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 int 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->schedfrom, thread->schedfrom_line);
  78                 return ISIS_WARNING;
  79         }
  80
  81         if (circuit->u.bc.run_dr_elect[level - 1])
  82                 zlog_warn("isis_run_dr(): run_dr_elect already set for l%d", level);
  83
  84         circuit->u.bc.t_run_dr[level - 1] = NULL;
  85         circuit->u.bc.run_dr_elect[level - 1] = 1;
  86
  87         return ISIS_OK;
  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                 /* ok rotate the history list through */
 100                 for (i = DIS_RECORDS - 1; i > 0; i--) {
 101                         adj->dis_record[(i * ISIS_LEVELS) + level - 1].dis =
 102                                 adj->dis_record[((i - 1) * ISIS_LEVELS) + level
 103                                                 - 1]
 104                                         .dis;
 105                         adj->dis_record[(i * ISIS_LEVELS) + level - 1]
 106                                 .last_dis_change =
 107                                 adj->dis_record[((i - 1) * ISIS_LEVELS) + level
 108                                                 - 1]
 109                                         .last_dis_change;
 110                 }
 111         }
 112         return ISIS_OK;
 113 }
 114
 115 int isis_dr_elect(struct isis_circuit *circuit, int level)
 116 {
 117         struct list *adjdb;
 118         struct listnode *node;
 119         struct isis_adjacency *adj, *adj_dr = NULL;
 120         struct list *list = list_new();
 121         uint8_t own_prio;
 122         int biggest_prio = -1;
 123         int cmp_res, retval = ISIS_OK;
 124
 125         own_prio = circuit->priority[level - 1];
 126         adjdb = circuit->u.bc.adjdb[level - 1];
 127
 128         if (!adjdb) {
 129                 zlog_warn("isis_dr_elect() adjdb == NULL");
 130                 list_delete(&list);
 131                 return ISIS_WARNING;
 132         }
 133         isis_adj_build_up_list(adjdb, list);
 134
 135         /*
 136          * Loop the adjacencies and find the one with the biggest priority
 137          */
 138         for (ALL_LIST_ELEMENTS_RO(list, node, adj)) {
 139                 /* clear flag for show output */
 140                 adj->dis_record[level - 1].dis = ISIS_IS_NOT_DIS;
 141                 adj->dis_record[level - 1].last_dis_change = time(NULL);
 142
 143                 if (adj->prio[level - 1] > biggest_prio) {
 144                         biggest_prio = adj->prio[level - 1];
 145                         adj_dr = adj;
 146                 } else if (adj->prio[level - 1] == biggest_prio) {
 147                         /*
 148                          * Comparison of MACs breaks a tie
 149                          */
 150                         if (adj_dr) {
 151                                 cmp_res = memcmp(adj_dr->snpa, adj->snpa,
 152                                                  ETH_ALEN);
 153                                 if (cmp_res < 0) {
 154                                         adj_dr = adj;
 155                                 }
 156                                 if (cmp_res == 0)
 157                                         zlog_warn(
 158                                                 "isis_dr_elect(): multiple adjacencies with same SNPA");
 159                         } else {
 160                                 adj_dr = adj;
 161                         }
 162                 }
 163         }
 164
 165         if (!adj_dr) {
 166                 /*
 167                  * Could not find the DR - means we are alone. Resign if we were
 168                  * DR.
 169                  */
 170                 if (circuit->u.bc.is_dr[level - 1])
 171                         retval = isis_dr_resign(circuit, level);
 172                 list_delete(&list);
 173                 return retval;
 174         }
 175
 176         /*
 177          * Now we have the DR adjacency, compare it to self
 178          */
 179         if (adj_dr->prio[level - 1] < own_prio
 180             || (adj_dr->prio[level - 1] == own_prio
 181                 && memcmp(adj_dr->snpa, circuit->u.bc.snpa, ETH_ALEN) < 0)) {
 182                 adj_dr->dis_record[level - 1].dis = ISIS_IS_NOT_DIS;
 183                 adj_dr->dis_record[level - 1].last_dis_change = time(NULL);
 184
 185                 /* rotate the history log */
 186                 for (ALL_LIST_ELEMENTS_RO(list, node, adj))
 187                         isis_check_dr_change(adj, level);
 188
 189                 /* We are the DR, commence DR */
 190                 if (circuit->u.bc.is_dr[level - 1] == 0 && listcount(list) > 0)
 191                         retval = isis_dr_commence(circuit, level);
 192         } else {
 193                 /* ok we have found the DIS - lets mark the adjacency */
 194                 /* set flag for show output */
 195                 adj_dr->dis_record[level - 1].dis = ISIS_IS_DIS;
 196                 adj_dr->dis_record[level - 1].last_dis_change = time(NULL);
 197
 198                 /* now loop through a second time to check if there has been a
 199                  * DIS change
 200                  * if yes rotate the history log
 201                  */
 202
 203                 for (ALL_LIST_ELEMENTS_RO(list, node, adj))
 204                         isis_check_dr_change(adj, level);
 205
 206                 /*
 207                  * We are not DR - if we were -> resign
 208                  */
 209                 if (circuit->u.bc.is_dr[level - 1])
 210                         retval = isis_dr_resign(circuit, level);
 211         }
 212         list_delete(&list);
 213         return retval;
 214 }
 215
 216 int isis_dr_resign(struct isis_circuit *circuit, int level)
 217 {
 218         uint8_t id[ISIS_SYS_ID_LEN + 2];
 219
 220         zlog_debug("isis_dr_resign l%d", level);
 221
 222         circuit->u.bc.is_dr[level - 1] = 0;
 223         circuit->u.bc.run_dr_elect[level - 1] = 0;
 224         THREAD_TIMER_OFF(circuit->u.bc.t_run_dr[level - 1]);
 225         THREAD_TIMER_OFF(circuit->u.bc.t_refresh_pseudo_lsp[level - 1]);
 226         circuit->lsp_regenerate_pending[level - 1] = 0;
 227
 228         memcpy(id, isis->sysid, ISIS_SYS_ID_LEN);
 229         LSP_PSEUDO_ID(id) = circuit->circuit_id;
 230         LSP_FRAGMENT(id) = 0;
 231         lsp_purge_pseudo(id, circuit, level);
 232
 233         if (level == 1) {
 234                 memset(circuit->u.bc.l1_desig_is, 0, ISIS_SYS_ID_LEN + 1);
 235
 236                 thread_add_timer(master, send_l1_psnp, circuit,
 237                                  isis_jitter(circuit->psnp_interval[level - 1],
 238                                              PSNP_JITTER),
 239                                  &circuit->t_send_psnp[0]);
 240         } else {
 241                 memset(circuit->u.bc.l2_desig_is, 0, ISIS_SYS_ID_LEN + 1);
 242
 243                 thread_add_timer(master, send_l2_psnp, circuit,
 244                                  isis_jitter(circuit->psnp_interval[level - 1],
 245                                              PSNP_JITTER),
 246                                  &circuit->t_send_psnp[1]);
 247         }
 248
 249         THREAD_TIMER_OFF(circuit->t_send_csnp[level - 1]);
 250
 251         thread_add_timer(master, isis_run_dr,
 252                          &circuit->level_arg[level - 1],
 253                          2 * circuit->hello_interval[level - 1],
 254                          &circuit->u.bc.t_run_dr[level - 1]);
 255
 256
 257         thread_add_event(master, isis_event_dis_status_change, circuit, 0,
 258                          NULL);
 259
 260         return ISIS_OK;
 261 }
 262
 263 int isis_dr_commence(struct isis_circuit *circuit, int level)
 264 {
 265         uint8_t old_dr[ISIS_SYS_ID_LEN + 2];
 266
 267         if (isis->debugs & DEBUG_EVENTS)
 268                 zlog_debug("isis_dr_commence l%d", level);
 269
 270         /* Lets keep a pause in DR election */
 271         circuit->u.bc.run_dr_elect[level - 1] = 0;
 272         circuit->u.bc.is_dr[level - 1] = 1;
 273
 274         if (level == 1) {
 275                 memcpy(old_dr, circuit->u.bc.l1_desig_is, ISIS_SYS_ID_LEN + 1);
 276                 LSP_FRAGMENT(old_dr) = 0;
 277                 if (LSP_PSEUDO_ID(old_dr)) {
 278                         /* there was a dr elected, purge its LSPs from the db */
 279                         lsp_purge_pseudo(old_dr, circuit, level);
 280                 }
 281                 memcpy(circuit->u.bc.l1_desig_is, isis->sysid, ISIS_SYS_ID_LEN);
 282                 *(circuit->u.bc.l1_desig_is + ISIS_SYS_ID_LEN) =
 283                         circuit->circuit_id;
 284
 285                 assert(circuit->circuit_id); /* must be non-zero */
 286                 /*    if (circuit->t_send_l1_psnp)
 287                    thread_cancel (circuit->t_send_l1_psnp); */
 288                 lsp_generate_pseudo(circuit, 1);
 289
 290                 thread_add_timer(master, send_l1_csnp, circuit,
 291                                  isis_jitter(circuit->csnp_interval[level - 1],
 292                                              CSNP_JITTER),
 293                                  &circuit->t_send_csnp[0]);
 294
 295         } else {
 296                 memcpy(old_dr, circuit->u.bc.l2_desig_is, ISIS_SYS_ID_LEN + 1);
 297                 LSP_FRAGMENT(old_dr) = 0;
 298                 if (LSP_PSEUDO_ID(old_dr)) {
 299                         /* there was a dr elected, purge its LSPs from the db */
 300                         lsp_purge_pseudo(old_dr, circuit, level);
 301                 }
 302                 memcpy(circuit->u.bc.l2_desig_is, isis->sysid, ISIS_SYS_ID_LEN);
 303                 *(circuit->u.bc.l2_desig_is + ISIS_SYS_ID_LEN) =
 304                         circuit->circuit_id;
 305
 306                 assert(circuit->circuit_id); /* must be non-zero */
 307                 /*    if (circuit->t_send_l1_psnp)
 308                    thread_cancel (circuit->t_send_l1_psnp); */
 309                 lsp_generate_pseudo(circuit, 2);
 310
 311                 thread_add_timer(master, send_l2_csnp, circuit,
 312                                  isis_jitter(circuit->csnp_interval[level - 1],
 313                                              CSNP_JITTER),
 314                                  &circuit->t_send_csnp[1]);
 315         }
 316
 317         thread_add_timer(master, isis_run_dr,
 318                          &circuit->level_arg[level - 1],
 319                          2 * circuit->hello_interval[level - 1],
 320                          &circuit->u.bc.t_run_dr[level - 1]);
 321         thread_add_event(master, isis_event_dis_status_change, circuit, 0,
 322                          NULL);
 323
 324         return ISIS_OK;
 325 }