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   struct 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 (ALL_LIST_ELEMENTS_RO ((struct list *) rn->info, node, or))
  66     if (IPV4_ADDR_SAME (&or->u.std.area_id, &area->area_id)
  67         && (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_debug ("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_debug ("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_debug ("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_debug ("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_debug ("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_debug ("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_debug ("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_debug ("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_debug ("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   /* XXX: This check seems dubious to me. If an ABR has already decided
 245    * to consider summaries received in this area, then why would one wish
 246    * to exclude default?
 247    */
 248   if (IS_OSPF_ABR(ospf) &&
 249       ospf->abr_type != OSPF_ABR_STAND &&
 250       area->external_routing != OSPF_AREA_DEFAULT &&
 251       p.prefix.s_addr == OSPF_DEFAULT_DESTINATION &&
 252       p.prefixlen == 0)
 253     return 0; /* Ignore summary default from a stub area */
 254
 255   abr.family = AF_INET;
 256   abr.prefix = sl->header.adv_router;
 257   abr.prefixlen = IPV4_MAX_BITLEN;
 258   apply_mask_ipv4 (&abr);
 259
 260   abr_or = ospf_find_abr_route (rtrs, &abr, area);
 261
 262   if (abr_or == NULL)
 263     return 0;
 264
 265   new_or = ospf_route_new ();
 266   new_or->type = OSPF_DESTINATION_NETWORK;
 267   new_or->id = sl->header.id;
 268   new_or->mask = sl->mask;
 269   new_or->u.std.options = sl->header.options;
 270   new_or->u.std.origin = (struct lsa_header *) sl;
 271   new_or->cost = abr_or->cost + metric;
 272   new_or->u.std.area_id = area->area_id;
 273   new_or->u.std.external_routing = area->external_routing;
 274   new_or->path_type = OSPF_PATH_INTER_AREA;
 275
 276   if (sl->header.type == OSPF_SUMMARY_LSA)
 277     ospf_ia_network_route (ospf, rt, &p, new_or, abr_or);
 278   else
 279     {
 280       new_or->type = OSPF_DESTINATION_ROUTER;
 281       new_or->u.std.flags = ROUTER_LSA_EXTERNAL;
 282       ospf_ia_router_route (ospf, rtrs, &p, new_or, abr_or);
 283     }
 284
 285   return 0;
 286 }
 287
 288 void
 289 ospf_examine_summaries (struct ospf_area *area,
 290                         struct route_table *lsdb_rt,
 291                         struct route_table *rt,
 292                         struct route_table *rtrs)
 293 {
 294   struct ospf_lsa *lsa;
 295   struct route_node *rn;
 296
 297   LSDB_LOOP (lsdb_rt, rn, lsa)
 298     process_summary_lsa (area, rt, rtrs, lsa);
 299 }
 300
 301 int
 302 ospf_area_is_transit (struct ospf_area *area)
 303 {
 304   return (area->transit == OSPF_TRANSIT_TRUE) ||
 305     ospf_full_virtual_nbrs(area); /* Cisco forgets to set the V-bit :( */
 306 }
 307
 308 void
 309 ospf_update_network_route (struct ospf *ospf,
 310                            struct route_table *rt,
 311                            struct route_table *rtrs,
 312                            struct summary_lsa *lsa,
 313                            struct prefix_ipv4 *p,
 314                            struct ospf_area *area)
 315 {
 316   struct route_node *rn;
 317   struct ospf_route *or, *abr_or, *new_or;
 318   struct prefix_ipv4 abr;
 319   u_int32_t cost;
 320
 321   abr.family = AF_INET;
 322   abr.prefix =lsa->header.adv_router;
 323   abr.prefixlen = IPV4_MAX_BITLEN;
 324   apply_mask_ipv4 (&abr);
 325
 326   abr_or = ospf_find_abr_route (rtrs, &abr, area);
 327
 328   if (abr_or == NULL)
 329     {
 330       if (IS_DEBUG_OSPF_EVENT)
 331         zlog_debug ("ospf_update_network_route(): can't find a route to the ABR");
 332       return;
 333     }
 334
 335   cost = abr_or->cost + GET_METRIC (lsa->metric);
 336
 337   rn = route_node_lookup (rt, (struct prefix *) p);
 338
 339   if (! rn)
 340     {
 341       if (ospf->abr_type != OSPF_ABR_SHORTCUT)
 342         return; /* Standard ABR can update only already installed
 343                    backbone paths                                       */
 344       if (IS_DEBUG_OSPF_EVENT)
 345         zlog_debug ("ospf_update_network_route(): "
 346                    "Allowing Shortcut ABR to add new route");
 347       new_or = ospf_route_new ();
 348       new_or->type = OSPF_DESTINATION_NETWORK;
 349       new_or->id = lsa->header.id;
 350       new_or->mask = lsa->mask;
 351       new_or->u.std.options = lsa->header.options;
 352       new_or->u.std.origin = (struct lsa_header *) lsa;
 353       new_or->cost = cost;
 354       new_or->u.std.area_id = area->area_id;
 355       new_or->u.std.external_routing = area->external_routing;
 356       new_or->path_type = OSPF_PATH_INTER_AREA;
 357       ospf_route_add (rt, p, new_or, abr_or);
 358
 359       return;
 360     }
 361   else
 362     {
 363       route_unlock_node (rn);
 364       if (rn->info == NULL)
 365         return;
 366     }
 367
 368   or = rn->info;
 369
 370   if (or->path_type != OSPF_PATH_INTRA_AREA &&
 371       or->path_type != OSPF_PATH_INTER_AREA)
 372     {
 373       if (IS_DEBUG_OSPF_EVENT)
 374         zlog_debug ("ospf_update_network_route(): ERR: path type is wrong");
 375       return;
 376     }
 377
 378   if (ospf->abr_type == OSPF_ABR_SHORTCUT)
 379     {
 380       if (or->path_type == OSPF_PATH_INTRA_AREA &&
 381           !OSPF_IS_AREA_ID_BACKBONE (or->u.std.area_id))
 382         {
 383           if (IS_DEBUG_OSPF_EVENT)
 384             zlog_debug ("ospf_update_network_route(): Shortcut: "
 385                        "this intra-area path is not backbone");
 386           return;
 387         }
 388     }
 389   else   /* Not Shortcut ABR */
 390     {
 391       if (!OSPF_IS_AREA_ID_BACKBONE (or->u.std.area_id))
 392         {
 393           if (IS_DEBUG_OSPF_EVENT)
 394             zlog_debug ("ospf_update_network_route(): "
 395                        "route is not BB-associated");
 396           return; /* We can update only BB routes */
 397         }
 398     }
 399
 400   if (or->cost < cost)
 401     {
 402       if (IS_DEBUG_OSPF_EVENT)
 403         zlog_debug ("ospf_update_network_route(): new route is worse");
 404       return;
 405     }
 406
 407   if (or->cost == cost)
 408     {
 409       if (IS_DEBUG_OSPF_EVENT)
 410         zlog_debug ("ospf_update_network_route(): "
 411                    "new route is same distance, adding nexthops");
 412       ospf_route_copy_nexthops (or, abr_or->paths);
 413     }
 414
 415   if (or->cost > cost)
 416     {
 417       if (IS_DEBUG_OSPF_EVENT)
 418         zlog_debug ("ospf_update_network_route(): "
 419                    "new route is better, overriding nexthops");
 420       ospf_route_subst_nexthops (or, abr_or->paths);
 421       or->cost = cost;
 422
 423       if ((ospf->abr_type == OSPF_ABR_SHORTCUT) &&
 424           !OSPF_IS_AREA_ID_BACKBONE (or->u.std.area_id))
 425         {
 426           or->path_type = OSPF_PATH_INTER_AREA;
 427           or->u.std.area_id = area->area_id;
 428           or->u.std.external_routing = area->external_routing;
 429           /* Note that we can do this only in Shortcut ABR mode,
 430              because standard ABR must leave the route type and area
 431              unchanged
 432           */
 433         }
 434     }
 435 }
 436
 437 void
 438 ospf_update_router_route (struct ospf *ospf,
 439                           struct route_table *rtrs,
 440                           struct summary_lsa *lsa,
 441                           struct prefix_ipv4 *p,
 442                           struct ospf_area *area)
 443 {
 444   struct ospf_route *or, *abr_or, *new_or;
 445   struct prefix_ipv4 abr;
 446   u_int32_t cost;
 447
 448   abr.family = AF_INET;
 449   abr.prefix = lsa->header.adv_router;
 450   abr.prefixlen = IPV4_MAX_BITLEN;
 451   apply_mask_ipv4 (&abr);
 452
 453   abr_or = ospf_find_abr_route (rtrs, &abr, area);
 454
 455   if (abr_or == NULL)
 456     {
 457       if (IS_DEBUG_OSPF_EVENT)
 458         zlog_debug ("ospf_update_router_route(): can't find a route to the ABR");
 459       return;
 460     }
 461
 462   cost = abr_or->cost + GET_METRIC (lsa->metric);
 463
 464   /* First try to find a backbone path,
 465      because standard ABR can update only BB-associated paths */
 466
 467   if ((ospf->backbone == NULL) &&
 468       (ospf->abr_type != OSPF_ABR_SHORTCUT))
 469
 470      /* no BB area, not Shortcut ABR, exiting */
 471      return;
 472
 473   or = ospf_find_asbr_route_through_area (rtrs, p, ospf->backbone);
 474
 475   if (or == NULL)
 476     {
 477       if (ospf->abr_type != OSPF_ABR_SHORTCUT)
 478
 479          /* route to ASBR through the BB not found
 480             the router is not Shortcut ABR, exiting */
 481
 482           return;
 483       else
 484         /* We're a Shortcut ABR*/
 485         {
 486           /* Let it either add a new router or update the route
 487              through the same (non-BB) area. */
 488
 489           new_or = ospf_route_new ();
 490           new_or->type = OSPF_DESTINATION_ROUTER;
 491           new_or->id = lsa->header.id;
 492           new_or->mask = lsa->mask;
 493           new_or->u.std.options = lsa->header.options;
 494           new_or->u.std.origin = (struct lsa_header *)lsa;
 495           new_or->cost = cost;
 496           new_or->u.std.area_id = area->area_id;
 497           new_or->u.std.external_routing = area->external_routing;
 498           new_or->path_type = OSPF_PATH_INTER_AREA;
 499           new_or->u.std.flags = ROUTER_LSA_EXTERNAL;
 500           ospf_ia_router_route (ospf, rtrs, p, new_or, abr_or);
 501
 502           return;
 503         }
 504     }
 505
 506   /* At this point the "or" is always bb-associated */
 507
 508   if (!(or->u.std.flags & ROUTER_LSA_EXTERNAL))
 509     {
 510       if (IS_DEBUG_OSPF_EVENT)
 511         zlog_debug ("ospf_upd_router_route(): the remote router is not an ASBR");
 512       return;
 513     }
 514
 515   if (or->path_type != OSPF_PATH_INTRA_AREA &&
 516       or->path_type != OSPF_PATH_INTER_AREA)
 517     return;
 518
 519   if (or->cost < cost)
 520     return;
 521
 522   else if (or->cost == cost)
 523     ospf_route_copy_nexthops (or, abr_or->paths);
 524
 525   else if (or->cost > cost)
 526     {
 527       ospf_route_subst_nexthops (or, abr_or->paths);
 528       or->cost = cost;
 529
 530       /* Even if the ABR runs in Shortcut mode, we can't change
 531          the path type and area, because the "or" is always bb-associated
 532          at this point and even Shortcut ABR can't change these attributes */
 533     }
 534 }
 535
 536 int
 537 process_transit_summary_lsa (struct ospf_area *area, struct route_table *rt,
 538                              struct route_table *rtrs, struct ospf_lsa *lsa)
 539 {
 540   struct ospf *ospf = area->ospf;
 541   struct summary_lsa *sl;
 542   struct prefix_ipv4 p;
 543   u_int32_t metric;
 544
 545   if (lsa == NULL)
 546     return 0;
 547
 548   sl = (struct summary_lsa *) lsa->data;
 549
 550   if (IS_DEBUG_OSPF_EVENT)
 551     zlog_debug ("process_transit_summaries(): LS ID: %s",
 552                inet_ntoa (lsa->data->id));
 553   metric = GET_METRIC (sl->metric);
 554
 555   if (metric == OSPF_LS_INFINITY)
 556     {
 557       if (IS_DEBUG_OSPF_EVENT)
 558         zlog_debug ("process_transit_summaries(): metric is infinity, skip");
 559       return 0;
 560     }
 561
 562   if (IS_LSA_MAXAGE (lsa))
 563     {
 564       if (IS_DEBUG_OSPF_EVENT)
 565         zlog_debug ("process_transit_summaries(): This LSA is too old");
 566       return 0;
 567     }
 568
 569   if (ospf_lsa_is_self_originated (area->ospf, lsa))
 570     {
 571       if (IS_DEBUG_OSPF_EVENT)
 572         zlog_debug ("process_transit_summaries(): This LSA is mine, skip");
 573       return 0;
 574     }
 575
 576   p.family = AF_INET;
 577   p.prefix = sl->header.id;
 578
 579   if (sl->header.type == OSPF_SUMMARY_LSA)
 580     p.prefixlen = ip_masklen (sl->mask);
 581   else
 582     p.prefixlen = IPV4_MAX_BITLEN;
 583
 584   apply_mask_ipv4 (&p);
 585
 586   if (sl->header.type == OSPF_SUMMARY_LSA)
 587     ospf_update_network_route (ospf, rt, rtrs, sl, &p, area);
 588   else
 589     ospf_update_router_route (ospf, rtrs, sl, &p, area);
 590
 591   return 0;
 592 }
 593
 594 void
 595 ospf_examine_transit_summaries (struct ospf_area *area,
 596                                 struct route_table *lsdb_rt,
 597                                 struct route_table *rt,
 598                                 struct route_table *rtrs)
 599 {
 600   struct ospf_lsa *lsa;
 601   struct route_node *rn;
 602
 603   LSDB_LOOP (lsdb_rt, rn, lsa)
 604     process_transit_summary_lsa (area, rt, rtrs, lsa);
 605 }
 606
 607 void
 608 ospf_ia_routing (struct ospf *ospf,
 609                  struct route_table *rt,
 610                  struct route_table *rtrs)
 611 {
 612   struct ospf_area * area;
 613
 614   if (IS_DEBUG_OSPF_EVENT)
 615     zlog_debug ("ospf_ia_routing():start");
 616
 617   if (IS_OSPF_ABR (ospf))
 618     {
 619       struct listnode *node;
 620       struct ospf_area *area;
 621
 622       switch (ospf->abr_type)
 623         {
 624         case OSPF_ABR_STAND:
 625           if (IS_DEBUG_OSPF_EVENT)
 626             zlog_debug ("ospf_ia_routing():Standard ABR");
 627
 628           if ((area = ospf->backbone))
 629             {
 630               struct listnode *node;
 631
 632               if (IS_DEBUG_OSPF_EVENT)
 633                 {
 634                   zlog_debug ("ospf_ia_routing():backbone area found");
 635                   zlog_debug ("ospf_ia_routing():examining summaries");
 636                 }
 637
 638               OSPF_EXAMINE_SUMMARIES_ALL (area, rt, rtrs);
 639
 640               for (ALL_LIST_ELEMENTS_RO (ospf->areas, node, area))
 641                 if (area != ospf->backbone)
 642                   if (ospf_area_is_transit (area))
 643                     OSPF_EXAMINE_TRANSIT_SUMMARIES_ALL (area, rt, rtrs);
 644             }
 645           else
 646             if (IS_DEBUG_OSPF_EVENT)
 647               zlog_debug ("ospf_ia_routing():backbone area NOT found");
 648           break;
 649         case OSPF_ABR_IBM:
 650         case OSPF_ABR_CISCO:
 651           if (IS_DEBUG_OSPF_EVENT)
 652             zlog_debug ("ospf_ia_routing():Alternative Cisco/IBM ABR");
 653           area = ospf->backbone; /* Find the BB */
 654
 655           /* If we have an active BB connection */
 656           if (area && ospf_act_bb_connection (ospf))
 657             {
 658               if (IS_DEBUG_OSPF_EVENT)
 659                 {
 660                   zlog_debug ("ospf_ia_routing(): backbone area found");
 661                   zlog_debug ("ospf_ia_routing(): examining BB summaries");
 662                 }
 663
 664               OSPF_EXAMINE_SUMMARIES_ALL (area, rt, rtrs);
 665
 666               for (ALL_LIST_ELEMENTS_RO (ospf->areas, node, area))
 667                 if (area != ospf->backbone)
 668                   if (ospf_area_is_transit (area))
 669                     OSPF_EXAMINE_TRANSIT_SUMMARIES_ALL (area, rt, rtrs);
 670             }
 671           else
 672             { /* No active BB connection--consider all areas */
 673               if (IS_DEBUG_OSPF_EVENT)
 674                 zlog_debug ("ospf_ia_routing(): "
 675                            "Active BB connection not found");
 676               for (ALL_LIST_ELEMENTS_RO (ospf->areas, node, area))
 677                 OSPF_EXAMINE_SUMMARIES_ALL (area, rt, rtrs);
 678             }
 679           break;
 680         case OSPF_ABR_SHORTCUT:
 681           if (IS_DEBUG_OSPF_EVENT)
 682             zlog_debug ("ospf_ia_routing():Alternative Shortcut");
 683           area = ospf->backbone; /* Find the BB */
 684
 685           /* If we have an active BB connection */
 686           if (area && ospf_act_bb_connection (ospf))
 687             {
 688               if (IS_DEBUG_OSPF_EVENT)
 689                 {
 690                   zlog_debug ("ospf_ia_routing(): backbone area found");
 691                   zlog_debug ("ospf_ia_routing(): examining BB summaries");
 692                 }
 693               OSPF_EXAMINE_SUMMARIES_ALL (area, rt, rtrs);
 694             }
 695
 696           for (ALL_LIST_ELEMENTS_RO (ospf->areas, node, area))
 697             if (area != ospf->backbone)
 698               if (ospf_area_is_transit (area) ||
 699                   ((area->shortcut_configured != OSPF_SHORTCUT_DISABLE) &&
 700                   ((ospf->backbone == NULL) ||
 701                   ((area->shortcut_configured == OSPF_SHORTCUT_ENABLE) &&
 702                   area->shortcut_capability))))
 703                 OSPF_EXAMINE_TRANSIT_SUMMARIES_ALL (area, rt, rtrs);
 704           break;
 705         default:
 706           break;
 707         }
 708     }
 709   else
 710     {
 711       struct listnode *node;
 712
 713       if (IS_DEBUG_OSPF_EVENT)
 714         zlog_debug ("ospf_ia_routing():not ABR, considering all areas");
 715
 716       for (ALL_LIST_ELEMENTS_RO (ospf->areas, node, area))
 717         OSPF_EXAMINE_SUMMARIES_ALL (area, rt, rtrs);
 718     }
 719 }