BGP Dampening Reuse Timer

Hi GS,

I have hard time understanding the meaning of the BGP dampening reuse
timer in the "show ip bgp" command.

Page 180 in the following document stated
ftp://www.avmeiecuador.com/pub/manuales/cisco/pdfs/Cisco%20Bgp%20(Oreilly%200-596-00254-8).pdf

"You can wait for the route to be used again when the reuse time
arrives, or you can clear all flap dampening with the clear ip bgp
dampening command."

I think the reuse timer in the show ip bgp command is misleading.

     "Dampinfo: penalty 1310, flapped 7 times in 00:27:30, reuse in 00:01:04"

With penalty of 1310, and half life of 15 minutes then it will take
arround 12 minutes to get to 750 to be reused. It can not be 01min &
04 sec as stated in the "show ip bgp" output. Could you please explain
what does "reuse in 00:01:04" really mean?

Full output show below. It's taken on an Optus looking glass. You can
pick up a dampened path via "sh ip bgp dampening dampened-paths" and
"show ip bgp" to have a closer look at a paticular dampened prefix.

Regards,

Huan

route-views.optus.net.au>sh ip bgp dampening parameters
 dampening 15 750 2000 60 (DEFAULT)
  Half-life time : 15 mins Decay Time : 2320 secs
  Max suppress penalty: 12000 Max suppress time: 60 mins
  Suppress penalty : 2000 Reuse penalty : 750

route-views.optus.net.au>sh clock
06:19:55.963 UTC Tue Aug 31 2010
route-views.optus.net.au>sh ip bgp 66.232.192.0/19
BGP routing table entry for 66.232.192.0/19, version 51875338
Paths: (3 available, no best path)
  Not advertised to any peer
  7473 22773 30612 30612 30612 30612 30612 30612 30612 30612 30612
30612, (suppressed due to dampening)
    202.160.242.71 from 202.160.242.71 (202.160.242.71)
      Origin IGP, localpref 100, valid, external
      Community: 7473:22015 7473:32265
      Dampinfo: penalty 1310, flapped 7 times in 00:27:30, reuse in 00:01:04
  7474 7473 22773 30612 30612 30612 30612 30612 30612 30612 30612
30612 30612, (suppressed due to dampening)
    203.13.132.53 from 203.13.132.53 (172.26.32.13)
      Origin IGP, localpref 100, valid, external
      Community: 7473:22015 7473:32265 7474:1403
      Dampinfo: penalty 1146, flapped 8 times in 00:47:18, reuse in 00:09:10
  7474 7473 22773 30612 30612 30612 30612 30612 30612 30612 30612
30612 30612, (suppressed due to dampening)
    203.13.132.35 from 203.13.132.35 (172.26.32.42)
      Origin IGP, localpref 100, valid, external
      Community: 7473:22015 7473:32265 7474:1403
      Dampinfo: penalty 1138, flapped 8 times in 00:47:18, reuse in 00:09:00

route-views.optus.net.au>sh clock
06:21:09.475 UTC Tue Aug 31 2010
route-views.optus.net.au>sh ip bgp 66.232.192.0/19
BGP routing table entry for 66.232.192.0/19, version 51875338
Paths: (3 available, no best path)
  Not advertised to any peer
  7473 22773 30612 30612 30612 30612 30612 30612 30612 30612 30612
30612, (suppressed due to dampening)
    202.160.242.71 from 202.160.242.71 (202.160.242.71)
      Origin IGP, localpref 100, valid, external
      Community: 7473:22015 7473:32265
      Dampinfo: penalty 1240, flapped 7 times in 00:28:45, reuse in 00:10:50
  7474 7473 22773 30612 30612 30612 30612 30612 30612 30612 30612
30612 30612, (suppressed due to dampening)
    203.13.132.53 from 203.13.132.53 (172.26.32.13)
      Origin IGP, localpref 100, valid, external
      Community: 7473:22015 7473:32265 7474:1403
      Dampinfo: penalty 1085, flapped 8 times in 00:48:32, reuse in 00:08:00
  7474 7473 22773 30612 30612 30612 30612 30612 30612 30612 30612
30612 30612, (suppressed due to dampening)
    203.13.132.35 from 203.13.132.35 (172.26.32.42)
      Origin IGP, localpref 100, valid, external
      Community: 7473:22015 7473:32265 7474:1403
      Dampinfo: penalty 1077, flapped 8 times in 00:48:32, reuse in 00:07:50

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Received on Tue Aug 31 2010 - 16:36:25 ART