Re: BGP Dampening Reuse Timer

All, FYI, TAC engineer just confirmed this behavior is a bug.

Andrian, curiosity improves knowledge :)

On Thursday, September 2, 2010, Adrian Brayton <abrayton_at_gmail.com> wrote:
> I admire your curiosity and drive to figure things like this out! We look forward to hearing what they have got to say.
>
> On a lighter note, You'll understand what I am saying soon enough.
>
> Sent from my iPad
>
> On Sep 1, 2010, at 9:04 PM, Tech Guy <autechguy_at_gmail.com> wrote:
>
>> Thanks Adrian for your link. However, I understand how BGP dampening
>> work, and know how to twick the default parameters for my own use. I
>> am more interested in what the "reuse timer" shown in the Cisco "show
>> ip bgp x.x.x.x" or "sh ip bgp dampening dampened-paths" commands
>> really mean.
>>
>> Just to satisfy my curiosity, I raised a case with Cisco. The initial
>> feedback from TAC is that the "reuse timer" looks misleading. TAC can
>> reproduce the behaviour, and it seems the counter reset to 11 minutes
>> when it reaches 0, same as what I reported.
>>
>> I will update group if I get a better explaination to the meaning of
>> that counter.
>>
>>
>> On Wed, Sep 1, 2010 at 9:55 PM, Adrian Brayton <abrayton_at_gmail.com> wrote:
>>> Hey Tech Guy,
>>>
>>> Please read this RFC...
>>>
>>> http://tools.ietf.org/rfc/rfc2439.txt
>>>
>>> BGP dampening is just one of those technologies where it just kinda works but to get to deep into it is futile.
>>>
>>> Just learn the different types of dampening, the default values and how to change them. I am not going to discuss this as the details of how everything behind the scene's works is way over my head and once you read the RFC you will probably feel the same way.
>>>
>>>
>>> On Aug 31, 2010, at 9:54 PM, Tech Guy wrote:
>>>
>>>> Andrian,
>>>>
>>>> The reuse timer seems to be reset back to 11 minutes minutes once it
>>>> reaches 0. It is not related to the half-time of 15 minutes. (see
>>>> below outputs for further details)
>>>>
>>>>
>>>> Everyone can telnet to an open looking glass and have a try. I can not
>>>> lab this, as the IOS I have for Dynamips do not show the "reuse"
>>>> timer. But the same behaviour is seen on various platforms and IOS.
>>>>
>>>>
>>>> route-views.optus.net.au>sh ver | in IOS
>>>> IOS (tm) 7200 Software (C7200-P-M), Version 12.0(32)S13, RELEASE SOFTWARE (fc3)
>>>>
>>>> (AT&T looking glass route-server.ip.att.net IP address 12.0.1.28 )
>>>> route-server>sh ver | in IOS
>>>> Cisco IOS Software, 7200 Software (C7200-JS-M), Version 12.2(31)SB10,
>>>> RELEASE SOFTWARE (fc2)
>>>>
>>>> Another Production router
>>>> Cisco-7606>sh ver | in IOS
>>>> Cisco IOS Software, c7600s72033_rp Software
>>>> (c7600s72033_rp-ADVIPSERVICESK9-M), Version 12.2(33)SRB6, RELEASE
>>>> SOFTWARE (fc1)
>>>>
>>>>
>>>>
>>>> route-views.optus.net.au>sh ip bgp 89.25.60.0/23
>>>> BGP routing table entry for 89.25.60.0/23, version 52091189
>>>> Paths: (3 available, no best path)
>>>> Not advertised to any peer
>>>> 7473 3356 701 12301 9070 31340, (suppressed due to dampening) (history entry)
>>>> 202.160.242.71 from 202.160.242.71 (202.160.242.71)
>>>> Origin IGP, localpref 100, external
>>>> Community: 7473:12165
>>>> Dampinfo: penalty 4648, flapped 15 times in 00:16:53, reuse in 00:06:43
>>>> 7474 7473 3356 701 12301 9070 31340, (suppressed due to dampening)
>>>> (history entry)
>>>> 203.13.132.53 from 203.13.132.53 (172.26.32.13)
>>>> Origin IGP, localpref 100, external
>>>> Community: 7473:12165 7474:1403
>>>> Dampinfo: penalty 3719, flapped 12 times in 00:16:51, reuse in 00:01:43
>>>> 7474 7473 3356 701 12301 9070 31340, (suppressed due to dampening)
>>>> (history entry)
>>>> 203.13.132.35 from 203.13.132.35 (172.26.32.42)
>>>> Origin IGP, localpref 100, external
>>>>

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