bgpd/bgp_damp.c

   1 /* BGP flap dampening
   2    Copyright (C) 2001 IP Infusion Inc.
   3
   4 This file is part of GNU Zebra.
   5
   6 GNU Zebra is free software; you can redistribute it and/or modify it
   7 under the terms of the GNU General Public License as published by the
   8 Free Software Foundation; either version 2, or (at your option) any
   9 later version.
  10
  11 GNU Zebra is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Zebra; see the file COPYING.  If not, write to the Free
  18 Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  19 02111-1307, USA.  */
  20
  21 #include <zebra.h>
  22 #include <math.h>
  23
  24 #include "prefix.h"
  25 #include "memory.h"
  26 #include "command.h"
  27 #include "log.h"
  28 #include "thread.h"
  29
  30 #include "bgpd/bgpd.h"
  31 #include "bgpd/bgp_damp.h"
  32 #include "bgpd/bgp_table.h"
  33 #include "bgpd/bgp_route.h"
  34 #include "bgpd/bgp_attr.h"
  35 #include "bgpd/bgp_advertise.h"
  36
  37 /* Global variable to access damping configuration */
  38 struct bgp_damp_config bgp_damp_cfg;
  39 static struct bgp_damp_config *damp = &bgp_damp_cfg;
  40
  41 /* Utility macro to add and delete BGP dampening information to no
  42    used list.  */
  43 #define BGP_DAMP_LIST_ADD(N,A)  BGP_INFO_ADD(N,A,no_reuse_list)
  44 #define BGP_DAMP_LIST_DEL(N,A)  BGP_INFO_DEL(N,A,no_reuse_list)
  45 \f
  46 /* Calculate reuse list index by penalty value.  */
  47 static int
  48 bgp_reuse_index (int penalty)
  49 {
  50   unsigned int i;
  51   int index;
  52
  53   i = (int)(((double) penalty / damp->reuse_limit - 1.0) * damp->scale_factor);
  54
  55   if ( i >= damp->reuse_index_size )
  56     i = damp->reuse_index_size - 1;
  57
  58   index = damp->reuse_index[i] - damp->reuse_index[0];
  59
  60   return (damp->reuse_offset + index) % damp->reuse_list_size;
  61 }
  62
  63 /* Add BGP dampening information to reuse list.  */
  64 static void
  65 bgp_reuse_list_add (struct bgp_damp_info *bdi)
  66 {
  67   int index;
  68
  69   index = bdi->index = bgp_reuse_index (bdi->penalty);
  70
  71   bdi->prev = NULL;
  72   bdi->next = damp->reuse_list[index];
  73   if (damp->reuse_list[index])
  74     damp->reuse_list[index]->prev = bdi;
  75   damp->reuse_list[index] = bdi;
  76 }
  77
  78 /* Delete BGP dampening information from reuse list.  */
  79 static void
  80 bgp_reuse_list_delete (struct bgp_damp_info *bdi)
  81 {
  82   if (bdi->next)
  83     bdi->next->prev = bdi->prev;
  84   if (bdi->prev)
  85     bdi->prev->next = bdi->next;
  86   else
  87     damp->reuse_list[bdi->index] = bdi->next;
  88 }
  89 \f
  90 /* Return decayed penalty value.  */
  91 int
  92 bgp_damp_decay (time_t tdiff, int penalty)
  93 {
  94   unsigned int i;
  95
  96   i = (int) ((double) tdiff / DELTA_T);
  97
  98   if (i == 0)
  99     return penalty;
 100
 101   if (i >= damp->decay_array_size)
 102     return 0;
 103
 104   return (int) (penalty * damp->decay_array[i]);
 105 }
 106
 107 /* Handler of reuse timer event.  Each route in the current reuse-list
 108    is evaluated.  RFC2439 Section 4.8.7.  */
 109 static int
 110 bgp_reuse_timer (struct thread *t)
 111 {
 112   struct bgp_damp_info *bdi;
 113   struct bgp_damp_info *next;
 114   time_t t_now, t_diff;
 115
 116   damp->t_reuse = NULL;
 117   damp->t_reuse =
 118     thread_add_timer (master, bgp_reuse_timer, NULL, DELTA_REUSE);
 119
 120   t_now = bgp_clock ();
 121
 122   /* 1.  save a pointer to the current zeroth queue head and zero the
 123      list head entry.  */
 124   bdi = damp->reuse_list[damp->reuse_offset];
 125   damp->reuse_list[damp->reuse_offset] = NULL;
 126
 127   /* 2.  set offset = modulo reuse-list-size ( offset + 1 ), thereby
 128      rotating the circular queue of list-heads.  */
 129   damp->reuse_offset = (damp->reuse_offset + 1) % damp->reuse_list_size;
 130
 131   /* 3. if ( the saved list head pointer is non-empty ) */
 132   for (; bdi; bdi = next)
 133     {
 134       struct bgp *bgp = bdi->binfo->peer->bgp;
 135
 136       next = bdi->next;
 137
 138       /* Set t-diff = t-now - t-updated.  */
 139       t_diff = t_now - bdi->t_updated;
 140
 141       /* Set figure-of-merit = figure-of-merit * decay-array-ok [t-diff] */
 142       bdi->penalty = bgp_damp_decay (t_diff, bdi->penalty);
 143
 144       /* Set t-updated = t-now.  */
 145       bdi->t_updated = t_now;
 146
 147       /* if (figure-of-merit < reuse).  */
 148       if (bdi->penalty < damp->reuse_limit)
 149         {
 150           /* Reuse the route.  */
 151           bgp_info_unset_flag (bdi->rn, bdi->binfo, BGP_INFO_DAMPED);
 152           bdi->suppress_time = 0;
 153
 154           if (bdi->lastrecord == BGP_RECORD_UPDATE)
 155             {
 156               bgp_info_unset_flag (bdi->rn, bdi->binfo, BGP_INFO_HISTORY);
 157               bgp_aggregate_increment (bgp, &bdi->rn->p, bdi->binfo,
 158                                        bdi->afi, bdi->safi);
 159               bgp_process (bgp, bdi->rn, bdi->afi, bdi->safi);
 160             }
 161
 162           if (bdi->penalty <= damp->reuse_limit / 2.0)
 163             bgp_damp_info_free (bdi, 1);
 164           else
 165             BGP_DAMP_LIST_ADD (damp, bdi);
 166         }
 167       else
 168         /* Re-insert into another list (See RFC2439 Section 4.8.6).  */
 169         bgp_reuse_list_add (bdi);
 170     }
 171
 172   return 0;
 173 }
 174
 175 /* A route becomes unreachable (RFC2439 Section 4.8.2).  */
 176 int
 177 bgp_damp_withdraw (struct bgp_info *binfo, struct bgp_node *rn,
 178                    afi_t afi, safi_t safi, int attr_change)
 179 {
 180   time_t t_now;
 181   struct bgp_damp_info *bdi = NULL;
 182   double last_penalty = 0;
 183
 184   t_now = bgp_clock ();
 185
 186   /* Processing Unreachable Messages.  */
 187   if (binfo->extra)
 188     bdi = binfo->extra->damp_info;
 189
 190   if (bdi == NULL)
 191     {
 192       /* If there is no previous stability history. */
 193
 194       /* RFC2439 said:
 195          1. allocate a damping structure.
 196          2. set figure-of-merit = 1.
 197          3. withdraw the route.  */
 198
 199       bdi =  XCALLOC (MTYPE_BGP_DAMP_INFO, sizeof (struct bgp_damp_info));
 200       bdi->binfo = binfo;
 201       bdi->rn = rn;
 202       bdi->penalty = (attr_change ? DEFAULT_PENALTY / 2 : DEFAULT_PENALTY);
 203       bdi->flap = 1;
 204       bdi->start_time = t_now;
 205       bdi->suppress_time = 0;
 206       bdi->index = -1;
 207       bdi->afi = afi;
 208       bdi->safi = safi;
 209       (bgp_info_extra_get (binfo))->damp_info = bdi;
 210       BGP_DAMP_LIST_ADD (damp, bdi);
 211     }
 212   else
 213     {
 214       last_penalty = bdi->penalty;
 215
 216       /* 1. Set t-diff = t-now - t-updated.  */
 217       bdi->penalty =
 218         (bgp_damp_decay (t_now - bdi->t_updated, bdi->penalty)
 219          + (attr_change ? DEFAULT_PENALTY / 2 : DEFAULT_PENALTY));
 220
 221       if (bdi->penalty > damp->ceiling)
 222         bdi->penalty = damp->ceiling;
 223
 224       bdi->flap++;
 225     }
 226
 227   assert ((rn == bdi->rn) && (binfo == bdi->binfo));
 228
 229   bdi->lastrecord = BGP_RECORD_WITHDRAW;
 230   bdi->t_updated = t_now;
 231
 232   /* Make this route as historical status.  */
 233   bgp_info_set_flag (rn, binfo, BGP_INFO_HISTORY);
 234
 235   /* Remove the route from a reuse list if it is on one.  */
 236   if (CHECK_FLAG (bdi->binfo->flags, BGP_INFO_DAMPED))
 237     {
 238       /* If decay rate isn't equal to 0, reinsert brn. */
 239       if (bdi->penalty != last_penalty)
 240         {
 241           bgp_reuse_list_delete (bdi);
 242           bgp_reuse_list_add (bdi);
 243         }
 244       return BGP_DAMP_SUPPRESSED;
 245     }
 246
 247   /* If not suppressed before, do annonunce this withdraw and
 248      insert into reuse_list.  */
 249   if (bdi->penalty >= damp->suppress_value)
 250     {
 251       bgp_info_set_flag (rn, binfo, BGP_INFO_DAMPED);
 252       bdi->suppress_time = t_now;
 253       BGP_DAMP_LIST_DEL (damp, bdi);
 254       bgp_reuse_list_add (bdi);
 255     }
 256
 257   return BGP_DAMP_USED;
 258 }
 259
 260 int
 261 bgp_damp_update (struct bgp_info *binfo, struct bgp_node *rn,
 262                  afi_t afi, safi_t safi)
 263 {
 264   time_t t_now;
 265   struct bgp_damp_info *bdi;
 266   int status;
 267
 268   if (!binfo->extra || !((bdi = binfo->extra->damp_info)))
 269     return BGP_DAMP_USED;
 270
 271   t_now = bgp_clock ();
 272   bgp_info_unset_flag (rn, binfo, BGP_INFO_HISTORY);
 273
 274   bdi->lastrecord = BGP_RECORD_UPDATE;
 275   bdi->penalty = bgp_damp_decay (t_now - bdi->t_updated, bdi->penalty);
 276
 277   if (! CHECK_FLAG (bdi->binfo->flags, BGP_INFO_DAMPED)
 278       && (bdi->penalty < damp->suppress_value))
 279     status = BGP_DAMP_USED;
 280   else if (CHECK_FLAG (bdi->binfo->flags, BGP_INFO_DAMPED)
 281            && (bdi->penalty < damp->reuse_limit) )
 282     {
 283       bgp_info_unset_flag (rn, binfo, BGP_INFO_DAMPED);
 284       bgp_reuse_list_delete (bdi);
 285       BGP_DAMP_LIST_ADD (damp, bdi);
 286       bdi->suppress_time = 0;
 287       status = BGP_DAMP_USED;
 288     }
 289   else
 290     status = BGP_DAMP_SUPPRESSED;
 291
 292   if (bdi->penalty > damp->reuse_limit / 2.0)
 293     bdi->t_updated = t_now;
 294   else
 295     bgp_damp_info_free (bdi, 0);
 296
 297   return status;
 298 }
 299
 300 /* Remove dampening information and history route.  */
 301 int
 302 bgp_damp_scan (struct bgp_info *binfo, afi_t afi, safi_t safi)
 303 {
 304   time_t t_now, t_diff;
 305   struct bgp_damp_info *bdi;
 306
 307   assert (binfo->extra && binfo->extra->damp_info);
 308
 309   t_now = bgp_clock ();
 310   bdi = binfo->extra->damp_info;
 311
 312   if (CHECK_FLAG (binfo->flags, BGP_INFO_DAMPED))
 313     {
 314       t_diff = t_now - bdi->suppress_time;
 315
 316       if (t_diff >= damp->max_suppress_time)
 317         {
 318           bgp_info_unset_flag (bdi->rn, binfo, BGP_INFO_DAMPED);
 319           bgp_reuse_list_delete (bdi);
 320           BGP_DAMP_LIST_ADD (damp, bdi);
 321           bdi->penalty = damp->reuse_limit;
 322           bdi->suppress_time = 0;
 323           bdi->t_updated = t_now;
 324
 325           /* Need to announce UPDATE once this binfo is usable again. */
 326           if (bdi->lastrecord == BGP_RECORD_UPDATE)
 327             return 1;
 328           else
 329             return 0;
 330         }
 331     }
 332   else
 333     {
 334       t_diff = t_now - bdi->t_updated;
 335       bdi->penalty = bgp_damp_decay (t_diff, bdi->penalty);
 336
 337       if (bdi->penalty <= damp->reuse_limit / 2.0)
 338         {
 339           /* release the bdi, bdi->binfo. */
 340           bgp_damp_info_free (bdi, 1);
 341           return 0;
 342         }
 343       else
 344         bdi->t_updated = t_now;
 345     }
 346   return 0;
 347 }
 348
 349 void
 350 bgp_damp_info_free (struct bgp_damp_info *bdi, int withdraw)
 351 {
 352   struct bgp_info *binfo;
 353
 354   if (! bdi)
 355     return;
 356
 357   binfo = bdi->binfo;
 358   binfo->extra->damp_info = NULL;
 359
 360   if (CHECK_FLAG (binfo->flags, BGP_INFO_DAMPED))
 361     bgp_reuse_list_delete (bdi);
 362   else
 363     BGP_DAMP_LIST_DEL (damp, bdi);
 364
 365   bgp_info_unset_flag (bdi->rn, binfo, BGP_INFO_HISTORY|BGP_INFO_DAMPED);
 366
 367   if (bdi->lastrecord == BGP_RECORD_WITHDRAW && withdraw)
 368     bgp_info_delete (bdi->rn, binfo);
 369
 370   XFREE (MTYPE_BGP_DAMP_INFO, bdi);
 371 }
 372
 373 static void
 374 bgp_damp_parameter_set (int hlife, int reuse, int sup, int maxsup)
 375 {
 376   double reuse_max_ratio;
 377   unsigned int i;
 378   double j;
 379
 380   damp->suppress_value = sup;
 381   damp->half_life = hlife;
 382   damp->reuse_limit = reuse;
 383   damp->max_suppress_time = maxsup;
 384
 385   /* Initialize params per bgp_damp_config. */
 386   damp->reuse_index_size = REUSE_ARRAY_SIZE;
 387
 388   damp->ceiling = (int)(damp->reuse_limit * (pow(2, (double)damp->max_suppress_time/damp->half_life)));
 389
 390   /* Decay-array computations */
 391   damp->decay_array_size = ceil ((double) damp->max_suppress_time / DELTA_T);
 392   damp->decay_array = XMALLOC (MTYPE_BGP_DAMP_ARRAY,
 393                                sizeof(double) * (damp->decay_array_size));
 394   damp->decay_array[0] = 1.0;
 395   damp->decay_array[1] = exp ((1.0/((double)damp->half_life/DELTA_T)) * log(0.5));
 396
 397   /* Calculate decay values for all possible times */
 398   for (i = 2; i < damp->decay_array_size; i++)
 399     damp->decay_array[i] = damp->decay_array[i-1] * damp->decay_array[1];
 400
 401   /* Reuse-list computations */
 402   i = ceil ((double)damp->max_suppress_time / DELTA_REUSE) + 1;
 403   if (i > REUSE_LIST_SIZE || i == 0)
 404     i = REUSE_LIST_SIZE;
 405   damp->reuse_list_size = i;
 406
 407   damp->reuse_list = XCALLOC (MTYPE_BGP_DAMP_ARRAY,
 408                               damp->reuse_list_size
 409                               * sizeof (struct bgp_reuse_node *));
 410   memset (damp->reuse_list, 0x00,
 411           damp->reuse_list_size * sizeof (struct bgp_reuse_node *));
 412
 413   /* Reuse-array computations */
 414   damp->reuse_index = XMALLOC (MTYPE_BGP_DAMP_ARRAY,
 415                                sizeof(int) * damp->reuse_index_size);
 416   memset (damp->reuse_index, 0x00,
 417           damp->reuse_list_size * sizeof (int));
 418
 419   reuse_max_ratio = (double)damp->ceiling/damp->reuse_limit;
 420   j = (exp((double)damp->max_suppress_time/damp->half_life) * log10(2.0));
 421   if ( reuse_max_ratio > j && j != 0 )
 422     reuse_max_ratio = j;
 423
 424   damp->scale_factor = (double)damp->reuse_index_size/(reuse_max_ratio - 1);
 425
 426   for (i = 0; i < damp->reuse_index_size; i++)
 427     {
 428       damp->reuse_index[i] =
 429         (int)(((double)damp->half_life / DELTA_REUSE)
 430               * log10 (1.0 / (damp->reuse_limit * ( 1.0 + ((double)i/damp->scale_factor)))) / log10(0.5));
 431     }
 432 }
 433
 434 int
 435 bgp_damp_enable (struct bgp *bgp, afi_t afi, safi_t safi, time_t half,
 436                  unsigned int reuse, unsigned int suppress, time_t max)
 437 {
 438   if (CHECK_FLAG (bgp->af_flags[afi][safi], BGP_CONFIG_DAMPENING))
 439     {
 440       if (damp->half_life == half
 441           && damp->reuse_limit == reuse
 442           && damp->suppress_value == suppress
 443           && damp->max_suppress_time == max)
 444         return 0;
 445       bgp_damp_disable (bgp, afi, safi);
 446     }
 447
 448   SET_FLAG (bgp->af_flags[afi][safi], BGP_CONFIG_DAMPENING);
 449   bgp_damp_parameter_set (half, reuse, suppress, max);
 450
 451   /* Register reuse timer.  */
 452   if (! damp->t_reuse)
 453     damp->t_reuse =
 454       thread_add_timer (master, bgp_reuse_timer, NULL, DELTA_REUSE);
 455
 456   return 0;
 457 }
 458
 459 static void
 460 bgp_damp_config_clean (struct bgp_damp_config *damp)
 461 {
 462   /* Free decay array */
 463   XFREE (MTYPE_BGP_DAMP_ARRAY, damp->decay_array);
 464
 465   /* Free reuse index array */
 466   XFREE (MTYPE_BGP_DAMP_ARRAY, damp->reuse_index);
 467
 468   /* Free reuse list array. */
 469   XFREE (MTYPE_BGP_DAMP_ARRAY, damp->reuse_list);
 470 }
 471
 472 /* Clean all the bgp_damp_info stored in reuse_list. */
 473 void
 474 bgp_damp_info_clean (void)
 475 {
 476   unsigned int i;
 477   struct bgp_damp_info *bdi, *next;
 478
 479   damp->reuse_offset = 0;
 480
 481   for (i = 0; i < damp->reuse_list_size; i++)
 482     {
 483       if (! damp->reuse_list[i])
 484         continue;
 485
 486       for (bdi = damp->reuse_list[i]; bdi; bdi = next)
 487         {
 488           next = bdi->next;
 489           bgp_damp_info_free (bdi, 1);
 490         }
 491       damp->reuse_list[i] = NULL;
 492     }
 493
 494   for (bdi = damp->no_reuse_list; bdi; bdi = next)
 495     {
 496       next = bdi->next;
 497       bgp_damp_info_free (bdi, 1);
 498     }
 499   damp->no_reuse_list = NULL;
 500 }
 501
 502 int
 503 bgp_damp_disable (struct bgp *bgp, afi_t afi, safi_t safi)
 504 {
 505   /* Cancel reuse thread. */
 506   if (damp->t_reuse )
 507     thread_cancel (damp->t_reuse);
 508   damp->t_reuse = NULL;
 509
 510   /* Clean BGP dampening information.  */
 511   bgp_damp_info_clean ();
 512
 513   /* Clear configuration */
 514   bgp_damp_config_clean (&bgp_damp_cfg);
 515
 516   UNSET_FLAG (bgp->af_flags[afi][safi], BGP_CONFIG_DAMPENING);
 517   return 0;
 518 }
 519
 520 void
 521 bgp_config_write_damp (struct vty *vty)
 522 {
 523   if (bgp_damp_cfg.half_life == DEFAULT_HALF_LIFE*60
 524       && bgp_damp_cfg.reuse_limit == DEFAULT_REUSE
 525       && bgp_damp_cfg.suppress_value == DEFAULT_SUPPRESS
 526       && bgp_damp_cfg.max_suppress_time == bgp_damp_cfg.half_life*4)
 527     vty_out (vty, " bgp dampening%s", VTY_NEWLINE);
 528   else if (bgp_damp_cfg.half_life != DEFAULT_HALF_LIFE*60
 529            && bgp_damp_cfg.reuse_limit == DEFAULT_REUSE
 530            && bgp_damp_cfg.suppress_value == DEFAULT_SUPPRESS
 531            && bgp_damp_cfg.max_suppress_time == bgp_damp_cfg.half_life*4)
 532     vty_out (vty, " bgp dampening %ld%s",
 533              bgp_damp_cfg.half_life/60,
 534              VTY_NEWLINE);
 535   else
 536     vty_out (vty, " bgp dampening %ld %d %d %ld%s",
 537              bgp_damp_cfg.half_life/60,
 538              bgp_damp_cfg.reuse_limit,
 539              bgp_damp_cfg.suppress_value,
 540              bgp_damp_cfg.max_suppress_time/60,
 541              VTY_NEWLINE);
 542 }
 543
 544 static const char *
 545 bgp_get_reuse_time (unsigned int penalty, char *buf, size_t len)
 546 {
 547   time_t reuse_time = 0;
 548   struct tm *tm = NULL;
 549
 550   if (penalty > damp->reuse_limit)
 551     {
 552       reuse_time = (int) (DELTA_T * ((log((double)damp->reuse_limit/penalty))/(log(damp->decay_array[1]))));
 553
 554       if (reuse_time > damp->max_suppress_time)
 555         reuse_time = damp->max_suppress_time;
 556
 557       tm = gmtime (&reuse_time);
 558     }
 559   else
 560     reuse_time = 0;
 561
 562   /* Making formatted timer strings. */
 563 #define ONE_DAY_SECOND 60*60*24
 564 #define ONE_WEEK_SECOND 60*60*24*7
 565   if (reuse_time == 0)
 566     snprintf (buf, len, "00:00:00");
 567   else if (reuse_time < ONE_DAY_SECOND)
 568     snprintf (buf, len, "%02d:%02d:%02d",
 569               tm->tm_hour, tm->tm_min, tm->tm_sec);
 570   else if (reuse_time < ONE_WEEK_SECOND)
 571     snprintf (buf, len, "%dd%02dh%02dm",
 572               tm->tm_yday, tm->tm_hour, tm->tm_min);
 573   else
 574     snprintf (buf, len, "%02dw%dd%02dh",
 575               tm->tm_yday/7, tm->tm_yday - ((tm->tm_yday/7) * 7), tm->tm_hour);
 576
 577   return buf;
 578 }
 579
 580 void
 581 bgp_damp_info_vty (struct vty *vty, struct bgp_info *binfo)
 582 {
 583   struct bgp_damp_info *bdi;
 584   time_t t_now, t_diff;
 585   char timebuf[BGP_UPTIME_LEN];
 586   int penalty;
 587
 588   if (!binfo->extra)
 589     return;
 590
 591   /* BGP dampening information.  */
 592   bdi = binfo->extra->damp_info;
 593
 594   /* If dampening is not enabled or there is no dampening information,
 595      return immediately.  */
 596   if (! damp || ! bdi)
 597     return;
 598
 599   /* Calculate new penalty.  */
 600   t_now = bgp_clock ();
 601   t_diff = t_now - bdi->t_updated;
 602   penalty = bgp_damp_decay (t_diff, bdi->penalty);
 603
 604   vty_out (vty, "      Dampinfo: penalty %d, flapped %d times in %s",
 605            penalty, bdi->flap,
 606            peer_uptime (bdi->start_time, timebuf, BGP_UPTIME_LEN));
 607
 608   if (CHECK_FLAG (binfo->flags, BGP_INFO_DAMPED)
 609       && ! CHECK_FLAG (binfo->flags, BGP_INFO_HISTORY))
 610     vty_out (vty, ", reuse in %s",
 611              bgp_get_reuse_time (penalty, timebuf, BGP_UPTIME_LEN));
 612
 613   vty_out (vty, "%s", VTY_NEWLINE);
 614 }
 615
 616 const char *
 617 bgp_damp_reuse_time_vty (struct vty *vty, struct bgp_info *binfo,
 618                          char *timebuf, size_t len)
 619 {
 620   struct bgp_damp_info *bdi;
 621   time_t t_now, t_diff;
 622   int penalty;
 623
 624   if (!binfo->extra)
 625     return NULL;
 626
 627   /* BGP dampening information.  */
 628   bdi = binfo->extra->damp_info;
 629
 630   /* If dampening is not enabled or there is no dampening information,
 631      return immediately.  */
 632   if (! damp || ! bdi)
 633     return NULL;
 634
 635   /* Calculate new penalty.  */
 636   t_now = bgp_clock ();
 637   t_diff = t_now - bdi->t_updated;
 638   penalty = bgp_damp_decay (t_diff, bdi->penalty);
 639
 640   return  bgp_get_reuse_time (penalty, timebuf, len);
 641 }