2 * Copyright (c) 2008, 2009 Nicira Networks.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 /* Based on sample implementation in 802.1D-1998. Above copyright and license
18 * applies to all modifications. */
21 #include <arpa/inet.h>
31 #define THIS_MODULE VLM_stp
33 /* Ethernet address used as the destination for STP frames. */
34 const uint8_t stp_eth_addr
[ETH_ADDR_LEN
]
35 = { 0x01, 0x80, 0xC2, 0x00, 0x00, 0x01 };
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 uint16_t 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 uint64_t root_id
; /* 8.5.1.1: Bridge believed to be root. */
58 uint32_t root_path_cost
; /* 8.5.1.2: Cost of path to root. */
59 uint64_t bridge_id
; /* 8.5.1.3: ID of transmitting bridge. */
60 uint16_t port_id
; /* 8.5.1.4: Port transmitting the BPDU. */
61 uint16_t message_age
; /* 8.5.1.5: Age of BPDU at tx time. */
62 uint16_t max_age
; /* 8.5.1.6: Timeout for received data. */
63 uint16_t hello_time
; /* 8.5.1.7: Time between BPDU generation. */
64 uint16_t 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 int port_id
; /* 8.5.5.1: Unique port identifier. */
81 enum stp_state state
; /* 8.5.5.2: Current state. */
82 int path_cost
; /* 8.5.5.3: Cost of tx/rx on this port. */
83 stp_identifier designated_root
; /* 8.5.5.4. */
84 int designated_cost
; /* 8.5.5.5: Path cost to root on port. */
85 stp_identifier designated_bridge
; /* 8.5.5.6. */
86 int designated_port
; /* 8.5.5.7: Port to send config msgs on. */
87 bool topology_change_ack
; /* 8.5.5.8: Flag for next config BPDU. */
88 bool config_pending
; /* 8.5.5.9: Send BPDU when hold expires? */
89 bool change_detection_enabled
; /* 8.5.5.10: Detect topology changes? */
91 struct stp_timer message_age_timer
; /* 8.5.6.1: Age of received info. */
92 struct stp_timer forward_delay_timer
; /* 8.5.6.2: State change timer. */
93 struct stp_timer hold_timer
; /* 8.5.6.3: BPDU rate limit timer. */
99 /* Static bridge data. */
100 char *name
; /* Human-readable name for log messages. */
101 stp_identifier bridge_id
; /* 8.5.3.7: This bridge. */
102 int max_age
; /* 8.5.3.4: Time to drop received data. */
103 int hello_time
; /* 8.5.3.5: Time between sending BPDUs. */
104 int forward_delay
; /* 8.5.3.6: Delay between state changes. */
105 int bridge_max_age
; /* 8.5.3.8: max_age when we're root. */
106 int bridge_hello_time
; /* 8.5.3.9: hello_time as root. */
107 int bridge_forward_delay
; /* 8.5.3.10: forward_delay as root. */
108 int rq_max_age
; /* User-requested max age, in ms. */
109 int rq_hello_time
; /* User-requested hello time, in ms. */
110 int rq_forward_delay
; /* User-requested forward delay, in ms. */
111 int elapsed_remainder
; /* Left-over msecs from last stp_tick(). */
113 /* Dynamic bridge data. */
114 stp_identifier designated_root
; /* 8.5.3.1: Bridge believed to be root. */
115 unsigned int root_path_cost
; /* 8.5.3.2: Cost of path to root. */
116 struct stp_port
*root_port
; /* 8.5.3.3: Lowest cost port to root. */
117 bool topology_change_detected
; /* 8.5.3.11: Detected a topology change? */
118 bool topology_change
; /* 8.5.3.12: Received topology change? */
121 struct stp_timer hello_timer
; /* 8.5.4.1: Hello timer. */
122 struct stp_timer tcn_timer
; /* 8.5.4.2: Topology change timer. */
123 struct stp_timer topology_change_timer
; /* 8.5.4.3. */
126 struct stp_port ports
[STP_MAX_PORTS
];
128 /* Interface to client. */
129 struct stp_port
*first_changed_port
;
130 void (*send_bpdu
)(struct ofpbuf
*bpdu
, int port_no
, void *aux
);
134 #define FOR_EACH_ENABLED_PORT(PORT, STP) \
135 for ((PORT) = stp_next_enabled_port((STP), (STP)->ports); \
137 (PORT) = stp_next_enabled_port((STP), (PORT) + 1))
138 static struct stp_port
*
139 stp_next_enabled_port(const struct stp
*stp
, const struct stp_port
*port
)
141 for (; port
< &stp
->ports
[ARRAY_SIZE(stp
->ports
)]; port
++) {
142 if (port
->state
!= STP_DISABLED
) {
143 return (struct stp_port
*) port
;
149 #define MESSAGE_AGE_INCREMENT 1
151 static void stp_transmit_config(struct stp_port
*);
152 static bool stp_supersedes_port_info(const struct stp_port
*,
153 const struct stp_config_bpdu
*);
154 static void stp_record_config_information(struct stp_port
*,
155 const struct stp_config_bpdu
*);
156 static void stp_record_config_timeout_values(struct stp
*,
157 const struct stp_config_bpdu
*);
158 static bool stp_is_designated_port(const struct stp_port
*);
159 static void stp_config_bpdu_generation(struct stp
*);
160 static void stp_transmit_tcn(struct stp
*);
161 static void stp_configuration_update(struct stp
*);
162 static bool stp_supersedes_root(const struct stp_port
*root
,
163 const struct stp_port
*);
164 static void stp_root_selection(struct stp
*);
165 static void stp_designated_port_selection(struct stp
*);
166 static void stp_become_designated_port(struct stp_port
*);
167 static void stp_port_state_selection(struct stp
*);
168 static void stp_make_forwarding(struct stp_port
*);
169 static void stp_make_blocking(struct stp_port
*);
170 static void stp_set_port_state(struct stp_port
*, enum stp_state
);
171 static void stp_topology_change_detection(struct stp
*);
172 static void stp_topology_change_acknowledged(struct stp
*);
173 static void stp_acknowledge_topology_change(struct stp_port
*);
174 static void stp_received_config_bpdu(struct stp
*, struct stp_port
*,
175 const struct stp_config_bpdu
*);
176 static void stp_received_tcn_bpdu(struct stp
*, struct stp_port
*);
177 static void stp_hello_timer_expiry(struct stp
*);
178 static void stp_message_age_timer_expiry(struct stp_port
*);
179 static bool stp_is_designated_for_some_port(const struct stp
*);
180 static void stp_forward_delay_timer_expiry(struct stp_port
*);
181 static void stp_tcn_timer_expiry(struct stp
*);
182 static void stp_topology_change_timer_expiry(struct stp
*);
183 static void stp_hold_timer_expiry(struct stp_port
*);
184 static void stp_initialize_port(struct stp_port
*, enum stp_state
);
185 static void stp_become_root_bridge(struct stp
*);
186 static void stp_update_bridge_timers(struct stp
*);
188 static int clamp(int x
, int min
, int max
);
189 static int ms_to_timer(int ms
);
190 static int ms_to_timer_remainder(int ms
);
191 static int timer_to_ms(int timer
);
192 static void stp_start_timer(struct stp_timer
*, int value
);
193 static void stp_stop_timer(struct stp_timer
*);
194 static bool stp_timer_expired(struct stp_timer
*, int elapsed
, int timeout
);
196 static void stp_send_bpdu(struct stp_port
*, const void *, size_t);
198 /* Creates and returns a new STP instance that initially has no ports enabled.
200 * 'bridge_id' should be a 48-bit MAC address as returned by
201 * eth_addr_to_uint64(). 'bridge_id' may also have a priority value in its top
202 * 16 bits; if those bits are set to 0, STP_DEFAULT_BRIDGE_PRIORITY is used.
203 * (This priority may be changed with stp_set_bridge_priority().)
205 * When the bridge needs to send out a BPDU, it calls 'send_bpdu'. This
206 * callback may be called from stp_tick() or stp_received_bpdu(). The
207 * arguments to 'send_bpdu' are an STP BPDU encapsulated in
210 stp_create(const char *name
, stp_identifier bridge_id
,
211 void (*send_bpdu
)(struct ofpbuf
*bpdu
, int port_no
, void *aux
),
217 stp
= xzalloc(sizeof *stp
);
218 stp
->name
= xstrdup(name
);
219 stp
->bridge_id
= bridge_id
;
220 if (!(stp
->bridge_id
>> 48)) {
221 stp
->bridge_id
|= (uint64_t) STP_DEFAULT_BRIDGE_PRIORITY
<< 48;
224 stp
->rq_max_age
= 6000;
225 stp
->rq_hello_time
= 2000;
226 stp
->rq_forward_delay
= 4000;
227 stp_update_bridge_timers(stp
);
228 stp
->max_age
= stp
->bridge_max_age
;
229 stp
->hello_time
= stp
->bridge_hello_time
;
230 stp
->forward_delay
= stp
->bridge_forward_delay
;
232 stp
->designated_root
= stp
->bridge_id
;
233 stp
->root_path_cost
= 0;
234 stp
->root_port
= NULL
;
235 stp
->topology_change_detected
= false;
236 stp
->topology_change
= false;
238 stp_stop_timer(&stp
->tcn_timer
);
239 stp_stop_timer(&stp
->topology_change_timer
);
240 stp_start_timer(&stp
->hello_timer
, 0);
242 stp
->send_bpdu
= send_bpdu
;
245 stp
->first_changed_port
= &stp
->ports
[ARRAY_SIZE(stp
->ports
)];
246 for (p
= stp
->ports
; p
< &stp
->ports
[ARRAY_SIZE(stp
->ports
)]; p
++) {
248 p
->port_id
= (stp_port_no(p
) + 1) | (STP_DEFAULT_PORT_PRIORITY
<< 8);
249 p
->path_cost
= 19; /* Recommended default for 100 Mb/s link. */
250 stp_initialize_port(p
, STP_DISABLED
);
255 /* Destroys 'stp'. */
257 stp_destroy(struct stp
*stp
)
262 /* Runs 'stp' given that 'ms' milliseconds have passed. */
264 stp_tick(struct stp
*stp
, int ms
)
269 /* Convert 'ms' to STP timer ticks. Preserve any leftover milliseconds
270 * from previous stp_tick() calls so that we don't lose STP ticks when we
271 * are called too frequently. */
272 ms
= clamp(ms
, 0, INT_MAX
- 1000) + stp
->elapsed_remainder
;
273 elapsed
= ms_to_timer(ms
);
274 stp
->elapsed_remainder
= ms_to_timer_remainder(ms
);
279 if (stp_timer_expired(&stp
->hello_timer
, elapsed
, stp
->hello_time
)) {
280 stp_hello_timer_expiry(stp
);
282 if (stp_timer_expired(&stp
->tcn_timer
, elapsed
, stp
->bridge_hello_time
)) {
283 stp_tcn_timer_expiry(stp
);
285 if (stp_timer_expired(&stp
->topology_change_timer
, elapsed
,
286 stp
->max_age
+ stp
->forward_delay
)) {
287 stp_topology_change_timer_expiry(stp
);
289 FOR_EACH_ENABLED_PORT (p
, stp
) {
290 if (stp_timer_expired(&p
->message_age_timer
, elapsed
, stp
->max_age
)) {
291 stp_message_age_timer_expiry(p
);
294 FOR_EACH_ENABLED_PORT (p
, stp
) {
295 if (stp_timer_expired(&p
->forward_delay_timer
, elapsed
,
296 stp
->forward_delay
)) {
297 stp_forward_delay_timer_expiry(p
);
299 if (stp_timer_expired(&p
->hold_timer
, elapsed
, ms_to_timer(1000))) {
300 stp_hold_timer_expiry(p
);
306 set_bridge_id(struct stp
*stp
, stp_identifier new_bridge_id
)
308 if (new_bridge_id
!= stp
->bridge_id
) {
312 root
= stp_is_root_bridge(stp
);
313 FOR_EACH_ENABLED_PORT (p
, stp
) {
314 if (stp_is_designated_port(p
)) {
315 p
->designated_bridge
= new_bridge_id
;
318 stp
->bridge_id
= new_bridge_id
;
319 stp_configuration_update(stp
);
320 stp_port_state_selection(stp
);
321 if (stp_is_root_bridge(stp
) && !root
) {
322 stp_become_root_bridge(stp
);
328 stp_set_bridge_id(struct stp
*stp
, stp_identifier bridge_id
)
330 const uint64_t mac_bits
= (UINT64_C(1) << 48) - 1;
331 const uint64_t pri_bits
= ~mac_bits
;
332 set_bridge_id(stp
, (stp
->bridge_id
& pri_bits
) | (bridge_id
& mac_bits
));
336 stp_set_bridge_priority(struct stp
*stp
, uint16_t new_priority
)
338 const uint64_t mac_bits
= (UINT64_C(1) << 48) - 1;
339 set_bridge_id(stp
, ((stp
->bridge_id
& mac_bits
)
340 | ((uint64_t) new_priority
<< 48)));
343 /* Sets the desired hello time for 'stp' to 'ms', in milliseconds. The actual
344 * hello time is clamped to the range of 1 to 10 seconds and subject to the
345 * relationship (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge
346 * hello time is only used when 'stp' is the root bridge. */
348 stp_set_hello_time(struct stp
*stp
, int ms
)
350 stp
->rq_hello_time
= ms
;
351 stp_update_bridge_timers(stp
);
354 /* Sets the desired max age for 'stp' to 'ms', in milliseconds. The actual max
355 * age is clamped to the range of 6 to 40 seconds and subject to the
356 * relationships (2 * (bridge_forward_delay - 1 s) >= bridge_max_age) and
357 * (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge max age is
358 * only used when 'stp' is the root bridge. */
360 stp_set_max_age(struct stp
*stp
, int ms
)
362 stp
->rq_max_age
= ms
;
363 stp_update_bridge_timers(stp
);
366 /* Sets the desired forward delay for 'stp' to 'ms', in milliseconds. The
367 * actual forward delay is clamped to the range of 4 to 30 seconds and subject
368 * to the relationship (2 * (bridge_forward_delay - 1 s) >= bridge_max_age).
369 * The bridge forward delay is only used when 'stp' is the root bridge. */
371 stp_set_forward_delay(struct stp
*stp
, int ms
)
373 stp
->rq_forward_delay
= ms
;
374 stp_update_bridge_timers(stp
);
377 /* Returns the name given to 'stp' in the call to stp_create(). */
379 stp_get_name(const struct stp
*stp
)
384 /* Returns the bridge ID for 'stp'. */
386 stp_get_bridge_id(const struct stp
*stp
)
388 return stp
->bridge_id
;
391 /* Returns the bridge ID of the bridge currently believed to be the root. */
393 stp_get_designated_root(const struct stp
*stp
)
395 return stp
->designated_root
;
398 /* Returns true if 'stp' believes itself to the be root of the spanning tree,
399 * false otherwise. */
401 stp_is_root_bridge(const struct stp
*stp
)
403 return stp
->bridge_id
== stp
->designated_root
;
406 /* Returns the cost of the path from 'stp' to the root of the spanning tree. */
408 stp_get_root_path_cost(const struct stp
*stp
)
410 return stp
->root_path_cost
;
413 /* Returns the bridge hello time, in ms. The returned value is not necessarily
414 * the value passed to stp_set_hello_time(): it is clamped to the valid range
415 * and quantized to the STP timer resolution. */
417 stp_get_hello_time(const struct stp
*stp
)
419 return timer_to_ms(stp
->bridge_hello_time
);
422 /* Returns the bridge max age, in ms. The returned value is not necessarily
423 * the value passed to stp_set_max_age(): it is clamped to the valid range,
424 * quantized to the STP timer resolution, and adjusted to match the constraints
425 * due to the hello time. */
427 stp_get_max_age(const struct stp
*stp
)
429 return timer_to_ms(stp
->bridge_max_age
);
432 /* Returns the bridge forward delay, in ms. The returned value is not
433 * necessarily the value passed to stp_set_forward_delay(): it is clamped to
434 * the valid range, quantized to the STP timer resolution, and adjusted to
435 * match the constraints due to the forward delay. */
437 stp_get_forward_delay(const struct stp
*stp
)
439 return timer_to_ms(stp
->bridge_forward_delay
);
442 /* Returns the port in 'stp' with index 'port_no', which must be between 0 and
445 stp_get_port(struct stp
*stp
, int port_no
)
447 assert(port_no
>= 0 && port_no
< ARRAY_SIZE(stp
->ports
));
448 return &stp
->ports
[port_no
];
451 /* Returns the port connecting 'stp' to the root bridge, or a null pointer if
452 * there is no such port. */
454 stp_get_root_port(struct stp
*stp
)
456 return stp
->root_port
;
459 /* Finds a port whose state has changed. If successful, stores the port whose
460 * state changed in '*portp' and returns true. If no port has changed, stores
461 * NULL in '*portp' and returns false. */
463 stp_get_changed_port(struct stp
*stp
, struct stp_port
**portp
)
465 struct stp_port
*end
= &stp
->ports
[ARRAY_SIZE(stp
->ports
)];
468 for (p
= stp
->first_changed_port
; p
< end
; p
++) {
469 if (p
->state_changed
) {
470 p
->state_changed
= false;
471 stp
->first_changed_port
= p
+ 1;
476 stp
->first_changed_port
= end
;
481 /* Returns the name for the given 'state' (for use in debugging and log
484 stp_state_name(enum stp_state state
)
502 /* Returns true if 'state' is one in which packets received on a port should
503 * be forwarded, false otherwise.
505 * Returns true if 'state' is STP_DISABLED, since presumably in that case the
506 * port should still work, just not have STP applied to it. */
508 stp_forward_in_state(enum stp_state state
)
510 return (state
& (STP_DISABLED
| STP_FORWARDING
)) != 0;
513 /* Returns true if 'state' is one in which MAC learning should be done on
514 * packets received on a port, false otherwise.
516 * Returns true if 'state' is STP_DISABLED, since presumably in that case the
517 * port should still work, just not have STP applied to it. */
519 stp_learn_in_state(enum stp_state state
)
521 return (state
& (STP_DISABLED
| STP_LEARNING
| STP_FORWARDING
)) != 0;
524 /* Notifies the STP entity that bridge protocol data unit 'bpdu', which is
525 * 'bpdu_size' bytes in length, was received on port 'p'.
527 * This function may call the 'send_bpdu' function provided to stp_create(). */
529 stp_received_bpdu(struct stp_port
*p
, const void *bpdu
, size_t bpdu_size
)
531 struct stp
*stp
= p
->stp
;
532 const struct stp_bpdu_header
*header
;
534 if (p
->state
== STP_DISABLED
) {
538 if (bpdu_size
< sizeof(struct stp_bpdu_header
)) {
539 VLOG_WARN("%s: received runt %zu-byte BPDU", stp
->name
, bpdu_size
);
544 if (header
->protocol_id
!= htons(STP_PROTOCOL_ID
)) {
545 VLOG_WARN("%s: received BPDU with unexpected protocol ID %"PRIu16
,
546 stp
->name
, ntohs(header
->protocol_id
));
549 if (header
->protocol_version
!= STP_PROTOCOL_VERSION
) {
550 VLOG_DBG("%s: received BPDU with unexpected protocol version %"PRIu8
,
551 stp
->name
, header
->protocol_version
);
554 switch (header
->bpdu_type
) {
555 case STP_TYPE_CONFIG
:
556 if (bpdu_size
< sizeof(struct stp_config_bpdu
)) {
557 VLOG_WARN("%s: received config BPDU with invalid size %zu",
558 stp
->name
, bpdu_size
);
561 stp_received_config_bpdu(stp
, p
, bpdu
);
565 if (bpdu_size
!= sizeof(struct stp_tcn_bpdu
)) {
566 VLOG_WARN("%s: received TCN BPDU with invalid size %zu",
567 stp
->name
, bpdu_size
);
570 stp_received_tcn_bpdu(stp
, p
);
574 VLOG_WARN("%s: received BPDU of unexpected type %"PRIu8
,
575 stp
->name
, header
->bpdu_type
);
580 /* Returns the STP entity in which 'p' is nested. */
582 stp_port_get_stp(struct stp_port
*p
)
587 /* Returns the index of port 'p' within its bridge. */
589 stp_port_no(const struct stp_port
*p
)
591 struct stp
*stp
= p
->stp
;
592 assert(p
>= stp
->ports
&& p
< &stp
->ports
[ARRAY_SIZE(stp
->ports
)]);
593 return p
- stp
->ports
;
596 /* Returns the state of port 'p'. */
598 stp_port_get_state(const struct stp_port
*p
)
603 /* Disables STP on port 'p'. */
605 stp_port_disable(struct stp_port
*p
)
607 struct stp
*stp
= p
->stp
;
608 if (p
->state
!= STP_DISABLED
) {
609 bool root
= stp_is_root_bridge(stp
);
610 stp_become_designated_port(p
);
611 stp_set_port_state(p
, STP_DISABLED
);
612 p
->topology_change_ack
= false;
613 p
->config_pending
= false;
614 stp_stop_timer(&p
->message_age_timer
);
615 stp_stop_timer(&p
->forward_delay_timer
);
616 stp_configuration_update(stp
);
617 stp_port_state_selection(stp
);
618 if (stp_is_root_bridge(stp
) && !root
) {
619 stp_become_root_bridge(stp
);
624 /* Enables STP on port 'p'. The port will initially be in "blocking" state. */
626 stp_port_enable(struct stp_port
*p
)
628 if (p
->state
== STP_DISABLED
) {
629 stp_initialize_port(p
, STP_BLOCKING
);
630 stp_port_state_selection(p
->stp
);
634 /* Sets the priority of port 'p' to 'new_priority'. Lower numerical values
635 * are interpreted as higher priorities. */
637 stp_port_set_priority(struct stp_port
*p
, uint8_t new_priority
)
639 uint16_t new_port_id
= (p
->port_id
& 0xff) | (new_priority
<< 8);
640 if (p
->port_id
!= new_port_id
) {
641 struct stp
*stp
= p
->stp
;
642 if (stp_is_designated_port(p
)) {
643 p
->designated_port
= new_port_id
;
645 p
->port_id
= new_port_id
;
646 if (stp
->bridge_id
== p
->designated_bridge
647 && p
->port_id
< p
->designated_port
) {
648 stp_become_designated_port(p
);
649 stp_port_state_selection(stp
);
654 /* Sets the path cost of port 'p' to 'path_cost'. Lower values are generally
655 * used to indicate faster links. Use stp_port_set_speed() to automatically
656 * generate a default path cost from a link speed. */
658 stp_port_set_path_cost(struct stp_port
*p
, uint16_t path_cost
)
660 if (p
->path_cost
!= path_cost
) {
661 struct stp
*stp
= p
->stp
;
662 p
->path_cost
= path_cost
;
663 stp_configuration_update(stp
);
664 stp_port_state_selection(stp
);
668 /* Sets the path cost of port 'p' based on 'speed' (measured in Mb/s). */
670 stp_port_set_speed(struct stp_port
*p
, unsigned int speed
)
672 stp_port_set_path_cost(p
, (speed
>= 10000 ? 2 /* 10 Gb/s. */
673 : speed
>= 1000 ? 4 /* 1 Gb/s. */
674 : speed
>= 100 ? 19 /* 100 Mb/s. */
675 : speed
>= 16 ? 62 /* 16 Mb/s. */
676 : speed
>= 10 ? 100 /* 10 Mb/s. */
677 : speed
>= 4 ? 250 /* 4 Mb/s. */
678 : 19)); /* 100 Mb/s (guess). */
681 /* Enables topology change detection on port 'p'. */
683 stp_port_enable_change_detection(struct stp_port
*p
)
685 p
->change_detection_enabled
= true;
688 /* Disables topology change detection on port 'p'. */
690 stp_port_disable_change_detection(struct stp_port
*p
)
692 p
->change_detection_enabled
= false;
696 stp_transmit_config(struct stp_port
*p
)
698 struct stp
*stp
= p
->stp
;
699 bool root
= stp_is_root_bridge(stp
);
700 if (!root
&& !stp
->root_port
) {
703 if (p
->hold_timer
.active
) {
704 p
->config_pending
= true;
706 struct stp_config_bpdu config
;
707 memset(&config
, 0, sizeof config
);
708 config
.header
.protocol_id
= htons(STP_PROTOCOL_ID
);
709 config
.header
.protocol_version
= STP_PROTOCOL_VERSION
;
710 config
.header
.bpdu_type
= STP_TYPE_CONFIG
;
712 if (p
->topology_change_ack
) {
713 config
.flags
|= htons(STP_CONFIG_TOPOLOGY_CHANGE_ACK
);
715 if (stp
->topology_change
) {
716 config
.flags
|= htons(STP_CONFIG_TOPOLOGY_CHANGE
);
718 config
.root_id
= htonll(stp
->designated_root
);
719 config
.root_path_cost
= htonl(stp
->root_path_cost
);
720 config
.bridge_id
= htonll(stp
->bridge_id
);
721 config
.port_id
= htons(p
->port_id
);
723 config
.message_age
= htons(0);
725 config
.message_age
= htons(stp
->root_port
->message_age_timer
.value
726 + MESSAGE_AGE_INCREMENT
);
728 config
.max_age
= htons(stp
->max_age
);
729 config
.hello_time
= htons(stp
->hello_time
);
730 config
.forward_delay
= htons(stp
->forward_delay
);
731 if (ntohs(config
.message_age
) < stp
->max_age
) {
732 p
->topology_change_ack
= false;
733 p
->config_pending
= false;
734 stp_send_bpdu(p
, &config
, sizeof config
);
735 stp_start_timer(&p
->hold_timer
, 0);
741 stp_supersedes_port_info(const struct stp_port
*p
,
742 const struct stp_config_bpdu
*config
)
744 if (ntohll(config
->root_id
) != p
->designated_root
) {
745 return ntohll(config
->root_id
) < p
->designated_root
;
746 } else if (ntohl(config
->root_path_cost
) != p
->designated_cost
) {
747 return ntohl(config
->root_path_cost
) < p
->designated_cost
;
748 } else if (ntohll(config
->bridge_id
) != p
->designated_bridge
) {
749 return ntohll(config
->bridge_id
) < p
->designated_bridge
;
751 return (ntohll(config
->bridge_id
) != p
->stp
->bridge_id
752 || ntohs(config
->port_id
) <= p
->designated_port
);
757 stp_record_config_information(struct stp_port
*p
,
758 const struct stp_config_bpdu
*config
)
760 p
->designated_root
= ntohll(config
->root_id
);
761 p
->designated_cost
= ntohl(config
->root_path_cost
);
762 p
->designated_bridge
= ntohll(config
->bridge_id
);
763 p
->designated_port
= ntohs(config
->port_id
);
764 stp_start_timer(&p
->message_age_timer
, ntohs(config
->message_age
));
768 stp_record_config_timeout_values(struct stp
*stp
,
769 const struct stp_config_bpdu
*config
)
771 stp
->max_age
= ntohs(config
->max_age
);
772 stp
->hello_time
= ntohs(config
->hello_time
);
773 stp
->forward_delay
= ntohs(config
->forward_delay
);
774 stp
->topology_change
= config
->flags
& htons(STP_CONFIG_TOPOLOGY_CHANGE
);
778 stp_is_designated_port(const struct stp_port
*p
)
780 return (p
->designated_bridge
== p
->stp
->bridge_id
781 && p
->designated_port
== p
->port_id
);
785 stp_config_bpdu_generation(struct stp
*stp
)
789 FOR_EACH_ENABLED_PORT (p
, stp
) {
790 if (stp_is_designated_port(p
)) {
791 stp_transmit_config(p
);
797 stp_transmit_tcn(struct stp
*stp
)
799 struct stp_port
*p
= stp
->root_port
;
800 struct stp_tcn_bpdu tcn_bpdu
;
804 tcn_bpdu
.header
.protocol_id
= htons(STP_PROTOCOL_ID
);
805 tcn_bpdu
.header
.protocol_version
= STP_PROTOCOL_VERSION
;
806 tcn_bpdu
.header
.bpdu_type
= STP_TYPE_TCN
;
807 stp_send_bpdu(p
, &tcn_bpdu
, sizeof tcn_bpdu
);
811 stp_configuration_update(struct stp
*stp
)
813 stp_root_selection(stp
);
814 stp_designated_port_selection(stp
);
818 stp_supersedes_root(const struct stp_port
*root
, const struct stp_port
*p
)
820 int p_cost
= p
->designated_cost
+ p
->path_cost
;
821 int root_cost
= root
->designated_cost
+ root
->path_cost
;
823 if (p
->designated_root
!= root
->designated_root
) {
824 return p
->designated_root
< root
->designated_root
;
825 } else if (p_cost
!= root_cost
) {
826 return p_cost
< root_cost
;
827 } else if (p
->designated_bridge
!= root
->designated_bridge
) {
828 return p
->designated_bridge
< root
->designated_bridge
;
829 } else if (p
->designated_port
!= root
->designated_port
) {
830 return p
->designated_port
< root
->designated_port
;
832 return p
->port_id
< root
->port_id
;
837 stp_root_selection(struct stp
*stp
)
839 struct stp_port
*p
, *root
;
842 FOR_EACH_ENABLED_PORT (p
, stp
) {
843 if (stp_is_designated_port(p
)
844 || p
->designated_root
>= stp
->bridge_id
) {
847 if (root
&& !stp_supersedes_root(root
, p
)) {
852 stp
->root_port
= root
;
854 stp
->designated_root
= stp
->bridge_id
;
855 stp
->root_path_cost
= 0;
857 stp
->designated_root
= root
->designated_root
;
858 stp
->root_path_cost
= root
->designated_cost
+ root
->path_cost
;
863 stp_designated_port_selection(struct stp
*stp
)
867 FOR_EACH_ENABLED_PORT (p
, stp
) {
868 if (stp_is_designated_port(p
)
869 || p
->designated_root
!= stp
->designated_root
870 || stp
->root_path_cost
< p
->designated_cost
871 || (stp
->root_path_cost
== p
->designated_cost
872 && (stp
->bridge_id
< p
->designated_bridge
873 || (stp
->bridge_id
== p
->designated_bridge
874 && p
->port_id
<= p
->designated_port
))))
876 stp_become_designated_port(p
);
882 stp_become_designated_port(struct stp_port
*p
)
884 struct stp
*stp
= p
->stp
;
885 p
->designated_root
= stp
->designated_root
;
886 p
->designated_cost
= stp
->root_path_cost
;
887 p
->designated_bridge
= stp
->bridge_id
;
888 p
->designated_port
= p
->port_id
;
892 stp_port_state_selection(struct stp
*stp
)
896 FOR_EACH_ENABLED_PORT (p
, stp
) {
897 if (p
== stp
->root_port
) {
898 p
->config_pending
= false;
899 p
->topology_change_ack
= false;
900 stp_make_forwarding(p
);
901 } else if (stp_is_designated_port(p
)) {
902 stp_stop_timer(&p
->message_age_timer
);
903 stp_make_forwarding(p
);
905 p
->config_pending
= false;
906 p
->topology_change_ack
= false;
907 stp_make_blocking(p
);
913 stp_make_forwarding(struct stp_port
*p
)
915 if (p
->state
== STP_BLOCKING
) {
916 stp_set_port_state(p
, STP_LISTENING
);
917 stp_start_timer(&p
->forward_delay_timer
, 0);
922 stp_make_blocking(struct stp_port
*p
)
924 if (!(p
->state
& (STP_DISABLED
| STP_BLOCKING
))) {
925 if (p
->state
& (STP_FORWARDING
| STP_LEARNING
)) {
926 if (p
->change_detection_enabled
) {
927 stp_topology_change_detection(p
->stp
);
930 stp_set_port_state(p
, STP_BLOCKING
);
931 stp_stop_timer(&p
->forward_delay_timer
);
936 stp_set_port_state(struct stp_port
*p
, enum stp_state state
)
938 if (state
!= p
->state
&& !p
->state_changed
) {
939 p
->state_changed
= true;
940 if (p
< p
->stp
->first_changed_port
) {
941 p
->stp
->first_changed_port
= p
;
948 stp_topology_change_detection(struct stp
*stp
)
950 if (stp_is_root_bridge(stp
)) {
951 stp
->topology_change
= true;
952 stp_start_timer(&stp
->topology_change_timer
, 0);
953 } else if (!stp
->topology_change_detected
) {
954 stp_transmit_tcn(stp
);
955 stp_start_timer(&stp
->tcn_timer
, 0);
957 stp
->topology_change_detected
= true;
961 stp_topology_change_acknowledged(struct stp
*stp
)
963 stp
->topology_change_detected
= false;
964 stp_stop_timer(&stp
->tcn_timer
);
968 stp_acknowledge_topology_change(struct stp_port
*p
)
970 p
->topology_change_ack
= true;
971 stp_transmit_config(p
);
975 stp_received_config_bpdu(struct stp
*stp
, struct stp_port
*p
,
976 const struct stp_config_bpdu
*config
)
978 if (ntohs(config
->message_age
) >= ntohs(config
->max_age
)) {
979 VLOG_WARN("%s: received config BPDU with message age (%u) greater "
982 ntohs(config
->message_age
), ntohs(config
->max_age
));
985 if (p
->state
!= STP_DISABLED
) {
986 bool root
= stp_is_root_bridge(stp
);
987 if (stp_supersedes_port_info(p
, config
)) {
988 stp_record_config_information(p
, config
);
989 stp_configuration_update(stp
);
990 stp_port_state_selection(stp
);
991 if (!stp_is_root_bridge(stp
) && root
) {
992 stp_stop_timer(&stp
->hello_timer
);
993 if (stp
->topology_change_detected
) {
994 stp_stop_timer(&stp
->topology_change_timer
);
995 stp_transmit_tcn(stp
);
996 stp_start_timer(&stp
->tcn_timer
, 0);
999 if (p
== stp
->root_port
) {
1000 stp_record_config_timeout_values(stp
, config
);
1001 stp_config_bpdu_generation(stp
);
1002 if (config
->flags
& htons(STP_CONFIG_TOPOLOGY_CHANGE_ACK
)) {
1003 stp_topology_change_acknowledged(stp
);
1006 } else if (stp_is_designated_port(p
)) {
1007 stp_transmit_config(p
);
1013 stp_received_tcn_bpdu(struct stp
*stp
, struct stp_port
*p
)
1015 if (p
->state
!= STP_DISABLED
) {
1016 if (stp_is_designated_port(p
)) {
1017 stp_topology_change_detection(stp
);
1018 stp_acknowledge_topology_change(p
);
1024 stp_hello_timer_expiry(struct stp
*stp
)
1026 stp_config_bpdu_generation(stp
);
1027 stp_start_timer(&stp
->hello_timer
, 0);
1031 stp_message_age_timer_expiry(struct stp_port
*p
)
1033 struct stp
*stp
= p
->stp
;
1034 bool root
= stp_is_root_bridge(stp
);
1035 stp_become_designated_port(p
);
1036 stp_configuration_update(stp
);
1037 stp_port_state_selection(stp
);
1038 if (stp_is_root_bridge(stp
) && !root
) {
1039 stp
->max_age
= stp
->bridge_max_age
;
1040 stp
->hello_time
= stp
->bridge_hello_time
;
1041 stp
->forward_delay
= stp
->bridge_forward_delay
;
1042 stp_topology_change_detection(stp
);
1043 stp_stop_timer(&stp
->tcn_timer
);
1044 stp_config_bpdu_generation(stp
);
1045 stp_start_timer(&stp
->hello_timer
, 0);
1050 stp_is_designated_for_some_port(const struct stp
*stp
)
1052 const struct stp_port
*p
;
1054 FOR_EACH_ENABLED_PORT (p
, stp
) {
1055 if (p
->designated_bridge
== stp
->bridge_id
) {
1063 stp_forward_delay_timer_expiry(struct stp_port
*p
)
1065 if (p
->state
== STP_LISTENING
) {
1066 stp_set_port_state(p
, STP_LEARNING
);
1067 stp_start_timer(&p
->forward_delay_timer
, 0);
1068 } else if (p
->state
== STP_LEARNING
) {
1069 stp_set_port_state(p
, STP_FORWARDING
);
1070 if (stp_is_designated_for_some_port(p
->stp
)) {
1071 if (p
->change_detection_enabled
) {
1072 stp_topology_change_detection(p
->stp
);
1079 stp_tcn_timer_expiry(struct stp
*stp
)
1081 stp_transmit_tcn(stp
);
1082 stp_start_timer(&stp
->tcn_timer
, 0);
1086 stp_topology_change_timer_expiry(struct stp
*stp
)
1088 stp
->topology_change_detected
= false;
1089 stp
->topology_change
= false;
1093 stp_hold_timer_expiry(struct stp_port
*p
)
1095 if (p
->config_pending
) {
1096 stp_transmit_config(p
);
1101 stp_initialize_port(struct stp_port
*p
, enum stp_state state
)
1103 assert(state
& (STP_DISABLED
| STP_BLOCKING
));
1104 stp_become_designated_port(p
);
1105 stp_set_port_state(p
, state
);
1106 p
->topology_change_ack
= false;
1107 p
->config_pending
= false;
1108 p
->change_detection_enabled
= true;
1109 stp_stop_timer(&p
->message_age_timer
);
1110 stp_stop_timer(&p
->forward_delay_timer
);
1111 stp_stop_timer(&p
->hold_timer
);
1115 stp_become_root_bridge(struct stp
*stp
)
1117 stp
->max_age
= stp
->bridge_max_age
;
1118 stp
->hello_time
= stp
->bridge_hello_time
;
1119 stp
->forward_delay
= stp
->bridge_forward_delay
;
1120 stp_topology_change_detection(stp
);
1121 stp_stop_timer(&stp
->tcn_timer
);
1122 stp_config_bpdu_generation(stp
);
1123 stp_start_timer(&stp
->hello_timer
, 0);
1127 stp_start_timer(struct stp_timer
*timer
, int value
)
1129 timer
->value
= value
;
1130 timer
->active
= true;
1134 stp_stop_timer(struct stp_timer
*timer
)
1136 timer
->active
= false;
1140 stp_timer_expired(struct stp_timer
*timer
, int elapsed
, int timeout
)
1142 if (timer
->active
) {
1143 timer
->value
+= elapsed
;
1144 if (timer
->value
>= timeout
) {
1145 timer
->active
= false;
1152 /* Returns the number of whole STP timer ticks in 'ms' milliseconds. There
1153 * are 256 STP timer ticks per second. */
1157 return ms
* 0x100 / 1000;
1160 /* Returns the number of leftover milliseconds when 'ms' is converted to STP
1163 ms_to_timer_remainder(int ms
)
1165 return ms
* 0x100 % 1000;
1168 /* Returns the number of whole milliseconds in 'timer' STP timer ticks. There
1169 * are 256 STP timer ticks per second. */
1171 timer_to_ms(int timer
)
1173 return timer
* 1000 / 0x100;
1177 clamp(int x
, int min
, int max
)
1179 return x
< min
? min
: x
> max
? max
: x
;
1183 stp_update_bridge_timers(struct stp
*stp
)
1187 ht
= clamp(stp
->rq_hello_time
, 1000, 10000);
1188 ma
= clamp(stp
->rq_max_age
, MAX(2 * (ht
+ 1000), 6000), 40000);
1189 fd
= clamp(stp
->rq_forward_delay
, ma
/ 2 + 1000, 30000);
1191 stp
->bridge_hello_time
= ms_to_timer(ht
);
1192 stp
->bridge_max_age
= ms_to_timer(ma
);
1193 stp
->bridge_forward_delay
= ms_to_timer(fd
);
1195 if (stp_is_root_bridge(stp
)) {
1196 stp
->max_age
= stp
->bridge_max_age
;
1197 stp
->hello_time
= stp
->bridge_hello_time
;
1198 stp
->forward_delay
= stp
->bridge_forward_delay
;
1203 stp_send_bpdu(struct stp_port
*p
, const void *bpdu
, size_t bpdu_size
)
1205 struct eth_header
*eth
;
1206 struct llc_header
*llc
;
1210 pkt
= ofpbuf_new(ETH_HEADER_LEN
+ LLC_HEADER_LEN
+ bpdu_size
);
1211 pkt
->l2
= eth
= ofpbuf_put_zeros(pkt
, sizeof *eth
);
1212 llc
= ofpbuf_put_zeros(pkt
, sizeof *llc
);
1213 pkt
->l3
= ofpbuf_put(pkt
, bpdu
, bpdu_size
);
1216 memcpy(eth
->eth_dst
, stp_eth_addr
, ETH_ADDR_LEN
);
1217 /* p->stp->send_bpdu() must fill in source address. */
1218 eth
->eth_type
= htons(pkt
->size
- ETH_HEADER_LEN
);
1221 llc
->llc_dsap
= STP_LLC_DSAP
;
1222 llc
->llc_ssap
= STP_LLC_SSAP
;
1223 llc
->llc_cntl
= STP_LLC_CNTL
;
1225 p
->stp
->send_bpdu(pkt
, stp_port_no(p
), p
->stp
->aux
);