2 * OSPF version 2 Interface State Machine
3 * From RFC2328 [OSPF Version 2]
4 * Copyright (C) 1999, 2000 Toshiaki Takada
6 * This file is part of GNU Zebra.
8 * GNU Zebra is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License as published by the
10 * Free Software Foundation; either version 2, or (at your option) any
13 * GNU Zebra is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License along
19 * with this program; see the file COPYING; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
32 #include "ospfd/ospfd.h"
33 #include "ospfd/ospf_interface.h"
34 #include "ospfd/ospf_ism.h"
35 #include "ospfd/ospf_asbr.h"
36 #include "ospfd/ospf_lsa.h"
37 #include "ospfd/ospf_lsdb.h"
38 #include "ospfd/ospf_neighbor.h"
39 #include "ospfd/ospf_nsm.h"
40 #include "ospfd/ospf_network.h"
41 #include "ospfd/ospf_dump.h"
42 #include "ospfd/ospf_packet.h"
43 #include "ospfd/ospf_flood.h"
44 #include "ospfd/ospf_abr.h"
46 DEFINE_HOOK(ospf_ism_change
,
47 (struct ospf_interface
* oi
, int state
, int oldstate
),
48 (oi
, state
, oldstate
));
50 /* elect DR and BDR. Refer to RFC2319 section 9.4 */
51 static struct ospf_neighbor
*ospf_dr_election_sub(struct list
*routers
)
53 struct listnode
*node
;
54 struct ospf_neighbor
*nbr
, *max
= NULL
;
56 /* Choose highest router priority.
57 In case of tie, choose highest Router ID. */
58 for (ALL_LIST_ELEMENTS_RO(routers
, node
, nbr
)) {
62 if (max
->priority
< nbr
->priority
)
64 else if (max
->priority
== nbr
->priority
)
65 if (IPV4_ADDR_CMP(&max
->router_id
,
75 static struct ospf_neighbor
*ospf_elect_dr(struct ospf_interface
*oi
,
79 struct listnode
*node
;
80 struct ospf_neighbor
*nbr
, *dr
= NULL
, *bdr
= NULL
;
84 /* Add neighbors to the list. */
85 for (ALL_LIST_ELEMENTS_RO(el_list
, node
, nbr
)) {
86 /* neighbor declared to be DR. */
88 listnode_add(dr_list
, nbr
);
90 /* Preserve neighbor BDR. */
91 if (IPV4_ADDR_SAME(&BDR(oi
), &nbr
->address
.u
.prefix4
))
95 /* Elect Designated Router. */
96 if (listcount(dr_list
) > 0)
97 dr
= ospf_dr_election_sub(dr_list
);
101 /* Set DR to interface. */
103 DR(oi
) = dr
->address
.u
.prefix4
;
107 list_delete(&dr_list
);
112 static struct ospf_neighbor
*ospf_elect_bdr(struct ospf_interface
*oi
,
113 struct list
*el_list
)
115 struct list
*bdr_list
, *no_dr_list
;
116 struct listnode
*node
;
117 struct ospf_neighbor
*nbr
, *bdr
= NULL
;
119 bdr_list
= list_new();
120 no_dr_list
= list_new();
122 /* Add neighbors to the list. */
123 for (ALL_LIST_ELEMENTS_RO(el_list
, node
, nbr
)) {
124 /* neighbor declared to be DR. */
128 /* neighbor declared to be BDR. */
130 listnode_add(bdr_list
, nbr
);
132 listnode_add(no_dr_list
, nbr
);
135 /* Elect Backup Designated Router. */
136 if (listcount(bdr_list
) > 0)
137 bdr
= ospf_dr_election_sub(bdr_list
);
139 bdr
= ospf_dr_election_sub(no_dr_list
);
141 /* Set BDR to interface. */
143 BDR(oi
) = bdr
->address
.u
.prefix4
;
147 list_delete(&bdr_list
);
148 list_delete(&no_dr_list
);
153 static int ospf_ism_state(struct ospf_interface
*oi
)
155 if (IPV4_ADDR_SAME(&DR(oi
), &oi
->address
->u
.prefix4
))
157 else if (IPV4_ADDR_SAME(&BDR(oi
), &oi
->address
->u
.prefix4
))
163 static void ospf_dr_eligible_routers(struct route_table
*nbrs
,
164 struct list
*el_list
)
166 struct route_node
*rn
;
167 struct ospf_neighbor
*nbr
;
169 for (rn
= route_top(nbrs
); rn
; rn
= route_next(rn
))
170 if ((nbr
= rn
->info
) != NULL
)
171 /* Ignore 0.0.0.0 node*/
172 if (nbr
->router_id
.s_addr
!= INADDR_ANY
)
173 /* Is neighbor eligible? */
174 if (nbr
->priority
> 0)
175 /* Is neighbor upper 2-Way? */
176 if (nbr
->state
>= NSM_TwoWay
)
177 listnode_add(el_list
, nbr
);
180 /* Generate AdjOK? NSM event. */
181 static void ospf_dr_change(struct ospf
*ospf
, struct route_table
*nbrs
)
183 struct route_node
*rn
;
184 struct ospf_neighbor
*nbr
;
186 for (rn
= route_top(nbrs
); rn
; rn
= route_next(rn
)) {
193 * Ignore 0.0.0.0 node
197 if (nbr
->router_id
.s_addr
!= INADDR_ANY
198 && nbr
->state
>= NSM_TwoWay
199 && !IPV4_ADDR_SAME(&nbr
->router_id
, &ospf
->router_id
))
200 OSPF_NSM_EVENT_SCHEDULE(nbr
, NSM_AdjOK
);
204 int ospf_dr_election(struct ospf_interface
*oi
)
206 struct in_addr old_dr
, old_bdr
;
207 int old_state
, new_state
;
208 struct list
*el_list
;
210 /* backup current values. */
213 old_state
= oi
->state
;
215 el_list
= list_new();
217 /* List eligible routers. */
218 ospf_dr_eligible_routers(oi
->nbrs
, el_list
);
220 /* First election of DR and BDR. */
221 ospf_elect_bdr(oi
, el_list
);
222 ospf_elect_dr(oi
, el_list
);
224 new_state
= ospf_ism_state(oi
);
226 zlog_debug("DR-Election[1st]: Backup %pI4", &BDR(oi
));
227 zlog_debug("DR-Election[1st]: DR %pI4", &DR(oi
));
229 if (new_state
!= old_state
230 && !(new_state
== ISM_DROther
&& old_state
< ISM_DROther
)) {
231 ospf_elect_bdr(oi
, el_list
);
232 ospf_elect_dr(oi
, el_list
);
234 new_state
= ospf_ism_state(oi
);
236 zlog_debug("DR-Election[2nd]: Backup %pI4", &BDR(oi
));
237 zlog_debug("DR-Election[2nd]: DR %pI4", &DR(oi
));
240 list_delete(&el_list
);
242 /* if DR or BDR changes, cause AdjOK? neighbor event. */
243 if (!IPV4_ADDR_SAME(&old_dr
, &DR(oi
))
244 || !IPV4_ADDR_SAME(&old_bdr
, &BDR(oi
)))
245 ospf_dr_change(oi
->ospf
, oi
->nbrs
);
251 void ospf_hello_timer(struct thread
*thread
)
253 struct ospf_interface
*oi
;
255 oi
= THREAD_ARG(thread
);
258 if (IS_DEBUG_OSPF(ism
, ISM_TIMERS
))
259 zlog_debug("ISM[%s]: Timer (Hello timer expire)", IF_NAME(oi
));
261 /* Sending hello packet. */
264 /* Hello timer set. */
265 OSPF_HELLO_TIMER_ON(oi
);
268 static void ospf_wait_timer(struct thread
*thread
)
270 struct ospf_interface
*oi
;
272 oi
= THREAD_ARG(thread
);
275 if (IS_DEBUG_OSPF(ism
, ISM_TIMERS
))
276 zlog_debug("ISM[%s]: Timer (Wait timer expire)", IF_NAME(oi
));
278 OSPF_ISM_EVENT_SCHEDULE(oi
, ISM_WaitTimer
);
281 /* Hook function called after ospf ISM event is occurred. And vty's
282 network command invoke this function after making interface
284 static void ism_timer_set(struct ospf_interface
*oi
)
288 /* First entry point of ospf interface state machine. In this
290 interface parameters must be set to initial values, and
293 THREAD_OFF(oi
->t_hello
);
294 THREAD_OFF(oi
->t_wait
);
295 THREAD_OFF(oi
->t_ls_ack
);
298 /* In this state, the interface may be looped back and will be
299 unavailable for regular data traffic. */
300 THREAD_OFF(oi
->t_hello
);
301 THREAD_OFF(oi
->t_wait
);
302 THREAD_OFF(oi
->t_ls_ack
);
305 /* The router is trying to determine the identity of DRouter and
306 BDRouter. The router begin to receive and send Hello Packets.
308 /* send first hello immediately */
309 OSPF_ISM_TIMER_MSEC_ON(oi
->t_hello
, ospf_hello_timer
, 1);
310 OSPF_ISM_TIMER_ON(oi
->t_wait
, ospf_wait_timer
,
311 OSPF_IF_PARAM(oi
, v_wait
));
312 THREAD_OFF(oi
->t_ls_ack
);
314 case ISM_PointToPoint
:
315 /* The interface connects to a physical Point-to-point network
317 virtual link. The router attempts to form an adjacency with
318 neighboring router. Hello packets are also sent. */
319 /* send first hello immediately */
320 OSPF_ISM_TIMER_MSEC_ON(oi
->t_hello
, ospf_hello_timer
, 1);
321 THREAD_OFF(oi
->t_wait
);
322 OSPF_ISM_TIMER_ON(oi
->t_ls_ack
, ospf_ls_ack_timer
,
326 /* The network type of the interface is broadcast or NBMA
328 and the router itself is neither Designated Router nor
329 Backup Designated Router. */
330 OSPF_HELLO_TIMER_ON(oi
);
331 THREAD_OFF(oi
->t_wait
);
332 OSPF_ISM_TIMER_ON(oi
->t_ls_ack
, ospf_ls_ack_timer
,
336 /* The network type of the interface is broadcast os NBMA
338 and the router is Backup Designated Router. */
339 OSPF_HELLO_TIMER_ON(oi
);
340 THREAD_OFF(oi
->t_wait
);
341 OSPF_ISM_TIMER_ON(oi
->t_ls_ack
, ospf_ls_ack_timer
,
345 /* The network type of the interface is broadcast or NBMA
347 and the router is Designated Router. */
348 OSPF_HELLO_TIMER_ON(oi
);
349 THREAD_OFF(oi
->t_wait
);
350 OSPF_ISM_TIMER_ON(oi
->t_ls_ack
, ospf_ls_ack_timer
,
356 static int ism_interface_up(struct ospf_interface
*oi
)
360 /* if network type is point-to-point, Point-to-MultiPoint or virtual
362 the state transitions to Point-to-Point. */
363 if (oi
->type
== OSPF_IFTYPE_POINTOPOINT
364 || oi
->type
== OSPF_IFTYPE_POINTOMULTIPOINT
365 || oi
->type
== OSPF_IFTYPE_VIRTUALLINK
)
366 next_state
= ISM_PointToPoint
;
367 /* Else if the router is not eligible to DR, the state transitions to
369 else if (PRIORITY(oi
) == 0) /* router is eligible? */
370 next_state
= ISM_DROther
;
372 /* Otherwise, the state transitions to Waiting. */
373 next_state
= ISM_Waiting
;
375 if (oi
->type
== OSPF_IFTYPE_NBMA
)
376 ospf_nbr_nbma_if_update(oi
->ospf
, oi
);
378 /* ospf_ism_event (t); */
382 static int ism_loop_ind(struct ospf_interface
*oi
)
384 /* call ism_interface_down. */
385 /* ret = ism_interface_down (oi); */
390 /* Interface down event handler. */
391 static int ism_interface_down(struct ospf_interface
*oi
)
398 static int ism_backup_seen(struct ospf_interface
*oi
)
400 return ospf_dr_election(oi
);
403 static int ism_wait_timer(struct ospf_interface
*oi
)
405 return ospf_dr_election(oi
);
408 static int ism_neighbor_change(struct ospf_interface
*oi
)
410 return ospf_dr_election(oi
);
413 static int ism_ignore(struct ospf_interface
*oi
)
415 if (IS_DEBUG_OSPF(ism
, ISM_EVENTS
))
416 zlog_debug("ISM[%s]: ism_ignore called", IF_NAME(oi
));
421 /* Interface State Machine */
423 int (*func
)(struct ospf_interface
*);
425 } ISM
[OSPF_ISM_STATE_MAX
][OSPF_ISM_EVENT_MAX
] = {
427 /* DependUpon: dummy state. */
428 {ism_ignore
, ISM_DependUpon
}, /* NoEvent */
429 {ism_ignore
, ISM_DependUpon
}, /* InterfaceUp */
430 {ism_ignore
, ISM_DependUpon
}, /* WaitTimer */
431 {ism_ignore
, ISM_DependUpon
}, /* BackupSeen */
432 {ism_ignore
, ISM_DependUpon
}, /* NeighborChange */
433 {ism_ignore
, ISM_DependUpon
}, /* LoopInd */
434 {ism_ignore
, ISM_DependUpon
}, /* UnloopInd */
435 {ism_ignore
, ISM_DependUpon
}, /* InterfaceDown */
439 {ism_ignore
, ISM_DependUpon
}, /* NoEvent */
440 {ism_interface_up
, ISM_DependUpon
}, /* InterfaceUp */
441 {ism_ignore
, ISM_Down
}, /* WaitTimer */
442 {ism_ignore
, ISM_Down
}, /* BackupSeen */
443 {ism_ignore
, ISM_Down
}, /* NeighborChange */
444 {ism_loop_ind
, ISM_Loopback
}, /* LoopInd */
445 {ism_ignore
, ISM_Down
}, /* UnloopInd */
446 {ism_interface_down
, ISM_Down
}, /* InterfaceDown */
450 {ism_ignore
, ISM_DependUpon
}, /* NoEvent */
451 {ism_ignore
, ISM_Loopback
}, /* InterfaceUp */
452 {ism_ignore
, ISM_Loopback
}, /* WaitTimer */
453 {ism_ignore
, ISM_Loopback
}, /* BackupSeen */
454 {ism_ignore
, ISM_Loopback
}, /* NeighborChange */
455 {ism_ignore
, ISM_Loopback
}, /* LoopInd */
456 {ism_ignore
, ISM_Down
}, /* UnloopInd */
457 {ism_interface_down
, ISM_Down
}, /* InterfaceDown */
461 {ism_ignore
, ISM_DependUpon
}, /* NoEvent */
462 {ism_ignore
, ISM_Waiting
}, /* InterfaceUp */
463 {ism_wait_timer
, ISM_DependUpon
}, /* WaitTimer */
464 {ism_backup_seen
, ISM_DependUpon
}, /* BackupSeen */
465 {ism_ignore
, ISM_Waiting
}, /* NeighborChange */
466 {ism_loop_ind
, ISM_Loopback
}, /* LoopInd */
467 {ism_ignore
, ISM_Waiting
}, /* UnloopInd */
468 {ism_interface_down
, ISM_Down
}, /* InterfaceDown */
471 /* Point-to-Point: */
472 {ism_ignore
, ISM_DependUpon
}, /* NoEvent */
473 {ism_ignore
, ISM_PointToPoint
}, /* InterfaceUp */
474 {ism_ignore
, ISM_PointToPoint
}, /* WaitTimer */
475 {ism_ignore
, ISM_PointToPoint
}, /* BackupSeen */
476 {ism_ignore
, ISM_PointToPoint
}, /* NeighborChange */
477 {ism_loop_ind
, ISM_Loopback
}, /* LoopInd */
478 {ism_ignore
, ISM_PointToPoint
}, /* UnloopInd */
479 {ism_interface_down
, ISM_Down
}, /* InterfaceDown */
483 {ism_ignore
, ISM_DependUpon
}, /* NoEvent */
484 {ism_ignore
, ISM_DROther
}, /* InterfaceUp */
485 {ism_ignore
, ISM_DROther
}, /* WaitTimer */
486 {ism_ignore
, ISM_DROther
}, /* BackupSeen */
487 {ism_neighbor_change
, ISM_DependUpon
}, /* NeighborChange */
488 {ism_loop_ind
, ISM_Loopback
}, /* LoopInd */
489 {ism_ignore
, ISM_DROther
}, /* UnloopInd */
490 {ism_interface_down
, ISM_Down
}, /* InterfaceDown */
494 {ism_ignore
, ISM_DependUpon
}, /* NoEvent */
495 {ism_ignore
, ISM_Backup
}, /* InterfaceUp */
496 {ism_ignore
, ISM_Backup
}, /* WaitTimer */
497 {ism_ignore
, ISM_Backup
}, /* BackupSeen */
498 {ism_neighbor_change
, ISM_DependUpon
}, /* NeighborChange */
499 {ism_loop_ind
, ISM_Loopback
}, /* LoopInd */
500 {ism_ignore
, ISM_Backup
}, /* UnloopInd */
501 {ism_interface_down
, ISM_Down
}, /* InterfaceDown */
505 {ism_ignore
, ISM_DependUpon
}, /* NoEvent */
506 {ism_ignore
, ISM_DR
}, /* InterfaceUp */
507 {ism_ignore
, ISM_DR
}, /* WaitTimer */
508 {ism_ignore
, ISM_DR
}, /* BackupSeen */
509 {ism_neighbor_change
, ISM_DependUpon
}, /* NeighborChange */
510 {ism_loop_ind
, ISM_Loopback
}, /* LoopInd */
511 {ism_ignore
, ISM_DR
}, /* UnloopInd */
512 {ism_interface_down
, ISM_Down
}, /* InterfaceDown */
516 static const char *const ospf_ism_event_str
[] = {
517 "NoEvent", "InterfaceUp", "WaitTimer", "BackupSeen",
518 "NeighborChange", "LoopInd", "UnLoopInd", "InterfaceDown",
521 static void ism_change_state(struct ospf_interface
*oi
, int state
)
524 struct ospf_lsa
*lsa
;
526 /* Logging change of state. */
527 if (IS_DEBUG_OSPF(ism
, ISM_STATUS
))
528 zlog_debug("ISM[%s]: State change %s -> %s", IF_NAME(oi
),
529 lookup_msg(ospf_ism_state_msg
, oi
->state
, NULL
),
530 lookup_msg(ospf_ism_state_msg
, state
, NULL
));
532 old_state
= oi
->state
;
536 hook_call(ospf_ism_change
, oi
, state
, old_state
);
538 /* Set multicast memberships appropriately for new state. */
539 ospf_if_set_multicast(oi
);
541 if (old_state
== ISM_Down
|| state
== ISM_Down
)
542 ospf_check_abr_status(oi
->ospf
);
544 /* Originate router-LSA. */
545 if (state
== ISM_Down
) {
546 if (oi
->area
->act_ints
> 0)
547 oi
->area
->act_ints
--;
548 } else if (old_state
== ISM_Down
)
549 oi
->area
->act_ints
++;
551 /* schedule router-LSA originate. */
552 ospf_router_lsa_update_area(oi
->area
);
554 /* Originate network-LSA. */
555 if (old_state
!= ISM_DR
&& state
== ISM_DR
)
556 ospf_network_lsa_update(oi
);
557 else if (old_state
== ISM_DR
&& state
!= ISM_DR
) {
558 /* Free self originated network LSA. */
559 lsa
= oi
->network_lsa_self
;
561 ospf_lsa_flush_area(lsa
, oi
->area
);
563 ospf_lsa_unlock(&oi
->network_lsa_self
);
564 oi
->network_lsa_self
= NULL
;
567 ospf_opaque_ism_change(oi
, old_state
);
569 /* Check area border status. */
570 ospf_check_abr_status(oi
->ospf
);
573 /* Execute ISM event process. */
574 void ospf_ism_event(struct thread
*thread
)
578 struct ospf_interface
*oi
;
580 oi
= THREAD_ARG(thread
);
581 event
= THREAD_VAL(thread
);
584 next_state
= (*(ISM
[oi
->state
][event
].func
))(oi
);
587 next_state
= ISM
[oi
->state
][event
].next_state
;
589 if (IS_DEBUG_OSPF(ism
, ISM_EVENTS
))
590 zlog_debug("ISM[%s]: %s (%s)", IF_NAME(oi
),
591 lookup_msg(ospf_ism_state_msg
, oi
->state
, NULL
),
592 ospf_ism_event_str
[event
]);
594 /* If state is changed. */
595 if (next_state
!= oi
->state
)
596 ism_change_state(oi
, next_state
);
598 /* Make sure timer is set. */