ospfd/ospf_ism.c

   1 /*
   2  * OSPF version 2  Interface State Machine
   3  *   From RFC2328 [OSPF Version 2]
   4  * Copyright (C) 1999, 2000 Toshiaki Takada
   5  *
   6  * This file is part of GNU Zebra.
   7  *
   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
  11  * later version.
  12  *
  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.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with GNU Zebra; see the file COPYING.  If not, write to the Free
  20  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  21  * 02111-1307, USA.
  22  */
  23
  24 #include <zebra.h>
  25
  26 #include "thread.h"
  27 #include "linklist.h"
  28 #include "prefix.h"
  29 #include "if.h"
  30 #include "table.h"
  31 #include "log.h"
  32
  33 #include "ospfd/ospfd.h"
  34 #include "ospfd/ospf_interface.h"
  35 #include "ospfd/ospf_ism.h"
  36 #include "ospfd/ospf_asbr.h"
  37 #include "ospfd/ospf_lsa.h"
  38 #include "ospfd/ospf_lsdb.h"
  39 #include "ospfd/ospf_neighbor.h"
  40 #include "ospfd/ospf_nsm.h"
  41 #include "ospfd/ospf_network.h"
  42 #include "ospfd/ospf_dump.h"
  43 #include "ospfd/ospf_packet.h"
  44 #include "ospfd/ospf_flood.h"
  45 #include "ospfd/ospf_abr.h"
  46 #include "ospfd/ospf_snmp.h"
  47 \f
  48 /* elect DR and BDR. Refer to RFC2319 section 9.4 */
  49 static struct ospf_neighbor *
  50 ospf_dr_election_sub (struct list *routers)
  51 {
  52   struct listnode *node;
  53   struct ospf_neighbor *nbr, *max = NULL;
  54
  55   /* Choose highest router priority.
  56      In case of tie, choose highest Router ID. */
  57   for (ALL_LIST_ELEMENTS_RO (routers, node, nbr))
  58     {
  59       if (max == NULL)
  60         max = nbr;
  61       else
  62         {
  63           if (max->priority < nbr->priority)
  64             max = nbr;
  65           else if (max->priority == nbr->priority)
  66             if (IPV4_ADDR_CMP (&max->router_id, &nbr->router_id) < 0)
  67               max = nbr;
  68         }
  69     }
  70
  71   return max;
  72 }
  73
  74 static struct ospf_neighbor *
  75 ospf_elect_dr (struct ospf_interface *oi, struct list *el_list)
  76 {
  77   struct list *dr_list;
  78   struct listnode *node;
  79   struct ospf_neighbor *nbr, *dr = NULL, *bdr = NULL;
  80
  81   dr_list = list_new ();
  82
  83   /* Add neighbors to the list. */
  84   for (ALL_LIST_ELEMENTS_RO (el_list, node, nbr))
  85     {
  86       /* neighbor declared to be DR. */
  87       if (NBR_IS_DR (nbr))
  88         listnode_add (dr_list, nbr);
  89
  90       /* Preserve neighbor BDR. */
  91       if (IPV4_ADDR_SAME (&BDR (oi), &nbr->address.u.prefix4))
  92         bdr = nbr;
  93     }
  94
  95   /* Elect Designated Router. */
  96   if (listcount (dr_list) > 0)
  97     dr = ospf_dr_election_sub (dr_list);
  98   else
  99     dr = bdr;
 100
 101   /* Set DR to interface. */
 102   if (dr)
 103     DR (oi) = dr->address.u.prefix4;
 104   else
 105     DR (oi).s_addr = 0;
 106
 107   list_delete (dr_list);
 108
 109   return dr;
 110 }
 111
 112 static struct ospf_neighbor *
 113 ospf_elect_bdr (struct ospf_interface *oi, struct list *el_list)
 114 {
 115   struct list *bdr_list, *no_dr_list;
 116   struct listnode *node;
 117   struct ospf_neighbor *nbr, *bdr = NULL;
 118
 119   bdr_list = list_new ();
 120   no_dr_list = list_new ();
 121
 122   /* Add neighbors to the list. */
 123   for (ALL_LIST_ELEMENTS_RO (el_list, node, nbr))
 124     {
 125       /* neighbor declared to be DR. */
 126       if (NBR_IS_DR (nbr))
 127         continue;
 128
 129       /* neighbor declared to be BDR. */
 130       if (NBR_IS_BDR (nbr))
 131         listnode_add (bdr_list, nbr);
 132
 133       listnode_add (no_dr_list, nbr);
 134     }
 135
 136   /* Elect Backup Designated Router. */
 137   if (listcount (bdr_list) > 0)
 138     bdr = ospf_dr_election_sub (bdr_list);
 139   else
 140     bdr = ospf_dr_election_sub (no_dr_list);
 141
 142   /* Set BDR to interface. */
 143   if (bdr)
 144     BDR (oi) = bdr->address.u.prefix4;
 145   else
 146     BDR (oi).s_addr = 0;
 147
 148   list_delete (bdr_list);
 149   list_delete (no_dr_list);
 150
 151   return bdr;
 152 }
 153
 154 static int
 155 ospf_ism_state (struct ospf_interface *oi)
 156 {
 157   if (IPV4_ADDR_SAME (&DR (oi), &oi->address->u.prefix4))
 158     return ISM_DR;
 159   else if (IPV4_ADDR_SAME (&BDR (oi), &oi->address->u.prefix4))
 160     return ISM_Backup;
 161   else
 162     return ISM_DROther;
 163 }
 164
 165 static void
 166 ospf_dr_eligible_routers (struct route_table *nbrs, struct list *el_list)
 167 {
 168   struct route_node *rn;
 169   struct ospf_neighbor *nbr;
 170
 171   for (rn = route_top (nbrs); rn; rn = route_next (rn))
 172     if ((nbr = rn->info) != NULL)
 173       /* Ignore 0.0.0.0 node*/
 174       if (nbr->router_id.s_addr != 0)
 175         /* Is neighbor eligible? */
 176         if (nbr->priority != 0)
 177           /* Is neighbor upper 2-Way? */
 178           if (nbr->state >= NSM_TwoWay)
 179             listnode_add (el_list, nbr);
 180 }
 181
 182 /* Generate AdjOK? NSM event. */
 183 static void
 184 ospf_dr_change (struct ospf *ospf, struct route_table *nbrs)
 185 {
 186   struct route_node *rn;
 187   struct ospf_neighbor *nbr;
 188
 189   for (rn = route_top (nbrs); rn; rn = route_next (rn))
 190     if ((nbr = rn->info) != NULL)
 191       /* Ignore 0.0.0.0 node*/
 192       if (nbr->router_id.s_addr != 0)
 193         /* Is neighbor upper 2-Way? */
 194         if (nbr->state >= NSM_TwoWay)
 195           /* Ignore myself. */
 196           if (!IPV4_ADDR_SAME (&nbr->router_id, &ospf->router_id))
 197             OSPF_NSM_EVENT_SCHEDULE (nbr, NSM_AdjOK);
 198 }
 199
 200 static int
 201 ospf_dr_election (struct ospf_interface *oi)
 202 {
 203   struct in_addr old_dr, old_bdr;
 204   int old_state, new_state;
 205   struct list *el_list;
 206   struct ospf_neighbor *dr, *bdr;
 207
 208   /* backup current values. */
 209   old_dr = DR (oi);
 210   old_bdr = BDR (oi);
 211   old_state = oi->state;
 212
 213   el_list = list_new ();
 214
 215   /* List eligible routers. */
 216   ospf_dr_eligible_routers (oi->nbrs, el_list);
 217
 218   /* First election of DR and BDR. */
 219   bdr = ospf_elect_bdr (oi, el_list);
 220   dr = ospf_elect_dr (oi, el_list);
 221
 222   new_state = ospf_ism_state (oi);
 223
 224   zlog_info ("DR-Election[1st]: Backup %s", inet_ntoa (BDR (oi)));
 225   zlog_info ("DR-Election[1st]: DR     %s", inet_ntoa (DR (oi)));
 226
 227   if (new_state != old_state &&
 228       !(new_state == ISM_DROther && old_state < ISM_DROther))
 229     {
 230       ospf_elect_bdr (oi, el_list);
 231       ospf_elect_dr (oi, el_list);
 232
 233       new_state = ospf_ism_state (oi);
 234
 235       zlog_info ("DR-Election[2nd]: Backup %s", inet_ntoa (BDR (oi)));
 236       zlog_info ("DR-Election[2nd]: DR     %s", inet_ntoa (DR (oi)));
 237     }
 238
 239   list_delete (el_list);
 240
 241   /* if DR or BDR changes, cause AdjOK? neighbor event. */
 242   if (!IPV4_ADDR_SAME (&old_dr, &DR (oi)) ||
 243       !IPV4_ADDR_SAME (&old_bdr, &BDR (oi)))
 244     ospf_dr_change (oi->ospf, oi->nbrs);
 245
 246   return new_state;
 247 }
 248
 249 \f
 250 int
 251 ospf_hello_timer (struct thread *thread)
 252 {
 253   struct ospf_interface *oi;
 254
 255   oi = THREAD_ARG (thread);
 256   oi->t_hello = NULL;
 257
 258   if (IS_DEBUG_OSPF (ism, ISM_TIMERS))
 259     zlog (NULL, LOG_DEBUG, "ISM[%s]: Timer (Hello timer expire)",
 260           IF_NAME (oi));
 261
 262   /* Sending hello packet. */
 263   ospf_hello_send (oi);
 264
 265   /* Hello timer set. */
 266   OSPF_HELLO_TIMER_ON (oi);
 267
 268   return 0;
 269 }
 270
 271 static int
 272 ospf_wait_timer (struct thread *thread)
 273 {
 274   struct ospf_interface *oi;
 275
 276   oi = THREAD_ARG (thread);
 277   oi->t_wait = NULL;
 278
 279   if (IS_DEBUG_OSPF (ism, ISM_TIMERS))
 280     zlog (NULL, LOG_DEBUG, "ISM[%s]: Timer (Wait timer expire)",
 281           IF_NAME (oi));
 282
 283   OSPF_ISM_EVENT_SCHEDULE (oi, ISM_WaitTimer);
 284
 285   return 0;
 286 }
 287
 288 /* Hook function called after ospf ISM event is occured. And vty's
 289    network command invoke this function after making interface
 290    structure. */
 291 static void
 292 ism_timer_set (struct ospf_interface *oi)
 293 {
 294   switch (oi->state)
 295     {
 296     case ISM_Down:
 297       /* First entry point of ospf interface state machine. In this state
 298          interface parameters must be set to initial values, and timers are
 299          reset also. */
 300       OSPF_ISM_TIMER_OFF (oi->t_hello);
 301       OSPF_ISM_TIMER_OFF (oi->t_wait);
 302       OSPF_ISM_TIMER_OFF (oi->t_ls_ack);
 303       break;
 304     case ISM_Loopback:
 305       /* In this state, the interface may be looped back and will be
 306          unavailable for regular data traffic. */
 307       OSPF_ISM_TIMER_OFF (oi->t_hello);
 308       OSPF_ISM_TIMER_OFF (oi->t_wait);
 309       OSPF_ISM_TIMER_OFF (oi->t_ls_ack);
 310       break;
 311     case ISM_Waiting:
 312       /* The router is trying to determine the identity of DRouter and
 313          BDRouter. The router begin to receive and send Hello Packets. */
 314       /* send first hello immediately */
 315       OSPF_ISM_TIMER_MSEC_ON (oi->t_hello, ospf_hello_timer, 1);
 316       OSPF_ISM_TIMER_ON (oi->t_wait, ospf_wait_timer,
 317                          OSPF_IF_PARAM (oi, v_wait));
 318       OSPF_ISM_TIMER_OFF (oi->t_ls_ack);
 319       break;
 320     case ISM_PointToPoint:
 321       /* The interface connects to a physical Point-to-point network or
 322          virtual link. The router attempts to form an adjacency with
 323          neighboring router. Hello packets are also sent. */
 324       /* send first hello immediately */
 325       OSPF_ISM_TIMER_MSEC_ON (oi->t_hello, ospf_hello_timer, 1);
 326       OSPF_ISM_TIMER_OFF (oi->t_wait);
 327       OSPF_ISM_TIMER_ON (oi->t_ls_ack, ospf_ls_ack_timer, oi->v_ls_ack);
 328       break;
 329     case ISM_DROther:
 330       /* The network type of the interface is broadcast or NBMA network,
 331          and the router itself is neither Designated Router nor
 332          Backup Designated Router. */
 333       OSPF_HELLO_TIMER_ON (oi);
 334       OSPF_ISM_TIMER_OFF (oi->t_wait);
 335       OSPF_ISM_TIMER_ON (oi->t_ls_ack, ospf_ls_ack_timer, oi->v_ls_ack);
 336       break;
 337     case ISM_Backup:
 338       /* The network type of the interface is broadcast os NBMA network,
 339          and the router is Backup Designated Router. */
 340       OSPF_HELLO_TIMER_ON (oi);
 341       OSPF_ISM_TIMER_OFF (oi->t_wait);
 342       OSPF_ISM_TIMER_ON (oi->t_ls_ack, ospf_ls_ack_timer, oi->v_ls_ack);
 343       break;
 344     case ISM_DR:
 345       /* The network type of the interface is broadcast or NBMA network,
 346          and the router is Designated Router. */
 347       OSPF_HELLO_TIMER_ON (oi);
 348       OSPF_ISM_TIMER_OFF (oi->t_wait);
 349       OSPF_ISM_TIMER_ON (oi->t_ls_ack, ospf_ls_ack_timer, oi->v_ls_ack);
 350       break;
 351     }
 352 }
 353
 354 static int
 355 ism_interface_up (struct ospf_interface *oi)
 356 {
 357   int next_state = 0;
 358
 359   /* if network type is point-to-point, Point-to-MultiPoint or virtual link,
 360      the state transitions to Point-to-Point. */
 361   if (oi->type == OSPF_IFTYPE_POINTOPOINT ||
 362       oi->type == OSPF_IFTYPE_POINTOMULTIPOINT ||
 363       oi->type == OSPF_IFTYPE_VIRTUALLINK)
 364     next_state = ISM_PointToPoint;
 365   /* Else if the router is not eligible to DR, the state transitions to
 366      DROther. */
 367   else if (PRIORITY (oi) == 0) /* router is eligible? */
 368     next_state = ISM_DROther;
 369   else
 370     /* Otherwise, the state transitions to Waiting. */
 371     next_state = ISM_Waiting;
 372
 373   if (oi->type == OSPF_IFTYPE_NBMA)
 374     ospf_nbr_nbma_if_update (oi->ospf, oi);
 375
 376   /*  ospf_ism_event (t); */
 377   return next_state;
 378 }
 379
 380 static int
 381 ism_loop_ind (struct ospf_interface *oi)
 382 {
 383   int ret = 0;
 384
 385   /* call ism_interface_down. */
 386   /* ret = ism_interface_down (oi); */
 387
 388   return ret;
 389 }
 390
 391 /* Interface down event handler. */
 392 static int
 393 ism_interface_down (struct ospf_interface *oi)
 394 {
 395   ospf_if_cleanup (oi);
 396   return 0;
 397 }
 398
 399
 400 static int
 401 ism_backup_seen (struct ospf_interface *oi)
 402 {
 403   return ospf_dr_election (oi);
 404 }
 405
 406 static int
 407 ism_wait_timer (struct ospf_interface *oi)
 408 {
 409   return ospf_dr_election (oi);
 410 }
 411
 412 static int
 413 ism_neighbor_change (struct ospf_interface *oi)
 414 {
 415   return ospf_dr_election (oi);
 416 }
 417
 418 static int
 419 ism_ignore (struct ospf_interface *oi)
 420 {
 421   if (IS_DEBUG_OSPF (ism, ISM_EVENTS))
 422     zlog (NULL, LOG_DEBUG, "ISM[%s]: ism_ignore called", IF_NAME (oi));
 423
 424   return 0;
 425 }
 426
 427 /* Interface State Machine */
 428 struct {
 429   int (*func) (struct ospf_interface *);
 430   int next_state;
 431 } ISM [OSPF_ISM_STATE_MAX][OSPF_ISM_EVENT_MAX] =
 432 {
 433   {
 434     /* DependUpon: dummy state. */
 435     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 436     { ism_ignore,          ISM_DependUpon },    /* InterfaceUp    */
 437     { ism_ignore,          ISM_DependUpon },    /* WaitTimer      */
 438     { ism_ignore,          ISM_DependUpon },    /* BackupSeen     */
 439     { ism_ignore,          ISM_DependUpon },    /* NeighborChange */
 440     { ism_ignore,          ISM_DependUpon },    /* LoopInd        */
 441     { ism_ignore,          ISM_DependUpon },    /* UnloopInd      */
 442     { ism_ignore,          ISM_DependUpon },    /* InterfaceDown  */
 443   },
 444   {
 445     /* Down:*/
 446     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 447     { ism_interface_up,    ISM_DependUpon },    /* InterfaceUp    */
 448     { ism_ignore,          ISM_Down },          /* WaitTimer      */
 449     { ism_ignore,          ISM_Down },          /* BackupSeen     */
 450     { ism_ignore,          ISM_Down },          /* NeighborChange */
 451     { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
 452     { ism_ignore,          ISM_Down },          /* UnloopInd      */
 453     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 454   },
 455   {
 456     /* Loopback: */
 457     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 458     { ism_ignore,          ISM_Loopback },      /* InterfaceUp    */
 459     { ism_ignore,          ISM_Loopback },      /* WaitTimer      */
 460     { ism_ignore,          ISM_Loopback },      /* BackupSeen     */
 461     { ism_ignore,          ISM_Loopback },      /* NeighborChange */
 462     { ism_ignore,          ISM_Loopback },      /* LoopInd        */
 463     { ism_ignore,          ISM_Down },          /* UnloopInd      */
 464     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 465   },
 466   {
 467     /* Waiting: */
 468     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 469     { ism_ignore,          ISM_Waiting },       /* InterfaceUp    */
 470     { ism_wait_timer,      ISM_DependUpon },    /* WaitTimer      */
 471     { ism_backup_seen,     ISM_DependUpon },    /* BackupSeen     */
 472     { ism_ignore,          ISM_Waiting },       /* NeighborChange */
 473     { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
 474     { ism_ignore,          ISM_Waiting },       /* UnloopInd      */
 475     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 476   },
 477   {
 478     /* Point-to-Point: */
 479     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 480     { ism_ignore,          ISM_PointToPoint },  /* InterfaceUp    */
 481     { ism_ignore,          ISM_PointToPoint },  /* WaitTimer      */
 482     { ism_ignore,          ISM_PointToPoint },  /* BackupSeen     */
 483     { ism_ignore,          ISM_PointToPoint },  /* NeighborChange */
 484     { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
 485     { ism_ignore,          ISM_PointToPoint },  /* UnloopInd      */
 486     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 487   },
 488   {
 489     /* DROther: */
 490     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 491     { ism_ignore,          ISM_DROther },       /* InterfaceUp    */
 492     { ism_ignore,          ISM_DROther },       /* WaitTimer      */
 493     { ism_ignore,          ISM_DROther },       /* BackupSeen     */
 494     { ism_neighbor_change, ISM_DependUpon },    /* NeighborChange */
 495     { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
 496     { ism_ignore,          ISM_DROther },       /* UnloopInd      */
 497     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 498   },
 499   {
 500     /* Backup: */
 501     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 502     { ism_ignore,          ISM_Backup },        /* InterfaceUp    */
 503     { ism_ignore,          ISM_Backup },        /* WaitTimer      */
 504     { ism_ignore,          ISM_Backup },        /* BackupSeen     */
 505     { ism_neighbor_change, ISM_DependUpon },    /* NeighborChange */
 506     { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
 507     { ism_ignore,          ISM_Backup },        /* UnloopInd      */
 508     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 509   },
 510   {
 511     /* DR: */
 512     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 513     { ism_ignore,          ISM_DR },            /* InterfaceUp    */
 514     { ism_ignore,          ISM_DR },            /* WaitTimer      */
 515     { ism_ignore,          ISM_DR },            /* BackupSeen     */
 516     { ism_neighbor_change, ISM_DependUpon },    /* NeighborChange */
 517     { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
 518     { ism_ignore,          ISM_DR },            /* UnloopInd      */
 519     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 520   },
 521 };
 522
 523 const static char *ospf_ism_event_str[] =
 524 {
 525   "NoEvent",
 526   "InterfaceUp",
 527   "WaitTimer",
 528   "BackupSeen",
 529   "NeighborChange",
 530   "LoopInd",
 531   "UnLoopInd",
 532   "InterfaceDown",
 533 };
 534
 535 static void
 536 ism_change_state (struct ospf_interface *oi, int state)
 537 {
 538   int old_state;
 539   struct ospf_lsa *lsa;
 540
 541   /* Logging change of state. */
 542   if (IS_DEBUG_OSPF (ism, ISM_STATUS))
 543     zlog (NULL, LOG_DEBUG, "ISM[%s]: State change %s -> %s", IF_NAME (oi),
 544           LOOKUP (ospf_ism_state_msg, oi->state),
 545           LOOKUP (ospf_ism_state_msg, state));
 546
 547   old_state = oi->state;
 548   oi->state = state;
 549   oi->state_change++;
 550
 551 #ifdef HAVE_SNMP
 552   /* Terminal state or regression */
 553   if ((state == ISM_DR) || (state == ISM_Backup) || (state == ISM_DROther) ||
 554       (state == ISM_PointToPoint) || (state < old_state))
 555     {
 556       /* ospfVirtIfStateChange */
 557       if (oi->type == OSPF_IFTYPE_VIRTUALLINK)
 558         ospfTrapVirtIfStateChange (oi);
 559       /* ospfIfStateChange */
 560       else
 561         ospfTrapIfStateChange (oi);
 562     }
 563 #endif
 564
 565   /* Set multicast memberships appropriately for new state. */
 566   ospf_if_set_multicast(oi);
 567
 568   if (old_state == ISM_Down || state == ISM_Down)
 569     ospf_check_abr_status (oi->ospf);
 570
 571   /* Originate router-LSA. */
 572   if (oi->area)
 573     {
 574       if (state == ISM_Down)
 575         {
 576           if (oi->area->act_ints > 0)
 577             oi->area->act_ints--;
 578         }
 579       else if (old_state == ISM_Down)
 580         oi->area->act_ints++;
 581
 582       /* schedule router-LSA originate. */
 583       ospf_router_lsa_timer_add (oi->area);
 584     }
 585
 586   /* Originate network-LSA. */
 587   if (old_state != ISM_DR && state == ISM_DR)
 588     ospf_network_lsa_timer_add (oi);
 589   else if (old_state == ISM_DR && state != ISM_DR)
 590     {
 591       /* Free self originated network LSA. */
 592       lsa = oi->network_lsa_self;
 593       if (lsa)
 594         {
 595           ospf_lsa_flush_area (lsa, oi->area);
 596           OSPF_TIMER_OFF (oi->t_network_lsa_self);
 597         }
 598
 599       ospf_lsa_unlock (oi->network_lsa_self);
 600       oi->network_lsa_self = NULL;
 601     }
 602
 603 #ifdef HAVE_OPAQUE_LSA
 604   ospf_opaque_ism_change (oi, old_state);
 605 #endif /* HAVE_OPAQUE_LSA */
 606
 607   /* Check area border status.  */
 608   ospf_check_abr_status (oi->ospf);
 609 }
 610
 611 /* Execute ISM event process. */
 612 int
 613 ospf_ism_event (struct thread *thread)
 614 {
 615   int event;
 616   int next_state;
 617   struct ospf_interface *oi;
 618
 619   oi = THREAD_ARG (thread);
 620   event = THREAD_VAL (thread);
 621
 622   /* Call function. */
 623   next_state = (*(ISM [oi->state][event].func))(oi);
 624
 625   if (! next_state)
 626     next_state = ISM [oi->state][event].next_state;
 627
 628   if (IS_DEBUG_OSPF (ism, ISM_EVENTS))
 629     zlog (NULL, LOG_DEBUG, "ISM[%s]: %s (%s)", IF_NAME (oi),
 630           LOOKUP (ospf_ism_state_msg, oi->state),
 631           ospf_ism_event_str[event]);
 632
 633   /* If state is changed. */
 634   if (next_state != oi->state)
 635     ism_change_state (oi, next_state);
 636
 637   /* Make sure timer is set. */
 638   ism_timer_set (oi);
 639
 640   return 0;
 641 }
 642