2 * Copyright (c) 2008, 2009, 2010, 2011 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. */
23 #include <sys/types.h>
24 #include <netinet/in.h>
25 #include <arpa/inet.h>
29 #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
42 struct stp_bpdu_header {
43 ovs_be16 protocol_id; /* STP_PROTOCOL_ID. */
44 uint8_t protocol_version; /* STP_PROTOCOL_VERSION. */
45 uint8_t bpdu_type; /* One of STP_TYPE_*. */
46 } __attribute__((packed));
47 BUILD_ASSERT_DECL(sizeof(struct stp_bpdu_header) == 4);
49 enum stp_config_bpdu_flags {
50 STP_CONFIG_TOPOLOGY_CHANGE_ACK = 0x80,
51 STP_CONFIG_TOPOLOGY_CHANGE = 0x01
54 struct stp_config_bpdu {
55 struct stp_bpdu_header header; /* Type STP_TYPE_CONFIG. */
56 uint8_t flags; /* STP_CONFIG_* flags. */
57 ovs_be64 root_id; /* 8.5.1.1: Bridge believed to be root. */
58 ovs_be32 root_path_cost; /* 8.5.1.2: Cost of path to root. */
59 ovs_be64 bridge_id; /* 8.5.1.3: ID of transmitting bridge. */
60 ovs_be16 port_id; /* 8.5.1.4: Port transmitting the BPDU. */
61 ovs_be16 message_age; /* 8.5.1.5: Age of BPDU at tx time. */
62 ovs_be16 max_age; /* 8.5.1.6: Timeout for received data. */
63 ovs_be16 hello_time; /* 8.5.1.7: Time between BPDU generation. */
64 ovs_be16 forward_delay; /* 8.5.1.8: State progression delay. */
65 } __attribute__((packed));
66 BUILD_ASSERT_DECL(sizeof(struct stp_config_bpdu) == 35);
69 struct stp_bpdu_header header; /* Type STP_TYPE_TCN. */
70 } __attribute__((packed));
71 BUILD_ASSERT_DECL(sizeof(struct stp_tcn_bpdu) == 4);
74 bool active; /* Timer in use? */
75 int value; /* Current value of timer, counting up. */
80 void *aux; /* Auxiliary data the user may retrieve. */
81 int port_id; /* 8.5.5.1: Unique port identifier. */
82 enum stp_state state; /* 8.5.5.2: Current state. */
83 int path_cost; /* 8.5.5.3: Cost of tx/rx on this port. */
84 stp_identifier designated_root; /* 8.5.5.4. */
85 int designated_cost; /* 8.5.5.5: Path cost to root on port. */
86 stp_identifier designated_bridge; /* 8.5.5.6. */
87 int designated_port; /* 8.5.5.7: Port to send config msgs on. */
88 bool topology_change_ack; /* 8.5.5.8: Flag for next config BPDU. */
89 bool config_pending; /* 8.5.5.9: Send BPDU when hold expires? */
90 bool change_detection_enabled; /* 8.5.5.10: Detect topology changes? */
92 struct stp_timer message_age_timer; /* 8.5.6.1: Age of received info. */
93 struct stp_timer forward_delay_timer; /* 8.5.6.2: State change timer. */
94 struct stp_timer hold_timer; /* 8.5.6.3: BPDU rate limit timer. */
96 int tx_count; /* Number of BPDUs transmitted. */
97 int rx_count; /* Number of valid BPDUs received. */
98 int error_count; /* Number of bad BPDUs received. */
104 /* Static bridge data. */
105 char *name; /* Human-readable name for log messages. */
106 stp_identifier bridge_id; /* 8.5.3.7: This bridge. */
107 int max_age; /* 8.5.3.4: Time to drop received data. */
108 int hello_time; /* 8.5.3.5: Time between sending BPDUs. */
109 int forward_delay; /* 8.5.3.6: Delay between state changes. */
110 int bridge_max_age; /* 8.5.3.8: max_age when we're root. */
111 int bridge_hello_time; /* 8.5.3.9: hello_time as root. */
112 int bridge_forward_delay; /* 8.5.3.10: forward_delay as root. */
113 int rq_max_age; /* User-requested max age, in ms. */
114 int rq_hello_time; /* User-requested hello time, in ms. */
115 int rq_forward_delay; /* User-requested forward delay, in ms. */
116 int elapsed_remainder; /* Left-over msecs from last stp_tick(). */
118 /* Dynamic bridge data. */
119 stp_identifier designated_root; /* 8.5.3.1: Bridge believed to be root. */
120 unsigned int root_path_cost; /* 8.5.3.2: Cost of path to root. */
121 struct stp_port *root_port; /* 8.5.3.3: Lowest cost port to root. */
122 bool topology_change_detected; /* 8.5.3.11: Detected a topology change? */
123 bool topology_change; /* 8.5.3.12: Received topology change? */
126 struct stp_timer hello_timer; /* 8.5.4.1: Hello timer. */
127 struct stp_timer tcn_timer; /* 8.5.4.2: Topology change timer. */
128 struct stp_timer topology_change_timer; /* 8.5.4.3. */
131 struct stp_port ports[STP_MAX_PORTS];
133 /* Interface to client. */
134 struct stp_port *first_changed_port;
135 void (*send_bpdu)(struct ofpbuf *bpdu, int port_no, void *aux);
139 #define FOR_EACH_ENABLED_PORT(PORT, STP) \
140 for ((PORT) = stp_next_enabled_port((STP), (STP)->ports); \
142 (PORT) = stp_next_enabled_port((STP), (PORT) + 1))
143 static struct stp_port *
144 stp_next_enabled_port(const struct stp *stp, const struct stp_port *port)
146 for (; port < &stp->ports[ARRAY_SIZE(stp->ports)]; port++) {
147 if (port->state != STP_DISABLED) {
148 return (struct stp_port *) port;
154 #define MESSAGE_AGE_INCREMENT 1
156 static void stp_transmit_config(struct stp_port *);
157 static bool stp_supersedes_port_info(const struct stp_port *,
158 const struct stp_config_bpdu *);
159 static void stp_record_config_information(struct stp_port *,
160 const struct stp_config_bpdu *);
161 static void stp_record_config_timeout_values(struct stp *,
162 const struct stp_config_bpdu *);
163 static bool stp_is_designated_port(const struct stp_port *);
164 static void stp_config_bpdu_generation(struct stp *);
165 static void stp_transmit_tcn(struct stp *);
166 static void stp_configuration_update(struct stp *);
167 static bool stp_supersedes_root(const struct stp_port *root,
168 const struct stp_port *);
169 static void stp_root_selection(struct stp *);
170 static void stp_designated_port_selection(struct stp *);
171 static void stp_become_designated_port(struct stp_port *);
172 static void stp_port_state_selection(struct stp *);
173 static void stp_make_forwarding(struct stp_port *);
174 static void stp_make_blocking(struct stp_port *);
175 static void stp_set_port_state(struct stp_port *, enum stp_state);
176 static void stp_topology_change_detection(struct stp *);
177 static void stp_topology_change_acknowledged(struct stp *);
178 static void stp_acknowledge_topology_change(struct stp_port *);
179 static void stp_received_config_bpdu(struct stp *, struct stp_port *,
180 const struct stp_config_bpdu *);
181 static void stp_received_tcn_bpdu(struct stp *, struct stp_port *);
182 static void stp_hello_timer_expiry(struct stp *);
183 static void stp_message_age_timer_expiry(struct stp_port *);
184 static bool stp_is_designated_for_some_port(const struct stp *);
185 static void stp_forward_delay_timer_expiry(struct stp_port *);
186 static void stp_tcn_timer_expiry(struct stp *);
187 static void stp_topology_change_timer_expiry(struct stp *);
188 static void stp_hold_timer_expiry(struct stp_port *);
189 static void stp_initialize_port(struct stp_port *, enum stp_state);
190 static void stp_become_root_bridge(struct stp *);
191 static void stp_update_bridge_timers(struct stp *);
193 static int clamp(int x, int min, int max);
194 static int ms_to_timer(int ms);
195 static int ms_to_timer_remainder(int ms);
196 static int timer_to_ms(int timer);
197 static void stp_start_timer(struct stp_timer *, int value);
198 static void stp_stop_timer(struct stp_timer *);
199 static bool stp_timer_expired(struct stp_timer *, int elapsed, int timeout);
201 static void stp_send_bpdu(struct stp_port *, const void *, size_t);
203 /* Creates and returns a new STP instance that initially has no ports enabled.
205 * 'bridge_id' should be a 48-bit MAC address as returned by
206 * eth_addr_to_uint64(). 'bridge_id' may also have a priority value in its top
207 * 16 bits; if those bits are set to 0, STP_DEFAULT_BRIDGE_PRIORITY is used.
208 * (This priority may be changed with stp_set_bridge_priority().)
210 * When the bridge needs to send out a BPDU, it calls 'send_bpdu'. This
211 * callback may be called from stp_tick() or stp_received_bpdu(). The
212 * arguments to 'send_bpdu' are an STP BPDU encapsulated in 'bpdu',
213 * the spanning tree port number 'port_no' that should transmit the
214 * packet, and auxiliary data to be passed to the callback in 'aux'.
217 stp_create(const char *name, stp_identifier bridge_id,
218 void (*send_bpdu)(struct ofpbuf *bpdu, int port_no, void *aux),
224 stp = xzalloc(sizeof *stp);
225 stp->name = xstrdup(name);
226 stp->bridge_id = bridge_id;
227 if (!(stp->bridge_id >> 48)) {
228 stp->bridge_id |= (uint64_t) STP_DEFAULT_BRIDGE_PRIORITY << 48;
231 stp->rq_max_age = STP_DEFAULT_MAX_AGE;
232 stp->rq_hello_time = STP_DEFAULT_HELLO_TIME;
233 stp->rq_forward_delay = STP_DEFAULT_FWD_DELAY;
234 stp_update_bridge_timers(stp);
235 stp->max_age = stp->bridge_max_age;
236 stp->hello_time = stp->bridge_hello_time;
237 stp->forward_delay = stp->bridge_forward_delay;
239 stp->designated_root = stp->bridge_id;
240 stp->root_path_cost = 0;
241 stp->root_port = NULL;
242 stp->topology_change_detected = false;
243 stp->topology_change = false;
245 stp_stop_timer(&stp->tcn_timer);
246 stp_stop_timer(&stp->topology_change_timer);
247 stp_start_timer(&stp->hello_timer, 0);
249 stp->send_bpdu = send_bpdu;
252 stp->first_changed_port = &stp->ports[ARRAY_SIZE(stp->ports)];
253 for (p = stp->ports; p < &stp->ports[ARRAY_SIZE(stp->ports)]; p++) {
255 p->port_id = (stp_port_no(p) + 1) | (STP_DEFAULT_PORT_PRIORITY << 8);
256 p->path_cost = 19; /* Recommended default for 100 Mb/s link. */
257 stp_initialize_port(p, STP_DISABLED);
262 /* Destroys 'stp'. */
264 stp_destroy(struct stp *stp)
272 /* Runs 'stp' given that 'ms' milliseconds have passed. */
274 stp_tick(struct stp *stp, int ms)
279 /* Convert 'ms' to STP timer ticks. Preserve any leftover milliseconds
280 * from previous stp_tick() calls so that we don't lose STP ticks when we
281 * are called too frequently. */
282 ms = clamp(ms, 0, INT_MAX - 1000) + stp->elapsed_remainder;
283 elapsed = ms_to_timer(ms);
284 stp->elapsed_remainder = ms_to_timer_remainder(ms);
289 if (stp_timer_expired(&stp->hello_timer, elapsed, stp->hello_time)) {
290 stp_hello_timer_expiry(stp);
292 if (stp_timer_expired(&stp->tcn_timer, elapsed, stp->bridge_hello_time)) {
293 stp_tcn_timer_expiry(stp);
295 if (stp_timer_expired(&stp->topology_change_timer, elapsed,
296 stp->max_age + stp->forward_delay)) {
297 stp_topology_change_timer_expiry(stp);
299 FOR_EACH_ENABLED_PORT (p, stp) {
300 if (stp_timer_expired(&p->message_age_timer, elapsed, stp->max_age)) {
301 stp_message_age_timer_expiry(p);
304 FOR_EACH_ENABLED_PORT (p, stp) {
305 if (stp_timer_expired(&p->forward_delay_timer, elapsed,
306 stp->forward_delay)) {
307 stp_forward_delay_timer_expiry(p);
309 if (stp_timer_expired(&p->hold_timer, elapsed, ms_to_timer(1000))) {
310 stp_hold_timer_expiry(p);
316 set_bridge_id(struct stp *stp, stp_identifier new_bridge_id)
318 if (new_bridge_id != stp->bridge_id) {
322 root = stp_is_root_bridge(stp);
323 FOR_EACH_ENABLED_PORT (p, stp) {
324 if (stp_is_designated_port(p)) {
325 p->designated_bridge = new_bridge_id;
328 stp->bridge_id = new_bridge_id;
329 stp_configuration_update(stp);
330 stp_port_state_selection(stp);
331 if (stp_is_root_bridge(stp) && !root) {
332 stp_become_root_bridge(stp);
338 stp_set_bridge_id(struct stp *stp, stp_identifier bridge_id)
340 const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
341 const uint64_t pri_bits = ~mac_bits;
342 set_bridge_id(stp, (stp->bridge_id & pri_bits) | (bridge_id & mac_bits));
346 stp_set_bridge_priority(struct stp *stp, uint16_t new_priority)
348 const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
349 set_bridge_id(stp, ((stp->bridge_id & mac_bits)
350 | ((uint64_t) new_priority << 48)));
353 /* Sets the desired hello time for 'stp' to 'ms', in milliseconds. The actual
354 * hello time is clamped to the range of 1 to 10 seconds and subject to the
355 * relationship (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge
356 * hello time is only used when 'stp' is the root bridge. */
358 stp_set_hello_time(struct stp *stp, int ms)
360 stp->rq_hello_time = ms;
361 stp_update_bridge_timers(stp);
364 /* Sets the desired max age for 'stp' to 'ms', in milliseconds. The actual max
365 * age is clamped to the range of 6 to 40 seconds and subject to the
366 * relationships (2 * (bridge_forward_delay - 1 s) >= bridge_max_age) and
367 * (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge max age is
368 * only used when 'stp' is the root bridge. */
370 stp_set_max_age(struct stp *stp, int ms)
372 stp->rq_max_age = ms;
373 stp_update_bridge_timers(stp);
376 /* Sets the desired forward delay for 'stp' to 'ms', in milliseconds. The
377 * actual forward delay is clamped to the range of 4 to 30 seconds and subject
378 * to the relationship (2 * (bridge_forward_delay - 1 s) >= bridge_max_age).
379 * The bridge forward delay is only used when 'stp' is the root bridge. */
381 stp_set_forward_delay(struct stp *stp, int ms)
383 stp->rq_forward_delay = ms;
384 stp_update_bridge_timers(stp);
387 /* Returns the name given to 'stp' in the call to stp_create(). */
389 stp_get_name(const struct stp *stp)
394 /* Returns the bridge ID for 'stp'. */
396 stp_get_bridge_id(const struct stp *stp)
398 return stp->bridge_id;
401 /* Returns the bridge ID of the bridge currently believed to be the root. */
403 stp_get_designated_root(const struct stp *stp)
405 return stp->designated_root;
408 /* Returns true if 'stp' believes itself to the be root of the spanning tree,
409 * false otherwise. */
411 stp_is_root_bridge(const struct stp *stp)
413 return stp->bridge_id == stp->designated_root;
416 /* Returns the cost of the path from 'stp' to the root of the spanning tree. */
418 stp_get_root_path_cost(const struct stp *stp)
420 return stp->root_path_cost;
423 /* Returns the bridge hello time, in ms. The returned value is not necessarily
424 * the value passed to stp_set_hello_time(): it is clamped to the valid range
425 * and quantized to the STP timer resolution. */
427 stp_get_hello_time(const struct stp *stp)
429 return timer_to_ms(stp->bridge_hello_time);
432 /* Returns the bridge max age, in ms. The returned value is not necessarily
433 * the value passed to stp_set_max_age(): it is clamped to the valid range,
434 * quantized to the STP timer resolution, and adjusted to match the constraints
435 * due to the hello time. */
437 stp_get_max_age(const struct stp *stp)
439 return timer_to_ms(stp->bridge_max_age);
442 /* Returns the bridge forward delay, in ms. The returned value is not
443 * necessarily the value passed to stp_set_forward_delay(): it is clamped to
444 * the valid range, quantized to the STP timer resolution, and adjusted to
445 * match the constraints due to the forward delay. */
447 stp_get_forward_delay(const struct stp *stp)
449 return timer_to_ms(stp->bridge_forward_delay);
452 /* Returns the port in 'stp' with index 'port_no', which must be between 0 and
455 stp_get_port(struct stp *stp, int port_no)
457 assert(port_no >= 0 && port_no < ARRAY_SIZE(stp->ports));
458 return &stp->ports[port_no];
461 /* Returns the port connecting 'stp' to the root bridge, or a null pointer if
462 * there is no such port. */
464 stp_get_root_port(struct stp *stp)
466 return stp->root_port;
469 /* Finds a port whose state has changed. If successful, stores the port whose
470 * state changed in '*portp' and returns true. If no port has changed, stores
471 * NULL in '*portp' and returns false. */
473 stp_get_changed_port(struct stp *stp, struct stp_port **portp)
475 struct stp_port *end = &stp->ports[ARRAY_SIZE(stp->ports)];
478 for (p = stp->first_changed_port; p < end; p++) {
479 if (p->state_changed) {
480 p->state_changed = false;
481 stp->first_changed_port = p + 1;
486 stp->first_changed_port = end;
491 /* Returns the name for the given 'state' (for use in debugging and log
494 stp_state_name(enum stp_state state)
512 /* Returns true if 'state' is one in which packets received on a port should
513 * be forwarded, false otherwise.
515 * Returns true if 'state' is STP_DISABLED, since presumably in that case the
516 * port should still work, just not have STP applied to it. */
518 stp_forward_in_state(enum stp_state state)
520 return (state & (STP_DISABLED | STP_FORWARDING)) != 0;
523 /* Returns true if 'state' is one in which MAC learning should be done on
524 * packets received on a port, false otherwise.
526 * Returns true if 'state' is STP_DISABLED, since presumably in that case the
527 * port should still work, just not have STP applied to it. */
529 stp_learn_in_state(enum stp_state state)
531 return (state & (STP_DISABLED | STP_LEARNING | STP_FORWARDING)) != 0;
534 /* Returns the name for the given 'role' (for use in debugging and log
537 stp_role_name(enum stp_role role)
542 case STP_ROLE_DESIGNATED:
544 case STP_ROLE_ALTERNATE:
546 case STP_ROLE_DISABLED:
553 /* Notifies the STP entity that bridge protocol data unit 'bpdu', which is
554 * 'bpdu_size' bytes in length, was received on port 'p'.
556 * This function may call the 'send_bpdu' function provided to stp_create(). */
558 stp_received_bpdu(struct stp_port *p, const void *bpdu, size_t bpdu_size)
560 struct stp *stp = p->stp;
561 const struct stp_bpdu_header *header;
563 if (p->state == STP_DISABLED) {
567 if (bpdu_size < sizeof(struct stp_bpdu_header)) {
568 VLOG_WARN("%s: received runt %zu-byte BPDU", stp->name, bpdu_size);
574 if (header->protocol_id != htons(STP_PROTOCOL_ID)) {
575 VLOG_WARN("%s: received BPDU with unexpected protocol ID %"PRIu16,
576 stp->name, ntohs(header->protocol_id));
580 if (header->protocol_version != STP_PROTOCOL_VERSION) {
581 VLOG_DBG("%s: received BPDU with unexpected protocol version %"PRIu8,
582 stp->name, header->protocol_version);
585 switch (header->bpdu_type) {
586 case STP_TYPE_CONFIG:
587 if (bpdu_size < sizeof(struct stp_config_bpdu)) {
588 VLOG_WARN("%s: received config BPDU with invalid size %zu",
589 stp->name, bpdu_size);
593 stp_received_config_bpdu(stp, p, bpdu);
597 if (bpdu_size != sizeof(struct stp_tcn_bpdu)) {
598 VLOG_WARN("%s: received TCN BPDU with invalid size %zu",
599 stp->name, bpdu_size);
603 stp_received_tcn_bpdu(stp, p);
607 VLOG_WARN("%s: received BPDU of unexpected type %"PRIu8,
608 stp->name, header->bpdu_type);
615 /* Returns the STP entity in which 'p' is nested. */
617 stp_port_get_stp(struct stp_port *p)
622 /* Sets the 'aux' member of 'p'.
624 * The 'aux' member will be reset to NULL when stp_port_disable() is
625 * called or stp_port_enable() is called when the port is in a Disabled
628 stp_port_set_aux(struct stp_port *p, void *aux)
633 /* Returns the 'aux' member of 'p'. */
635 stp_port_get_aux(struct stp_port *p)
640 /* Returns the index of port 'p' within its bridge. */
642 stp_port_no(const struct stp_port *p)
644 struct stp *stp = p->stp;
645 assert(p >= stp->ports && p < &stp->ports[ARRAY_SIZE(stp->ports)]);
646 return p - stp->ports;
649 /* Returns the port ID for 'p'. */
651 stp_port_get_id(const struct stp_port *p)
656 /* Returns the state of port 'p'. */
658 stp_port_get_state(const struct stp_port *p)
663 /* Returns the role of port 'p'. */
665 stp_port_get_role(const struct stp_port *p)
667 struct stp_port *root_port = stp_get_root_port(p->stp);
669 if (root_port && root_port->port_id == p->port_id) {
670 return STP_ROLE_ROOT;
671 } else if (stp_is_designated_port(p)) {
672 return STP_ROLE_DESIGNATED;
673 } else if (p->state == STP_DISABLED) {
674 return STP_ROLE_DISABLED;
676 return STP_ROLE_ALTERNATE;
680 /* Retrieves BPDU transmit and receive counts for 'p'. */
681 void stp_port_get_counts(const struct stp_port *p,
682 int *tx_count, int *rx_count, int *error_count)
684 *tx_count = p->tx_count;
685 *rx_count = p->rx_count;
686 *error_count = p->error_count;
689 /* Disables STP on port 'p'. */
691 stp_port_disable(struct stp_port *p)
693 struct stp *stp = p->stp;
694 if (p->state != STP_DISABLED) {
695 bool root = stp_is_root_bridge(stp);
696 stp_become_designated_port(p);
697 stp_set_port_state(p, STP_DISABLED);
698 p->topology_change_ack = false;
699 p->config_pending = false;
700 stp_stop_timer(&p->message_age_timer);
701 stp_stop_timer(&p->forward_delay_timer);
702 stp_configuration_update(stp);
703 stp_port_state_selection(stp);
704 if (stp_is_root_bridge(stp) && !root) {
705 stp_become_root_bridge(stp);
711 /* Enables STP on port 'p'. The port will initially be in "blocking" state. */
713 stp_port_enable(struct stp_port *p)
715 if (p->state == STP_DISABLED) {
716 stp_initialize_port(p, STP_BLOCKING);
717 stp_port_state_selection(p->stp);
721 /* Sets the priority of port 'p' to 'new_priority'. Lower numerical values
722 * are interpreted as higher priorities. */
724 stp_port_set_priority(struct stp_port *p, uint8_t new_priority)
726 uint16_t new_port_id = (p->port_id & 0xff) | (new_priority << 8);
727 if (p->port_id != new_port_id) {
728 struct stp *stp = p->stp;
729 if (stp_is_designated_port(p)) {
730 p->designated_port = new_port_id;
732 p->port_id = new_port_id;
733 if (stp->bridge_id == p->designated_bridge
734 && p->port_id < p->designated_port) {
735 stp_become_designated_port(p);
736 stp_port_state_selection(stp);
741 /* Convert 'speed' (measured in Mb/s) into the path cost. */
743 stp_convert_speed_to_cost(unsigned int speed)
745 return speed >= 10000 ? 2 /* 10 Gb/s. */
746 : speed >= 1000 ? 4 /* 1 Gb/s. */
747 : speed >= 100 ? 19 /* 100 Mb/s. */
748 : speed >= 16 ? 62 /* 16 Mb/s. */
749 : speed >= 10 ? 100 /* 10 Mb/s. */
750 : speed >= 4 ? 250 /* 4 Mb/s. */
751 : 19; /* 100 Mb/s (guess). */
754 /* Sets the path cost of port 'p' to 'path_cost'. Lower values are generally
755 * used to indicate faster links. Use stp_port_set_speed() to automatically
756 * generate a default path cost from a link speed. */
758 stp_port_set_path_cost(struct stp_port *p, uint16_t path_cost)
760 if (p->path_cost != path_cost) {
761 struct stp *stp = p->stp;
762 p->path_cost = path_cost;
763 stp_configuration_update(stp);
764 stp_port_state_selection(stp);
768 /* Sets the path cost of port 'p' based on 'speed' (measured in Mb/s). */
770 stp_port_set_speed(struct stp_port *p, unsigned int speed)
772 stp_port_set_path_cost(p, stp_convert_speed_to_cost(speed));
775 /* Enables topology change detection on port 'p'. */
777 stp_port_enable_change_detection(struct stp_port *p)
779 p->change_detection_enabled = true;
782 /* Disables topology change detection on port 'p'. */
784 stp_port_disable_change_detection(struct stp_port *p)
786 p->change_detection_enabled = false;
790 stp_transmit_config(struct stp_port *p)
792 struct stp *stp = p->stp;
793 bool root = stp_is_root_bridge(stp);
794 if (!root && !stp->root_port) {
797 if (p->hold_timer.active) {
798 p->config_pending = true;
800 struct stp_config_bpdu config;
801 memset(&config, 0, sizeof config);
802 config.header.protocol_id = htons(STP_PROTOCOL_ID);
803 config.header.protocol_version = STP_PROTOCOL_VERSION;
804 config.header.bpdu_type = STP_TYPE_CONFIG;
806 if (p->topology_change_ack) {
807 config.flags |= STP_CONFIG_TOPOLOGY_CHANGE_ACK;
809 if (stp->topology_change) {
810 config.flags |= STP_CONFIG_TOPOLOGY_CHANGE;
812 config.root_id = htonll(stp->designated_root);
813 config.root_path_cost = htonl(stp->root_path_cost);
814 config.bridge_id = htonll(stp->bridge_id);
815 config.port_id = htons(p->port_id);
817 config.message_age = htons(0);
819 config.message_age = htons(stp->root_port->message_age_timer.value
820 + MESSAGE_AGE_INCREMENT);
822 config.max_age = htons(stp->max_age);
823 config.hello_time = htons(stp->hello_time);
824 config.forward_delay = htons(stp->forward_delay);
825 if (ntohs(config.message_age) < stp->max_age) {
826 p->topology_change_ack = false;
827 p->config_pending = false;
828 stp_send_bpdu(p, &config, sizeof config);
829 stp_start_timer(&p->hold_timer, 0);
835 stp_supersedes_port_info(const struct stp_port *p,
836 const struct stp_config_bpdu *config)
838 if (ntohll(config->root_id) != p->designated_root) {
839 return ntohll(config->root_id) < p->designated_root;
840 } else if (ntohl(config->root_path_cost) != p->designated_cost) {
841 return ntohl(config->root_path_cost) < p->designated_cost;
842 } else if (ntohll(config->bridge_id) != p->designated_bridge) {
843 return ntohll(config->bridge_id) < p->designated_bridge;
845 return (ntohll(config->bridge_id) != p->stp->bridge_id
846 || ntohs(config->port_id) <= p->designated_port);
851 stp_record_config_information(struct stp_port *p,
852 const struct stp_config_bpdu *config)
854 p->designated_root = ntohll(config->root_id);
855 p->designated_cost = ntohl(config->root_path_cost);
856 p->designated_bridge = ntohll(config->bridge_id);
857 p->designated_port = ntohs(config->port_id);
858 stp_start_timer(&p->message_age_timer, ntohs(config->message_age));
862 stp_record_config_timeout_values(struct stp *stp,
863 const struct stp_config_bpdu *config)
865 stp->max_age = ntohs(config->max_age);
866 stp->hello_time = ntohs(config->hello_time);
867 stp->forward_delay = ntohs(config->forward_delay);
868 stp->topology_change = config->flags & STP_CONFIG_TOPOLOGY_CHANGE;
872 stp_is_designated_port(const struct stp_port *p)
874 return (p->designated_bridge == p->stp->bridge_id
875 && p->designated_port == p->port_id);
879 stp_config_bpdu_generation(struct stp *stp)
883 FOR_EACH_ENABLED_PORT (p, stp) {
884 if (stp_is_designated_port(p)) {
885 stp_transmit_config(p);
891 stp_transmit_tcn(struct stp *stp)
893 struct stp_port *p = stp->root_port;
894 struct stp_tcn_bpdu tcn_bpdu;
898 tcn_bpdu.header.protocol_id = htons(STP_PROTOCOL_ID);
899 tcn_bpdu.header.protocol_version = STP_PROTOCOL_VERSION;
900 tcn_bpdu.header.bpdu_type = STP_TYPE_TCN;
901 stp_send_bpdu(p, &tcn_bpdu, sizeof tcn_bpdu);
905 stp_configuration_update(struct stp *stp)
907 stp_root_selection(stp);
908 stp_designated_port_selection(stp);
912 stp_supersedes_root(const struct stp_port *root, const struct stp_port *p)
914 int p_cost = p->designated_cost + p->path_cost;
915 int root_cost = root->designated_cost + root->path_cost;
917 if (p->designated_root != root->designated_root) {
918 return p->designated_root < root->designated_root;
919 } else if (p_cost != root_cost) {
920 return p_cost < root_cost;
921 } else if (p->designated_bridge != root->designated_bridge) {
922 return p->designated_bridge < root->designated_bridge;
923 } else if (p->designated_port != root->designated_port) {
924 return p->designated_port < root->designated_port;
926 return p->port_id < root->port_id;
931 stp_root_selection(struct stp *stp)
933 struct stp_port *p, *root;
936 FOR_EACH_ENABLED_PORT (p, stp) {
937 if (stp_is_designated_port(p)
938 || p->designated_root >= stp->bridge_id) {
941 if (root && !stp_supersedes_root(root, p)) {
946 stp->root_port = root;
948 stp->designated_root = stp->bridge_id;
949 stp->root_path_cost = 0;
951 stp->designated_root = root->designated_root;
952 stp->root_path_cost = root->designated_cost + root->path_cost;
957 stp_designated_port_selection(struct stp *stp)
961 FOR_EACH_ENABLED_PORT (p, stp) {
962 if (stp_is_designated_port(p)
963 || p->designated_root != stp->designated_root
964 || stp->root_path_cost < p->designated_cost
965 || (stp->root_path_cost == p->designated_cost
966 && (stp->bridge_id < p->designated_bridge
967 || (stp->bridge_id == p->designated_bridge
968 && p->port_id <= p->designated_port))))
970 stp_become_designated_port(p);
976 stp_become_designated_port(struct stp_port *p)
978 struct stp *stp = p->stp;
979 p->designated_root = stp->designated_root;
980 p->designated_cost = stp->root_path_cost;
981 p->designated_bridge = stp->bridge_id;
982 p->designated_port = p->port_id;
986 stp_port_state_selection(struct stp *stp)
990 FOR_EACH_ENABLED_PORT (p, stp) {
991 if (p == stp->root_port) {
992 p->config_pending = false;
993 p->topology_change_ack = false;
994 stp_make_forwarding(p);
995 } else if (stp_is_designated_port(p)) {
996 stp_stop_timer(&p->message_age_timer);
997 stp_make_forwarding(p);
999 p->config_pending = false;
1000 p->topology_change_ack = false;
1001 stp_make_blocking(p);
1007 stp_make_forwarding(struct stp_port *p)
1009 if (p->state == STP_BLOCKING) {
1010 stp_set_port_state(p, STP_LISTENING);
1011 stp_start_timer(&p->forward_delay_timer, 0);
1016 stp_make_blocking(struct stp_port *p)
1018 if (!(p->state & (STP_DISABLED | STP_BLOCKING))) {
1019 if (p->state & (STP_FORWARDING | STP_LEARNING)) {
1020 if (p->change_detection_enabled) {
1021 stp_topology_change_detection(p->stp);
1024 stp_set_port_state(p, STP_BLOCKING);
1025 stp_stop_timer(&p->forward_delay_timer);
1030 stp_set_port_state(struct stp_port *p, enum stp_state state)
1032 if (state != p->state && !p->state_changed) {
1033 p->state_changed = true;
1034 if (p < p->stp->first_changed_port) {
1035 p->stp->first_changed_port = p;
1042 stp_topology_change_detection(struct stp *stp)
1044 if (stp_is_root_bridge(stp)) {
1045 stp->topology_change = true;
1046 stp_start_timer(&stp->topology_change_timer, 0);
1047 } else if (!stp->topology_change_detected) {
1048 stp_transmit_tcn(stp);
1049 stp_start_timer(&stp->tcn_timer, 0);
1051 stp->topology_change_detected = true;
1055 stp_topology_change_acknowledged(struct stp *stp)
1057 stp->topology_change_detected = false;
1058 stp_stop_timer(&stp->tcn_timer);
1062 stp_acknowledge_topology_change(struct stp_port *p)
1064 p->topology_change_ack = true;
1065 stp_transmit_config(p);
1069 stp_received_config_bpdu(struct stp *stp, struct stp_port *p,
1070 const struct stp_config_bpdu *config)
1072 if (ntohs(config->message_age) >= ntohs(config->max_age)) {
1073 VLOG_WARN("%s: received config BPDU with message age (%u) greater "
1074 "than max age (%u)",
1076 ntohs(config->message_age), ntohs(config->max_age));
1079 if (p->state != STP_DISABLED) {
1080 bool root = stp_is_root_bridge(stp);
1081 if (stp_supersedes_port_info(p, config)) {
1082 stp_record_config_information(p, config);
1083 stp_configuration_update(stp);
1084 stp_port_state_selection(stp);
1085 if (!stp_is_root_bridge(stp) && root) {
1086 stp_stop_timer(&stp->hello_timer);
1087 if (stp->topology_change_detected) {
1088 stp_stop_timer(&stp->topology_change_timer);
1089 stp_transmit_tcn(stp);
1090 stp_start_timer(&stp->tcn_timer, 0);
1093 if (p == stp->root_port) {
1094 stp_record_config_timeout_values(stp, config);
1095 stp_config_bpdu_generation(stp);
1096 if (config->flags & STP_CONFIG_TOPOLOGY_CHANGE_ACK) {
1097 stp_topology_change_acknowledged(stp);
1100 } else if (stp_is_designated_port(p)) {
1101 stp_transmit_config(p);
1107 stp_received_tcn_bpdu(struct stp *stp, struct stp_port *p)
1109 if (p->state != STP_DISABLED) {
1110 if (stp_is_designated_port(p)) {
1111 stp_topology_change_detection(stp);
1112 stp_acknowledge_topology_change(p);
1118 stp_hello_timer_expiry(struct stp *stp)
1120 stp_config_bpdu_generation(stp);
1121 stp_start_timer(&stp->hello_timer, 0);
1125 stp_message_age_timer_expiry(struct stp_port *p)
1127 struct stp *stp = p->stp;
1128 bool root = stp_is_root_bridge(stp);
1129 stp_become_designated_port(p);
1130 stp_configuration_update(stp);
1131 stp_port_state_selection(stp);
1132 if (stp_is_root_bridge(stp) && !root) {
1133 stp->max_age = stp->bridge_max_age;
1134 stp->hello_time = stp->bridge_hello_time;
1135 stp->forward_delay = stp->bridge_forward_delay;
1136 stp_topology_change_detection(stp);
1137 stp_stop_timer(&stp->tcn_timer);
1138 stp_config_bpdu_generation(stp);
1139 stp_start_timer(&stp->hello_timer, 0);
1144 stp_is_designated_for_some_port(const struct stp *stp)
1146 const struct stp_port *p;
1148 FOR_EACH_ENABLED_PORT (p, stp) {
1149 if (p->designated_bridge == stp->bridge_id) {
1157 stp_forward_delay_timer_expiry(struct stp_port *p)
1159 if (p->state == STP_LISTENING) {
1160 stp_set_port_state(p, STP_LEARNING);
1161 stp_start_timer(&p->forward_delay_timer, 0);
1162 } else if (p->state == STP_LEARNING) {
1163 stp_set_port_state(p, STP_FORWARDING);
1164 if (stp_is_designated_for_some_port(p->stp)) {
1165 if (p->change_detection_enabled) {
1166 stp_topology_change_detection(p->stp);
1173 stp_tcn_timer_expiry(struct stp *stp)
1175 stp_transmit_tcn(stp);
1176 stp_start_timer(&stp->tcn_timer, 0);
1180 stp_topology_change_timer_expiry(struct stp *stp)
1182 stp->topology_change_detected = false;
1183 stp->topology_change = false;
1187 stp_hold_timer_expiry(struct stp_port *p)
1189 if (p->config_pending) {
1190 stp_transmit_config(p);
1195 stp_initialize_port(struct stp_port *p, enum stp_state state)
1197 assert(state & (STP_DISABLED | STP_BLOCKING));
1198 stp_become_designated_port(p);
1199 stp_set_port_state(p, state);
1200 p->topology_change_ack = false;
1201 p->config_pending = false;
1202 p->change_detection_enabled = true;
1204 stp_stop_timer(&p->message_age_timer);
1205 stp_stop_timer(&p->forward_delay_timer);
1206 stp_stop_timer(&p->hold_timer);
1207 p->tx_count = p->rx_count = p->error_count = 0;
1211 stp_become_root_bridge(struct stp *stp)
1213 stp->max_age = stp->bridge_max_age;
1214 stp->hello_time = stp->bridge_hello_time;
1215 stp->forward_delay = stp->bridge_forward_delay;
1216 stp_topology_change_detection(stp);
1217 stp_stop_timer(&stp->tcn_timer);
1218 stp_config_bpdu_generation(stp);
1219 stp_start_timer(&stp->hello_timer, 0);
1223 stp_start_timer(struct stp_timer *timer, int value)
1225 timer->value = value;
1226 timer->active = true;
1230 stp_stop_timer(struct stp_timer *timer)
1232 timer->active = false;
1236 stp_timer_expired(struct stp_timer *timer, int elapsed, int timeout)
1238 if (timer->active) {
1239 timer->value += elapsed;
1240 if (timer->value >= timeout) {
1241 timer->active = false;
1248 /* Returns the number of whole STP timer ticks in 'ms' milliseconds. There
1249 * are 256 STP timer ticks per second. */
1253 return ms * 0x100 / 1000;
1256 /* Returns the number of leftover milliseconds when 'ms' is converted to STP
1259 ms_to_timer_remainder(int ms)
1261 return ms * 0x100 % 1000;
1264 /* Returns the number of whole milliseconds in 'timer' STP timer ticks. There
1265 * are 256 STP timer ticks per second. */
1267 timer_to_ms(int timer)
1269 return timer * 1000 / 0x100;
1273 clamp(int x, int min, int max)
1275 return x < min ? min : x > max ? max : x;
1279 stp_update_bridge_timers(struct stp *stp)
1283 ht = clamp(stp->rq_hello_time, 1000, 10000);
1284 ma = clamp(stp->rq_max_age, MAX(2 * (ht + 1000), 6000), 40000);
1285 fd = clamp(stp->rq_forward_delay, ma / 2 + 1000, 30000);
1287 stp->bridge_hello_time = ms_to_timer(ht);
1288 stp->bridge_max_age = ms_to_timer(ma);
1289 stp->bridge_forward_delay = ms_to_timer(fd);
1291 if (stp_is_root_bridge(stp)) {
1292 stp->max_age = stp->bridge_max_age;
1293 stp->hello_time = stp->bridge_hello_time;
1294 stp->forward_delay = stp->bridge_forward_delay;
1299 stp_send_bpdu(struct stp_port *p, const void *bpdu, size_t bpdu_size)
1301 struct eth_header *eth;
1302 struct llc_header *llc;
1306 pkt = ofpbuf_new(ETH_HEADER_LEN + LLC_HEADER_LEN + bpdu_size);
1307 pkt->l2 = eth = ofpbuf_put_zeros(pkt, sizeof *eth);
1308 llc = ofpbuf_put_zeros(pkt, sizeof *llc);
1309 pkt->l3 = ofpbuf_put(pkt, bpdu, bpdu_size);
1312 memcpy(eth->eth_dst, eth_addr_stp, ETH_ADDR_LEN);
1313 /* p->stp->send_bpdu() must fill in source address. */
1314 eth->eth_type = htons(pkt->size - ETH_HEADER_LEN);
1317 llc->llc_dsap = STP_LLC_DSAP;
1318 llc->llc_ssap = STP_LLC_SSAP;
1319 llc->llc_cntl = STP_LLC_CNTL;
1321 p->stp->send_bpdu(pkt, stp_port_no(p), p->stp->aux);