isisd/isis_dr.c

   1 /*
   2  * IS-IS Rout(e)ing protocol - isis_dr.c
   3  *                             IS-IS designated router related routines
   4  *
   5  * Copyright (C) 2001,2002   Sampo Saaristo
   6  *                           Tampere University of Technology
   7  *                           Institute of Communications Engineering
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU General Public Licenseas published by the Free
  11  * Software Foundation; either version 2 of the License, or (at your option)
  12  * any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,but WITHOUT
  15  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  16  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  17  * more details.
  18
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write to the Free Software Foundation, Inc.,
  21  * 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  22  */
  23
  24
  25 #include <zebra.h>
  26
  27 #include "log.h"
  28 #include "hash.h"
  29 #include "thread.h"
  30 #include "linklist.h"
  31 #include "vty.h"
  32 #include "stream.h"
  33 #include "if.h"
  34
  35 #include "isisd/dict.h"
  36 #include "isisd/isis_constants.h"
  37 #include "isisd/isis_common.h"
  38 #include "isisd/isis_misc.h"
  39 #include "isisd/isis_flags.h"
  40 #include "isisd/isis_circuit.h"
  41 #include "isisd/isisd.h"
  42 #include "isisd/isis_adjacency.h"
  43 #include "isisd/isis_constants.h"
  44 #include "isisd/isis_pdu.h"
  45 #include "isisd/isis_tlv.h"
  46 #include "isisd/isis_lsp.h"
  47 #include "isisd/isis_dr.h"
  48 #include "isisd/isis_events.h"
  49
  50 extern struct isis *isis;
  51 extern struct thread_master *master;
  52
  53 const char *
  54 isis_disflag2string (int disflag)
  55 {
  56
  57   switch (disflag)
  58     {
  59     case ISIS_IS_NOT_DIS:
  60       return "is not DIS";
  61     case ISIS_IS_DIS:
  62       return "is DIS";
  63     case ISIS_WAS_DIS:
  64       return "was DIS";
  65     default:
  66       return "unknown DIS state";
  67     }
  68   return NULL;                  /* not reached */
  69 }
  70
  71 int
  72 isis_run_dr_l1 (struct thread *thread)
  73 {
  74   struct isis_circuit *circuit;
  75
  76   circuit = THREAD_ARG (thread);
  77   assert (circuit);
  78
  79   if (circuit->u.bc.run_dr_elect[0])
  80     zlog_warn ("isis_run_dr(): run_dr_elect already set for l1");
  81
  82   circuit->u.bc.t_run_dr[0] = NULL;
  83   circuit->u.bc.run_dr_elect[0] = 1;
  84
  85   return ISIS_OK;
  86 }
  87
  88 int
  89 isis_run_dr_l2 (struct thread *thread)
  90 {
  91   struct isis_circuit *circuit;
  92
  93   circuit = THREAD_ARG (thread);
  94   assert (circuit);
  95
  96   if (circuit->u.bc.run_dr_elect[1])
  97     zlog_warn ("isis_run_dr(): run_dr_elect already set for l2");
  98
  99
 100   circuit->u.bc.t_run_dr[1] = NULL;
 101   circuit->u.bc.run_dr_elect[1] = 1;
 102
 103   return ISIS_OK;
 104 }
 105
 106 static int
 107 isis_check_dr_change (struct isis_adjacency *adj, int level)
 108 {
 109   int i;
 110
 111   if (adj->dis_record[level - 1].dis !=
 112       adj->dis_record[(1 * ISIS_LEVELS) + level - 1].dis)
 113     /* was there a DIS state transition ? */
 114     {
 115       adj->dischanges[level - 1]++;
 116       /* ok rotate the history list through */
 117       for (i = DIS_RECORDS - 1; i > 0; i--)
 118         {
 119           adj->dis_record[(i * ISIS_LEVELS) + level - 1].dis =
 120             adj->dis_record[((i - 1) * ISIS_LEVELS) + level - 1].dis;
 121           adj->dis_record[(i * ISIS_LEVELS) + level - 1].last_dis_change =
 122             adj->dis_record[((i - 1) * ISIS_LEVELS) + level -
 123                             1].last_dis_change;
 124         }
 125     }
 126   return ISIS_OK;
 127 }
 128
 129 int
 130 isis_dr_elect (struct isis_circuit *circuit, int level)
 131 {
 132   struct list *adjdb;
 133   struct listnode *node, *nnode;
 134   struct isis_adjacency *adj, *adj_dr = NULL;
 135   struct list *list = list_new ();
 136   u_char own_prio;
 137   int biggest_prio = -1;
 138   int cmp_res, retval = ISIS_OK;
 139
 140   own_prio = circuit->u.bc.priority[level - 1];
 141   adjdb = circuit->u.bc.adjdb[level - 1];
 142
 143   if (!adjdb)
 144     {
 145       zlog_warn ("isis_dr_elect() adjdb == NULL");
 146       retval = ISIS_WARNING;
 147       list_delete (list);
 148       goto out;
 149     }
 150   isis_adj_build_up_list (adjdb, list);
 151
 152   /*
 153    * Loop the adjacencies and find the one with the biggest priority
 154    */
 155   for (ALL_LIST_ELEMENTS (list, node, nnode, adj))
 156     {
 157       /* clear flag for show output */
 158       adj->dis_record[level - 1].dis = ISIS_IS_NOT_DIS;
 159       adj->dis_record[level - 1].last_dis_change = time (NULL);
 160
 161       if (adj->prio[level - 1] > biggest_prio)
 162         {
 163           biggest_prio = adj->prio[level - 1];
 164           adj_dr = adj;
 165         }
 166       else if (adj->prio[level - 1] == biggest_prio)
 167         {
 168           /*
 169            * Comparison of MACs breaks a tie
 170            */
 171           if (adj_dr)
 172             {
 173               cmp_res = memcmp (adj_dr->snpa, adj->snpa, ETH_ALEN);
 174               if (cmp_res < 0)
 175                 {
 176                   adj_dr = adj;
 177                 }
 178               if (cmp_res == 0)
 179                 zlog_warn
 180                   ("isis_dr_elect(): multiple adjacencies with same SNPA");
 181             }
 182           else
 183             {
 184               adj_dr = adj;
 185             }
 186         }
 187     }
 188
 189   if (!adj_dr)
 190     {
 191       /*
 192        * Could not find the DR - means we are alone and thus the DR
 193        */
 194       if (!circuit->u.bc.is_dr[level - 1])
 195         {
 196           list_delete (list);
 197           list = NULL;
 198           return isis_dr_commence (circuit, level);
 199         }
 200       goto out;
 201     }
 202
 203   /*
 204    * Now we have the DR adjacency, compare it to self
 205    */
 206   if (adj_dr->prio[level - 1] < own_prio
 207       || (adj_dr->prio[level - 1] == own_prio
 208           && memcmp (adj_dr->snpa, circuit->u.bc.snpa, ETH_ALEN) < 0))
 209     {
 210       if (!circuit->u.bc.is_dr[level - 1])
 211         {
 212           /*
 213            * We are the DR
 214            */
 215
 216           /* rotate the history log */
 217           for (ALL_LIST_ELEMENTS (list, node, nnode, adj))
 218             isis_check_dr_change (adj, level);
 219
 220           /* commence */
 221           list_delete (list);
 222           return isis_dr_commence (circuit, level);
 223         }
 224     }
 225   else
 226     {
 227
 228       /* ok we have found the DIS - lets mark the adjacency */
 229       /* set flag for show output */
 230       adj_dr->dis_record[level - 1].dis = ISIS_IS_DIS;
 231       adj_dr->dis_record[level - 1].last_dis_change = time (NULL);
 232
 233       /* now loop through a second time to check if there has been a DIS change
 234        * if yes rotate the history log
 235        */
 236
 237       for (ALL_LIST_ELEMENTS (list, node, nnode, adj))
 238         isis_check_dr_change (adj, level);
 239
 240       /*
 241        * We are not DR - if we were -> resign
 242        */
 243
 244       if (circuit->u.bc.is_dr[level - 1])
 245         {
 246           list_delete (list);
 247           return isis_dr_resign (circuit, level);
 248         }
 249     }
 250 out:
 251   if (list)
 252     list_delete (list);
 253   return retval;
 254 }
 255
 256 int
 257 isis_dr_resign (struct isis_circuit *circuit, int level)
 258 {
 259   u_char id[ISIS_SYS_ID_LEN + 2];
 260
 261   zlog_debug ("isis_dr_resign l%d", level);
 262
 263   circuit->u.bc.is_dr[level - 1] = 0;
 264   circuit->u.bc.run_dr_elect[level - 1] = 0;
 265   THREAD_TIMER_OFF (circuit->u.bc.t_run_dr[level - 1]);
 266   THREAD_TIMER_OFF (circuit->u.bc.t_refresh_pseudo_lsp[level - 1]);
 267
 268   memcpy (id, isis->sysid, ISIS_SYS_ID_LEN);
 269   LSP_PSEUDO_ID (id) = circuit->circuit_id;
 270   LSP_FRAGMENT (id) = 0;
 271   lsp_purge_dr (id, circuit, level);
 272
 273   if (level == 1)
 274     {
 275       memset (circuit->u.bc.l1_desig_is, 0, ISIS_SYS_ID_LEN + 1);
 276
 277       THREAD_TIMER_OFF (circuit->t_send_csnp[0]);
 278
 279       THREAD_TIMER_ON (master, circuit->u.bc.t_run_dr[0], isis_run_dr_l1,
 280                        circuit, 2 * circuit->hello_interval[1]);
 281
 282       THREAD_TIMER_ON (master, circuit->t_send_psnp[0], send_l1_psnp, circuit,
 283                        isis_jitter (circuit->psnp_interval[level - 1],
 284                                     PSNP_JITTER));
 285     }
 286   else
 287     {
 288       memset (circuit->u.bc.l2_desig_is, 0, ISIS_SYS_ID_LEN + 1);
 289
 290       THREAD_TIMER_OFF (circuit->t_send_csnp[1]);
 291
 292       THREAD_TIMER_ON (master, circuit->u.bc.t_run_dr[1], isis_run_dr_l2,
 293                        circuit, 2 * circuit->hello_interval[1]);
 294
 295       THREAD_TIMER_ON (master, circuit->t_send_psnp[1], send_l2_psnp, circuit,
 296                        isis_jitter (circuit->psnp_interval[level - 1],
 297                                     PSNP_JITTER));
 298     }
 299
 300   thread_add_event (master, isis_event_dis_status_change, circuit, 0);
 301
 302   return ISIS_OK;
 303 }
 304
 305 int
 306 isis_dr_commence (struct isis_circuit *circuit, int level)
 307 {
 308   u_char old_dr[ISIS_SYS_ID_LEN + 2];
 309
 310   zlog_debug ("isis_dr_commence l%d", level);
 311
 312   /* Lets keep a pause in DR election */
 313   circuit->u.bc.run_dr_elect[level - 1] = 0;
 314   if (level == 1)
 315     THREAD_TIMER_ON (master, circuit->u.bc.t_run_dr[0], isis_run_dr_l1,
 316                      circuit, 2 * circuit->hello_interval[0]);
 317   else
 318     THREAD_TIMER_ON (master, circuit->u.bc.t_run_dr[1], isis_run_dr_l2,
 319                      circuit, 2 * circuit->hello_interval[1]);
 320   circuit->u.bc.is_dr[level - 1] = 1;
 321
 322   if (level == 1)
 323     {
 324       memcpy (old_dr, circuit->u.bc.l1_desig_is, ISIS_SYS_ID_LEN + 1);
 325       LSP_FRAGMENT (old_dr) = 0;
 326       if (LSP_PSEUDO_ID (old_dr))
 327         {
 328           /* there was a dr elected, purge its LSPs from the db */
 329           lsp_purge_dr (old_dr, circuit, level);
 330         }
 331       memcpy (circuit->u.bc.l1_desig_is, isis->sysid, ISIS_SYS_ID_LEN);
 332       *(circuit->u.bc.l1_desig_is + ISIS_SYS_ID_LEN) = circuit->circuit_id;
 333
 334       assert (circuit->circuit_id);     /* must be non-zero */
 335       /*    if (circuit->t_send_l1_psnp)
 336          thread_cancel (circuit->t_send_l1_psnp); */
 337       lsp_l1_pseudo_generate (circuit);
 338
 339       THREAD_TIMER_OFF (circuit->u.bc.t_run_dr[0]);
 340       THREAD_TIMER_ON (master, circuit->u.bc.t_run_dr[0], isis_run_dr_l1,
 341                        circuit, 2 * circuit->hello_interval[0]);
 342
 343       THREAD_TIMER_ON (master, circuit->t_send_csnp[0], send_l1_csnp, circuit,
 344                        isis_jitter (circuit->csnp_interval[level - 1],
 345                                     CSNP_JITTER));
 346
 347     }
 348   else
 349     {
 350       memcpy (old_dr, circuit->u.bc.l2_desig_is, ISIS_SYS_ID_LEN + 1);
 351       LSP_FRAGMENT (old_dr) = 0;
 352       if (LSP_PSEUDO_ID (old_dr))
 353         {
 354           /* there was a dr elected, purge its LSPs from the db */
 355           lsp_purge_dr (old_dr, circuit, level);
 356         }
 357       memcpy (circuit->u.bc.l2_desig_is, isis->sysid, ISIS_SYS_ID_LEN);
 358       *(circuit->u.bc.l2_desig_is + ISIS_SYS_ID_LEN) = circuit->circuit_id;
 359
 360       assert (circuit->circuit_id);     /* must be non-zero */
 361       /*    if (circuit->t_send_l1_psnp)
 362          thread_cancel (circuit->t_send_l1_psnp); */
 363       lsp_l2_pseudo_generate (circuit);
 364
 365       THREAD_TIMER_OFF (circuit->u.bc.t_run_dr[1]);
 366       THREAD_TIMER_ON (master, circuit->u.bc.t_run_dr[1], isis_run_dr_l2,
 367                        circuit, 2 * circuit->hello_interval[1]);
 368
 369       THREAD_TIMER_ON (master, circuit->t_send_csnp[1], send_l2_csnp, circuit,
 370                        isis_jitter (circuit->csnp_interval[level - 1],
 371                                     CSNP_JITTER));
 372     }
 373
 374   thread_add_event (master, isis_event_dis_status_change, circuit, 0);
 375
 376   return ISIS_OK;
 377 }