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. */
100 /* Static bridge data. */
101 char *name; /* Human-readable name for log messages. */
102 stp_identifier bridge_id; /* 8.5.3.7: This bridge. */
103 int max_age; /* 8.5.3.4: Time to drop received data. */
104 int hello_time; /* 8.5.3.5: Time between sending BPDUs. */
105 int forward_delay; /* 8.5.3.6: Delay between state changes. */
106 int bridge_max_age; /* 8.5.3.8: max_age when we're root. */
107 int bridge_hello_time; /* 8.5.3.9: hello_time as root. */
108 int bridge_forward_delay; /* 8.5.3.10: forward_delay as root. */
109 int rq_max_age; /* User-requested max age, in ms. */
110 int rq_hello_time; /* User-requested hello time, in ms. */
111 int rq_forward_delay; /* User-requested forward delay, in ms. */
112 int elapsed_remainder; /* Left-over msecs from last stp_tick(). */
114 /* Dynamic bridge data. */
115 stp_identifier designated_root; /* 8.5.3.1: Bridge believed to be root. */
116 unsigned int root_path_cost; /* 8.5.3.2: Cost of path to root. */
117 struct stp_port *root_port; /* 8.5.3.3: Lowest cost port to root. */
118 bool topology_change_detected; /* 8.5.3.11: Detected a topology change? */
119 bool topology_change; /* 8.5.3.12: Received topology change? */
122 struct stp_timer hello_timer; /* 8.5.4.1: Hello timer. */
123 struct stp_timer tcn_timer; /* 8.5.4.2: Topology change timer. */
124 struct stp_timer topology_change_timer; /* 8.5.4.3. */
127 struct stp_port ports[STP_MAX_PORTS];
129 /* Interface to client. */
130 struct stp_port *first_changed_port;
131 void (*send_bpdu)(struct ofpbuf *bpdu, int port_no, void *aux);
135 #define FOR_EACH_ENABLED_PORT(PORT, STP) \
136 for ((PORT) = stp_next_enabled_port((STP), (STP)->ports); \
138 (PORT) = stp_next_enabled_port((STP), (PORT) + 1))
139 static struct stp_port *
140 stp_next_enabled_port(const struct stp *stp, const struct stp_port *port)
142 for (; port < &stp->ports[ARRAY_SIZE(stp->ports)]; port++) {
143 if (port->state != STP_DISABLED) {
144 return (struct stp_port *) port;
150 #define MESSAGE_AGE_INCREMENT 1
152 static void stp_transmit_config(struct stp_port *);
153 static bool stp_supersedes_port_info(const struct stp_port *,
154 const struct stp_config_bpdu *);
155 static void stp_record_config_information(struct stp_port *,
156 const struct stp_config_bpdu *);
157 static void stp_record_config_timeout_values(struct stp *,
158 const struct stp_config_bpdu *);
159 static bool stp_is_designated_port(const struct stp_port *);
160 static void stp_config_bpdu_generation(struct stp *);
161 static void stp_transmit_tcn(struct stp *);
162 static void stp_configuration_update(struct stp *);
163 static bool stp_supersedes_root(const struct stp_port *root,
164 const struct stp_port *);
165 static void stp_root_selection(struct stp *);
166 static void stp_designated_port_selection(struct stp *);
167 static void stp_become_designated_port(struct stp_port *);
168 static void stp_port_state_selection(struct stp *);
169 static void stp_make_forwarding(struct stp_port *);
170 static void stp_make_blocking(struct stp_port *);
171 static void stp_set_port_state(struct stp_port *, enum stp_state);
172 static void stp_topology_change_detection(struct stp *);
173 static void stp_topology_change_acknowledged(struct stp *);
174 static void stp_acknowledge_topology_change(struct stp_port *);
175 static void stp_received_config_bpdu(struct stp *, struct stp_port *,
176 const struct stp_config_bpdu *);
177 static void stp_received_tcn_bpdu(struct stp *, struct stp_port *);
178 static void stp_hello_timer_expiry(struct stp *);
179 static void stp_message_age_timer_expiry(struct stp_port *);
180 static bool stp_is_designated_for_some_port(const struct stp *);
181 static void stp_forward_delay_timer_expiry(struct stp_port *);
182 static void stp_tcn_timer_expiry(struct stp *);
183 static void stp_topology_change_timer_expiry(struct stp *);
184 static void stp_hold_timer_expiry(struct stp_port *);
185 static void stp_initialize_port(struct stp_port *, enum stp_state);
186 static void stp_become_root_bridge(struct stp *);
187 static void stp_update_bridge_timers(struct stp *);
189 static int clamp(int x, int min, int max);
190 static int ms_to_timer(int ms);
191 static int ms_to_timer_remainder(int ms);
192 static int timer_to_ms(int timer);
193 static void stp_start_timer(struct stp_timer *, int value);
194 static void stp_stop_timer(struct stp_timer *);
195 static bool stp_timer_expired(struct stp_timer *, int elapsed, int timeout);
197 static void stp_send_bpdu(struct stp_port *, const void *, size_t);
199 /* Creates and returns a new STP instance that initially has no ports enabled.
201 * 'bridge_id' should be a 48-bit MAC address as returned by
202 * eth_addr_to_uint64(). 'bridge_id' may also have a priority value in its top
203 * 16 bits; if those bits are set to 0, STP_DEFAULT_BRIDGE_PRIORITY is used.
204 * (This priority may be changed with stp_set_bridge_priority().)
206 * When the bridge needs to send out a BPDU, it calls 'send_bpdu'. This
207 * callback may be called from stp_tick() or stp_received_bpdu(). The
208 * arguments to 'send_bpdu' are an STP BPDU encapsulated in 'bpdu',
209 * the spanning tree port number 'port_no' that should transmit the
210 * packet, and auxiliary data to be passed to the callback in 'aux'.
213 stp_create(const char *name, stp_identifier bridge_id,
214 void (*send_bpdu)(struct ofpbuf *bpdu, int port_no, void *aux),
220 stp = xzalloc(sizeof *stp);
221 stp->name = xstrdup(name);
222 stp->bridge_id = bridge_id;
223 if (!(stp->bridge_id >> 48)) {
224 stp->bridge_id |= (uint64_t) STP_DEFAULT_BRIDGE_PRIORITY << 48;
227 stp->rq_max_age = STP_DEFAULT_MAX_AGE;
228 stp->rq_hello_time = STP_DEFAULT_HELLO_TIME;
229 stp->rq_forward_delay = STP_DEFAULT_FWD_DELAY;
230 stp_update_bridge_timers(stp);
231 stp->max_age = stp->bridge_max_age;
232 stp->hello_time = stp->bridge_hello_time;
233 stp->forward_delay = stp->bridge_forward_delay;
235 stp->designated_root = stp->bridge_id;
236 stp->root_path_cost = 0;
237 stp->root_port = NULL;
238 stp->topology_change_detected = false;
239 stp->topology_change = false;
241 stp_stop_timer(&stp->tcn_timer);
242 stp_stop_timer(&stp->topology_change_timer);
243 stp_start_timer(&stp->hello_timer, 0);
245 stp->send_bpdu = send_bpdu;
248 stp->first_changed_port = &stp->ports[ARRAY_SIZE(stp->ports)];
249 for (p = stp->ports; p < &stp->ports[ARRAY_SIZE(stp->ports)]; p++) {
251 p->port_id = (stp_port_no(p) + 1) | (STP_DEFAULT_PORT_PRIORITY << 8);
252 p->path_cost = 19; /* Recommended default for 100 Mb/s link. */
253 stp_initialize_port(p, STP_DISABLED);
258 /* Destroys 'stp'. */
260 stp_destroy(struct stp *stp)
268 /* Runs 'stp' given that 'ms' milliseconds have passed. */
270 stp_tick(struct stp *stp, int ms)
275 /* Convert 'ms' to STP timer ticks. Preserve any leftover milliseconds
276 * from previous stp_tick() calls so that we don't lose STP ticks when we
277 * are called too frequently. */
278 ms = clamp(ms, 0, INT_MAX - 1000) + stp->elapsed_remainder;
279 elapsed = ms_to_timer(ms);
280 stp->elapsed_remainder = ms_to_timer_remainder(ms);
285 if (stp_timer_expired(&stp->hello_timer, elapsed, stp->hello_time)) {
286 stp_hello_timer_expiry(stp);
288 if (stp_timer_expired(&stp->tcn_timer, elapsed, stp->bridge_hello_time)) {
289 stp_tcn_timer_expiry(stp);
291 if (stp_timer_expired(&stp->topology_change_timer, elapsed,
292 stp->max_age + stp->forward_delay)) {
293 stp_topology_change_timer_expiry(stp);
295 FOR_EACH_ENABLED_PORT (p, stp) {
296 if (stp_timer_expired(&p->message_age_timer, elapsed, stp->max_age)) {
297 stp_message_age_timer_expiry(p);
300 FOR_EACH_ENABLED_PORT (p, stp) {
301 if (stp_timer_expired(&p->forward_delay_timer, elapsed,
302 stp->forward_delay)) {
303 stp_forward_delay_timer_expiry(p);
305 if (stp_timer_expired(&p->hold_timer, elapsed, ms_to_timer(1000))) {
306 stp_hold_timer_expiry(p);
312 set_bridge_id(struct stp *stp, stp_identifier new_bridge_id)
314 if (new_bridge_id != stp->bridge_id) {
318 root = stp_is_root_bridge(stp);
319 FOR_EACH_ENABLED_PORT (p, stp) {
320 if (stp_is_designated_port(p)) {
321 p->designated_bridge = new_bridge_id;
324 stp->bridge_id = new_bridge_id;
325 stp_configuration_update(stp);
326 stp_port_state_selection(stp);
327 if (stp_is_root_bridge(stp) && !root) {
328 stp_become_root_bridge(stp);
334 stp_set_bridge_id(struct stp *stp, stp_identifier bridge_id)
336 const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
337 const uint64_t pri_bits = ~mac_bits;
338 set_bridge_id(stp, (stp->bridge_id & pri_bits) | (bridge_id & mac_bits));
342 stp_set_bridge_priority(struct stp *stp, uint16_t new_priority)
344 const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
345 set_bridge_id(stp, ((stp->bridge_id & mac_bits)
346 | ((uint64_t) new_priority << 48)));
349 /* Sets the desired hello time for 'stp' to 'ms', in milliseconds. The actual
350 * hello time is clamped to the range of 1 to 10 seconds and subject to the
351 * relationship (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge
352 * hello time is only used when 'stp' is the root bridge. */
354 stp_set_hello_time(struct stp *stp, int ms)
356 stp->rq_hello_time = ms;
357 stp_update_bridge_timers(stp);
360 /* Sets the desired max age for 'stp' to 'ms', in milliseconds. The actual max
361 * age is clamped to the range of 6 to 40 seconds and subject to the
362 * relationships (2 * (bridge_forward_delay - 1 s) >= bridge_max_age) and
363 * (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge max age is
364 * only used when 'stp' is the root bridge. */
366 stp_set_max_age(struct stp *stp, int ms)
368 stp->rq_max_age = ms;
369 stp_update_bridge_timers(stp);
372 /* Sets the desired forward delay for 'stp' to 'ms', in milliseconds. The
373 * actual forward delay is clamped to the range of 4 to 30 seconds and subject
374 * to the relationship (2 * (bridge_forward_delay - 1 s) >= bridge_max_age).
375 * The bridge forward delay is only used when 'stp' is the root bridge. */
377 stp_set_forward_delay(struct stp *stp, int ms)
379 stp->rq_forward_delay = ms;
380 stp_update_bridge_timers(stp);
383 /* Returns the name given to 'stp' in the call to stp_create(). */
385 stp_get_name(const struct stp *stp)
390 /* Returns the bridge ID for 'stp'. */
392 stp_get_bridge_id(const struct stp *stp)
394 return stp->bridge_id;
397 /* Returns the bridge ID of the bridge currently believed to be the root. */
399 stp_get_designated_root(const struct stp *stp)
401 return stp->designated_root;
404 /* Returns true if 'stp' believes itself to the be root of the spanning tree,
405 * false otherwise. */
407 stp_is_root_bridge(const struct stp *stp)
409 return stp->bridge_id == stp->designated_root;
412 /* Returns the cost of the path from 'stp' to the root of the spanning tree. */
414 stp_get_root_path_cost(const struct stp *stp)
416 return stp->root_path_cost;
419 /* Returns the bridge hello time, in ms. The returned value is not necessarily
420 * the value passed to stp_set_hello_time(): it is clamped to the valid range
421 * and quantized to the STP timer resolution. */
423 stp_get_hello_time(const struct stp *stp)
425 return timer_to_ms(stp->bridge_hello_time);
428 /* Returns the bridge max age, in ms. The returned value is not necessarily
429 * the value passed to stp_set_max_age(): it is clamped to the valid range,
430 * quantized to the STP timer resolution, and adjusted to match the constraints
431 * due to the hello time. */
433 stp_get_max_age(const struct stp *stp)
435 return timer_to_ms(stp->bridge_max_age);
438 /* Returns the bridge forward delay, in ms. The returned value is not
439 * necessarily the value passed to stp_set_forward_delay(): it is clamped to
440 * the valid range, quantized to the STP timer resolution, and adjusted to
441 * match the constraints due to the forward delay. */
443 stp_get_forward_delay(const struct stp *stp)
445 return timer_to_ms(stp->bridge_forward_delay);
448 /* Returns the port in 'stp' with index 'port_no', which must be between 0 and
451 stp_get_port(struct stp *stp, int port_no)
453 assert(port_no >= 0 && port_no < ARRAY_SIZE(stp->ports));
454 return &stp->ports[port_no];
457 /* Returns the port connecting 'stp' to the root bridge, or a null pointer if
458 * there is no such port. */
460 stp_get_root_port(struct stp *stp)
462 return stp->root_port;
465 /* Finds a port whose state has changed. If successful, stores the port whose
466 * state changed in '*portp' and returns true. If no port has changed, stores
467 * NULL in '*portp' and returns false. */
469 stp_get_changed_port(struct stp *stp, struct stp_port **portp)
471 struct stp_port *end = &stp->ports[ARRAY_SIZE(stp->ports)];
474 for (p = stp->first_changed_port; p < end; p++) {
475 if (p->state_changed) {
476 p->state_changed = false;
477 stp->first_changed_port = p + 1;
482 stp->first_changed_port = end;
487 /* Returns the name for the given 'state' (for use in debugging and log
490 stp_state_name(enum stp_state state)
508 /* Returns true if 'state' is one in which packets received on a port should
509 * be forwarded, false otherwise.
511 * Returns true if 'state' is STP_DISABLED, since presumably in that case the
512 * port should still work, just not have STP applied to it. */
514 stp_forward_in_state(enum stp_state state)
516 return (state & (STP_DISABLED | STP_FORWARDING)) != 0;
519 /* Returns true if 'state' is one in which MAC learning should be done on
520 * packets received on a port, false otherwise.
522 * Returns true if 'state' is STP_DISABLED, since presumably in that case the
523 * port should still work, just not have STP applied to it. */
525 stp_learn_in_state(enum stp_state state)
527 return (state & (STP_DISABLED | STP_LEARNING | STP_FORWARDING)) != 0;
530 /* Returns the name for the given 'role' (for use in debugging and log
533 stp_role_name(enum stp_role role)
538 case STP_ROLE_DESIGNATED:
540 case STP_ROLE_ALTERNATE:
542 case STP_ROLE_DISABLED:
549 /* Notifies the STP entity that bridge protocol data unit 'bpdu', which is
550 * 'bpdu_size' bytes in length, was received on port 'p'.
552 * This function may call the 'send_bpdu' function provided to stp_create(). */
554 stp_received_bpdu(struct stp_port *p, const void *bpdu, size_t bpdu_size)
556 struct stp *stp = p->stp;
557 const struct stp_bpdu_header *header;
559 if (p->state == STP_DISABLED) {
563 if (bpdu_size < sizeof(struct stp_bpdu_header)) {
564 VLOG_WARN("%s: received runt %zu-byte BPDU", stp->name, bpdu_size);
569 if (header->protocol_id != htons(STP_PROTOCOL_ID)) {
570 VLOG_WARN("%s: received BPDU with unexpected protocol ID %"PRIu16,
571 stp->name, ntohs(header->protocol_id));
574 if (header->protocol_version != STP_PROTOCOL_VERSION) {
575 VLOG_DBG("%s: received BPDU with unexpected protocol version %"PRIu8,
576 stp->name, header->protocol_version);
579 switch (header->bpdu_type) {
580 case STP_TYPE_CONFIG:
581 if (bpdu_size < sizeof(struct stp_config_bpdu)) {
582 VLOG_WARN("%s: received config BPDU with invalid size %zu",
583 stp->name, bpdu_size);
586 stp_received_config_bpdu(stp, p, bpdu);
590 if (bpdu_size != sizeof(struct stp_tcn_bpdu)) {
591 VLOG_WARN("%s: received TCN BPDU with invalid size %zu",
592 stp->name, bpdu_size);
595 stp_received_tcn_bpdu(stp, p);
599 VLOG_WARN("%s: received BPDU of unexpected type %"PRIu8,
600 stp->name, header->bpdu_type);
605 /* Returns the STP entity in which 'p' is nested. */
607 stp_port_get_stp(struct stp_port *p)
612 /* Sets the 'aux' member of 'p'.
614 * The 'aux' member will be reset to NULL when stp_port_disable() is
615 * called or stp_port_enable() is called when the port is in a Disabled
618 stp_port_set_aux(struct stp_port *p, void *aux)
623 /* Returns the 'aux' member of 'p'. */
625 stp_port_get_aux(struct stp_port *p)
630 /* Returns the index of port 'p' within its bridge. */
632 stp_port_no(const struct stp_port *p)
634 struct stp *stp = p->stp;
635 assert(p >= stp->ports && p < &stp->ports[ARRAY_SIZE(stp->ports)]);
636 return p - stp->ports;
639 /* Returns the port ID for 'p'. */
641 stp_port_get_id(const struct stp_port *p)
646 /* Returns the state of port 'p'. */
648 stp_port_get_state(const struct stp_port *p)
653 /* Returns the role of port 'p'. */
655 stp_port_get_role(const struct stp_port *p)
657 struct stp_port *root_port = stp_get_root_port(p->stp);
659 if (root_port && root_port->port_id == p->port_id) {
660 return STP_ROLE_ROOT;
661 } else if (stp_is_designated_port(p)) {
662 return STP_ROLE_DESIGNATED;
663 } else if (p->state == STP_DISABLED) {
664 return STP_ROLE_DISABLED;
666 return STP_ROLE_ALTERNATE;
670 /* Disables STP on port 'p'. */
672 stp_port_disable(struct stp_port *p)
674 struct stp *stp = p->stp;
675 if (p->state != STP_DISABLED) {
676 bool root = stp_is_root_bridge(stp);
677 stp_become_designated_port(p);
678 stp_set_port_state(p, STP_DISABLED);
679 p->topology_change_ack = false;
680 p->config_pending = false;
681 stp_stop_timer(&p->message_age_timer);
682 stp_stop_timer(&p->forward_delay_timer);
683 stp_configuration_update(stp);
684 stp_port_state_selection(stp);
685 if (stp_is_root_bridge(stp) && !root) {
686 stp_become_root_bridge(stp);
692 /* Enables STP on port 'p'. The port will initially be in "blocking" state. */
694 stp_port_enable(struct stp_port *p)
696 if (p->state == STP_DISABLED) {
697 stp_initialize_port(p, STP_BLOCKING);
698 stp_port_state_selection(p->stp);
702 /* Sets the priority of port 'p' to 'new_priority'. Lower numerical values
703 * are interpreted as higher priorities. */
705 stp_port_set_priority(struct stp_port *p, uint8_t new_priority)
707 uint16_t new_port_id = (p->port_id & 0xff) | (new_priority << 8);
708 if (p->port_id != new_port_id) {
709 struct stp *stp = p->stp;
710 if (stp_is_designated_port(p)) {
711 p->designated_port = new_port_id;
713 p->port_id = new_port_id;
714 if (stp->bridge_id == p->designated_bridge
715 && p->port_id < p->designated_port) {
716 stp_become_designated_port(p);
717 stp_port_state_selection(stp);
722 /* Convert 'speed' (measured in Mb/s) into the path cost. */
724 stp_convert_speed_to_cost(unsigned int speed)
726 return speed >= 10000 ? 2 /* 10 Gb/s. */
727 : speed >= 1000 ? 4 /* 1 Gb/s. */
728 : speed >= 100 ? 19 /* 100 Mb/s. */
729 : speed >= 16 ? 62 /* 16 Mb/s. */
730 : speed >= 10 ? 100 /* 10 Mb/s. */
731 : speed >= 4 ? 250 /* 4 Mb/s. */
732 : 19; /* 100 Mb/s (guess). */
735 /* Sets the path cost of port 'p' to 'path_cost'. Lower values are generally
736 * used to indicate faster links. Use stp_port_set_speed() to automatically
737 * generate a default path cost from a link speed. */
739 stp_port_set_path_cost(struct stp_port *p, uint16_t path_cost)
741 if (p->path_cost != path_cost) {
742 struct stp *stp = p->stp;
743 p->path_cost = path_cost;
744 stp_configuration_update(stp);
745 stp_port_state_selection(stp);
749 /* Sets the path cost of port 'p' based on 'speed' (measured in Mb/s). */
751 stp_port_set_speed(struct stp_port *p, unsigned int speed)
753 stp_port_set_path_cost(p, stp_convert_speed_to_cost(speed));
756 /* Enables topology change detection on port 'p'. */
758 stp_port_enable_change_detection(struct stp_port *p)
760 p->change_detection_enabled = true;
763 /* Disables topology change detection on port 'p'. */
765 stp_port_disable_change_detection(struct stp_port *p)
767 p->change_detection_enabled = false;
771 stp_transmit_config(struct stp_port *p)
773 struct stp *stp = p->stp;
774 bool root = stp_is_root_bridge(stp);
775 if (!root && !stp->root_port) {
778 if (p->hold_timer.active) {
779 p->config_pending = true;
781 struct stp_config_bpdu config;
782 memset(&config, 0, sizeof config);
783 config.header.protocol_id = htons(STP_PROTOCOL_ID);
784 config.header.protocol_version = STP_PROTOCOL_VERSION;
785 config.header.bpdu_type = STP_TYPE_CONFIG;
787 if (p->topology_change_ack) {
788 config.flags |= STP_CONFIG_TOPOLOGY_CHANGE_ACK;
790 if (stp->topology_change) {
791 config.flags |= STP_CONFIG_TOPOLOGY_CHANGE;
793 config.root_id = htonll(stp->designated_root);
794 config.root_path_cost = htonl(stp->root_path_cost);
795 config.bridge_id = htonll(stp->bridge_id);
796 config.port_id = htons(p->port_id);
798 config.message_age = htons(0);
800 config.message_age = htons(stp->root_port->message_age_timer.value
801 + MESSAGE_AGE_INCREMENT);
803 config.max_age = htons(stp->max_age);
804 config.hello_time = htons(stp->hello_time);
805 config.forward_delay = htons(stp->forward_delay);
806 if (ntohs(config.message_age) < stp->max_age) {
807 p->topology_change_ack = false;
808 p->config_pending = false;
809 stp_send_bpdu(p, &config, sizeof config);
810 stp_start_timer(&p->hold_timer, 0);
816 stp_supersedes_port_info(const struct stp_port *p,
817 const struct stp_config_bpdu *config)
819 if (ntohll(config->root_id) != p->designated_root) {
820 return ntohll(config->root_id) < p->designated_root;
821 } else if (ntohl(config->root_path_cost) != p->designated_cost) {
822 return ntohl(config->root_path_cost) < p->designated_cost;
823 } else if (ntohll(config->bridge_id) != p->designated_bridge) {
824 return ntohll(config->bridge_id) < p->designated_bridge;
826 return (ntohll(config->bridge_id) != p->stp->bridge_id
827 || ntohs(config->port_id) <= p->designated_port);
832 stp_record_config_information(struct stp_port *p,
833 const struct stp_config_bpdu *config)
835 p->designated_root = ntohll(config->root_id);
836 p->designated_cost = ntohl(config->root_path_cost);
837 p->designated_bridge = ntohll(config->bridge_id);
838 p->designated_port = ntohs(config->port_id);
839 stp_start_timer(&p->message_age_timer, ntohs(config->message_age));
843 stp_record_config_timeout_values(struct stp *stp,
844 const struct stp_config_bpdu *config)
846 stp->max_age = ntohs(config->max_age);
847 stp->hello_time = ntohs(config->hello_time);
848 stp->forward_delay = ntohs(config->forward_delay);
849 stp->topology_change = config->flags & STP_CONFIG_TOPOLOGY_CHANGE;
853 stp_is_designated_port(const struct stp_port *p)
855 return (p->designated_bridge == p->stp->bridge_id
856 && p->designated_port == p->port_id);
860 stp_config_bpdu_generation(struct stp *stp)
864 FOR_EACH_ENABLED_PORT (p, stp) {
865 if (stp_is_designated_port(p)) {
866 stp_transmit_config(p);
872 stp_transmit_tcn(struct stp *stp)
874 struct stp_port *p = stp->root_port;
875 struct stp_tcn_bpdu tcn_bpdu;
879 tcn_bpdu.header.protocol_id = htons(STP_PROTOCOL_ID);
880 tcn_bpdu.header.protocol_version = STP_PROTOCOL_VERSION;
881 tcn_bpdu.header.bpdu_type = STP_TYPE_TCN;
882 stp_send_bpdu(p, &tcn_bpdu, sizeof tcn_bpdu);
886 stp_configuration_update(struct stp *stp)
888 stp_root_selection(stp);
889 stp_designated_port_selection(stp);
893 stp_supersedes_root(const struct stp_port *root, const struct stp_port *p)
895 int p_cost = p->designated_cost + p->path_cost;
896 int root_cost = root->designated_cost + root->path_cost;
898 if (p->designated_root != root->designated_root) {
899 return p->designated_root < root->designated_root;
900 } else if (p_cost != root_cost) {
901 return p_cost < root_cost;
902 } else if (p->designated_bridge != root->designated_bridge) {
903 return p->designated_bridge < root->designated_bridge;
904 } else if (p->designated_port != root->designated_port) {
905 return p->designated_port < root->designated_port;
907 return p->port_id < root->port_id;
912 stp_root_selection(struct stp *stp)
914 struct stp_port *p, *root;
917 FOR_EACH_ENABLED_PORT (p, stp) {
918 if (stp_is_designated_port(p)
919 || p->designated_root >= stp->bridge_id) {
922 if (root && !stp_supersedes_root(root, p)) {
927 stp->root_port = root;
929 stp->designated_root = stp->bridge_id;
930 stp->root_path_cost = 0;
932 stp->designated_root = root->designated_root;
933 stp->root_path_cost = root->designated_cost + root->path_cost;
938 stp_designated_port_selection(struct stp *stp)
942 FOR_EACH_ENABLED_PORT (p, stp) {
943 if (stp_is_designated_port(p)
944 || p->designated_root != stp->designated_root
945 || stp->root_path_cost < p->designated_cost
946 || (stp->root_path_cost == p->designated_cost
947 && (stp->bridge_id < p->designated_bridge
948 || (stp->bridge_id == p->designated_bridge
949 && p->port_id <= p->designated_port))))
951 stp_become_designated_port(p);
957 stp_become_designated_port(struct stp_port *p)
959 struct stp *stp = p->stp;
960 p->designated_root = stp->designated_root;
961 p->designated_cost = stp->root_path_cost;
962 p->designated_bridge = stp->bridge_id;
963 p->designated_port = p->port_id;
967 stp_port_state_selection(struct stp *stp)
971 FOR_EACH_ENABLED_PORT (p, stp) {
972 if (p == stp->root_port) {
973 p->config_pending = false;
974 p->topology_change_ack = false;
975 stp_make_forwarding(p);
976 } else if (stp_is_designated_port(p)) {
977 stp_stop_timer(&p->message_age_timer);
978 stp_make_forwarding(p);
980 p->config_pending = false;
981 p->topology_change_ack = false;
982 stp_make_blocking(p);
988 stp_make_forwarding(struct stp_port *p)
990 if (p->state == STP_BLOCKING) {
991 stp_set_port_state(p, STP_LISTENING);
992 stp_start_timer(&p->forward_delay_timer, 0);
997 stp_make_blocking(struct stp_port *p)
999 if (!(p->state & (STP_DISABLED | STP_BLOCKING))) {
1000 if (p->state & (STP_FORWARDING | STP_LEARNING)) {
1001 if (p->change_detection_enabled) {
1002 stp_topology_change_detection(p->stp);
1005 stp_set_port_state(p, STP_BLOCKING);
1006 stp_stop_timer(&p->forward_delay_timer);
1011 stp_set_port_state(struct stp_port *p, enum stp_state state)
1013 if (state != p->state && !p->state_changed) {
1014 p->state_changed = true;
1015 if (p < p->stp->first_changed_port) {
1016 p->stp->first_changed_port = p;
1023 stp_topology_change_detection(struct stp *stp)
1025 if (stp_is_root_bridge(stp)) {
1026 stp->topology_change = true;
1027 stp_start_timer(&stp->topology_change_timer, 0);
1028 } else if (!stp->topology_change_detected) {
1029 stp_transmit_tcn(stp);
1030 stp_start_timer(&stp->tcn_timer, 0);
1032 stp->topology_change_detected = true;
1036 stp_topology_change_acknowledged(struct stp *stp)
1038 stp->topology_change_detected = false;
1039 stp_stop_timer(&stp->tcn_timer);
1043 stp_acknowledge_topology_change(struct stp_port *p)
1045 p->topology_change_ack = true;
1046 stp_transmit_config(p);
1050 stp_received_config_bpdu(struct stp *stp, struct stp_port *p,
1051 const struct stp_config_bpdu *config)
1053 if (ntohs(config->message_age) >= ntohs(config->max_age)) {
1054 VLOG_WARN("%s: received config BPDU with message age (%u) greater "
1055 "than max age (%u)",
1057 ntohs(config->message_age), ntohs(config->max_age));
1060 if (p->state != STP_DISABLED) {
1061 bool root = stp_is_root_bridge(stp);
1062 if (stp_supersedes_port_info(p, config)) {
1063 stp_record_config_information(p, config);
1064 stp_configuration_update(stp);
1065 stp_port_state_selection(stp);
1066 if (!stp_is_root_bridge(stp) && root) {
1067 stp_stop_timer(&stp->hello_timer);
1068 if (stp->topology_change_detected) {
1069 stp_stop_timer(&stp->topology_change_timer);
1070 stp_transmit_tcn(stp);
1071 stp_start_timer(&stp->tcn_timer, 0);
1074 if (p == stp->root_port) {
1075 stp_record_config_timeout_values(stp, config);
1076 stp_config_bpdu_generation(stp);
1077 if (config->flags & STP_CONFIG_TOPOLOGY_CHANGE_ACK) {
1078 stp_topology_change_acknowledged(stp);
1081 } else if (stp_is_designated_port(p)) {
1082 stp_transmit_config(p);
1088 stp_received_tcn_bpdu(struct stp *stp, struct stp_port *p)
1090 if (p->state != STP_DISABLED) {
1091 if (stp_is_designated_port(p)) {
1092 stp_topology_change_detection(stp);
1093 stp_acknowledge_topology_change(p);
1099 stp_hello_timer_expiry(struct stp *stp)
1101 stp_config_bpdu_generation(stp);
1102 stp_start_timer(&stp->hello_timer, 0);
1106 stp_message_age_timer_expiry(struct stp_port *p)
1108 struct stp *stp = p->stp;
1109 bool root = stp_is_root_bridge(stp);
1110 stp_become_designated_port(p);
1111 stp_configuration_update(stp);
1112 stp_port_state_selection(stp);
1113 if (stp_is_root_bridge(stp) && !root) {
1114 stp->max_age = stp->bridge_max_age;
1115 stp->hello_time = stp->bridge_hello_time;
1116 stp->forward_delay = stp->bridge_forward_delay;
1117 stp_topology_change_detection(stp);
1118 stp_stop_timer(&stp->tcn_timer);
1119 stp_config_bpdu_generation(stp);
1120 stp_start_timer(&stp->hello_timer, 0);
1125 stp_is_designated_for_some_port(const struct stp *stp)
1127 const struct stp_port *p;
1129 FOR_EACH_ENABLED_PORT (p, stp) {
1130 if (p->designated_bridge == stp->bridge_id) {
1138 stp_forward_delay_timer_expiry(struct stp_port *p)
1140 if (p->state == STP_LISTENING) {
1141 stp_set_port_state(p, STP_LEARNING);
1142 stp_start_timer(&p->forward_delay_timer, 0);
1143 } else if (p->state == STP_LEARNING) {
1144 stp_set_port_state(p, STP_FORWARDING);
1145 if (stp_is_designated_for_some_port(p->stp)) {
1146 if (p->change_detection_enabled) {
1147 stp_topology_change_detection(p->stp);
1154 stp_tcn_timer_expiry(struct stp *stp)
1156 stp_transmit_tcn(stp);
1157 stp_start_timer(&stp->tcn_timer, 0);
1161 stp_topology_change_timer_expiry(struct stp *stp)
1163 stp->topology_change_detected = false;
1164 stp->topology_change = false;
1168 stp_hold_timer_expiry(struct stp_port *p)
1170 if (p->config_pending) {
1171 stp_transmit_config(p);
1176 stp_initialize_port(struct stp_port *p, enum stp_state state)
1178 assert(state & (STP_DISABLED | STP_BLOCKING));
1179 stp_become_designated_port(p);
1180 stp_set_port_state(p, state);
1181 p->topology_change_ack = false;
1182 p->config_pending = false;
1183 p->change_detection_enabled = true;
1185 stp_stop_timer(&p->message_age_timer);
1186 stp_stop_timer(&p->forward_delay_timer);
1187 stp_stop_timer(&p->hold_timer);
1191 stp_become_root_bridge(struct stp *stp)
1193 stp->max_age = stp->bridge_max_age;
1194 stp->hello_time = stp->bridge_hello_time;
1195 stp->forward_delay = stp->bridge_forward_delay;
1196 stp_topology_change_detection(stp);
1197 stp_stop_timer(&stp->tcn_timer);
1198 stp_config_bpdu_generation(stp);
1199 stp_start_timer(&stp->hello_timer, 0);
1203 stp_start_timer(struct stp_timer *timer, int value)
1205 timer->value = value;
1206 timer->active = true;
1210 stp_stop_timer(struct stp_timer *timer)
1212 timer->active = false;
1216 stp_timer_expired(struct stp_timer *timer, int elapsed, int timeout)
1218 if (timer->active) {
1219 timer->value += elapsed;
1220 if (timer->value >= timeout) {
1221 timer->active = false;
1228 /* Returns the number of whole STP timer ticks in 'ms' milliseconds. There
1229 * are 256 STP timer ticks per second. */
1233 return ms * 0x100 / 1000;
1236 /* Returns the number of leftover milliseconds when 'ms' is converted to STP
1239 ms_to_timer_remainder(int ms)
1241 return ms * 0x100 % 1000;
1244 /* Returns the number of whole milliseconds in 'timer' STP timer ticks. There
1245 * are 256 STP timer ticks per second. */
1247 timer_to_ms(int timer)
1249 return timer * 1000 / 0x100;
1253 clamp(int x, int min, int max)
1255 return x < min ? min : x > max ? max : x;
1259 stp_update_bridge_timers(struct stp *stp)
1263 ht = clamp(stp->rq_hello_time, 1000, 10000);
1264 ma = clamp(stp->rq_max_age, MAX(2 * (ht + 1000), 6000), 40000);
1265 fd = clamp(stp->rq_forward_delay, ma / 2 + 1000, 30000);
1267 stp->bridge_hello_time = ms_to_timer(ht);
1268 stp->bridge_max_age = ms_to_timer(ma);
1269 stp->bridge_forward_delay = ms_to_timer(fd);
1271 if (stp_is_root_bridge(stp)) {
1272 stp->max_age = stp->bridge_max_age;
1273 stp->hello_time = stp->bridge_hello_time;
1274 stp->forward_delay = stp->bridge_forward_delay;
1279 stp_send_bpdu(struct stp_port *p, const void *bpdu, size_t bpdu_size)
1281 struct eth_header *eth;
1282 struct llc_header *llc;
1286 pkt = ofpbuf_new(ETH_HEADER_LEN + LLC_HEADER_LEN + bpdu_size);
1287 pkt->l2 = eth = ofpbuf_put_zeros(pkt, sizeof *eth);
1288 llc = ofpbuf_put_zeros(pkt, sizeof *llc);
1289 pkt->l3 = ofpbuf_put(pkt, bpdu, bpdu_size);
1292 memcpy(eth->eth_dst, eth_addr_stp, ETH_ADDR_LEN);
1293 /* p->stp->send_bpdu() must fill in source address. */
1294 eth->eth_type = htons(pkt->size - ETH_HEADER_LEN);
1297 llc->llc_dsap = STP_LLC_DSAP;
1298 llc->llc_ssap = STP_LLC_SSAP;
1299 llc->llc_cntl = STP_LLC_CNTL;
1301 p->stp->send_bpdu(pkt, stp_port_no(p), p->stp->aux);