2 * Copyright (c) 2008, 2009, 2010 Nicira Networks.
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. */
21 #include <sys/types.h>
22 #include <netinet/in.h>
23 #include <arpa/inet.h>
33 #define THIS_MODULE VLM_stp
35 /* Ethernet address used as the destination for STP frames. */
36 const uint8_t stp_eth_addr[ETH_ADDR_LEN]
37 = { 0x01, 0x80, 0xC2, 0x00, 0x00, 0x01 };
39 #define STP_PROTOCOL_ID 0x0000
40 #define STP_PROTOCOL_VERSION 0x00
41 #define STP_TYPE_CONFIG 0x00
42 #define STP_TYPE_TCN 0x80
44 struct stp_bpdu_header {
45 uint16_t protocol_id; /* STP_PROTOCOL_ID. */
46 uint8_t protocol_version; /* STP_PROTOCOL_VERSION. */
47 uint8_t bpdu_type; /* One of STP_TYPE_*. */
48 } __attribute__((packed));
49 BUILD_ASSERT_DECL(sizeof(struct stp_bpdu_header) == 4);
51 enum stp_config_bpdu_flags {
52 STP_CONFIG_TOPOLOGY_CHANGE_ACK = 0x80,
53 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 uint64_t root_id; /* 8.5.1.1: Bridge believed to be root. */
60 uint32_t root_path_cost; /* 8.5.1.2: Cost of path to root. */
61 uint64_t bridge_id; /* 8.5.1.3: ID of transmitting bridge. */
62 uint16_t port_id; /* 8.5.1.4: Port transmitting the BPDU. */
63 uint16_t message_age; /* 8.5.1.5: Age of BPDU at tx time. */
64 uint16_t max_age; /* 8.5.1.6: Timeout for received data. */
65 uint16_t hello_time; /* 8.5.1.7: Time between BPDU generation. */
66 uint16_t forward_delay; /* 8.5.1.8: State progression delay. */
67 } __attribute__((packed));
68 BUILD_ASSERT_DECL(sizeof(struct stp_config_bpdu) == 35);
71 struct stp_bpdu_header header; /* Type STP_TYPE_TCN. */
72 } __attribute__((packed));
73 BUILD_ASSERT_DECL(sizeof(struct stp_tcn_bpdu) == 4);
76 bool active; /* Timer in use? */
77 int value; /* Current value of timer, counting up. */
82 int port_id; /* 8.5.5.1: Unique port identifier. */
83 enum stp_state state; /* 8.5.5.2: Current state. */
84 int path_cost; /* 8.5.5.3: Cost of tx/rx on this port. */
85 stp_identifier designated_root; /* 8.5.5.4. */
86 int designated_cost; /* 8.5.5.5: Path cost to root on port. */
87 stp_identifier designated_bridge; /* 8.5.5.6. */
88 int designated_port; /* 8.5.5.7: Port to send config msgs on. */
89 bool topology_change_ack; /* 8.5.5.8: Flag for next config BPDU. */
90 bool config_pending; /* 8.5.5.9: Send BPDU when hold expires? */
91 bool change_detection_enabled; /* 8.5.5.10: Detect topology changes? */
93 struct stp_timer message_age_timer; /* 8.5.6.1: Age of received info. */
94 struct stp_timer forward_delay_timer; /* 8.5.6.2: State change timer. */
95 struct stp_timer hold_timer; /* 8.5.6.3: BPDU rate limit timer. */
101 /* Static bridge data. */
102 char *name; /* Human-readable name for log messages. */
103 stp_identifier bridge_id; /* 8.5.3.7: This bridge. */
104 int max_age; /* 8.5.3.4: Time to drop received data. */
105 int hello_time; /* 8.5.3.5: Time between sending BPDUs. */
106 int forward_delay; /* 8.5.3.6: Delay between state changes. */
107 int bridge_max_age; /* 8.5.3.8: max_age when we're root. */
108 int bridge_hello_time; /* 8.5.3.9: hello_time as root. */
109 int bridge_forward_delay; /* 8.5.3.10: forward_delay as root. */
110 int rq_max_age; /* User-requested max age, in ms. */
111 int rq_hello_time; /* User-requested hello time, in ms. */
112 int rq_forward_delay; /* User-requested forward delay, in ms. */
113 int elapsed_remainder; /* Left-over msecs from last stp_tick(). */
115 /* Dynamic bridge data. */
116 stp_identifier designated_root; /* 8.5.3.1: Bridge believed to be root. */
117 unsigned int root_path_cost; /* 8.5.3.2: Cost of path to root. */
118 struct stp_port *root_port; /* 8.5.3.3: Lowest cost port to root. */
119 bool topology_change_detected; /* 8.5.3.11: Detected a topology change? */
120 bool topology_change; /* 8.5.3.12: Received topology change? */
123 struct stp_timer hello_timer; /* 8.5.4.1: Hello timer. */
124 struct stp_timer tcn_timer; /* 8.5.4.2: Topology change timer. */
125 struct stp_timer topology_change_timer; /* 8.5.4.3. */
128 struct stp_port ports[STP_MAX_PORTS];
130 /* Interface to client. */
131 struct stp_port *first_changed_port;
132 void (*send_bpdu)(struct ofpbuf *bpdu, int port_no, void *aux);
136 #define FOR_EACH_ENABLED_PORT(PORT, STP) \
137 for ((PORT) = stp_next_enabled_port((STP), (STP)->ports); \
139 (PORT) = stp_next_enabled_port((STP), (PORT) + 1))
140 static struct stp_port *
141 stp_next_enabled_port(const struct stp *stp, const struct stp_port *port)
143 for (; port < &stp->ports[ARRAY_SIZE(stp->ports)]; port++) {
144 if (port->state != STP_DISABLED) {
145 return (struct stp_port *) port;
151 #define MESSAGE_AGE_INCREMENT 1
153 static void stp_transmit_config(struct stp_port *);
154 static bool stp_supersedes_port_info(const struct stp_port *,
155 const struct stp_config_bpdu *);
156 static void stp_record_config_information(struct stp_port *,
157 const struct stp_config_bpdu *);
158 static void stp_record_config_timeout_values(struct stp *,
159 const struct stp_config_bpdu *);
160 static bool stp_is_designated_port(const struct stp_port *);
161 static void stp_config_bpdu_generation(struct stp *);
162 static void stp_transmit_tcn(struct stp *);
163 static void stp_configuration_update(struct stp *);
164 static bool stp_supersedes_root(const struct stp_port *root,
165 const struct stp_port *);
166 static void stp_root_selection(struct stp *);
167 static void stp_designated_port_selection(struct stp *);
168 static void stp_become_designated_port(struct stp_port *);
169 static void stp_port_state_selection(struct stp *);
170 static void stp_make_forwarding(struct stp_port *);
171 static void stp_make_blocking(struct stp_port *);
172 static void stp_set_port_state(struct stp_port *, enum stp_state);
173 static void stp_topology_change_detection(struct stp *);
174 static void stp_topology_change_acknowledged(struct stp *);
175 static void stp_acknowledge_topology_change(struct stp_port *);
176 static void stp_received_config_bpdu(struct stp *, struct stp_port *,
177 const struct stp_config_bpdu *);
178 static void stp_received_tcn_bpdu(struct stp *, struct stp_port *);
179 static void stp_hello_timer_expiry(struct stp *);
180 static void stp_message_age_timer_expiry(struct stp_port *);
181 static bool stp_is_designated_for_some_port(const struct stp *);
182 static void stp_forward_delay_timer_expiry(struct stp_port *);
183 static void stp_tcn_timer_expiry(struct stp *);
184 static void stp_topology_change_timer_expiry(struct stp *);
185 static void stp_hold_timer_expiry(struct stp_port *);
186 static void stp_initialize_port(struct stp_port *, enum stp_state);
187 static void stp_become_root_bridge(struct stp *);
188 static void stp_update_bridge_timers(struct stp *);
190 static int clamp(int x, int min, int max);
191 static int ms_to_timer(int ms);
192 static int ms_to_timer_remainder(int ms);
193 static int timer_to_ms(int timer);
194 static void stp_start_timer(struct stp_timer *, int value);
195 static void stp_stop_timer(struct stp_timer *);
196 static bool stp_timer_expired(struct stp_timer *, int elapsed, int timeout);
198 static void stp_send_bpdu(struct stp_port *, const void *, size_t);
200 /* Creates and returns a new STP instance that initially has no ports enabled.
202 * 'bridge_id' should be a 48-bit MAC address as returned by
203 * eth_addr_to_uint64(). 'bridge_id' may also have a priority value in its top
204 * 16 bits; if those bits are set to 0, STP_DEFAULT_BRIDGE_PRIORITY is used.
205 * (This priority may be changed with stp_set_bridge_priority().)
207 * When the bridge needs to send out a BPDU, it calls 'send_bpdu'. This
208 * callback may be called from stp_tick() or stp_received_bpdu(). The
209 * arguments to 'send_bpdu' are an STP BPDU encapsulated in
212 stp_create(const char *name, stp_identifier bridge_id,
213 void (*send_bpdu)(struct ofpbuf *bpdu, int port_no, void *aux),
219 stp = xcalloc(1, sizeof *stp);
220 stp->name = xstrdup(name);
221 stp->bridge_id = bridge_id;
222 if (!(stp->bridge_id >> 48)) {
223 stp->bridge_id |= (uint64_t) STP_DEFAULT_BRIDGE_PRIORITY << 48;
226 stp->rq_max_age = 6000;
227 stp->rq_hello_time = 2000;
228 stp->rq_forward_delay = 4000;
229 stp_update_bridge_timers(stp);
230 stp->max_age = stp->bridge_max_age;
231 stp->hello_time = stp->bridge_hello_time;
232 stp->forward_delay = stp->bridge_forward_delay;
234 stp->designated_root = stp->bridge_id;
235 stp->root_path_cost = 0;
236 stp->root_port = NULL;
237 stp->topology_change_detected = false;
238 stp->topology_change = false;
240 stp_stop_timer(&stp->tcn_timer);
241 stp_stop_timer(&stp->topology_change_timer);
242 stp_start_timer(&stp->hello_timer, 0);
244 stp->send_bpdu = send_bpdu;
247 stp->first_changed_port = &stp->ports[ARRAY_SIZE(stp->ports)];
248 for (p = stp->ports; p < &stp->ports[ARRAY_SIZE(stp->ports)]; p++) {
250 p->port_id = (stp_port_no(p) + 1) | (STP_DEFAULT_PORT_PRIORITY << 8);
251 p->path_cost = 19; /* Recommended default for 100 Mb/s link. */
252 stp_initialize_port(p, STP_DISABLED);
257 /* Destroys 'stp'. */
259 stp_destroy(struct stp *stp)
264 /* Runs 'stp' given that 'ms' milliseconds have passed. */
266 stp_tick(struct stp *stp, int ms)
271 /* Convert 'ms' to STP timer ticks. Preserve any leftover milliseconds
272 * from previous stp_tick() calls so that we don't lose STP ticks when we
273 * are called too frequently. */
274 ms = clamp(ms, 0, INT_MAX - 1000) + stp->elapsed_remainder;
275 elapsed = ms_to_timer(ms);
276 stp->elapsed_remainder = ms_to_timer_remainder(ms);
281 if (stp_timer_expired(&stp->hello_timer, elapsed, stp->hello_time)) {
282 stp_hello_timer_expiry(stp);
284 if (stp_timer_expired(&stp->tcn_timer, elapsed, stp->bridge_hello_time)) {
285 stp_tcn_timer_expiry(stp);
287 if (stp_timer_expired(&stp->topology_change_timer, elapsed,
288 stp->max_age + stp->forward_delay)) {
289 stp_topology_change_timer_expiry(stp);
291 FOR_EACH_ENABLED_PORT (p, stp) {
292 if (stp_timer_expired(&p->message_age_timer, elapsed, stp->max_age)) {
293 stp_message_age_timer_expiry(p);
296 FOR_EACH_ENABLED_PORT (p, stp) {
297 if (stp_timer_expired(&p->forward_delay_timer, elapsed,
298 stp->forward_delay)) {
299 stp_forward_delay_timer_expiry(p);
301 if (stp_timer_expired(&p->hold_timer, elapsed, ms_to_timer(1000))) {
302 stp_hold_timer_expiry(p);
308 set_bridge_id(struct stp *stp, stp_identifier new_bridge_id)
310 if (new_bridge_id != stp->bridge_id) {
314 root = stp_is_root_bridge(stp);
315 FOR_EACH_ENABLED_PORT (p, stp) {
316 if (stp_is_designated_port(p)) {
317 p->designated_bridge = new_bridge_id;
320 stp->bridge_id = new_bridge_id;
321 stp_configuration_update(stp);
322 stp_port_state_selection(stp);
323 if (stp_is_root_bridge(stp) && !root) {
324 stp_become_root_bridge(stp);
330 stp_set_bridge_id(struct stp *stp, stp_identifier bridge_id)
332 const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
333 const uint64_t pri_bits = ~mac_bits;
334 set_bridge_id(stp, (stp->bridge_id & pri_bits) | (bridge_id & mac_bits));
338 stp_set_bridge_priority(struct stp *stp, uint16_t new_priority)
340 const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
341 set_bridge_id(stp, ((stp->bridge_id & mac_bits)
342 | ((uint64_t) new_priority << 48)));
345 /* Sets the desired hello time for 'stp' to 'ms', in milliseconds. The actual
346 * hello time is clamped to the range of 1 to 10 seconds and subject to the
347 * relationship (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge
348 * hello time is only used when 'stp' is the root bridge. */
350 stp_set_hello_time(struct stp *stp, int ms)
352 stp->rq_hello_time = ms;
353 stp_update_bridge_timers(stp);
356 /* Sets the desired max age for 'stp' to 'ms', in milliseconds. The actual max
357 * age is clamped to the range of 6 to 40 seconds and subject to the
358 * relationships (2 * (bridge_forward_delay - 1 s) >= bridge_max_age) and
359 * (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge max age is
360 * only used when 'stp' is the root bridge. */
362 stp_set_max_age(struct stp *stp, int ms)
364 stp->rq_max_age = ms;
365 stp_update_bridge_timers(stp);
368 /* Sets the desired forward delay for 'stp' to 'ms', in milliseconds. The
369 * actual forward delay is clamped to the range of 4 to 30 seconds and subject
370 * to the relationship (2 * (bridge_forward_delay - 1 s) >= bridge_max_age).
371 * The bridge forward delay is only used when 'stp' is the root bridge. */
373 stp_set_forward_delay(struct stp *stp, int ms)
375 stp->rq_forward_delay = ms;
376 stp_update_bridge_timers(stp);
379 /* Returns the name given to 'stp' in the call to stp_create(). */
381 stp_get_name(const struct stp *stp)
386 /* Returns the bridge ID for 'stp'. */
388 stp_get_bridge_id(const struct stp *stp)
390 return stp->bridge_id;
393 /* Returns the bridge ID of the bridge currently believed to be the root. */
395 stp_get_designated_root(const struct stp *stp)
397 return stp->designated_root;
400 /* Returns true if 'stp' believes itself to the be root of the spanning tree,
401 * false otherwise. */
403 stp_is_root_bridge(const struct stp *stp)
405 return stp->bridge_id == stp->designated_root;
408 /* Returns the cost of the path from 'stp' to the root of the spanning tree. */
410 stp_get_root_path_cost(const struct stp *stp)
412 return stp->root_path_cost;
415 /* Returns the bridge hello time, in ms. The returned value is not necessarily
416 * the value passed to stp_set_hello_time(): it is clamped to the valid range
417 * and quantized to the STP timer resolution. */
419 stp_get_hello_time(const struct stp *stp)
421 return timer_to_ms(stp->bridge_hello_time);
424 /* Returns the bridge max age, in ms. The returned value is not necessarily
425 * the value passed to stp_set_max_age(): it is clamped to the valid range,
426 * quantized to the STP timer resolution, and adjusted to match the constraints
427 * due to the hello time. */
429 stp_get_max_age(const struct stp *stp)
431 return timer_to_ms(stp->bridge_max_age);
434 /* Returns the bridge forward delay, in ms. The returned value is not
435 * necessarily the value passed to stp_set_forward_delay(): it is clamped to
436 * the valid range, quantized to the STP timer resolution, and adjusted to
437 * match the constraints due to the forward delay. */
439 stp_get_forward_delay(const struct stp *stp)
441 return timer_to_ms(stp->bridge_forward_delay);
444 /* Returns the port in 'stp' with index 'port_no', which must be between 0 and
447 stp_get_port(struct stp *stp, int port_no)
449 assert(port_no >= 0 && port_no < ARRAY_SIZE(stp->ports));
450 return &stp->ports[port_no];
453 /* Returns the port connecting 'stp' to the root bridge, or a null pointer if
454 * there is no such port. */
456 stp_get_root_port(struct stp *stp)
458 return stp->root_port;
461 /* Finds a port whose state has changed. If successful, stores the port whose
462 * state changed in '*portp' and returns true. If no port has changed, stores
463 * NULL in '*portp' and returns false. */
465 stp_get_changed_port(struct stp *stp, struct stp_port **portp)
467 struct stp_port *end = &stp->ports[ARRAY_SIZE(stp->ports)];
470 for (p = stp->first_changed_port; p < end; p++) {
471 if (p->state_changed) {
472 p->state_changed = false;
473 stp->first_changed_port = p + 1;
478 stp->first_changed_port = end;
483 /* Returns the name for the given 'state' (for use in debugging and log
486 stp_state_name(enum stp_state state)
504 /* Returns true if 'state' is one in which packets received on a port should
505 * be forwarded, false otherwise.
507 * Returns true if 'state' is STP_DISABLED, since presumably in that case the
508 * port should still work, just not have STP applied to it. */
510 stp_forward_in_state(enum stp_state state)
512 return (state & (STP_DISABLED | STP_FORWARDING)) != 0;
515 /* Returns true if 'state' is one in which MAC learning should be done on
516 * packets received on a port, false otherwise.
518 * Returns true if 'state' is STP_DISABLED, since presumably in that case the
519 * port should still work, just not have STP applied to it. */
521 stp_learn_in_state(enum stp_state state)
523 return (state & (STP_DISABLED | STP_LEARNING | STP_FORWARDING)) != 0;
526 /* Notifies the STP entity that bridge protocol data unit 'bpdu', which is
527 * 'bpdu_size' bytes in length, was received on port 'p'.
529 * This function may call the 'send_bpdu' function provided to stp_create(). */
531 stp_received_bpdu(struct stp_port *p, const void *bpdu, size_t bpdu_size)
533 struct stp *stp = p->stp;
534 const struct stp_bpdu_header *header;
536 if (p->state == STP_DISABLED) {
540 if (bpdu_size < sizeof(struct stp_bpdu_header)) {
541 VLOG_WARN("%s: received runt %zu-byte BPDU", stp->name, bpdu_size);
546 if (header->protocol_id != htons(STP_PROTOCOL_ID)) {
547 VLOG_WARN("%s: received BPDU with unexpected protocol ID %"PRIu16,
548 stp->name, ntohs(header->protocol_id));
551 if (header->protocol_version != STP_PROTOCOL_VERSION) {
552 VLOG_DBG("%s: received BPDU with unexpected protocol version %"PRIu8,
553 stp->name, header->protocol_version);
556 switch (header->bpdu_type) {
557 case STP_TYPE_CONFIG:
558 if (bpdu_size < sizeof(struct stp_config_bpdu)) {
559 VLOG_WARN("%s: received config BPDU with invalid size %zu",
560 stp->name, bpdu_size);
563 stp_received_config_bpdu(stp, p, bpdu);
567 if (bpdu_size != sizeof(struct stp_tcn_bpdu)) {
568 VLOG_WARN("%s: received TCN BPDU with invalid size %zu",
569 stp->name, bpdu_size);
572 stp_received_tcn_bpdu(stp, p);
576 VLOG_WARN("%s: received BPDU of unexpected type %"PRIu8,
577 stp->name, header->bpdu_type);
582 /* Returns the STP entity in which 'p' is nested. */
584 stp_port_get_stp(struct stp_port *p)
589 /* Returns the index of port 'p' within its bridge. */
591 stp_port_no(const struct stp_port *p)
593 struct stp *stp = p->stp;
594 assert(p >= stp->ports && p < &stp->ports[ARRAY_SIZE(stp->ports)]);
595 return p - stp->ports;
598 /* Returns the state of port 'p'. */
600 stp_port_get_state(const struct stp_port *p)
605 /* Disables STP on port 'p'. */
607 stp_port_disable(struct stp_port *p)
609 struct stp *stp = p->stp;
610 if (p->state != STP_DISABLED) {
611 bool root = stp_is_root_bridge(stp);
612 stp_become_designated_port(p);
613 stp_set_port_state(p, STP_DISABLED);
614 p->topology_change_ack = false;
615 p->config_pending = false;
616 stp_stop_timer(&p->message_age_timer);
617 stp_stop_timer(&p->forward_delay_timer);
618 stp_configuration_update(stp);
619 stp_port_state_selection(stp);
620 if (stp_is_root_bridge(stp) && !root) {
621 stp_become_root_bridge(stp);
626 /* Enables STP on port 'p'. The port will initially be in "blocking" state. */
628 stp_port_enable(struct stp_port *p)
630 if (p->state == STP_DISABLED) {
631 stp_initialize_port(p, STP_BLOCKING);
632 stp_port_state_selection(p->stp);
636 /* Sets the priority of port 'p' to 'new_priority'. Lower numerical values
637 * are interpreted as higher priorities. */
639 stp_port_set_priority(struct stp_port *p, uint8_t new_priority)
641 uint16_t new_port_id = (p->port_id & 0xff) | (new_priority << 8);
642 if (p->port_id != new_port_id) {
643 struct stp *stp = p->stp;
644 if (stp_is_designated_port(p)) {
645 p->designated_port = new_port_id;
647 p->port_id = new_port_id;
648 if (stp->bridge_id == p->designated_bridge
649 && p->port_id < p->designated_port) {
650 stp_become_designated_port(p);
651 stp_port_state_selection(stp);
656 /* Sets the path cost of port 'p' to 'path_cost'. Lower values are generally
657 * used to indicate faster links. Use stp_port_set_speed() to automatically
658 * generate a default path cost from a link speed. */
660 stp_port_set_path_cost(struct stp_port *p, uint16_t path_cost)
662 if (p->path_cost != path_cost) {
663 struct stp *stp = p->stp;
664 p->path_cost = path_cost;
665 stp_configuration_update(stp);
666 stp_port_state_selection(stp);
670 /* Sets the path cost of port 'p' based on 'speed' (measured in Mb/s). */
672 stp_port_set_speed(struct stp_port *p, unsigned int speed)
674 stp_port_set_path_cost(p, (speed >= 10000 ? 2 /* 10 Gb/s. */
675 : speed >= 1000 ? 4 /* 1 Gb/s. */
676 : speed >= 100 ? 19 /* 100 Mb/s. */
677 : speed >= 16 ? 62 /* 16 Mb/s. */
678 : speed >= 10 ? 100 /* 10 Mb/s. */
679 : speed >= 4 ? 250 /* 4 Mb/s. */
680 : 19)); /* 100 Mb/s (guess). */
683 /* Enables topology change detection on port 'p'. */
685 stp_port_enable_change_detection(struct stp_port *p)
687 p->change_detection_enabled = true;
690 /* Disables topology change detection on port 'p'. */
692 stp_port_disable_change_detection(struct stp_port *p)
694 p->change_detection_enabled = false;
698 stp_transmit_config(struct stp_port *p)
700 struct stp *stp = p->stp;
701 bool root = stp_is_root_bridge(stp);
702 if (!root && !stp->root_port) {
705 if (p->hold_timer.active) {
706 p->config_pending = true;
708 struct stp_config_bpdu config;
709 memset(&config, 0, sizeof config);
710 config.header.protocol_id = htons(STP_PROTOCOL_ID);
711 config.header.protocol_version = STP_PROTOCOL_VERSION;
712 config.header.bpdu_type = STP_TYPE_CONFIG;
714 if (p->topology_change_ack) {
715 config.flags |= htons(STP_CONFIG_TOPOLOGY_CHANGE_ACK);
717 if (stp->topology_change) {
718 config.flags |= htons(STP_CONFIG_TOPOLOGY_CHANGE);
720 config.root_id = htonll(stp->designated_root);
721 config.root_path_cost = htonl(stp->root_path_cost);
722 config.bridge_id = htonll(stp->bridge_id);
723 config.port_id = htons(p->port_id);
725 config.message_age = htons(0);
727 config.message_age = htons(stp->root_port->message_age_timer.value
728 + MESSAGE_AGE_INCREMENT);
730 config.max_age = htons(stp->max_age);
731 config.hello_time = htons(stp->hello_time);
732 config.forward_delay = htons(stp->forward_delay);
733 if (ntohs(config.message_age) < stp->max_age) {
734 p->topology_change_ack = false;
735 p->config_pending = false;
736 stp_send_bpdu(p, &config, sizeof config);
737 stp_start_timer(&p->hold_timer, 0);
743 stp_supersedes_port_info(const struct stp_port *p,
744 const struct stp_config_bpdu *config)
746 if (ntohll(config->root_id) != p->designated_root) {
747 return ntohll(config->root_id) < p->designated_root;
748 } else if (ntohl(config->root_path_cost) != p->designated_cost) {
749 return ntohl(config->root_path_cost) < p->designated_cost;
750 } else if (ntohll(config->bridge_id) != p->designated_bridge) {
751 return ntohll(config->bridge_id) < p->designated_bridge;
753 return (ntohll(config->bridge_id) != p->stp->bridge_id
754 || ntohs(config->port_id) <= p->designated_port);
759 stp_record_config_information(struct stp_port *p,
760 const struct stp_config_bpdu *config)
762 p->designated_root = ntohll(config->root_id);
763 p->designated_cost = ntohl(config->root_path_cost);
764 p->designated_bridge = ntohll(config->bridge_id);
765 p->designated_port = ntohs(config->port_id);
766 stp_start_timer(&p->message_age_timer, ntohs(config->message_age));
770 stp_record_config_timeout_values(struct stp *stp,
771 const struct stp_config_bpdu *config)
773 stp->max_age = ntohs(config->max_age);
774 stp->hello_time = ntohs(config->hello_time);
775 stp->forward_delay = ntohs(config->forward_delay);
776 stp->topology_change = config->flags & htons(STP_CONFIG_TOPOLOGY_CHANGE);
780 stp_is_designated_port(const struct stp_port *p)
782 return (p->designated_bridge == p->stp->bridge_id
783 && p->designated_port == p->port_id);
787 stp_config_bpdu_generation(struct stp *stp)
791 FOR_EACH_ENABLED_PORT (p, stp) {
792 if (stp_is_designated_port(p)) {
793 stp_transmit_config(p);
799 stp_transmit_tcn(struct stp *stp)
801 struct stp_port *p = stp->root_port;
802 struct stp_tcn_bpdu tcn_bpdu;
806 tcn_bpdu.header.protocol_id = htons(STP_PROTOCOL_ID);
807 tcn_bpdu.header.protocol_version = STP_PROTOCOL_VERSION;
808 tcn_bpdu.header.bpdu_type = STP_TYPE_TCN;
809 stp_send_bpdu(p, &tcn_bpdu, sizeof tcn_bpdu);
813 stp_configuration_update(struct stp *stp)
815 stp_root_selection(stp);
816 stp_designated_port_selection(stp);
820 stp_supersedes_root(const struct stp_port *root, const struct stp_port *p)
822 int p_cost = p->designated_cost + p->path_cost;
823 int root_cost = root->designated_cost + root->path_cost;
825 if (p->designated_root != root->designated_root) {
826 return p->designated_root < root->designated_root;
827 } else if (p_cost != root_cost) {
828 return p_cost < root_cost;
829 } else if (p->designated_bridge != root->designated_bridge) {
830 return p->designated_bridge < root->designated_bridge;
831 } else if (p->designated_port != root->designated_port) {
832 return p->designated_port < root->designated_port;
834 return p->port_id < root->port_id;
839 stp_root_selection(struct stp *stp)
841 struct stp_port *p, *root;
844 FOR_EACH_ENABLED_PORT (p, stp) {
845 if (stp_is_designated_port(p)
846 || p->designated_root >= stp->bridge_id) {
849 if (root && !stp_supersedes_root(root, p)) {
854 stp->root_port = root;
856 stp->designated_root = stp->bridge_id;
857 stp->root_path_cost = 0;
859 stp->designated_root = root->designated_root;
860 stp->root_path_cost = root->designated_cost + root->path_cost;
865 stp_designated_port_selection(struct stp *stp)
869 FOR_EACH_ENABLED_PORT (p, stp) {
870 if (stp_is_designated_port(p)
871 || p->designated_root != stp->designated_root
872 || stp->root_path_cost < p->designated_cost
873 || (stp->root_path_cost == p->designated_cost
874 && (stp->bridge_id < p->designated_bridge
875 || (stp->bridge_id == p->designated_bridge
876 && p->port_id <= p->designated_port))))
878 stp_become_designated_port(p);
884 stp_become_designated_port(struct stp_port *p)
886 struct stp *stp = p->stp;
887 p->designated_root = stp->designated_root;
888 p->designated_cost = stp->root_path_cost;
889 p->designated_bridge = stp->bridge_id;
890 p->designated_port = p->port_id;
894 stp_port_state_selection(struct stp *stp)
898 FOR_EACH_ENABLED_PORT (p, stp) {
899 if (p == stp->root_port) {
900 p->config_pending = false;
901 p->topology_change_ack = false;
902 stp_make_forwarding(p);
903 } else if (stp_is_designated_port(p)) {
904 stp_stop_timer(&p->message_age_timer);
905 stp_make_forwarding(p);
907 p->config_pending = false;
908 p->topology_change_ack = false;
909 stp_make_blocking(p);
915 stp_make_forwarding(struct stp_port *p)
917 if (p->state == STP_BLOCKING) {
918 stp_set_port_state(p, STP_LISTENING);
919 stp_start_timer(&p->forward_delay_timer, 0);
924 stp_make_blocking(struct stp_port *p)
926 if (!(p->state & (STP_DISABLED | STP_BLOCKING))) {
927 if (p->state & (STP_FORWARDING | STP_LEARNING)) {
928 if (p->change_detection_enabled) {
929 stp_topology_change_detection(p->stp);
932 stp_set_port_state(p, STP_BLOCKING);
933 stp_stop_timer(&p->forward_delay_timer);
938 stp_set_port_state(struct stp_port *p, enum stp_state state)
940 if (state != p->state && !p->state_changed) {
941 p->state_changed = true;
942 if (p < p->stp->first_changed_port) {
943 p->stp->first_changed_port = p;
950 stp_topology_change_detection(struct stp *stp)
952 if (stp_is_root_bridge(stp)) {
953 stp->topology_change = true;
954 stp_start_timer(&stp->topology_change_timer, 0);
955 } else if (!stp->topology_change_detected) {
956 stp_transmit_tcn(stp);
957 stp_start_timer(&stp->tcn_timer, 0);
959 stp->topology_change_detected = true;
963 stp_topology_change_acknowledged(struct stp *stp)
965 stp->topology_change_detected = false;
966 stp_stop_timer(&stp->tcn_timer);
970 stp_acknowledge_topology_change(struct stp_port *p)
972 p->topology_change_ack = true;
973 stp_transmit_config(p);
977 stp_received_config_bpdu(struct stp *stp, struct stp_port *p,
978 const struct stp_config_bpdu *config)
980 if (ntohs(config->message_age) >= ntohs(config->max_age)) {
981 VLOG_WARN("%s: received config BPDU with message age (%u) greater "
984 ntohs(config->message_age), ntohs(config->max_age));
987 if (p->state != STP_DISABLED) {
988 bool root = stp_is_root_bridge(stp);
989 if (stp_supersedes_port_info(p, config)) {
990 stp_record_config_information(p, config);
991 stp_configuration_update(stp);
992 stp_port_state_selection(stp);
993 if (!stp_is_root_bridge(stp) && root) {
994 stp_stop_timer(&stp->hello_timer);
995 if (stp->topology_change_detected) {
996 stp_stop_timer(&stp->topology_change_timer);
997 stp_transmit_tcn(stp);
998 stp_start_timer(&stp->tcn_timer, 0);
1001 if (p == stp->root_port) {
1002 stp_record_config_timeout_values(stp, config);
1003 stp_config_bpdu_generation(stp);
1004 if (config->flags & htons(STP_CONFIG_TOPOLOGY_CHANGE_ACK)) {
1005 stp_topology_change_acknowledged(stp);
1008 } else if (stp_is_designated_port(p)) {
1009 stp_transmit_config(p);
1015 stp_received_tcn_bpdu(struct stp *stp, struct stp_port *p)
1017 if (p->state != STP_DISABLED) {
1018 if (stp_is_designated_port(p)) {
1019 stp_topology_change_detection(stp);
1020 stp_acknowledge_topology_change(p);
1026 stp_hello_timer_expiry(struct stp *stp)
1028 stp_config_bpdu_generation(stp);
1029 stp_start_timer(&stp->hello_timer, 0);
1033 stp_message_age_timer_expiry(struct stp_port *p)
1035 struct stp *stp = p->stp;
1036 bool root = stp_is_root_bridge(stp);
1037 stp_become_designated_port(p);
1038 stp_configuration_update(stp);
1039 stp_port_state_selection(stp);
1040 if (stp_is_root_bridge(stp) && !root) {
1041 stp->max_age = stp->bridge_max_age;
1042 stp->hello_time = stp->bridge_hello_time;
1043 stp->forward_delay = stp->bridge_forward_delay;
1044 stp_topology_change_detection(stp);
1045 stp_stop_timer(&stp->tcn_timer);
1046 stp_config_bpdu_generation(stp);
1047 stp_start_timer(&stp->hello_timer, 0);
1052 stp_is_designated_for_some_port(const struct stp *stp)
1054 const struct stp_port *p;
1056 FOR_EACH_ENABLED_PORT (p, stp) {
1057 if (p->designated_bridge == stp->bridge_id) {
1065 stp_forward_delay_timer_expiry(struct stp_port *p)
1067 if (p->state == STP_LISTENING) {
1068 stp_set_port_state(p, STP_LEARNING);
1069 stp_start_timer(&p->forward_delay_timer, 0);
1070 } else if (p->state == STP_LEARNING) {
1071 stp_set_port_state(p, STP_FORWARDING);
1072 if (stp_is_designated_for_some_port(p->stp)) {
1073 if (p->change_detection_enabled) {
1074 stp_topology_change_detection(p->stp);
1081 stp_tcn_timer_expiry(struct stp *stp)
1083 stp_transmit_tcn(stp);
1084 stp_start_timer(&stp->tcn_timer, 0);
1088 stp_topology_change_timer_expiry(struct stp *stp)
1090 stp->topology_change_detected = false;
1091 stp->topology_change = false;
1095 stp_hold_timer_expiry(struct stp_port *p)
1097 if (p->config_pending) {
1098 stp_transmit_config(p);
1103 stp_initialize_port(struct stp_port *p, enum stp_state state)
1105 assert(state & (STP_DISABLED | STP_BLOCKING));
1106 stp_become_designated_port(p);
1107 stp_set_port_state(p, state);
1108 p->topology_change_ack = false;
1109 p->config_pending = false;
1110 p->change_detection_enabled = true;
1111 stp_stop_timer(&p->message_age_timer);
1112 stp_stop_timer(&p->forward_delay_timer);
1113 stp_stop_timer(&p->hold_timer);
1117 stp_become_root_bridge(struct stp *stp)
1119 stp->max_age = stp->bridge_max_age;
1120 stp->hello_time = stp->bridge_hello_time;
1121 stp->forward_delay = stp->bridge_forward_delay;
1122 stp_topology_change_detection(stp);
1123 stp_stop_timer(&stp->tcn_timer);
1124 stp_config_bpdu_generation(stp);
1125 stp_start_timer(&stp->hello_timer, 0);
1129 stp_start_timer(struct stp_timer *timer, int value)
1131 timer->value = value;
1132 timer->active = true;
1136 stp_stop_timer(struct stp_timer *timer)
1138 timer->active = false;
1142 stp_timer_expired(struct stp_timer *timer, int elapsed, int timeout)
1144 if (timer->active) {
1145 timer->value += elapsed;
1146 if (timer->value >= timeout) {
1147 timer->active = false;
1154 /* Returns the number of whole STP timer ticks in 'ms' milliseconds. There
1155 * are 256 STP timer ticks per second. */
1159 return ms * 0x100 / 1000;
1162 /* Returns the number of leftover milliseconds when 'ms' is converted to STP
1165 ms_to_timer_remainder(int ms)
1167 return ms * 0x100 % 1000;
1170 /* Returns the number of whole milliseconds in 'timer' STP timer ticks. There
1171 * are 256 STP timer ticks per second. */
1173 timer_to_ms(int timer)
1175 return timer * 1000 / 0x100;
1179 clamp(int x, int min, int max)
1181 return x < min ? min : x > max ? max : x;
1185 stp_update_bridge_timers(struct stp *stp)
1189 ht = clamp(stp->rq_hello_time, 1000, 10000);
1190 ma = clamp(stp->rq_max_age, MAX(2 * (ht + 1000), 6000), 40000);
1191 fd = clamp(stp->rq_forward_delay, ma / 2 + 1000, 30000);
1193 stp->bridge_hello_time = ms_to_timer(ht);
1194 stp->bridge_max_age = ms_to_timer(ma);
1195 stp->bridge_forward_delay = ms_to_timer(fd);
1197 if (stp_is_root_bridge(stp)) {
1198 stp->max_age = stp->bridge_max_age;
1199 stp->hello_time = stp->bridge_hello_time;
1200 stp->forward_delay = stp->bridge_forward_delay;
1205 stp_send_bpdu(struct stp_port *p, const void *bpdu, size_t bpdu_size)
1207 struct eth_header *eth;
1208 struct llc_header *llc;
1212 pkt = ofpbuf_new(ETH_HEADER_LEN + LLC_HEADER_LEN + bpdu_size);
1213 pkt->l2 = eth = ofpbuf_put_zeros(pkt, sizeof *eth);
1214 llc = ofpbuf_put_zeros(pkt, sizeof *llc);
1215 pkt->l3 = ofpbuf_put(pkt, bpdu, bpdu_size);
1218 memcpy(eth->eth_dst, stp_eth_addr, ETH_ADDR_LEN);
1219 /* p->stp->send_bpdu() must fill in source address. */
1220 eth->eth_type = htons(pkt->size - ETH_HEADER_LEN);
1223 llc->llc_dsap = STP_LLC_DSAP;
1224 llc->llc_ssap = STP_LLC_SSAP;
1225 llc->llc_cntl = STP_LLC_CNTL;
1227 p->stp->send_bpdu(pkt, stp_port_no(p), p->stp->aux);