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 timer_to_ms(int timer);
196 static void stp_start_timer(struct stp_timer *, int value);
197 static void stp_stop_timer(struct stp_timer *);
198 static bool stp_timer_expired(struct stp_timer *, int elapsed, int timeout);
200 static void stp_send_bpdu(struct stp_port *, const void *, size_t);
202 /* Creates and returns a new STP instance that initially has no ports enabled.
204 * 'bridge_id' should be a 48-bit MAC address as returned by
205 * eth_addr_to_uint64(). 'bridge_id' may also have a priority value in its top
206 * 16 bits; if those bits are set to 0, STP_DEFAULT_BRIDGE_PRIORITY is used.
207 * (This priority may be changed with stp_set_bridge_priority().)
209 * When the bridge needs to send out a BPDU, it calls 'send_bpdu'. This
210 * callback may be called from stp_tick() or stp_received_bpdu(). The
211 * arguments to 'send_bpdu' are an STP BPDU encapsulated in 'bpdu',
212 * the spanning tree port number 'port_no' that should transmit the
213 * packet, and auxiliary data to be passed to the callback in 'aux'.
216 stp_create(const char *name, stp_identifier bridge_id,
217 void (*send_bpdu)(struct ofpbuf *bpdu, int port_no, void *aux),
223 stp = xzalloc(sizeof *stp);
224 stp->name = xstrdup(name);
225 stp->bridge_id = bridge_id;
226 if (!(stp->bridge_id >> 48)) {
227 stp->bridge_id |= (uint64_t) STP_DEFAULT_BRIDGE_PRIORITY << 48;
230 stp->rq_max_age = STP_DEFAULT_MAX_AGE;
231 stp->rq_hello_time = STP_DEFAULT_HELLO_TIME;
232 stp->rq_forward_delay = STP_DEFAULT_FWD_DELAY;
233 stp_update_bridge_timers(stp);
234 stp->max_age = stp->bridge_max_age;
235 stp->hello_time = stp->bridge_hello_time;
236 stp->forward_delay = stp->bridge_forward_delay;
238 stp->designated_root = stp->bridge_id;
239 stp->root_path_cost = 0;
240 stp->root_port = NULL;
241 stp->topology_change_detected = false;
242 stp->topology_change = false;
244 stp_stop_timer(&stp->tcn_timer);
245 stp_stop_timer(&stp->topology_change_timer);
246 stp_start_timer(&stp->hello_timer, 0);
248 stp->send_bpdu = send_bpdu;
251 stp->first_changed_port = &stp->ports[ARRAY_SIZE(stp->ports)];
252 for (p = stp->ports; p < &stp->ports[ARRAY_SIZE(stp->ports)]; p++) {
254 p->port_id = (stp_port_no(p) + 1) | (STP_DEFAULT_PORT_PRIORITY << 8);
255 p->path_cost = 19; /* Recommended default for 100 Mb/s link. */
256 stp_initialize_port(p, STP_DISABLED);
261 /* Destroys 'stp'. */
263 stp_destroy(struct stp *stp)
271 /* Runs 'stp' given that 'ms' milliseconds have passed. */
273 stp_tick(struct stp *stp, int ms)
278 /* Convert 'ms' to STP timer ticks. Preserve any leftover milliseconds
279 * from previous stp_tick() calls so that we don't lose STP ticks when we
280 * are called too frequently. */
281 ms = clamp(ms, 0, INT_MAX - 1000) + stp->elapsed_remainder;
282 elapsed = ms_to_timer(ms);
283 stp->elapsed_remainder = ms - timer_to_ms(elapsed);
288 if (stp_timer_expired(&stp->hello_timer, elapsed, stp->hello_time)) {
289 stp_hello_timer_expiry(stp);
291 if (stp_timer_expired(&stp->tcn_timer, elapsed, stp->bridge_hello_time)) {
292 stp_tcn_timer_expiry(stp);
294 if (stp_timer_expired(&stp->topology_change_timer, elapsed,
295 stp->max_age + stp->forward_delay)) {
296 stp_topology_change_timer_expiry(stp);
298 FOR_EACH_ENABLED_PORT (p, stp) {
299 if (stp_timer_expired(&p->message_age_timer, elapsed, stp->max_age)) {
300 stp_message_age_timer_expiry(p);
303 FOR_EACH_ENABLED_PORT (p, stp) {
304 if (stp_timer_expired(&p->forward_delay_timer, elapsed,
305 stp->forward_delay)) {
306 stp_forward_delay_timer_expiry(p);
308 if (stp_timer_expired(&p->hold_timer, elapsed, ms_to_timer(1000))) {
309 stp_hold_timer_expiry(p);
315 set_bridge_id(struct stp *stp, stp_identifier new_bridge_id)
317 if (new_bridge_id != stp->bridge_id) {
321 root = stp_is_root_bridge(stp);
322 FOR_EACH_ENABLED_PORT (p, stp) {
323 if (stp_is_designated_port(p)) {
324 p->designated_bridge = new_bridge_id;
327 stp->bridge_id = new_bridge_id;
328 stp_configuration_update(stp);
329 stp_port_state_selection(stp);
330 if (stp_is_root_bridge(stp) && !root) {
331 stp_become_root_bridge(stp);
337 stp_set_bridge_id(struct stp *stp, stp_identifier bridge_id)
339 const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
340 const uint64_t pri_bits = ~mac_bits;
341 set_bridge_id(stp, (stp->bridge_id & pri_bits) | (bridge_id & mac_bits));
345 stp_set_bridge_priority(struct stp *stp, uint16_t new_priority)
347 const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
348 set_bridge_id(stp, ((stp->bridge_id & mac_bits)
349 | ((uint64_t) new_priority << 48)));
352 /* Sets the desired hello time for 'stp' to 'ms', in milliseconds. The actual
353 * hello time is clamped to the range of 1 to 10 seconds and subject to the
354 * relationship (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge
355 * hello time is only used when 'stp' is the root bridge. */
357 stp_set_hello_time(struct stp *stp, int ms)
359 stp->rq_hello_time = ms;
360 stp_update_bridge_timers(stp);
363 /* Sets the desired max age for 'stp' to 'ms', in milliseconds. The actual max
364 * age is clamped to the range of 6 to 40 seconds and subject to the
365 * relationships (2 * (bridge_forward_delay - 1 s) >= bridge_max_age) and
366 * (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge max age is
367 * only used when 'stp' is the root bridge. */
369 stp_set_max_age(struct stp *stp, int ms)
371 stp->rq_max_age = ms;
372 stp_update_bridge_timers(stp);
375 /* Sets the desired forward delay for 'stp' to 'ms', in milliseconds. The
376 * actual forward delay is clamped to the range of 4 to 30 seconds and subject
377 * to the relationship (2 * (bridge_forward_delay - 1 s) >= bridge_max_age).
378 * The bridge forward delay is only used when 'stp' is the root bridge. */
380 stp_set_forward_delay(struct stp *stp, int ms)
382 stp->rq_forward_delay = ms;
383 stp_update_bridge_timers(stp);
386 /* Returns the name given to 'stp' in the call to stp_create(). */
388 stp_get_name(const struct stp *stp)
393 /* Returns the bridge ID for 'stp'. */
395 stp_get_bridge_id(const struct stp *stp)
397 return stp->bridge_id;
400 /* Returns the bridge ID of the bridge currently believed to be the root. */
402 stp_get_designated_root(const struct stp *stp)
404 return stp->designated_root;
407 /* Returns true if 'stp' believes itself to the be root of the spanning tree,
408 * false otherwise. */
410 stp_is_root_bridge(const struct stp *stp)
412 return stp->bridge_id == stp->designated_root;
415 /* Returns the cost of the path from 'stp' to the root of the spanning tree. */
417 stp_get_root_path_cost(const struct stp *stp)
419 return stp->root_path_cost;
422 /* Returns the bridge hello time, in ms. The returned value is not necessarily
423 * the value passed to stp_set_hello_time(): it is clamped to the valid range
424 * and quantized to the STP timer resolution. */
426 stp_get_hello_time(const struct stp *stp)
428 return timer_to_ms(stp->bridge_hello_time);
431 /* Returns the bridge max age, in ms. The returned value is not necessarily
432 * the value passed to stp_set_max_age(): it is clamped to the valid range,
433 * quantized to the STP timer resolution, and adjusted to match the constraints
434 * due to the hello time. */
436 stp_get_max_age(const struct stp *stp)
438 return timer_to_ms(stp->bridge_max_age);
441 /* Returns the bridge forward delay, in ms. The returned value is not
442 * necessarily the value passed to stp_set_forward_delay(): it is clamped to
443 * the valid range, quantized to the STP timer resolution, and adjusted to
444 * match the constraints due to the forward delay. */
446 stp_get_forward_delay(const struct stp *stp)
448 return timer_to_ms(stp->bridge_forward_delay);
451 /* Returns the port in 'stp' with index 'port_no', which must be between 0 and
454 stp_get_port(struct stp *stp, int port_no)
456 assert(port_no >= 0 && port_no < ARRAY_SIZE(stp->ports));
457 return &stp->ports[port_no];
460 /* Returns the port connecting 'stp' to the root bridge, or a null pointer if
461 * there is no such port. */
463 stp_get_root_port(struct stp *stp)
465 return stp->root_port;
468 /* Finds a port whose state has changed. If successful, stores the port whose
469 * state changed in '*portp' and returns true. If no port has changed, stores
470 * NULL in '*portp' and returns false. */
472 stp_get_changed_port(struct stp *stp, struct stp_port **portp)
474 struct stp_port *end = &stp->ports[ARRAY_SIZE(stp->ports)];
477 for (p = stp->first_changed_port; p < end; p++) {
478 if (p->state_changed) {
479 p->state_changed = false;
480 stp->first_changed_port = p + 1;
485 stp->first_changed_port = end;
490 /* Returns the name for the given 'state' (for use in debugging and log
493 stp_state_name(enum stp_state state)
511 /* Returns true if 'state' is one in which packets received on a port should
512 * be forwarded, false otherwise.
514 * Returns true if 'state' is STP_DISABLED, since presumably in that case the
515 * port should still work, just not have STP applied to it. */
517 stp_forward_in_state(enum stp_state state)
519 return (state & (STP_DISABLED | STP_FORWARDING)) != 0;
522 /* Returns true if 'state' is one in which MAC learning should be done on
523 * packets received on a port, false otherwise.
525 * Returns true if 'state' is STP_DISABLED, since presumably in that case the
526 * port should still work, just not have STP applied to it. */
528 stp_learn_in_state(enum stp_state state)
530 return (state & (STP_DISABLED | STP_LEARNING | STP_FORWARDING)) != 0;
533 /* Returns the name for the given 'role' (for use in debugging and log
536 stp_role_name(enum stp_role role)
541 case STP_ROLE_DESIGNATED:
543 case STP_ROLE_ALTERNATE:
545 case STP_ROLE_DISABLED:
552 /* Notifies the STP entity that bridge protocol data unit 'bpdu', which is
553 * 'bpdu_size' bytes in length, was received on port 'p'.
555 * This function may call the 'send_bpdu' function provided to stp_create(). */
557 stp_received_bpdu(struct stp_port *p, const void *bpdu, size_t bpdu_size)
559 struct stp *stp = p->stp;
560 const struct stp_bpdu_header *header;
562 if (p->state == STP_DISABLED) {
566 if (bpdu_size < sizeof(struct stp_bpdu_header)) {
567 VLOG_WARN("%s: received runt %zu-byte BPDU", stp->name, bpdu_size);
573 if (header->protocol_id != htons(STP_PROTOCOL_ID)) {
574 VLOG_WARN("%s: received BPDU with unexpected protocol ID %"PRIu16,
575 stp->name, ntohs(header->protocol_id));
579 if (header->protocol_version != STP_PROTOCOL_VERSION) {
580 VLOG_DBG("%s: received BPDU with unexpected protocol version %"PRIu8,
581 stp->name, header->protocol_version);
584 switch (header->bpdu_type) {
585 case STP_TYPE_CONFIG:
586 if (bpdu_size < sizeof(struct stp_config_bpdu)) {
587 VLOG_WARN("%s: received config BPDU with invalid size %zu",
588 stp->name, bpdu_size);
592 stp_received_config_bpdu(stp, p, bpdu);
596 if (bpdu_size != sizeof(struct stp_tcn_bpdu)) {
597 VLOG_WARN("%s: received TCN BPDU with invalid size %zu",
598 stp->name, bpdu_size);
602 stp_received_tcn_bpdu(stp, p);
606 VLOG_WARN("%s: received BPDU of unexpected type %"PRIu8,
607 stp->name, header->bpdu_type);
614 /* Returns the STP entity in which 'p' is nested. */
616 stp_port_get_stp(struct stp_port *p)
621 /* Sets the 'aux' member of 'p'.
623 * The 'aux' member will be reset to NULL when stp_port_disable() is
624 * called or stp_port_enable() is called when the port is in a Disabled
627 stp_port_set_aux(struct stp_port *p, void *aux)
632 /* Returns the 'aux' member of 'p'. */
634 stp_port_get_aux(struct stp_port *p)
639 /* Returns the index of port 'p' within its bridge. */
641 stp_port_no(const struct stp_port *p)
643 struct stp *stp = p->stp;
644 assert(p >= stp->ports && p < &stp->ports[ARRAY_SIZE(stp->ports)]);
645 return p - stp->ports;
648 /* Returns the port ID for 'p'. */
650 stp_port_get_id(const struct stp_port *p)
655 /* Returns the state of port 'p'. */
657 stp_port_get_state(const struct stp_port *p)
662 /* Returns the role of port 'p'. */
664 stp_port_get_role(const struct stp_port *p)
666 struct stp_port *root_port = stp_get_root_port(p->stp);
668 if (root_port && root_port->port_id == p->port_id) {
669 return STP_ROLE_ROOT;
670 } else if (stp_is_designated_port(p)) {
671 return STP_ROLE_DESIGNATED;
672 } else if (p->state == STP_DISABLED) {
673 return STP_ROLE_DISABLED;
675 return STP_ROLE_ALTERNATE;
679 /* Retrieves BPDU transmit and receive counts for 'p'. */
680 void stp_port_get_counts(const struct stp_port *p,
681 int *tx_count, int *rx_count, int *error_count)
683 *tx_count = p->tx_count;
684 *rx_count = p->rx_count;
685 *error_count = p->error_count;
688 /* Disables STP on port 'p'. */
690 stp_port_disable(struct stp_port *p)
692 struct stp *stp = p->stp;
693 if (p->state != STP_DISABLED) {
694 bool root = stp_is_root_bridge(stp);
695 stp_become_designated_port(p);
696 stp_set_port_state(p, STP_DISABLED);
697 p->topology_change_ack = false;
698 p->config_pending = false;
699 stp_stop_timer(&p->message_age_timer);
700 stp_stop_timer(&p->forward_delay_timer);
701 stp_configuration_update(stp);
702 stp_port_state_selection(stp);
703 if (stp_is_root_bridge(stp) && !root) {
704 stp_become_root_bridge(stp);
710 /* Enables STP on port 'p'. The port will initially be in "blocking" state. */
712 stp_port_enable(struct stp_port *p)
714 if (p->state == STP_DISABLED) {
715 stp_initialize_port(p, STP_BLOCKING);
716 stp_port_state_selection(p->stp);
720 /* Sets the priority of port 'p' to 'new_priority'. Lower numerical values
721 * are interpreted as higher priorities. */
723 stp_port_set_priority(struct stp_port *p, uint8_t new_priority)
725 uint16_t new_port_id = (p->port_id & 0xff) | (new_priority << 8);
726 if (p->port_id != new_port_id) {
727 struct stp *stp = p->stp;
728 if (stp_is_designated_port(p)) {
729 p->designated_port = new_port_id;
731 p->port_id = new_port_id;
732 if (stp->bridge_id == p->designated_bridge
733 && p->port_id < p->designated_port) {
734 stp_become_designated_port(p);
735 stp_port_state_selection(stp);
740 /* Convert 'speed' (measured in Mb/s) into the path cost. */
742 stp_convert_speed_to_cost(unsigned int speed)
744 return speed >= 10000 ? 2 /* 10 Gb/s. */
745 : speed >= 1000 ? 4 /* 1 Gb/s. */
746 : speed >= 100 ? 19 /* 100 Mb/s. */
747 : speed >= 16 ? 62 /* 16 Mb/s. */
748 : speed >= 10 ? 100 /* 10 Mb/s. */
749 : speed >= 4 ? 250 /* 4 Mb/s. */
750 : 19; /* 100 Mb/s (guess). */
753 /* Sets the path cost of port 'p' to 'path_cost'. Lower values are generally
754 * used to indicate faster links. Use stp_port_set_speed() to automatically
755 * generate a default path cost from a link speed. */
757 stp_port_set_path_cost(struct stp_port *p, uint16_t path_cost)
759 if (p->path_cost != path_cost) {
760 struct stp *stp = p->stp;
761 p->path_cost = path_cost;
762 stp_configuration_update(stp);
763 stp_port_state_selection(stp);
767 /* Sets the path cost of port 'p' based on 'speed' (measured in Mb/s). */
769 stp_port_set_speed(struct stp_port *p, unsigned int speed)
771 stp_port_set_path_cost(p, stp_convert_speed_to_cost(speed));
774 /* Enables topology change detection on port 'p'. */
776 stp_port_enable_change_detection(struct stp_port *p)
778 p->change_detection_enabled = true;
781 /* Disables topology change detection on port 'p'. */
783 stp_port_disable_change_detection(struct stp_port *p)
785 p->change_detection_enabled = false;
789 stp_transmit_config(struct stp_port *p)
791 struct stp *stp = p->stp;
792 bool root = stp_is_root_bridge(stp);
793 if (!root && !stp->root_port) {
796 if (p->hold_timer.active) {
797 p->config_pending = true;
799 struct stp_config_bpdu config;
800 memset(&config, 0, sizeof config);
801 config.header.protocol_id = htons(STP_PROTOCOL_ID);
802 config.header.protocol_version = STP_PROTOCOL_VERSION;
803 config.header.bpdu_type = STP_TYPE_CONFIG;
805 if (p->topology_change_ack) {
806 config.flags |= STP_CONFIG_TOPOLOGY_CHANGE_ACK;
808 if (stp->topology_change) {
809 config.flags |= STP_CONFIG_TOPOLOGY_CHANGE;
811 config.root_id = htonll(stp->designated_root);
812 config.root_path_cost = htonl(stp->root_path_cost);
813 config.bridge_id = htonll(stp->bridge_id);
814 config.port_id = htons(p->port_id);
816 config.message_age = htons(0);
818 config.message_age = htons(stp->root_port->message_age_timer.value
819 + MESSAGE_AGE_INCREMENT);
821 config.max_age = htons(stp->max_age);
822 config.hello_time = htons(stp->hello_time);
823 config.forward_delay = htons(stp->forward_delay);
824 if (ntohs(config.message_age) < stp->max_age) {
825 p->topology_change_ack = false;
826 p->config_pending = false;
827 stp_send_bpdu(p, &config, sizeof config);
828 stp_start_timer(&p->hold_timer, 0);
834 stp_supersedes_port_info(const struct stp_port *p,
835 const struct stp_config_bpdu *config)
837 if (ntohll(config->root_id) != p->designated_root) {
838 return ntohll(config->root_id) < p->designated_root;
839 } else if (ntohl(config->root_path_cost) != p->designated_cost) {
840 return ntohl(config->root_path_cost) < p->designated_cost;
841 } else if (ntohll(config->bridge_id) != p->designated_bridge) {
842 return ntohll(config->bridge_id) < p->designated_bridge;
844 return (ntohll(config->bridge_id) != p->stp->bridge_id
845 || ntohs(config->port_id) <= p->designated_port);
850 stp_record_config_information(struct stp_port *p,
851 const struct stp_config_bpdu *config)
853 p->designated_root = ntohll(config->root_id);
854 p->designated_cost = ntohl(config->root_path_cost);
855 p->designated_bridge = ntohll(config->bridge_id);
856 p->designated_port = ntohs(config->port_id);
857 stp_start_timer(&p->message_age_timer, ntohs(config->message_age));
861 stp_record_config_timeout_values(struct stp *stp,
862 const struct stp_config_bpdu *config)
864 stp->max_age = ntohs(config->max_age);
865 stp->hello_time = ntohs(config->hello_time);
866 stp->forward_delay = ntohs(config->forward_delay);
867 stp->topology_change = config->flags & STP_CONFIG_TOPOLOGY_CHANGE;
871 stp_is_designated_port(const struct stp_port *p)
873 return (p->designated_bridge == p->stp->bridge_id
874 && p->designated_port == p->port_id);
878 stp_config_bpdu_generation(struct stp *stp)
882 FOR_EACH_ENABLED_PORT (p, stp) {
883 if (stp_is_designated_port(p)) {
884 stp_transmit_config(p);
890 stp_transmit_tcn(struct stp *stp)
892 struct stp_port *p = stp->root_port;
893 struct stp_tcn_bpdu tcn_bpdu;
897 tcn_bpdu.header.protocol_id = htons(STP_PROTOCOL_ID);
898 tcn_bpdu.header.protocol_version = STP_PROTOCOL_VERSION;
899 tcn_bpdu.header.bpdu_type = STP_TYPE_TCN;
900 stp_send_bpdu(p, &tcn_bpdu, sizeof tcn_bpdu);
904 stp_configuration_update(struct stp *stp)
906 stp_root_selection(stp);
907 stp_designated_port_selection(stp);
911 stp_supersedes_root(const struct stp_port *root, const struct stp_port *p)
913 int p_cost = p->designated_cost + p->path_cost;
914 int root_cost = root->designated_cost + root->path_cost;
916 if (p->designated_root != root->designated_root) {
917 return p->designated_root < root->designated_root;
918 } else if (p_cost != root_cost) {
919 return p_cost < root_cost;
920 } else if (p->designated_bridge != root->designated_bridge) {
921 return p->designated_bridge < root->designated_bridge;
922 } else if (p->designated_port != root->designated_port) {
923 return p->designated_port < root->designated_port;
925 return p->port_id < root->port_id;
930 stp_root_selection(struct stp *stp)
932 struct stp_port *p, *root;
935 FOR_EACH_ENABLED_PORT (p, stp) {
936 if (stp_is_designated_port(p)
937 || p->designated_root >= stp->bridge_id) {
940 if (root && !stp_supersedes_root(root, p)) {
945 stp->root_port = root;
947 stp->designated_root = stp->bridge_id;
948 stp->root_path_cost = 0;
950 stp->designated_root = root->designated_root;
951 stp->root_path_cost = root->designated_cost + root->path_cost;
956 stp_designated_port_selection(struct stp *stp)
960 FOR_EACH_ENABLED_PORT (p, stp) {
961 if (stp_is_designated_port(p)
962 || p->designated_root != stp->designated_root
963 || stp->root_path_cost < p->designated_cost
964 || (stp->root_path_cost == p->designated_cost
965 && (stp->bridge_id < p->designated_bridge
966 || (stp->bridge_id == p->designated_bridge
967 && p->port_id <= p->designated_port))))
969 stp_become_designated_port(p);
975 stp_become_designated_port(struct stp_port *p)
977 struct stp *stp = p->stp;
978 p->designated_root = stp->designated_root;
979 p->designated_cost = stp->root_path_cost;
980 p->designated_bridge = stp->bridge_id;
981 p->designated_port = p->port_id;
985 stp_port_state_selection(struct stp *stp)
989 FOR_EACH_ENABLED_PORT (p, stp) {
990 if (p == stp->root_port) {
991 p->config_pending = false;
992 p->topology_change_ack = false;
993 stp_make_forwarding(p);
994 } else if (stp_is_designated_port(p)) {
995 stp_stop_timer(&p->message_age_timer);
996 stp_make_forwarding(p);
998 p->config_pending = false;
999 p->topology_change_ack = false;
1000 stp_make_blocking(p);
1006 stp_make_forwarding(struct stp_port *p)
1008 if (p->state == STP_BLOCKING) {
1009 stp_set_port_state(p, STP_LISTENING);
1010 stp_start_timer(&p->forward_delay_timer, 0);
1015 stp_make_blocking(struct stp_port *p)
1017 if (!(p->state & (STP_DISABLED | STP_BLOCKING))) {
1018 if (p->state & (STP_FORWARDING | STP_LEARNING)) {
1019 if (p->change_detection_enabled) {
1020 stp_topology_change_detection(p->stp);
1023 stp_set_port_state(p, STP_BLOCKING);
1024 stp_stop_timer(&p->forward_delay_timer);
1029 stp_set_port_state(struct stp_port *p, enum stp_state state)
1031 if (state != p->state && !p->state_changed) {
1032 p->state_changed = true;
1033 if (p < p->stp->first_changed_port) {
1034 p->stp->first_changed_port = p;
1041 stp_topology_change_detection(struct stp *stp)
1043 if (stp_is_root_bridge(stp)) {
1044 stp->topology_change = true;
1045 stp_start_timer(&stp->topology_change_timer, 0);
1046 } else if (!stp->topology_change_detected) {
1047 stp_transmit_tcn(stp);
1048 stp_start_timer(&stp->tcn_timer, 0);
1050 stp->topology_change_detected = true;
1054 stp_topology_change_acknowledged(struct stp *stp)
1056 stp->topology_change_detected = false;
1057 stp_stop_timer(&stp->tcn_timer);
1061 stp_acknowledge_topology_change(struct stp_port *p)
1063 p->topology_change_ack = true;
1064 stp_transmit_config(p);
1068 stp_received_config_bpdu(struct stp *stp, struct stp_port *p,
1069 const struct stp_config_bpdu *config)
1071 if (ntohs(config->message_age) >= ntohs(config->max_age)) {
1072 VLOG_WARN("%s: received config BPDU with message age (%u) greater "
1073 "than max age (%u)",
1075 ntohs(config->message_age), ntohs(config->max_age));
1078 if (p->state != STP_DISABLED) {
1079 bool root = stp_is_root_bridge(stp);
1080 if (stp_supersedes_port_info(p, config)) {
1081 stp_record_config_information(p, config);
1082 stp_configuration_update(stp);
1083 stp_port_state_selection(stp);
1084 if (!stp_is_root_bridge(stp) && root) {
1085 stp_stop_timer(&stp->hello_timer);
1086 if (stp->topology_change_detected) {
1087 stp_stop_timer(&stp->topology_change_timer);
1088 stp_transmit_tcn(stp);
1089 stp_start_timer(&stp->tcn_timer, 0);
1092 if (p == stp->root_port) {
1093 stp_record_config_timeout_values(stp, config);
1094 stp_config_bpdu_generation(stp);
1095 if (config->flags & STP_CONFIG_TOPOLOGY_CHANGE_ACK) {
1096 stp_topology_change_acknowledged(stp);
1099 } else if (stp_is_designated_port(p)) {
1100 stp_transmit_config(p);
1106 stp_received_tcn_bpdu(struct stp *stp, struct stp_port *p)
1108 if (p->state != STP_DISABLED) {
1109 if (stp_is_designated_port(p)) {
1110 stp_topology_change_detection(stp);
1111 stp_acknowledge_topology_change(p);
1117 stp_hello_timer_expiry(struct stp *stp)
1119 stp_config_bpdu_generation(stp);
1120 stp_start_timer(&stp->hello_timer, 0);
1124 stp_message_age_timer_expiry(struct stp_port *p)
1126 struct stp *stp = p->stp;
1127 bool root = stp_is_root_bridge(stp);
1128 stp_become_designated_port(p);
1129 stp_configuration_update(stp);
1130 stp_port_state_selection(stp);
1131 if (stp_is_root_bridge(stp) && !root) {
1132 stp->max_age = stp->bridge_max_age;
1133 stp->hello_time = stp->bridge_hello_time;
1134 stp->forward_delay = stp->bridge_forward_delay;
1135 stp_topology_change_detection(stp);
1136 stp_stop_timer(&stp->tcn_timer);
1137 stp_config_bpdu_generation(stp);
1138 stp_start_timer(&stp->hello_timer, 0);
1143 stp_is_designated_for_some_port(const struct stp *stp)
1145 const struct stp_port *p;
1147 FOR_EACH_ENABLED_PORT (p, stp) {
1148 if (p->designated_bridge == stp->bridge_id) {
1156 stp_forward_delay_timer_expiry(struct stp_port *p)
1158 if (p->state == STP_LISTENING) {
1159 stp_set_port_state(p, STP_LEARNING);
1160 stp_start_timer(&p->forward_delay_timer, 0);
1161 } else if (p->state == STP_LEARNING) {
1162 stp_set_port_state(p, STP_FORWARDING);
1163 if (stp_is_designated_for_some_port(p->stp)) {
1164 if (p->change_detection_enabled) {
1165 stp_topology_change_detection(p->stp);
1172 stp_tcn_timer_expiry(struct stp *stp)
1174 stp_transmit_tcn(stp);
1175 stp_start_timer(&stp->tcn_timer, 0);
1179 stp_topology_change_timer_expiry(struct stp *stp)
1181 stp->topology_change_detected = false;
1182 stp->topology_change = false;
1186 stp_hold_timer_expiry(struct stp_port *p)
1188 if (p->config_pending) {
1189 stp_transmit_config(p);
1194 stp_initialize_port(struct stp_port *p, enum stp_state state)
1196 assert(state & (STP_DISABLED | STP_BLOCKING));
1197 stp_become_designated_port(p);
1198 stp_set_port_state(p, state);
1199 p->topology_change_ack = false;
1200 p->config_pending = false;
1201 p->change_detection_enabled = true;
1203 stp_stop_timer(&p->message_age_timer);
1204 stp_stop_timer(&p->forward_delay_timer);
1205 stp_stop_timer(&p->hold_timer);
1206 p->tx_count = p->rx_count = p->error_count = 0;
1210 stp_become_root_bridge(struct stp *stp)
1212 stp->max_age = stp->bridge_max_age;
1213 stp->hello_time = stp->bridge_hello_time;
1214 stp->forward_delay = stp->bridge_forward_delay;
1215 stp_topology_change_detection(stp);
1216 stp_stop_timer(&stp->tcn_timer);
1217 stp_config_bpdu_generation(stp);
1218 stp_start_timer(&stp->hello_timer, 0);
1222 stp_start_timer(struct stp_timer *timer, int value)
1224 timer->value = value;
1225 timer->active = true;
1229 stp_stop_timer(struct stp_timer *timer)
1231 timer->active = false;
1235 stp_timer_expired(struct stp_timer *timer, int elapsed, int timeout)
1237 if (timer->active) {
1238 timer->value += elapsed;
1239 if (timer->value >= timeout) {
1240 timer->active = false;
1247 /* Returns the number of whole STP timer ticks in 'ms' milliseconds. There
1248 * are 256 STP timer ticks per second. */
1252 return ms * 0x100 / 1000;
1255 /* Returns the number of whole milliseconds in 'timer' STP timer ticks. There
1256 * are 256 STP timer ticks per second. */
1258 timer_to_ms(int timer)
1260 return timer * 1000 / 0x100;
1264 clamp(int x, int min, int max)
1266 return x < min ? min : x > max ? max : x;
1270 stp_update_bridge_timers(struct stp *stp)
1274 ht = clamp(stp->rq_hello_time, 1000, 10000);
1275 ma = clamp(stp->rq_max_age, MAX(2 * (ht + 1000), 6000), 40000);
1276 fd = clamp(stp->rq_forward_delay, ma / 2 + 1000, 30000);
1278 stp->bridge_hello_time = ms_to_timer(ht);
1279 stp->bridge_max_age = ms_to_timer(ma);
1280 stp->bridge_forward_delay = ms_to_timer(fd);
1282 if (stp_is_root_bridge(stp)) {
1283 stp->max_age = stp->bridge_max_age;
1284 stp->hello_time = stp->bridge_hello_time;
1285 stp->forward_delay = stp->bridge_forward_delay;
1290 stp_send_bpdu(struct stp_port *p, const void *bpdu, size_t bpdu_size)
1292 struct eth_header *eth;
1293 struct llc_header *llc;
1297 pkt = ofpbuf_new(ETH_HEADER_LEN + LLC_HEADER_LEN + bpdu_size);
1298 pkt->l2 = eth = ofpbuf_put_zeros(pkt, sizeof *eth);
1299 llc = ofpbuf_put_zeros(pkt, sizeof *llc);
1300 pkt->l3 = ofpbuf_put(pkt, bpdu, bpdu_size);
1303 memcpy(eth->eth_dst, eth_addr_stp, ETH_ADDR_LEN);
1304 /* p->stp->send_bpdu() must fill in source address. */
1305 eth->eth_type = htons(pkt->size - ETH_HEADER_LEN);
1308 llc->llc_dsap = STP_LLC_DSAP;
1309 llc->llc_ssap = STP_LLC_SSAP;
1310 llc->llc_cntl = STP_LLC_CNTL;
1312 p->stp->send_bpdu(pkt, stp_port_no(p), p->stp->aux);