From: Robert Watson (watson.robert@gmail.com)
Date: Mon May 22 2006 - 22:48:42 ART
My take on interface dampening is that it is taking from the BGP route
dampening so to get the most of the interface level dampening behavior go to
BGP route dampening on cco and then apply what is on that to cisco's
approach to interface level dampening.
The tricky part of this is that although its an interface level command you
will not find it in the interface section of the command reference but under
routing protocol -> protocol independent features
http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chap
ter09186a0080457c1d.html
My .02
" wouldn't it be cool if I had a content engine preloaded with the entire
content of cco on my local subnet? If I broke my network I could find a way
to fix it! heh"
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Roberto Fernandez
Sent: Friday, May 19, 2006 6:24 PM
To: ccielab@groupstudy.com
Subject: RE: Interface Flapping Question
Friends,
The question about interface dampening has been coming and going on the
list, and in fact it is tricky even knowing how IP dampening works.
I still can't figure out a satisfactory answer. I'm just tossing facts,
perhaps someone can pick from there and shead the light. In practice is
really hard to dampen the interface for two reasons:
1- The decay of the penalty is really fast
2- The interface can detect the flaps only upon the miss of a given
number of keepalives (at least one).
The fastest the Ethernet interface can detect a flap is 1 second, so it
takes at least the same time to recover (detect the recovering) so the
interface; in the best case is able to detect the second flap only two
seconds after the first flap, and for then the penalty would have
decayed a lot. How much? I don't know...
In the worst case "no keepalive" the interface will never detect the
flap...
by default the keepalaive is 10 seconds so the interface could take a
lot to discover the flap and in 10 seconds the penalty decays a lot,
even is half life is set to 30 (the maximum).
Best Regards,
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Montgomery, Jerry
Sent: Friday, May 19, 2006 1:38 PM
To: ccielab@groupstudy.com
Subject: Interface Flapping Question
Good afternoon, all,
How does one configure a router so that the IOS will withdraw an
interface from participating from routing if the interface flaps 3 times
in a 30 second period?
I researched the CD and can not find the solution. I thought it was
interface tracking but I really don't know.
Respectfully,
Jerry Montgomery, CCDP, CCNP, CCDA, & CCNA
Senior Infrastructure Specialist
E Enterprise Network Architecture & Technology
H1-5F-55 5400 Legacy Drive, Plano, Texas
*: 972.797.2783 (8-834) (Office)
*: 972.605.4830 (Fax)
*: mailto:jerry.montgomery@eds.com
www.eds.com
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