ospfd/ospf_ia.c

   1 /*
   2  * OSPF inter-area routing.
   3  * Copyright (C) 1999, 2000 Alex Zinin, Toshiaki Takada
   4  *
   5  * This file is part of GNU Zebra.
   6  *
   7  * GNU Zebra is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License as published by the
   9  * Free Software Foundation; either version 2, or (at your option) any
  10  * later version.
  11  *
  12  * GNU Zebra is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with GNU Zebra; see the file COPYING.  If not, write to the Free
  19  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  20  * 02111-1307, USA.
  21  */
  22
  23
  24 #include <zebra.h>
  25
  26 #include "thread.h"
  27 #include "memory.h"
  28 #include "hash.h"
  29 #include "linklist.h"
  30 #include "prefix.h"
  31 #include "table.h"
  32 #include "log.h"
  33
  34 #include "ospfd/ospfd.h"
  35 #include "ospfd/ospf_interface.h"
  36 #include "ospfd/ospf_ism.h"
  37 #include "ospfd/ospf_asbr.h"
  38 #include "ospfd/ospf_lsa.h"
  39 #include "ospfd/ospf_lsdb.h"
  40 #include "ospfd/ospf_neighbor.h"
  41 #include "ospfd/ospf_nsm.h"
  42 #include "ospfd/ospf_spf.h"
  43 #include "ospfd/ospf_route.h"
  44 #include "ospfd/ospf_ase.h"
  45 #include "ospfd/ospf_abr.h"
  46 #include "ospfd/ospf_ia.h"
  47 #include "ospfd/ospf_dump.h"
  48
  49 #define DEBUG
  50
  51 struct ospf_route *
  52 ospf_find_abr_route (struct route_table *rtrs,
  53                      struct prefix_ipv4 *abr,
  54                      struct ospf_area *area)
  55 {
  56   struct route_node *rn;
  57   struct ospf_route *or;
  58   listnode node;
  59
  60   if ((rn = route_node_lookup (rtrs, (struct prefix *) abr)) == NULL)
  61     return NULL;
  62
  63   route_unlock_node (rn);
  64
  65   for (node = listhead ((list) rn->info); node; nextnode (node))
  66     if ((or = getdata (node)) != NULL)
  67       if (IPV4_ADDR_SAME (&or->u.std.area_id, &area->area_id) && (or->u.std.flags & ROUTER_LSA_BORDER))
  68         return or;
  69
  70   return NULL;
  71 }
  72
  73 void
  74 ospf_ia_network_route (struct ospf *ospf, struct route_table *rt,
  75                        struct prefix_ipv4 *p, struct ospf_route *new_or,
  76                        struct ospf_route *abr_or)
  77 {
  78   struct route_node *rn1;
  79   struct ospf_route *or;
  80
  81   if (IS_DEBUG_OSPF_EVENT)
  82     zlog_info ("ospf_ia_network_route(): processing summary route to %s/%d",
  83                inet_ntoa (p->prefix), p->prefixlen);
  84
  85   /* Find a route to the same dest */
  86   if ((rn1 = route_node_lookup (rt, (struct prefix *) p)))
  87     {
  88       int res;
  89
  90       route_unlock_node (rn1);
  91
  92       if ((or = rn1->info))
  93         {
  94           if (IS_DEBUG_OSPF_EVENT)
  95             zlog_info ("ospf_ia_network_route(): "
  96                        "Found a route to the same network");
  97           /* Check the existing route. */
  98           if ((res = ospf_route_cmp (ospf, new_or, or)) < 0)
  99             {
 100               /* New route is better, so replace old one. */
 101               ospf_route_subst (rn1, new_or, abr_or);
 102             }
 103           else if (res == 0)
 104             {
 105               /* New and old route are equal, so next hops can be added. */
 106               route_lock_node (rn1);
 107               ospf_route_copy_nexthops (or, abr_or->paths);
 108               route_unlock_node (rn1);
 109
 110               /* new route can be deleted, because existing route has been updated. */
 111               ospf_route_free (new_or);
 112             }
 113           else
 114             {
 115               /* New route is worse, so free it. */
 116               ospf_route_free (new_or);
 117               return;
 118             }
 119         } /* if (or)*/
 120     } /*if (rn1)*/
 121   else
 122     { /* no route */
 123       if (IS_DEBUG_OSPF_EVENT)
 124         zlog_info ("ospf_ia_network_route(): add new route to %s/%d",
 125                    inet_ntoa (p->prefix), p->prefixlen);
 126       ospf_route_add (rt, p, new_or, abr_or);
 127     }
 128 }
 129
 130 void
 131 ospf_ia_router_route (struct ospf *ospf, struct route_table *rtrs,
 132                       struct prefix_ipv4 *p,
 133                       struct ospf_route *new_or, struct ospf_route *abr_or)
 134 {
 135   struct ospf_route *or = NULL;
 136   struct route_node *rn;
 137   int ret;
 138
 139   if (IS_DEBUG_OSPF_EVENT)
 140     zlog_info ("ospf_ia_router_route(): considering %s/%d",
 141                inet_ntoa (p->prefix), p->prefixlen);
 142   /* Find a route to the same dest */
 143   rn = route_node_get (rtrs, (struct prefix *) p);
 144
 145   if (rn->info == NULL)
 146     /* This is a new route */
 147     rn->info = list_new ();
 148   else
 149     {
 150       struct ospf_area *or_area;
 151       or_area = ospf_area_lookup_by_area_id (ospf, new_or->u.std.area_id);
 152       assert (or_area);
 153       /* This is an additional route */
 154       route_unlock_node (rn);
 155       or = ospf_find_asbr_route_through_area (rtrs, p, or_area);
 156     }
 157
 158   if (or)
 159     {
 160       if (IS_DEBUG_OSPF_EVENT)
 161         zlog_info ("ospf_ia_router_route(): "
 162                    "a route to the same ABR through the same area exists");
 163       /* New route is better */
 164       if ((ret = ospf_route_cmp (ospf, new_or, or)) < 0)
 165         {
 166           listnode_delete (rn->info, or);
 167           ospf_route_free (or);
 168           /* proceed down */
 169         }
 170       /* Routes are the same */
 171       else if (ret == 0)
 172         {
 173           if (IS_DEBUG_OSPF_EVENT)
 174             zlog_info ("ospf_ia_router_route(): merging the new route");
 175
 176           ospf_route_copy_nexthops (or, abr_or->paths);
 177           ospf_route_free (new_or);
 178           return;
 179         }
 180       /* New route is worse */
 181       else
 182         {
 183           if (IS_DEBUG_OSPF_EVENT)
 184             zlog_info ("ospf_ia_router_route(): skipping the new route");
 185           ospf_route_free (new_or);
 186           return;
 187         }
 188     }
 189
 190   ospf_route_copy_nexthops (new_or, abr_or->paths);
 191
 192   if (IS_DEBUG_OSPF_EVENT)
 193     zlog_info ("ospf_ia_router_route(): adding the new route");
 194
 195   listnode_add (rn->info, new_or);
 196 }
 197
 198 \f
 199 int
 200 process_summary_lsa (struct ospf_area *area, struct route_table *rt,
 201                      struct route_table *rtrs, struct ospf_lsa *lsa)
 202 {
 203   struct ospf *ospf = area->ospf;
 204   struct ospf_area_range *range;
 205   struct ospf_route *abr_or, *new_or;
 206   struct summary_lsa *sl;
 207   struct prefix_ipv4 p, abr;
 208   u_int32_t metric;
 209
 210   if (lsa == NULL)
 211     return 0;
 212
 213   sl = (struct summary_lsa *) lsa->data;
 214
 215   if (IS_DEBUG_OSPF_EVENT)
 216     zlog_info ("process_summary_lsa(): LS ID: %s", inet_ntoa (sl->header.id));
 217
 218   metric = GET_METRIC (sl->metric);
 219
 220   if (metric == OSPF_LS_INFINITY)
 221     return 0;
 222
 223   if (IS_LSA_MAXAGE (lsa))
 224     return 0;
 225
 226   if (ospf_lsa_is_self_originated (area->ospf, lsa))
 227     return 0;
 228
 229   p.family = AF_INET;
 230   p.prefix = sl->header.id;
 231
 232   if (sl->header.type == OSPF_SUMMARY_LSA)
 233     p.prefixlen = ip_masklen (sl->mask);
 234   else
 235     p.prefixlen = IPV4_MAX_BITLEN;
 236
 237   apply_mask_ipv4 (&p);
 238
 239   if (sl->header.type == OSPF_SUMMARY_LSA &&
 240       (range = ospf_area_range_match_any (ospf, &p)) &&
 241       ospf_area_range_active (range))
 242     return 0;
 243
 244   if (ospf->abr_type != OSPF_ABR_STAND &&
 245       area->external_routing != OSPF_AREA_DEFAULT &&
 246       p.prefix.s_addr == OSPF_DEFAULT_DESTINATION &&
 247       p.prefixlen == 0)
 248     return 0; /* Ignore summary default from a stub area */
 249
 250   abr.family = AF_INET;
 251   abr.prefix = sl->header.adv_router;
 252   abr.prefixlen = IPV4_MAX_BITLEN;
 253   apply_mask_ipv4 (&abr);
 254
 255   abr_or = ospf_find_abr_route (rtrs, &abr, area);
 256
 257   if (abr_or == NULL)
 258     return 0;
 259
 260   new_or = ospf_route_new ();
 261   new_or->type = OSPF_DESTINATION_NETWORK;
 262   new_or->id = sl->header.id;
 263   new_or->mask = sl->mask;
 264   new_or->u.std.options = sl->header.options;
 265   new_or->u.std.origin = (struct lsa_header *) sl;
 266   new_or->cost = abr_or->cost + metric;
 267   new_or->u.std.area_id = area->area_id;
 268 #ifdef HAVE_NSSA
 269   new_or->u.std.external_routing = area->external_routing;
 270 #endif /* HAVE_NSSA */
 271   new_or->path_type = OSPF_PATH_INTER_AREA;
 272
 273   if (sl->header.type == OSPF_SUMMARY_LSA)
 274     ospf_ia_network_route (ospf, rt, &p, new_or, abr_or);
 275   else
 276     {
 277       new_or->type = OSPF_DESTINATION_ROUTER;
 278       new_or->u.std.flags = ROUTER_LSA_EXTERNAL;
 279       ospf_ia_router_route (ospf, rtrs, &p, new_or, abr_or);
 280     }
 281
 282   return 0;
 283 }
 284
 285 void
 286 ospf_examine_summaries (struct ospf_area *area,
 287                         struct route_table *lsdb_rt,
 288                         struct route_table *rt,
 289                         struct route_table *rtrs)
 290 {
 291   struct ospf_lsa *lsa;
 292   struct route_node *rn;
 293
 294   LSDB_LOOP (lsdb_rt, rn, lsa)
 295     process_summary_lsa (area, rt, rtrs, lsa);
 296 }
 297
 298 int
 299 ospf_area_is_transit (struct ospf_area *area)
 300 {
 301   return (area->transit == OSPF_TRANSIT_TRUE) ||
 302     ospf_full_virtual_nbrs(area); /* Cisco forgets to set the V-bit :( */
 303 }
 304
 305 void
 306 ospf_update_network_route (struct ospf *ospf,
 307                            struct route_table *rt,
 308                            struct route_table *rtrs,
 309                            struct summary_lsa *lsa,
 310                            struct prefix_ipv4 *p,
 311                            struct ospf_area *area)
 312 {
 313   struct route_node *rn;
 314   struct ospf_route *or, *abr_or, *new_or;
 315   struct prefix_ipv4 abr;
 316   u_int32_t cost;
 317
 318   abr.family = AF_INET;
 319   abr.prefix =lsa->header.adv_router;
 320   abr.prefixlen = IPV4_MAX_BITLEN;
 321   apply_mask_ipv4 (&abr);
 322
 323   abr_or = ospf_find_abr_route (rtrs, &abr, area);
 324
 325   if (abr_or == NULL)
 326     {
 327       if (IS_DEBUG_OSPF_EVENT)
 328         zlog_info ("ospf_update_network_route(): can't find a route to the ABR");
 329       return;
 330     }
 331
 332   cost = abr_or->cost + GET_METRIC (lsa->metric);
 333
 334   rn = route_node_lookup (rt, (struct prefix *) p);
 335
 336   if (! rn)
 337     {
 338       if (ospf->abr_type != OSPF_ABR_SHORTCUT)
 339         return; /* Standard ABR can update only already installed
 340                    backbone paths                                       */
 341       if (IS_DEBUG_OSPF_EVENT)
 342         zlog_info ("ospf_update_network_route(): "
 343                    "Allowing Shortcut ABR to add new route");
 344       new_or = ospf_route_new ();
 345       new_or->type = OSPF_DESTINATION_NETWORK;
 346       new_or->id = lsa->header.id;
 347       new_or->mask = lsa->mask;
 348       new_or->u.std.options = lsa->header.options;
 349       new_or->u.std.origin = (struct lsa_header *) lsa;
 350       new_or->cost = cost;
 351       new_or->u.std.area_id = area->area_id;
 352 #ifdef HAVE_NSSA
 353       new_or->u.std.external_routing = area->external_routing;
 354 #endif /* HAVE_NSSA */
 355       new_or->path_type = OSPF_PATH_INTER_AREA;
 356       ospf_route_add (rt, p, new_or, abr_or);
 357
 358       return;
 359     }
 360   else
 361     {
 362       route_unlock_node (rn);
 363       if (rn->info == NULL)
 364         return;
 365     }
 366
 367   or = rn->info;
 368
 369   if (or->path_type != OSPF_PATH_INTRA_AREA &&
 370       or->path_type != OSPF_PATH_INTER_AREA)
 371     {
 372       if (IS_DEBUG_OSPF_EVENT)
 373         zlog_info ("ospf_update_network_route(): ERR: path type is wrong");
 374       return;
 375     }
 376
 377   if (ospf->abr_type == OSPF_ABR_SHORTCUT)
 378     {
 379       if (or->path_type == OSPF_PATH_INTRA_AREA &&
 380           !OSPF_IS_AREA_ID_BACKBONE (or->u.std.area_id))
 381         {
 382           if (IS_DEBUG_OSPF_EVENT)
 383             zlog_info ("ospf_update_network_route(): Shortcut: "
 384                        "this intra-area path is not backbone");
 385           return;
 386         }
 387     }
 388   else   /* Not Shortcut ABR */
 389     {
 390       if (!OSPF_IS_AREA_ID_BACKBONE (or->u.std.area_id))
 391         {
 392           if (IS_DEBUG_OSPF_EVENT)
 393             zlog_info ("ospf_update_network_route(): "
 394                        "route is not BB-associated");
 395           return; /* We can update only BB routes */
 396         }
 397     }
 398
 399   if (or->cost < cost)
 400     {
 401       if (IS_DEBUG_OSPF_EVENT)
 402         zlog_info ("ospf_update_network_route(): new route is worse");
 403       return;
 404     }
 405
 406   if (or->cost == cost)
 407     {
 408       if (IS_DEBUG_OSPF_EVENT)
 409         zlog_info ("ospf_update_network_route(): "
 410                    "new route is same distance, adding nexthops");
 411       ospf_route_copy_nexthops (or, abr_or->paths);
 412     }
 413
 414   if (or->cost > cost)
 415     {
 416       if (IS_DEBUG_OSPF_EVENT)
 417         zlog_info ("ospf_update_network_route(): "
 418                    "new route is better, overriding nexthops");
 419       ospf_route_subst_nexthops (or, abr_or->paths);
 420       or->cost = cost;
 421
 422       if ((ospf->abr_type == OSPF_ABR_SHORTCUT) &&
 423           !OSPF_IS_AREA_ID_BACKBONE (or->u.std.area_id))
 424         {
 425           or->path_type = OSPF_PATH_INTER_AREA;
 426           or->u.std.area_id = area->area_id;
 427 #ifdef HAVE_NSSA
 428           or->u.std.external_routing = area->external_routing;
 429 #endif /* HAVE_NSSA */
 430           /* Note that we can do this only in Shortcut ABR mode,
 431              because standard ABR must leave the route type and area
 432              unchanged
 433           */
 434         }
 435     }
 436 }
 437
 438 void
 439 ospf_update_router_route (struct ospf *ospf,
 440                           struct route_table *rtrs,
 441                           struct summary_lsa *lsa,
 442                           struct prefix_ipv4 *p,
 443                           struct ospf_area *area)
 444 {
 445   struct ospf_route *or, *abr_or, *new_or;
 446   struct prefix_ipv4 abr;
 447   u_int32_t cost;
 448
 449   abr.family = AF_INET;
 450   abr.prefix = lsa->header.adv_router;
 451   abr.prefixlen = IPV4_MAX_BITLEN;
 452   apply_mask_ipv4 (&abr);
 453
 454   abr_or = ospf_find_abr_route (rtrs, &abr, area);
 455
 456   if (abr_or == NULL)
 457     {
 458       if (IS_DEBUG_OSPF_EVENT)
 459         zlog_info ("ospf_update_router_route(): can't find a route to the ABR");
 460       return;
 461     }
 462
 463   cost = abr_or->cost + GET_METRIC (lsa->metric);
 464
 465   /* First try to find a backbone path,
 466      because standard ABR can update only BB-associated paths */
 467
 468   if ((ospf->backbone == NULL) &&
 469       (ospf->abr_type != OSPF_ABR_SHORTCUT))
 470
 471      /* no BB area, not Shortcut ABR, exiting */
 472      return;
 473
 474   or = ospf_find_asbr_route_through_area (rtrs, p, ospf->backbone);
 475
 476   if (or == NULL)
 477     {
 478       if (ospf->abr_type != OSPF_ABR_SHORTCUT)
 479
 480          /* route to ASBR through the BB not found
 481             the router is not Shortcut ABR, exiting */
 482
 483           return;
 484       else
 485         /* We're a Shortcut ABR*/
 486         {
 487           /* Let it either add a new router or update the route
 488              through the same (non-BB) area. */
 489
 490           new_or = ospf_route_new ();
 491           new_or->type = OSPF_DESTINATION_ROUTER;
 492           new_or->id = lsa->header.id;
 493           new_or->mask = lsa->mask;
 494           new_or->u.std.options = lsa->header.options;
 495           new_or->u.std.origin = (struct lsa_header *)lsa;
 496           new_or->cost = cost;
 497           new_or->u.std.area_id = area->area_id;
 498 #ifdef HAVE_NSSA
 499           new_or->u.std.external_routing = area->external_routing;
 500 #endif /* HAVE_NSSA */
 501           new_or->path_type = OSPF_PATH_INTER_AREA;
 502           new_or->u.std.flags = ROUTER_LSA_EXTERNAL;
 503           ospf_ia_router_route (ospf, rtrs, p, new_or, abr_or);
 504
 505           return;
 506         }
 507     }
 508
 509   /* At this point the "or" is always bb-associated */
 510
 511   if (!(or->u.std.flags & ROUTER_LSA_EXTERNAL))
 512     {
 513       if (IS_DEBUG_OSPF_EVENT)
 514         zlog_info ("ospf_upd_router_route(): the remote router is not an ASBR");
 515       return;
 516     }
 517
 518   if (or->path_type != OSPF_PATH_INTRA_AREA &&
 519       or->path_type != OSPF_PATH_INTER_AREA)
 520     return;
 521
 522   if (or->cost < cost)
 523     return;
 524
 525   else if (or->cost == cost)
 526     ospf_route_copy_nexthops (or, abr_or->paths);
 527
 528   else if (or->cost > cost)
 529     {
 530       ospf_route_subst_nexthops (or, abr_or->paths);
 531       or->cost = cost;
 532
 533       /* Even if the ABR runs in Shortcut mode, we can't change
 534          the path type and area, because the "or" is always bb-associated
 535          at this point and even Shortcut ABR can't change these attributes */
 536     }
 537 }
 538
 539 int
 540 process_transit_summary_lsa (struct ospf_area *area, struct route_table *rt,
 541                              struct route_table *rtrs, struct ospf_lsa *lsa)
 542 {
 543   struct ospf *ospf = area->ospf;
 544   struct summary_lsa *sl;
 545   struct prefix_ipv4 p;
 546   u_int32_t metric;
 547
 548   if (lsa == NULL)
 549     return 0;
 550
 551   sl = (struct summary_lsa *) lsa->data;
 552
 553   if (IS_DEBUG_OSPF_EVENT)
 554     zlog_info ("process_transit_summaries(): LS ID: %s",
 555                inet_ntoa (lsa->data->id));
 556   metric = GET_METRIC (sl->metric);
 557
 558   if (metric == OSPF_LS_INFINITY)
 559     {
 560       if (IS_DEBUG_OSPF_EVENT)
 561         zlog_info ("process_transit_summaries(): metric is infinity, skip");
 562       return 0;
 563     }
 564
 565   if (IS_LSA_MAXAGE (lsa))
 566     {
 567       if (IS_DEBUG_OSPF_EVENT)
 568         zlog_info ("process_transit_summaries(): This LSA is too old");
 569       return 0;
 570     }
 571
 572   if (ospf_lsa_is_self_originated (area->ospf, lsa))
 573     {
 574       if (IS_DEBUG_OSPF_EVENT)
 575         zlog_info ("process_transit_summaries(): This LSA is mine, skip");
 576       return 0;
 577     }
 578
 579   p.family = AF_INET;
 580   p.prefix = sl->header.id;
 581
 582   if (sl->header.type == OSPF_SUMMARY_LSA)
 583     p.prefixlen = ip_masklen (sl->mask);
 584   else
 585     p.prefixlen = IPV4_MAX_BITLEN;
 586
 587   apply_mask_ipv4 (&p);
 588
 589   if (sl->header.type == OSPF_SUMMARY_LSA)
 590     ospf_update_network_route (ospf, rt, rtrs, sl, &p, area);
 591   else
 592     ospf_update_router_route (ospf, rtrs, sl, &p, area);
 593
 594   return 0;
 595 }
 596
 597 void
 598 ospf_examine_transit_summaries (struct ospf_area *area,
 599                                 struct route_table *lsdb_rt,
 600                                 struct route_table *rt,
 601                                 struct route_table *rtrs)
 602 {
 603   struct ospf_lsa *lsa;
 604   struct route_node *rn;
 605
 606   LSDB_LOOP (lsdb_rt, rn, lsa)
 607     process_transit_summary_lsa (area, rt, rtrs, lsa);
 608 }
 609
 610 void
 611 ospf_ia_routing (struct ospf *ospf,
 612                  struct route_table *rt,
 613                  struct route_table *rtrs)
 614 {
 615   struct ospf_area * area;
 616
 617   if (IS_DEBUG_OSPF_EVENT)
 618     zlog_info ("ospf_ia_routing():start");
 619
 620   if (IS_OSPF_ABR (ospf))
 621     {
 622       listnode node;
 623       struct ospf_area *area;
 624
 625       switch (ospf->abr_type)
 626         {
 627         case OSPF_ABR_STAND:
 628           if (IS_DEBUG_OSPF_EVENT)
 629             zlog_info ("ospf_ia_routing():Standard ABR");
 630
 631           if ((area = ospf->backbone))
 632             {
 633               listnode node;
 634
 635               if (IS_DEBUG_OSPF_EVENT)
 636                 {
 637                   zlog_info ("ospf_ia_routing():backbone area found");
 638                   zlog_info ("ospf_ia_routing():examining summaries");
 639                 }
 640
 641               OSPF_EXAMINE_SUMMARIES_ALL (area, rt, rtrs);
 642
 643               for (node = listhead (ospf->areas); node; nextnode (node))
 644                 if ((area = getdata (node)) != NULL)
 645                   if (area != ospf->backbone)
 646                     if (ospf_area_is_transit (area))
 647                       OSPF_EXAMINE_TRANSIT_SUMMARIES_ALL (area, rt, rtrs);
 648             }
 649           else
 650             if (IS_DEBUG_OSPF_EVENT)
 651               zlog_info ("ospf_ia_routing():backbone area NOT found");
 652           break;
 653         case OSPF_ABR_IBM:
 654         case OSPF_ABR_CISCO:
 655           if (IS_DEBUG_OSPF_EVENT)
 656             zlog_info ("ospf_ia_routing():Alternative Cisco/IBM ABR");
 657           area = ospf->backbone; /* Find the BB */
 658
 659           /* If we have an active BB connection */
 660           if (area && ospf_act_bb_connection (ospf))
 661             {
 662               if (IS_DEBUG_OSPF_EVENT)
 663                 {
 664                   zlog_info ("ospf_ia_routing(): backbone area found");
 665                   zlog_info ("ospf_ia_routing(): examining BB summaries");
 666                 }
 667
 668               OSPF_EXAMINE_SUMMARIES_ALL (area, rt, rtrs);
 669
 670               for (node = listhead (ospf->areas); node; nextnode (node))
 671                 if ((area = getdata (node)) != NULL)
 672                   if (area != ospf->backbone)
 673                     if (ospf_area_is_transit (area))
 674                       OSPF_EXAMINE_TRANSIT_SUMMARIES_ALL (area, rt, rtrs);
 675             }
 676           else
 677             { /* No active BB connection--consider all areas */
 678               if (IS_DEBUG_OSPF_EVENT)
 679                 zlog_info ("ospf_ia_routing(): "
 680                            "Active BB connection not found");
 681               for (node = listhead (ospf->areas); node; nextnode (node))
 682                 if ((area = getdata (node)) != NULL)
 683                   OSPF_EXAMINE_SUMMARIES_ALL (area, rt, rtrs);
 684             }
 685           break;
 686         case OSPF_ABR_SHORTCUT:
 687           if (IS_DEBUG_OSPF_EVENT)
 688             zlog_info ("ospf_ia_routing():Alternative Shortcut");
 689           area = ospf->backbone; /* Find the BB */
 690
 691           /* If we have an active BB connection */
 692           if (area && ospf_act_bb_connection (ospf))
 693             {
 694               if (IS_DEBUG_OSPF_EVENT)
 695                 {
 696                   zlog_info ("ospf_ia_routing(): backbone area found");
 697                   zlog_info ("ospf_ia_routing(): examining BB summaries");
 698                 }
 699               OSPF_EXAMINE_SUMMARIES_ALL (area, rt, rtrs);
 700             }
 701
 702           for (node = listhead (ospf->areas); node; nextnode (node))
 703             if ((area = getdata (node)) != NULL)
 704               if (area != ospf->backbone)
 705                 if (ospf_area_is_transit (area) ||
 706                     ((area->shortcut_configured != OSPF_SHORTCUT_DISABLE) &&
 707                      ((ospf->backbone == NULL) ||
 708                       ((area->shortcut_configured == OSPF_SHORTCUT_ENABLE) &&
 709                        area->shortcut_capability))))
 710                   OSPF_EXAMINE_TRANSIT_SUMMARIES_ALL (area, rt, rtrs);
 711           break;
 712         default:
 713           break;
 714         }
 715     }
 716   else
 717     {
 718       listnode node;
 719
 720       if (IS_DEBUG_OSPF_EVENT)
 721         zlog_info ("ospf_ia_routing():not ABR, considering all areas");
 722
 723       for (node = listhead (ospf->areas); node; nextnode (node))
 724         if ((area = getdata (node)) != NULL)
 725           OSPF_EXAMINE_SUMMARIES_ALL (area, rt, rtrs);
 726     }
 727 }