TIMER(1)));
244 stp->designated_root = stp->bridge_id;
245 stp->root_path_cost = 0;
246 stp->root_port = NULL;
247 stp->topology_change_detected = false;
248 stp->topology_change = false;
250 stp_stop_timer(&stp->tcn_timer);
251 stp_stop_timer(&stp->topology_change_timer);
252 stp_start_timer(&stp->hello_timer, 0);
254 stp->send_bpdu = send_bpdu;
257 stp->first_changed_port = &stp->ports[ARRAY_SIZE(stp->ports)];
258 for (p = stp->ports; p < &stp->ports[ARRAY_SIZE(stp->ports)]; p++) {
260 p->port_id = (stp_port_no(p) + 1) | (128 << 8);
261 p->path_cost = 19; /* Recommended default for 100 Mb/s link. */
262 stp_initialize_port(p, STP_DISABLED);
267 /* Destroys 'stp'. */
269 stp_destroy(struct stp *stp)
275 stp_tick(struct stp *stp, int elapsed)
279 if (stp_timer_expired(&stp->hello_timer, elapsed, stp->hello_time)) {
280 stp_hello_timer_expiry(stp);
282 if (stp_timer_expired(&stp->tcn_timer, elapsed, stp->bridge_hello_time)) {
283 stp_tcn_timer_expiry(stp);
285 if (stp_timer_expired(&stp->topology_change_timer, elapsed,
286 stp->max_age + stp->forward_delay)) {
287 stp_topology_change_timer_expiry(stp);
289 FOR_EACH_ENABLED_PORT (p, stp) {
290 if (stp_timer_expired(&p->message_age_timer, elapsed, stp->max_age)) {
291 stp_message_age_timer_expiry(p);
294 FOR_EACH_ENABLED_PORT (p, stp) {
295 if (stp_timer_expired(&p->forward_delay_timer, elapsed,
296 stp->forward_delay)) {
297 stp_forward_delay_timer_expiry(p);
299 if (stp_timer_expired(&p->hold_timer, elapsed, SECONDS_TO_TIMER(1))) {
300 stp_hold_timer_expiry(p);
306 set_bridge_id(struct stp *stp, stp_identifier new_bridge_id)
308 if (new_bridge_id != stp->bridge_id) {
312 root = stp_is_root_bridge(stp);
313 FOR_EACH_ENABLED_PORT (p, stp) {
314 if (stp_is_designated_port(p)) {
315 p->designated_bridge = new_bridge_id;
318 stp->bridge_id = new_bridge_id;
319 stp_configuration_update(stp);
320 stp_port_state_selection(stp);
321 if (stp_is_root_bridge(stp) && !root) {
322 stp_become_root_bridge(stp);
328 stp_set_bridge_id(struct stp *stp, stp_identifier bridge_id)
330 const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
331 const uint64_t pri_bits = ~mac_bits;
332 set_bridge_id(stp, (stp->bridge_id & pri_bits) | (bridge_id & mac_bits));
336 stp_set_bridge_priority(struct stp *stp, uint16_t new_priority)
338 const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
339 set_bridge_id(stp, ((stp->bridge_id & mac_bits)
340 | ((uint64_t) new_priority << 48)));
343 /* Returns the name given to 'stp' in the call to stp_create(). */
345 stp_get_name(const struct stp *stp)
350 /* Returns the bridge ID for 'stp'. */
352 stp_get_bridge_id(const struct stp *stp)
354 return stp->bridge_id;
357 /* Returns the bridge ID of the bridge currently believed to be the root. */
359 stp_get_designated_root(const struct stp *stp)
361 return stp->designated_root;
364 /* Returns true if 'stp' believes itself to the be root of the spanning tree,
365 * false otherwise. */
367 stp_is_root_bridge(const struct stp *stp)
369 return stp->bridge_id == stp->designated_root;
372 /* Returns the cost of the path from 'stp' to the root of the spanning tree. */
374 stp_get_root_path_cost(const struct stp *stp)
376 return stp->root_path_cost;
379 /* Returns the port in 'stp' with index 'port_no', which must be between 0 and
382 stp_get_port(struct stp *stp, int port_no)
384 assert(port_no >= 0 && port_no < ARRAY_SIZE(stp->ports));
385 return &stp->ports[port_no];
388 /* Returns the port connecting 'stp' to the root bridge, or a null pointer if
389 * there is no such port. */
391 stp_get_root_port(struct stp *stp)
393 return stp->root_port;
396 /* Finds a port whose state has changed. If successful, stores the port whose
397 * state changed in '*portp' and returns true. If no port has changed, stores
398 * NULL in '*portp' and returns false. */
400 stp_get_changed_port(struct stp *stp, struct stp_port **portp)
402 struct stp_port *end = &stp->ports[ARRAY_SIZE(stp->ports)];
405 for (p = stp->first_changed_port; p < end; p++) {
406 if (p->state_changed) {
407 p->state_changed = false;
408 stp->first_changed_port = p + 1;
413 stp->first_changed_port = end;
418 /* Returns the name for the given 'state' (for use in debugging and log
421 stp_state_name(enum stp_state state)
439 /* Returns true if 'state' is one in which packets received on a port should
440 * be forwarded, false otherwise. */
442 stp_forward_in_state(enum stp_state state)
444 return state == STP_FORWARDING;
447 /* Returns true if 'state' is one in which MAC learning should be done on
448 * packets received on a port, false otherwise. */
450 stp_learn_in_state(enum stp_state state)
452 return state & (STP_LEARNING | STP_FORWARDING);
455 /* Notifies the STP entity that bridge protocol data unit 'bpdu', which is
456 * 'bpdu_size' bytes in length, was received on port 'p'.
458 * This function may call the 'send_bpdu' function provided to stp_create(). */
460 stp_received_bpdu(struct stp_port *p, const void *bpdu, size_t bpdu_size)
462 struct stp *stp = p->stp;
463 const struct stp_bpdu_header *header;
465 if (p->state == STP_DISABLED) {
469 if (bpdu_size < sizeof(struct stp_bpdu_header)) {
470 VLOG_WARN("%s: received runt %zu-byte BPDU", stp->name, bpdu_size);
475 if (header->protocol_id != htons(STP_PROTOCOL_ID)) {
476 VLOG_WARN("%s: received BPDU with unexpected protocol ID %"PRIu16,
477 stp->name, ntohs(header->protocol_id));
480 if (header->protocol_version != STP_PROTOCOL_VERSION) {
481 VLOG_DBG("%s: received BPDU with unexpected protocol version %"PRIu8,
482 stp->name, header->protocol_version);
485 switch (header->bpdu_type) {
486 case STP_TYPE_CONFIG:
487 if (bpdu_size < sizeof(struct stp_config_bpdu)) {
488 VLOG_WARN("%s: received config BPDU with invalid size %zu",
489 stp->name, bpdu_size);
492 stp_received_config_bpdu(stp, p, bpdu);
496 if (bpdu_size != sizeof(struct stp_tcn_bpdu)) {
497 VLOG_WARN("%s: received TCN BPDU with invalid size %zu",
498 stp->name, bpdu_size);
501 stp_received_tcn_bpdu(stp, p, bpdu);
505 VLOG_WARN("%s: received BPDU of unexpected type %"PRIu8,
506 stp->name, header->bpdu_type);
511 /* Returns the STP entity in which 'p' is nested. */
513 stp_port_get_stp(struct stp_port *p)
518 /* Returns the index of port 'p' within its bridge. */
520 stp_port_no(const struct stp_port *p)
522 struct stp *stp = p->stp;
523 assert(p >= stp->ports && p < &stp->ports[ARRAY_SIZE(stp->ports)]);
524 return p - stp->ports;
527 /* Returns the state of port 'p'. */
529 stp_port_get_state(const struct stp_port *p)
534 /* Disables STP on port 'p'. */
536 stp_port_disable(struct stp_port *p)
538 struct stp *stp = p->stp;
539 if (p->state != STP_DISABLED) {
540 bool root = stp_is_root_bridge(stp);
541 stp_become_designated_port(p);
542 stp_set_port_state(p, STP_DISABLED);
543 p->topology_change_ack = false;
544 p->config_pending = false;
545 stp_stop_timer(&p->message_age_timer);
546 stp_stop_timer(&p->forward_delay_timer);
547 stp_configuration_update(stp);
548 stp_port_state_selection(stp);
549 if (stp_is_root_bridge(stp) && !root) {
550 stp_become_root_bridge(stp);
555 /* Enables STP on port 'p'. The port will initially be in "blocking" state. */
557 stp_port_enable(struct stp_port *p)
559 if (p->state == STP_DISABLED) {
560 stp_initialize_port(p, STP_BLOCKING);
561 stp_port_state_selection(p->stp);
565 /* Sets the priority of port 'p' to 'new_priority'. Lower numerical values
566 * are interpreted as higher priorities. */
568 stp_port_set_priority(struct stp_port *p, uint8_t new_priority)
570 uint16_t new_port_id = (p->port_id & 0xff) | (new_priority << 8);
571 if (p->port_id != new_port_id) {
572 struct stp *stp = p->stp;
573 if (stp_is_designated_port(p)) {
574 p->designated_port = new_port_id;
576 p->port_id = new_port_id;
577 if (stp->bridge_id == p->designated_bridge
578 && p->port_id < p->designated_port) {
579 stp_become_designated_port(p);
580 stp_port_state_selection(stp);
585 /* Sets the path cost of port 'p' to 'path_cost'. Lower values are generally
586 * used to indicate faster links. Use stp_port_set_speed() to automatically
587 * generate a default path cost from a link speed. */
589 stp_port_set_path_cost(struct stp_port *p, unsigned int path_cost)
591 if (p->path_cost != path_cost) {
592 struct stp *stp = p->stp;
593 p->path_cost = path_cost;
594 stp_configuration_update(stp);
595 stp_port_state_selection(stp);
599 /* Sets the path cost of port 'p' based on 'speed' (measured in Mb/s). */
601 stp_port_set_speed(struct stp_port *p, unsigned int speed)
603 stp_port_set_path_cost(p, (speed >= 10000 ? 2 /* 10 Gb/s. */
604 : speed >= 1000 ? 4 /* 1 Gb/s. */
605 : speed >= 100 ? 19 /* 100 Mb/s. */
606 : speed >= 16 ? 62 /* 16 Mb/s. */
607 : speed >= 10 ? 100 /* 10 Mb/s. */
608 : speed >= 4 ? 250 /* 4 Mb/s. */
609 : 19)); /* 100 Mb/s (guess). */
612 /* Enables topology change detection on port 'p'. */
614 stp_port_enable_change_detection(struct stp_port *p)
616 p->change_detection_enabled = true;
619 /* Disables topology change detection on port 'p'. */
621 stp_port_disable_change_detection(struct stp_port *p)
623 p->change_detection_enabled = false;
627 stp_transmit_config(struct stp_port *p)
629 struct stp *stp = p->stp;
630 bool root = stp_is_root_bridge(stp);
631 if (!root && !stp->root_port) {
634 if (p->hold_timer.active) {
635 p->config_pending = true;
637 struct stp_config_bpdu config;
638 memset(&config, 0, sizeof config);
639 config.header.protocol_id = htons(STP_PROTOCOL_ID);
640 config.header.protocol_version = STP_PROTOCOL_VERSION;
641 config.header.bpdu_type = STP_TYPE_CONFIG;
643 if (p->topology_change_ack) {
644 config.flags |= htons(STP_CONFIG_TOPOLOGY_CHANGE_ACK);
646 if (stp->topology_change) {
647 config.flags |= htons(STP_CONFIG_TOPOLOGY_CHANGE);
649 config.root_id = htonll(stp->designated_root);
650 config.root_path_cost = htonl(stp->root_path_cost);
651 config.bridge_id = htonll(stp->bridge_id);
652 config.port_id = htons(p->port_id);
654 config.message_age = htons(0);
656 config.message_age = htons(stp->root_port->message_age_timer.value
657 + MESSAGE_AGE_INCREMENT);
659 config.max_age = htons(stp->max_age);
660 config.hello_time = htons(stp->hello_time);
661 config.forward_delay = htons(stp->forward_delay);
662 if (ntohs(config.message_age) < stp->max_age) {
663 p->topology_change_ack = false;
664 p->config_pending = false;
665 stp->send_bpdu(&config, sizeof config, stp_port_no(p), stp->aux);
666 stp_start_timer(&p->hold_timer, 0);
672 stp_supersedes_port_info(const struct stp_port *p,
673 const struct stp_config_bpdu *config)
675 if (ntohll(config->root_id) != p->designated_root) {
676 return ntohll(config->root_id) < p->designated_root;
677 } else if (ntohl(config->root_path_cost) != p->designated_cost) {
678 return ntohl(config->root_path_cost) < p->designated_cost;
679 } else if (ntohll(config->bridge_id) != p->designated_bridge) {
680 return ntohll(config->bridge_id) < p->designated_bridge;
682 return (ntohll(config->bridge_id) != p->stp->bridge_id
683 || ntohs(config->port_id) <= p->designated_port);
688 stp_record_config_information(struct stp_port *p,
689 const struct stp_config_bpdu *config)
691 p->designated_root = ntohll(config->root_id);
692 p->designated_cost = ntohl(config->root_path_cost);
693 p->designated_bridge = ntohll(config->bridge_id);
694 p->designated_port = ntohs(config->port_id);
695 stp_start_timer(&p->message_age_timer, ntohs(config->message_age));
699 stp_record_config_timeout_values(struct stp *stp,
700 const struct stp_config_bpdu *config)
702 stp->max_age = ntohs(config->max_age);
703 stp->hello_time = ntohs(config->hello_time);
704 stp->forward_delay = ntohs(config->forward_delay);
705 stp->topology_change = config->flags & htons(STP_CONFIG_TOPOLOGY_CHANGE);
709 stp_is_designated_port(const struct stp_port *p)
711 return (p->designated_bridge == p->stp->bridge_id
712 && p->designated_port == p->port_id);
716 stp_config_bpdu_generation(struct stp *stp)
720 FOR_EACH_ENABLED_PORT (p, stp) {
721 if (stp_is_designated_port(p)) {
722 stp_transmit_config(p);
728 stp_transmit_tcn(struct stp *stp)
730 struct stp_port *p = stp->root_port;
731 struct stp_tcn_bpdu tcn_bpdu;
735 tcn_bpdu.header.protocol_id = htons(STP_PROTOCOL_ID);
736 tcn_bpdu.header.protocol_version = STP_PROTOCOL_VERSION;
737 tcn_bpdu.header.bpdu_type = STP_TYPE_TCN;
738 stp->send_bpdu(&tcn_bpdu, sizeof tcn_bpdu, stp_port_no(p), stp->aux);
742 stp_configuration_update(struct stp *stp)
744 stp_root_selection(stp);
745 stp_designated_port_selection(stp);
749 stp_supersedes_root(const struct stp_port *root, const struct stp_port *p)
751 int p_cost = p->designated_cost + p->path_cost;
752 int root_cost = root->designated_cost + root->path_cost;
754 if (p->designated_root != root->designated_root) {
755 return p->designated_root < root->designated_root;
756 } else if (p_cost != root_cost) {
757 return p_cost < root_cost;
758 } else if (p->designated_bridge != root->designated_bridge) {
759 return p->designated_bridge < root->designated_bridge;
760 } else if (p->designated_port != root->designated_port) {
761 return p->designated_port < root->designated_port;
763 return p->port_id < root->port_id;
768 stp_root_selection(struct stp *stp)
770 struct stp_port *p, *root;
773 FOR_EACH_ENABLED_PORT (p, stp) {
774 if (stp_is_designated_port(p)
775 || p->designated_root >= stp->bridge_id) {
778 if (root && !stp_supersedes_root(root, p)) {
783 stp->root_port = root;
785 stp->designated_root = stp->bridge_id;
786 stp->root_path_cost = 0;
788 stp->designated_root = root->designated_root;
789 stp->root_path_cost = root->designated_cost + root->path_cost;
794 stp_designated_port_selection(struct stp *stp)
798 FOR_EACH_ENABLED_PORT (p, stp) {
799 if (stp_is_designated_port(p)
800 || p->designated_root != stp->designated_root
801 || stp->root_path_cost < p->designated_cost
802 || (stp->root_path_cost == p->designated_cost
803 && (stp->bridge_id < p->designated_bridge
804 || (stp->bridge_id == p->designated_bridge
805 && p->port_id <= p->designated_port))))
807 stp_become_designated_port(p);
813 stp_become_designated_port(struct stp_port *p)
815 struct stp *stp = p->stp;
816 p->designated_root = stp->designated_root;
817 p->designated_cost = stp->root_path_cost;
818 p->designated_bridge = stp->bridge_id;
819 p->designated_port = p->port_id;
823 stp_port_state_selection(struct stp *stp)
827 FOR_EACH_ENABLED_PORT (p, stp) {
828 if (p == stp->root_port) {
829 p->config_pending = false;
830 p->topology_change_ack = false;
831 stp_make_forwarding(p);
832 } else if (stp_is_designated_port(p)) {
833 stp_stop_timer(&p->message_age_timer);
834 stp_make_forwarding(p);
836 p->config_pending = false;
837 p->topology_change_ack = false;
838 stp_make_blocking(p);
844 stp_make_forwarding(struct stp_port *p)
846 if (p->state == STP_BLOCKING) {
847 stp_set_port_state(p, STP_LISTENING);
848 stp_start_timer(&p->forward_delay_timer, 0);
853 stp_make_blocking(struct stp_port *p)
855 if (!(p->state & (STP_DISABLED | STP_BLOCKING))) {
856 if (p->state & (STP_FORWARDING | STP_LEARNING)) {
857 if (p->change_detection_enabled) {
858 stp_topology_change_detection(p->stp);
861 stp_set_port_state(p, STP_BLOCKING);
862 stp_stop_timer(&p->forward_delay_timer);
867 stp_set_port_state(struct stp_port *p, enum stp_state state)
869 if (state != p->state && !p->state_changed) {
870 p->state_changed = true;
871 if (p < p->stp->first_changed_port) {
872 p->stp->first_changed_port = p;
879 stp_topology_change_detection(struct stp *stp)
881 if (stp_is_root_bridge(stp)) {
882 stp->topology_change = true;
883 stp_start_timer(&stp->topology_change_timer, 0);
884 } else if (!stp->topology_change_detected) {
885 stp_transmit_tcn(stp);
886 stp_start_timer(&stp->tcn_timer, 0);
888 stp->topology_change_detected = true;
892 stp_topology_change_acknowledged(struct stp *stp)
894 stp->topology_change_detected = false;
895 stp_stop_timer(&stp->tcn_timer);
899 stp_acknowledge_topology_change(struct stp_port *p)
901 p->topology_change_ack = true;
902 stp_transmit_config(p);
906 stp_received_config_bpdu(struct stp *stp, struct stp_port *p,
907 const struct stp_config_bpdu *config)
909 if (ntohs(config->message_age) >= ntohs(config->max_age)) {
910 VLOG_WARN("%s: received config BPDU with message age (%u) greater "
913 ntohs(config->message_age), ntohs(config->max_age));
916 if (p->state != STP_DISABLED) {
917 bool root = stp_is_root_bridge(stp);
918 if (stp_supersedes_port_info(p, config)) {
919 stp_record_config_information(p, config);
920 stp_configuration_update(stp);
921 stp_port_state_selection(stp);
922 if (!stp_is_root_bridge(stp) && root) {
923 stp_stop_timer(&stp->hello_timer);
924 if (stp->topology_change_detected) {
925 stp_stop_timer(&stp->topology_change_timer);
926 stp_transmit_tcn(stp);
927 stp_start_timer(&stp->tcn_timer, 0);
930 if (p == stp->root_port) {
931 stp_record_config_timeout_values(stp, config);
932 stp_config_bpdu_generation(stp);
933 if (config->flags & htons(STP_CONFIG_TOPOLOGY_CHANGE_ACK)) {
934 stp_topology_change_acknowledged(stp);
937 } else if (stp_is_designated_port(p)) {
938 stp_transmit_config(p);
944 stp_received_tcn_bpdu(struct stp *stp, struct stp_port *p,
945 const struct stp_tcn_bpdu *tcn)
947 if (p->state != STP_DISABLED) {
948 if (stp_is_designated_port(p)) {
949 stp_topology_change_detection(stp);
950 stp_acknowledge_topology_change(p);
956 stp_hello_timer_expiry(struct stp *stp)
958 stp_config_bpdu_generation(stp);
959 stp_start_timer(&stp->hello_timer, 0);
963 stp_message_age_timer_expiry(struct stp_port *p)
965 struct stp *stp = p->stp;
966 bool root = stp_is_root_bridge(stp);
967 stp_become_designated_port(p);
968 stp_configuration_update(stp);
969 stp_port_state_selection(stp);
970 if (stp_is_root_bridge(stp) && !root) {
971 stp->max_age = stp->bridge_max_age;
972 stp->hello_time = stp->bridge_hello_time;
973 stp->forward_delay = stp->bridge_forward_delay;
974 stp_topology_change_detection(stp);
975 stp_stop_timer(&stp->tcn_timer);
976 stp_config_bpdu_generation(stp);
977 stp_start_timer(&stp->hello_timer, 0);
982 stp_is_designated_for_some_port(const struct stp *stp)
984 const struct stp_port *p;
986 FOR_EACH_ENABLED_PORT (p, stp) {
987 if (p->designated_bridge == stp->bridge_id) {
995 stp_forward_delay_timer_expiry(struct stp_port *p)
997 if (p->state == STP_LISTENING) {
998 stp_set_port_state(p, STP_LEARNING);
999 stp_start_timer(&p->forward_delay_timer, 0);
1000 } else if (p->state == STP_LEARNING) {
1001 stp_set_port_state(p, STP_FORWARDING);
1002 if (stp_is_designated_for_some_port(p->stp)) {
1003 if (p->change_detection_enabled) {
1004 stp_topology_change_detection(p->stp);
1011 stp_tcn_timer_expiry(struct stp *stp)
1013 stp_transmit_tcn(stp);
1014 stp_start_timer(&stp->tcn_timer, 0);
1018 stp_topology_change_timer_expiry(struct stp *stp)
1020 stp->topology_change_detected = false;
1021 stp->topology_change = false;
1025 stp_hold_timer_expiry(struct stp_port *p)
1027 if (p->config_pending) {
1028 stp_transmit_config(p);
1033 stp_initialize_port(struct stp_port *p, enum stp_state state)
1035 assert(state & (STP_DISABLED | STP_BLOCKING));
1036 stp_become_designated_port(p);
1037 stp_set_port_state(p, state);
1038 p->topology_change_ack = false;
1039 p->config_pending = false;
1040 p->change_detection_enabled = true;
1041 stp_stop_timer(&p->message_age_timer);
1042 stp_stop_timer(&p->forward_delay_timer);
1043 stp_stop_timer(&p->hold_timer);
1047 stp_become_root_bridge(struct stp *stp)
1049 stp->max_age = stp->bridge_max_age;
1050 stp->hello_time = stp->bridge_hello_time;
1051 stp->forward_delay = stp->bridge_forward_delay;
1052 stp_topology_change_detection(stp);
1053 stp_stop_timer(&stp->tcn_timer);
1054 stp_config_bpdu_generation(stp);
1055 stp_start_timer(&stp->hello_timer, 0);
1059 stp_start_timer(struct stp_timer *timer, int value)
1061 timer->value = value;
1062 timer->active = true;
1066 stp_stop_timer(struct stp_timer *timer)
1068 timer->active = false;
1072 stp_timer_expired(struct stp_timer *timer, int elapsed, int timeout)
1074 if (timer->active) {
1075 timer->value += elapsed;
1076 if (timer->value >= timeout) {
1077 timer->active = false;