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 \f
  47 /* elect DR and BDR. Refer to RFC2319 section 9.4 */
  48 struct ospf_neighbor *
  49 ospf_dr_election_sub (list routers)
  50 {
  51   listnode node;
  52   struct ospf_neighbor *nbr, *max = NULL;
  53
  54   /* Choose highest router priority.
  55      In case of tie, choose highest Router ID. */
  56   for (node = listhead (routers); node; nextnode (node))
  57     {
  58       nbr = getdata (node);
  59
  60       if (max == NULL)
  61         max = nbr;
  62       else
  63         {
  64           if (max->priority < nbr->priority)
  65             max = nbr;
  66           else if (max->priority == nbr->priority)
  67             if (IPV4_ADDR_CMP (&max->router_id, &nbr->router_id) < 0)
  68               max = nbr;
  69         }
  70     }
  71
  72   return max;
  73 }
  74
  75 struct ospf_neighbor *
  76 ospf_elect_dr (struct ospf_interface *oi, list el_list)
  77 {
  78   list dr_list;
  79   listnode node;
  80   struct ospf_neighbor *nbr, *dr = NULL, *bdr = NULL;
  81
  82   dr_list = list_new ();
  83
  84   /* Add neighbors to the list. */
  85   for (node = listhead (el_list); node; nextnode (node))
  86     {
  87       nbr = getdata (node);
  88
  89       /* neighbor declared to be DR. */
  90       if (NBR_IS_DR (nbr))
  91         listnode_add (dr_list, nbr);
  92
  93       /* Preserve neighbor BDR. */
  94       if (IPV4_ADDR_SAME (&BDR (oi), &nbr->address.u.prefix4))
  95         bdr = nbr;
  96     }
  97
  98   /* Elect Designated Router. */
  99   if (listcount (dr_list) > 0)
 100     dr = ospf_dr_election_sub (dr_list);
 101   else
 102     dr = bdr;
 103
 104   /* Set DR to interface. */
 105   if (dr)
 106     {
 107       DR (oi) = dr->address.u.prefix4;
 108       dr->d_router = dr->address.u.prefix4;
 109     }
 110   else
 111       DR (oi).s_addr = 0;
 112
 113   list_delete (dr_list);
 114
 115   return dr;
 116 }
 117
 118 struct ospf_neighbor *
 119 ospf_elect_bdr (struct ospf_interface *oi, list el_list)
 120 {
 121   list bdr_list, no_dr_list;
 122   listnode node;
 123   struct ospf_neighbor *nbr, *bdr = NULL;
 124
 125   bdr_list = list_new ();
 126   no_dr_list = list_new ();
 127
 128   /* Add neighbors to the list. */
 129   for (node = listhead (el_list); node; nextnode (node))
 130     {
 131       nbr = getdata (node);
 132
 133       /* neighbor declared to be DR. */
 134       if (NBR_IS_DR (nbr))
 135         continue;
 136
 137       /* neighbor declared to be BDR. */
 138       if (NBR_IS_BDR (nbr))
 139         listnode_add (bdr_list, nbr);
 140
 141       listnode_add (no_dr_list, nbr);
 142     }
 143
 144   /* Elect Backup Designated Router. */
 145   if (listcount (bdr_list) > 0)
 146     bdr = ospf_dr_election_sub (bdr_list);
 147   else
 148     bdr = ospf_dr_election_sub (no_dr_list);
 149
 150   /* Set BDR to interface. */
 151   if (bdr)
 152     {
 153       BDR (oi) = bdr->address.u.prefix4;
 154       bdr->bd_router = bdr->address.u.prefix4;
 155     }
 156   else
 157     BDR (oi).s_addr = 0;
 158
 159   list_delete (bdr_list);
 160   list_delete (no_dr_list);
 161
 162   return bdr;
 163 }
 164
 165 int
 166 ospf_ism_state (struct ospf_interface *oi)
 167 {
 168   if (IPV4_ADDR_SAME (&DR (oi), &oi->address->u.prefix4))
 169     return ISM_DR;
 170   else if (IPV4_ADDR_SAME (&BDR (oi), &oi->address->u.prefix4))
 171     return ISM_Backup;
 172   else
 173     return ISM_DROther;
 174 }
 175
 176 void
 177 ospf_dr_eligible_routers (struct route_table *nbrs, list el_list)
 178 {
 179   struct route_node *rn;
 180   struct ospf_neighbor *nbr;
 181
 182   for (rn = route_top (nbrs); rn; rn = route_next (rn))
 183     if ((nbr = rn->info) != NULL)
 184       /* Ignore 0.0.0.0 node*/
 185       if (nbr->router_id.s_addr != 0)
 186         /* Is neighbor eligible? */
 187         if (nbr->priority != 0)
 188           /* Is neighbor upper 2-Way? */
 189           if (nbr->state >= NSM_TwoWay)
 190             listnode_add (el_list, nbr);
 191 }
 192
 193 /* Generate AdjOK? NSM event. */
 194 void
 195 ospf_dr_change (struct ospf *ospf, struct route_table *nbrs)
 196 {
 197   struct route_node *rn;
 198   struct ospf_neighbor *nbr;
 199
 200   for (rn = route_top (nbrs); rn; rn = route_next (rn))
 201     if ((nbr = rn->info) != NULL)
 202       /* Ignore 0.0.0.0 node*/
 203       if (nbr->router_id.s_addr != 0)
 204         /* Is neighbor upper 2-Way? */
 205         if (nbr->state >= NSM_TwoWay)
 206           /* Ignore myself. */
 207           if (!IPV4_ADDR_SAME (&nbr->router_id, &ospf->router_id))
 208             OSPF_NSM_EVENT_SCHEDULE (nbr, NSM_AdjOK);
 209 }
 210
 211 int
 212 ospf_dr_election (struct ospf_interface *oi)
 213 {
 214   struct in_addr old_dr, old_bdr;
 215   int old_state, new_state;
 216   list el_list;
 217   struct ospf_neighbor *dr, *bdr;
 218
 219   /* backup current values. */
 220   old_dr = DR (oi);
 221   old_bdr = BDR (oi);
 222   old_state = oi->state;
 223
 224   el_list = list_new ();
 225
 226   /* List eligible routers. */
 227   ospf_dr_eligible_routers (oi->nbrs, el_list);
 228
 229   /* First election of DR and BDR. */
 230   bdr = ospf_elect_bdr (oi, el_list);
 231   dr = ospf_elect_dr (oi, el_list);
 232
 233   new_state = ospf_ism_state (oi);
 234
 235   zlog_info ("DR-Election[1st]: Backup %s", inet_ntoa (BDR (oi)));
 236   zlog_info ("DR-Election[1st]: DR     %s", inet_ntoa (DR (oi)));
 237
 238   if (new_state != old_state &&
 239       !(new_state == ISM_DROther && old_state < ISM_DROther))
 240     {
 241       ospf_elect_bdr (oi, el_list);
 242       ospf_elect_dr (oi, el_list);
 243
 244       new_state = ospf_ism_state (oi);
 245
 246       zlog_info ("DR-Election[2nd]: Backup %s", inet_ntoa (BDR (oi)));
 247       zlog_info ("DR-Election[2nd]: DR     %s", inet_ntoa (DR (oi)));
 248     }
 249
 250   list_delete (el_list);
 251
 252   /* if DR or BDR changes, cause AdjOK? neighbor event. */
 253   if (!IPV4_ADDR_SAME (&old_dr, &DR (oi)) ||
 254       !IPV4_ADDR_SAME (&old_bdr, &BDR (oi)))
 255     ospf_dr_change (oi->ospf, oi->nbrs);
 256
 257   if (oi->type == OSPF_IFTYPE_BROADCAST || oi->type == OSPF_IFTYPE_POINTOPOINT)
 258     {
 259       /* Multicast group change. */
 260       if ((old_state != ISM_DR && old_state != ISM_Backup) &&
 261           (new_state == ISM_DR || new_state == ISM_Backup))
 262         ospf_if_add_alldrouters (oi->ospf, oi->address, oi->ifp->ifindex);
 263       else if ((old_state == ISM_DR || old_state == ISM_Backup) &&
 264                (new_state != ISM_DR && new_state != ISM_Backup))
 265         ospf_if_drop_alldrouters (oi->ospf, oi->address, oi->ifp->ifindex);
 266     }
 267
 268   return new_state;
 269 }
 270
 271 \f
 272 int
 273 ospf_hello_timer (struct thread *thread)
 274 {
 275   struct ospf_interface *oi;
 276
 277   oi = THREAD_ARG (thread);
 278   oi->t_hello = NULL;
 279
 280   if (IS_DEBUG_OSPF (ism, ISM_TIMERS))
 281     zlog (NULL, LOG_DEBUG, "ISM[%s]: Timer (Hello timer expire)",
 282           IF_NAME (oi));
 283
 284   /* Sending hello packet. */
 285   ospf_hello_send (oi);
 286
 287   /* Hello timer set. */
 288   OSPF_ISM_TIMER_ON (oi->t_hello, ospf_hello_timer,
 289                      OSPF_IF_PARAM (oi, v_hello));
 290
 291   return 0;
 292 }
 293
 294 int
 295 ospf_wait_timer (struct thread *thread)
 296 {
 297   struct ospf_interface *oi;
 298
 299   oi = THREAD_ARG (thread);
 300   oi->t_wait = NULL;
 301
 302   if (IS_DEBUG_OSPF (ism, ISM_TIMERS))
 303     zlog (NULL, LOG_DEBUG, "ISM[%s]: Timer (Wait timer expire)",
 304           IF_NAME (oi));
 305
 306   OSPF_ISM_EVENT_SCHEDULE (oi, ISM_WaitTimer);
 307
 308   return 0;
 309 }
 310
 311 /* Hook function called after ospf ISM event is occured. And vty's
 312    network command invoke this function after making interface
 313    structure. */
 314 void
 315 ism_timer_set (struct ospf_interface *oi)
 316 {
 317   switch (oi->state)
 318     {
 319     case ISM_Down:
 320       /* First entry point of ospf interface state machine. In this state
 321          interface parameters must be set to initial values, and timers are
 322          reset also. */
 323       OSPF_ISM_TIMER_OFF (oi->t_hello);
 324       OSPF_ISM_TIMER_OFF (oi->t_wait);
 325       OSPF_ISM_TIMER_OFF (oi->t_ls_ack);
 326       break;
 327     case ISM_Loopback:
 328       /* In this state, the interface may be looped back and will be
 329          unavailable for regular data traffic. */
 330       OSPF_ISM_TIMER_OFF (oi->t_hello);
 331       OSPF_ISM_TIMER_OFF (oi->t_wait);
 332       OSPF_ISM_TIMER_OFF (oi->t_ls_ack);
 333       break;
 334     case ISM_Waiting:
 335       /* The router is trying to determine the identity of DRouter and
 336          BDRouter. The router begin to receive and send Hello Packets. */
 337       /* send first hello immediately */
 338       OSPF_ISM_TIMER_ON (oi->t_hello, ospf_hello_timer, 1);
 339       OSPF_ISM_TIMER_ON (oi->t_wait, ospf_wait_timer,
 340                          OSPF_IF_PARAM (oi, v_wait));
 341       OSPF_ISM_TIMER_OFF (oi->t_ls_ack);
 342       break;
 343     case ISM_PointToPoint:
 344       /* The interface connects to a physical Point-to-point network or
 345          virtual link. The router attempts to form an adjacency with
 346          neighboring router. Hello packets are also sent. */
 347       /* send first hello immediately */
 348       OSPF_ISM_TIMER_ON (oi->t_hello, ospf_hello_timer, 1);
 349
 350       OSPF_ISM_TIMER_OFF (oi->t_wait);
 351       OSPF_ISM_TIMER_ON (oi->t_ls_ack, ospf_ls_ack_timer, oi->v_ls_ack);
 352       break;
 353     case ISM_DROther:
 354       /* The network type of the interface is broadcast or NBMA network,
 355          and the router itself is neither Designated Router nor
 356          Backup Designated Router. */
 357       OSPF_ISM_TIMER_ON (oi->t_hello, ospf_hello_timer,
 358                          OSPF_IF_PARAM (oi, v_hello));
 359       OSPF_ISM_TIMER_OFF (oi->t_wait);
 360       OSPF_ISM_TIMER_ON (oi->t_ls_ack, ospf_ls_ack_timer, oi->v_ls_ack);
 361       break;
 362     case ISM_Backup:
 363       /* The network type of the interface is broadcast os NBMA network,
 364          and the router is Backup Designated Router. */
 365       OSPF_ISM_TIMER_ON (oi->t_hello, ospf_hello_timer,
 366                          OSPF_IF_PARAM (oi, v_hello));
 367       OSPF_ISM_TIMER_OFF (oi->t_wait);
 368       OSPF_ISM_TIMER_ON (oi->t_ls_ack, ospf_ls_ack_timer, oi->v_ls_ack);
 369       break;
 370     case ISM_DR:
 371       /* The network type of the interface is broadcast or NBMA network,
 372          and the router is Designated Router. */
 373       OSPF_ISM_TIMER_ON (oi->t_hello, ospf_hello_timer,
 374                          OSPF_IF_PARAM (oi, v_hello));
 375       OSPF_ISM_TIMER_OFF (oi->t_wait);
 376       OSPF_ISM_TIMER_ON (oi->t_ls_ack, ospf_ls_ack_timer, oi->v_ls_ack);
 377       break;
 378     }
 379 }
 380
 381 int
 382 ism_stop (struct ospf_interface *oi)
 383 {
 384   return 0;
 385 }
 386
 387 int
 388 ism_interface_up (struct ospf_interface *oi)
 389 {
 390   int next_state = 0;
 391
 392   /* if network type is point-to-point, Point-to-MultiPoint or virtual link,
 393      the state transitions to Point-to-Point. */
 394   if (oi->type == OSPF_IFTYPE_POINTOPOINT ||
 395       oi->type == OSPF_IFTYPE_POINTOMULTIPOINT ||
 396       oi->type == OSPF_IFTYPE_VIRTUALLINK)
 397     next_state = ISM_PointToPoint;
 398   /* Else if the router is not eligible to DR, the state transitions to
 399      DROther. */
 400   else if (PRIORITY (oi) == 0) /* router is eligible? */
 401     next_state = ISM_DROther;
 402   else
 403     /* Otherwise, the state transitions to Waiting. */
 404     next_state = ISM_Waiting;
 405
 406   if (oi->type == OSPF_IFTYPE_NBMA)
 407     ospf_nbr_nbma_if_update (oi->ospf, oi);
 408
 409   /*  ospf_ism_event (t); */
 410   return next_state;
 411 }
 412
 413 int
 414 ism_loop_ind (struct ospf_interface *oi)
 415 {
 416   int ret = 0;
 417
 418   /* call ism_interface_down. */
 419   /* ret = ism_interface_down (oi); */
 420
 421   return ret;
 422 }
 423
 424 /* Interface down event handler. */
 425 int
 426 ism_interface_down (struct ospf_interface *oi)
 427 {
 428   ospf_if_cleanup (oi);
 429   return 0;
 430 }
 431
 432
 433 int
 434 ism_backup_seen (struct ospf_interface *oi)
 435 {
 436   return ospf_dr_election (oi);
 437 }
 438
 439 int
 440 ism_wait_timer (struct ospf_interface *oi)
 441 {
 442   return ospf_dr_election (oi);
 443 }
 444
 445 int
 446 ism_neighbor_change (struct ospf_interface *oi)
 447 {
 448   return ospf_dr_election (oi);
 449 }
 450
 451 int
 452 ism_ignore (struct ospf_interface *oi)
 453 {
 454   if (IS_DEBUG_OSPF (ism, ISM_EVENTS))
 455     zlog (NULL, LOG_INFO, "ISM[%s]: ism_ignore called", IF_NAME (oi));
 456
 457   return 0;
 458 }
 459
 460 /* Interface State Machine */
 461 struct {
 462   int (*func) ();
 463   int next_state;
 464 } ISM [OSPF_ISM_STATE_MAX][OSPF_ISM_EVENT_MAX] =
 465 {
 466   {
 467     /* DependUpon: dummy state. */
 468     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 469     { ism_ignore,          ISM_DependUpon },    /* InterfaceUp    */
 470     { ism_ignore,          ISM_DependUpon },    /* WaitTimer      */
 471     { ism_ignore,          ISM_DependUpon },    /* BackupSeen     */
 472     { ism_ignore,          ISM_DependUpon },    /* NeighborChange */
 473     { ism_ignore,          ISM_DependUpon },    /* LoopInd        */
 474     { ism_ignore,          ISM_DependUpon },    /* UnloopInd      */
 475     { ism_ignore,          ISM_DependUpon },    /* InterfaceDown  */
 476   },
 477   {
 478     /* Down:*/
 479     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 480     { ism_interface_up,    ISM_DependUpon },    /* InterfaceUp    */
 481     { ism_ignore,          ISM_Down },          /* WaitTimer      */
 482     { ism_ignore,          ISM_Down },          /* BackupSeen     */
 483     { ism_ignore,          ISM_Down },          /* NeighborChange */
 484     { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
 485     { ism_ignore,          ISM_Down },          /* UnloopInd      */
 486     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 487   },
 488   {
 489     /* Loopback: */
 490     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 491     { ism_ignore,          ISM_Loopback },      /* InterfaceUp    */
 492     { ism_ignore,          ISM_Loopback },      /* WaitTimer      */
 493     { ism_ignore,          ISM_Loopback },      /* BackupSeen     */
 494     { ism_ignore,          ISM_Loopback },      /* NeighborChange */
 495     { ism_ignore,          ISM_Loopback },      /* LoopInd        */
 496     { ism_ignore,          ISM_Down },          /* UnloopInd      */
 497     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 498   },
 499   {
 500     /* Waiting: */
 501     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 502     { ism_ignore,          ISM_Waiting },       /* InterfaceUp    */
 503     { ism_wait_timer,      ISM_DependUpon },    /* WaitTimer      */
 504     { ism_backup_seen,     ISM_DependUpon },    /* BackupSeen     */
 505     { ism_ignore,          ISM_Waiting },       /* NeighborChange */
 506     { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
 507     { ism_ignore,          ISM_Waiting },       /* UnloopInd      */
 508     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 509   },
 510   {
 511     /* Point-to-Point: */
 512     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 513     { ism_ignore,          ISM_PointToPoint },  /* InterfaceUp    */
 514     { ism_ignore,          ISM_PointToPoint },  /* WaitTimer      */
 515     { ism_ignore,          ISM_PointToPoint },  /* BackupSeen     */
 516     { ism_ignore,          ISM_PointToPoint },  /* NeighborChange */
 517     { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
 518     { ism_ignore,          ISM_PointToPoint },  /* UnloopInd      */
 519     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 520   },
 521   {
 522     /* DROther: */
 523     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 524     { ism_ignore,          ISM_DROther },       /* InterfaceUp    */
 525     { ism_ignore,          ISM_DROther },       /* WaitTimer      */
 526     { ism_ignore,          ISM_DROther },       /* BackupSeen     */
 527     { ism_neighbor_change, ISM_DependUpon },    /* NeighborChange */
 528     { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
 529     { ism_ignore,          ISM_DROther },       /* UnloopInd      */
 530     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 531   },
 532   {
 533     /* Backup: */
 534     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 535     { ism_ignore,          ISM_Backup },        /* InterfaceUp    */
 536     { ism_ignore,          ISM_Backup },        /* WaitTimer      */
 537     { ism_ignore,          ISM_Backup },        /* BackupSeen     */
 538     { ism_neighbor_change, ISM_DependUpon },    /* NeighborChange */
 539     { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
 540     { ism_ignore,          ISM_Backup },        /* UnloopInd      */
 541     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 542   },
 543   {
 544     /* DR: */
 545     { ism_ignore,          ISM_DependUpon },    /* NoEvent        */
 546     { ism_ignore,          ISM_DR },            /* InterfaceUp    */
 547     { ism_ignore,          ISM_DR },            /* WaitTimer      */
 548     { ism_ignore,          ISM_DR },            /* BackupSeen     */
 549     { ism_neighbor_change, ISM_DependUpon },    /* NeighborChange */
 550     { ism_loop_ind,        ISM_Loopback },      /* LoopInd        */
 551     { ism_ignore,          ISM_DR },            /* UnloopInd      */
 552     { ism_interface_down,  ISM_Down },          /* InterfaceDown  */
 553   },
 554 };
 555
 556 static char *ospf_ism_event_str[] =
 557 {
 558   "NoEvent",
 559   "InterfaceUp",
 560   "WaitTimer",
 561   "BackupSeen",
 562   "NeighborChange",
 563   "LoopInd",
 564   "UnLoopInd",
 565   "InterfaceDown",
 566 };
 567
 568 void
 569 ism_change_state (struct ospf_interface *oi, int state)
 570 {
 571   int old_state;
 572   struct ospf_lsa *lsa;
 573
 574   /* Logging change of state. */
 575   if (IS_DEBUG_OSPF (ism, ISM_STATUS))
 576     zlog (NULL, LOG_INFO, "ISM[%s]: State change %s -> %s", IF_NAME (oi),
 577           LOOKUP (ospf_ism_state_msg, oi->state),
 578           LOOKUP (ospf_ism_state_msg, state));
 579
 580   old_state = oi->state;
 581   oi->state = state;
 582   oi->state_change++;
 583
 584   if (old_state == ISM_Down || state == ISM_Down)
 585     ospf_check_abr_status (oi->ospf);
 586
 587   /* Originate router-LSA. */
 588   if (oi->area)
 589     {
 590       if (state == ISM_Down)
 591         {
 592           if (oi->area->act_ints > 0)
 593             oi->area->act_ints--;
 594         }
 595       else if (old_state == ISM_Down)
 596         oi->area->act_ints++;
 597
 598       /* schedule router-LSA originate. */
 599       ospf_router_lsa_timer_add (oi->area);
 600     }
 601
 602   /* Originate network-LSA. */
 603   if (old_state != ISM_DR && state == ISM_DR)
 604     ospf_network_lsa_timer_add (oi);
 605   else if (old_state == ISM_DR && state != ISM_DR)
 606     {
 607       /* Free self originated network LSA. */
 608       lsa = oi->network_lsa_self;
 609       if (lsa)
 610         {
 611           ospf_lsa_flush_area (lsa, oi->area);
 612           OSPF_TIMER_OFF (oi->t_network_lsa_self);
 613         }
 614
 615       ospf_lsa_unlock (oi->network_lsa_self);
 616       oi->network_lsa_self = NULL;
 617     }
 618
 619 #ifdef HAVE_OPAQUE_LSA
 620   ospf_opaque_ism_change (oi, old_state);
 621 #endif /* HAVE_OPAQUE_LSA */
 622
 623   /* Check area border status.  */
 624   ospf_check_abr_status (oi->ospf);
 625 }
 626
 627 /* Execute ISM event process. */
 628 int
 629 ospf_ism_event (struct thread *thread)
 630 {
 631   int event;
 632   int next_state;
 633   struct ospf_interface *oi;
 634
 635   oi = THREAD_ARG (thread);
 636   event = THREAD_VAL (thread);
 637
 638   /* Call function. */
 639   next_state = (*(ISM [oi->state][event].func))(oi);
 640
 641   if (! next_state)
 642     next_state = ISM [oi->state][event].next_state;
 643
 644   if (IS_DEBUG_OSPF (ism, ISM_EVENTS))
 645     zlog (NULL, LOG_INFO, "ISM[%s]: %s (%s)", IF_NAME (oi),
 646           LOOKUP (ospf_ism_state_msg, oi->state),
 647           ospf_ism_event_str[event]);
 648
 649   /* If state is changed. */
 650   if (next_state != oi->state)
 651     ism_change_state (oi, next_state);
 652
 653   /* Make sure timer is set. */
 654   ism_timer_set (oi);
 655
 656   return 0;
 657 }
 658