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; see the file COPYING; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 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/isis_constants.h"
  36 #include "isisd/isis_common.h"
  37 #include "isisd/isis_misc.h"
  38 #include "isisd/isis_flags.h"
  39 #include "isisd/isis_circuit.h"
  40 #include "isisd/isisd.h"
  41 #include "isisd/isis_adjacency.h"
  42 #include "isisd/isis_constants.h"
  43 #include "isisd/isis_pdu.h"
  44 #include "isisd/isis_lsp.h"
  45 #include "isisd/isis_dr.h"
  46 #include "isisd/isis_events.h"
  47
  48 const char *isis_disflag2string(int disflag)
  49 {
  50
  51         switch (disflag) {
  52         case ISIS_IS_NOT_DIS:
  53                 return "is not DIS";
  54         case ISIS_IS_DIS:
  55                 return "is DIS";
  56         case ISIS_WAS_DIS:
  57                 return "was DIS";
  58         default:
  59                 return "unknown DIS state";
  60         }
  61         return NULL; /* not reached */
  62 }
  63
  64 void isis_run_dr(struct thread *thread)
  65 {
  66         struct isis_circuit_arg *arg = THREAD_ARG(thread);
  67
  68         assert(arg);
  69
  70         struct isis_circuit *circuit = arg->circuit;
  71         int level = arg->level;
  72
  73         assert(circuit);
  74
  75         if (circuit->circ_type != CIRCUIT_T_BROADCAST) {
  76                 zlog_warn("%s: scheduled for non broadcast circuit from %s:%d",
  77                           __func__, thread->xref->xref.file,
  78                           thread->xref->xref.line);
  79                 return;
  80         }
  81
  82         if (circuit->u.bc.run_dr_elect[level - 1])
  83                 zlog_warn("%s: run_dr_elect already set for l%d", __func__,
  84                           level);
  85
  86         circuit->u.bc.t_run_dr[level - 1] = NULL;
  87         circuit->u.bc.run_dr_elect[level - 1] = 1;
  88 }
  89
  90 static int isis_check_dr_change(struct isis_adjacency *adj, int level)
  91 {
  92         int i;
  93
  94         if (adj->dis_record[level - 1].dis
  95             != adj->dis_record[(1 * ISIS_LEVELS) + level - 1].dis)
  96         /* was there a DIS state transition ? */
  97         {
  98                 adj->dischanges[level - 1]++;
  99                 adj->circuit->desig_changes[level - 1]++;
 100                 /* ok rotate the history list through */
 101                 for (i = DIS_RECORDS - 1; i > 0; i--) {
 102                         adj->dis_record[(i * ISIS_LEVELS) + level - 1].dis =
 103                                 adj->dis_record[((i - 1) * ISIS_LEVELS) + level
 104                                                 - 1]
 105                                         .dis;
 106                         adj->dis_record[(i * ISIS_LEVELS) + level - 1]
 107                                 .last_dis_change =
 108                                 adj->dis_record[((i - 1) * ISIS_LEVELS) + level
 109                                                 - 1]
 110                                         .last_dis_change;
 111                 }
 112         }
 113         return ISIS_OK;
 114 }
 115
 116 int isis_dr_elect(struct isis_circuit *circuit, int level)
 117 {
 118         struct list *adjdb;
 119         struct listnode *node;
 120         struct isis_adjacency *adj, *adj_dr = NULL;
 121         struct list *list = list_new();
 122         uint8_t own_prio;
 123         int biggest_prio = -1;
 124         int cmp_res, retval = ISIS_OK;
 125
 126         own_prio = circuit->priority[level - 1];
 127         adjdb = circuit->u.bc.adjdb[level - 1];
 128
 129         if (!adjdb) {
 130                 zlog_warn("%s adjdb == NULL", __func__);
 131                 list_delete(&list);
 132                 return ISIS_WARNING;
 133         }
 134         isis_adj_build_up_list(adjdb, list);
 135
 136         /*
 137          * Loop the adjacencies and find the one with the biggest priority
 138          */
 139         for (ALL_LIST_ELEMENTS_RO(list, node, adj)) {
 140                 /* clear flag for show output */
 141                 adj->dis_record[level - 1].dis = ISIS_IS_NOT_DIS;
 142                 adj->dis_record[level - 1].last_dis_change = time(NULL);
 143
 144                 if (adj->prio[level - 1] > biggest_prio) {
 145                         biggest_prio = adj->prio[level - 1];
 146                         adj_dr = adj;
 147                 } else if (adj->prio[level - 1] == biggest_prio) {
 148                         /*
 149                          * Comparison of MACs breaks a tie
 150                          */
 151                         if (adj_dr) {
 152                                 cmp_res = memcmp(adj_dr->snpa, adj->snpa,
 153                                                  ETH_ALEN);
 154                                 if (cmp_res < 0) {
 155                                         adj_dr = adj;
 156                                 }
 157                                 if (cmp_res == 0)
 158                                         zlog_warn(
 159                                                 "%s: multiple adjacencies with same SNPA",
 160                                                 __func__);
 161                         } else {
 162                                 adj_dr = adj;
 163                         }
 164                 }
 165         }
 166
 167         if (!adj_dr) {
 168                 /*
 169                  * Could not find the DR - means we are alone. Resign if we were
 170                  * DR.
 171                  */
 172                 if (circuit->u.bc.is_dr[level - 1])
 173                         retval = isis_dr_resign(circuit, level);
 174                 list_delete(&list);
 175                 return retval;
 176         }
 177
 178         /*
 179          * Now we have the DR adjacency, compare it to self
 180          */
 181         if (adj_dr->prio[level - 1] < own_prio
 182             || (adj_dr->prio[level - 1] == own_prio
 183                 && memcmp(adj_dr->snpa, circuit->u.bc.snpa, ETH_ALEN) < 0)) {
 184                 adj_dr->dis_record[level - 1].dis = ISIS_IS_NOT_DIS;
 185                 adj_dr->dis_record[level - 1].last_dis_change = time(NULL);
 186
 187                 /* rotate the history log */
 188                 for (ALL_LIST_ELEMENTS_RO(list, node, adj))
 189                         isis_check_dr_change(adj, level);
 190
 191                 /* We are the DR, commence DR */
 192                 if (circuit->u.bc.is_dr[level - 1] == 0 && listcount(list) > 0)
 193                         retval = isis_dr_commence(circuit, level);
 194         } else {
 195                 /* ok we have found the DIS - lets mark the adjacency */
 196                 /* set flag for show output */
 197                 adj_dr->dis_record[level - 1].dis = ISIS_IS_DIS;
 198                 adj_dr->dis_record[level - 1].last_dis_change = time(NULL);
 199
 200                 /* now loop through a second time to check if there has been a
 201                  * DIS change
 202                  * if yes rotate the history log
 203                  */
 204
 205                 for (ALL_LIST_ELEMENTS_RO(list, node, adj))
 206                         isis_check_dr_change(adj, level);
 207
 208                 /*
 209                  * We are not DR - if we were -> resign
 210                  */
 211                 if (circuit->u.bc.is_dr[level - 1])
 212                         retval = isis_dr_resign(circuit, level);
 213         }
 214         list_delete(&list);
 215         return retval;
 216 }
 217
 218 int isis_dr_resign(struct isis_circuit *circuit, int level)
 219 {
 220         uint8_t id[ISIS_SYS_ID_LEN + 2];
 221
 222         if (IS_DEBUG_EVENTS)
 223                 zlog_debug("%s l%d", __func__, level);
 224
 225         circuit->u.bc.is_dr[level - 1] = 0;
 226         circuit->u.bc.run_dr_elect[level - 1] = 0;
 227         THREAD_OFF(circuit->u.bc.t_run_dr[level - 1]);
 228         THREAD_OFF(circuit->u.bc.t_refresh_pseudo_lsp[level - 1]);
 229         circuit->lsp_regenerate_pending[level - 1] = 0;
 230
 231         memcpy(id, circuit->isis->sysid, ISIS_SYS_ID_LEN);
 232         LSP_PSEUDO_ID(id) = circuit->circuit_id;
 233         LSP_FRAGMENT(id) = 0;
 234         lsp_purge_pseudo(id, circuit, level);
 235
 236         if (level == 1) {
 237                 memset(circuit->u.bc.l1_desig_is, 0, ISIS_SYS_ID_LEN + 1);
 238
 239                 thread_add_timer(master, send_l1_psnp, circuit,
 240                                  isis_jitter(circuit->psnp_interval[level - 1],
 241                                              PSNP_JITTER),
 242                                  &circuit->t_send_psnp[0]);
 243         } else {
 244                 memset(circuit->u.bc.l2_desig_is, 0, ISIS_SYS_ID_LEN + 1);
 245
 246                 thread_add_timer(master, send_l2_psnp, circuit,
 247                                  isis_jitter(circuit->psnp_interval[level - 1],
 248                                              PSNP_JITTER),
 249                                  &circuit->t_send_psnp[1]);
 250         }
 251
 252         THREAD_OFF(circuit->t_send_csnp[level - 1]);
 253
 254         thread_add_timer(master, isis_run_dr,
 255                          &circuit->level_arg[level - 1],
 256                          2 * circuit->hello_interval[level - 1],
 257                          &circuit->u.bc.t_run_dr[level - 1]);
 258
 259
 260         thread_add_event(master, isis_event_dis_status_change, circuit, 0,
 261                          NULL);
 262
 263         return ISIS_OK;
 264 }
 265
 266 int isis_dr_commence(struct isis_circuit *circuit, int level)
 267 {
 268         uint8_t old_dr[ISIS_SYS_ID_LEN + 2];
 269
 270         if (IS_DEBUG_EVENTS)
 271                 zlog_debug("%s l%d", __func__, level);
 272
 273         /* Lets keep a pause in DR election */
 274         circuit->u.bc.run_dr_elect[level - 1] = 0;
 275         circuit->u.bc.is_dr[level - 1] = 1;
 276
 277         if (level == 1) {
 278                 memcpy(old_dr, circuit->u.bc.l1_desig_is, ISIS_SYS_ID_LEN + 1);
 279                 LSP_FRAGMENT(old_dr) = 0;
 280                 if (LSP_PSEUDO_ID(old_dr)) {
 281                         /* there was a dr elected, purge its LSPs from the db */
 282                         lsp_purge_pseudo(old_dr, circuit, level);
 283                 }
 284                 memcpy(circuit->u.bc.l1_desig_is, circuit->isis->sysid,
 285                        ISIS_SYS_ID_LEN);
 286                 *(circuit->u.bc.l1_desig_is + ISIS_SYS_ID_LEN) =
 287                         circuit->circuit_id;
 288
 289                 assert(circuit->circuit_id); /* must be non-zero */
 290                 lsp_generate_pseudo(circuit, 1);
 291
 292                 thread_add_timer(master, send_l1_csnp, circuit,
 293                                  isis_jitter(circuit->csnp_interval[level - 1],
 294                                              CSNP_JITTER),
 295                                  &circuit->t_send_csnp[0]);
 296
 297         } else {
 298                 memcpy(old_dr, circuit->u.bc.l2_desig_is, ISIS_SYS_ID_LEN + 1);
 299                 LSP_FRAGMENT(old_dr) = 0;
 300                 if (LSP_PSEUDO_ID(old_dr)) {
 301                         /* there was a dr elected, purge its LSPs from the db */
 302                         lsp_purge_pseudo(old_dr, circuit, level);
 303                 }
 304                 memcpy(circuit->u.bc.l2_desig_is, circuit->isis->sysid,
 305                        ISIS_SYS_ID_LEN);
 306                 *(circuit->u.bc.l2_desig_is + ISIS_SYS_ID_LEN) =
 307                         circuit->circuit_id;
 308
 309                 assert(circuit->circuit_id); /* must be non-zero */
 310                 lsp_generate_pseudo(circuit, 2);
 311
 312                 thread_add_timer(master, send_l2_csnp, circuit,
 313                                  isis_jitter(circuit->csnp_interval[level - 1],
 314                                              CSNP_JITTER),
 315                                  &circuit->t_send_csnp[1]);
 316         }
 317
 318         thread_add_timer(master, isis_run_dr,
 319                          &circuit->level_arg[level - 1],
 320                          2 * circuit->hello_interval[level - 1],
 321                          &circuit->u.bc.t_run_dr[level - 1]);
 322         thread_add_event(master, isis_event_dis_status_change, circuit, 0,
 323                          NULL);
 324
 325         return ISIS_OK;
 326 }