From: Roberto Fernandez (rofernandez@us.telefonica.com)
Date: Fri May 19 2006 - 20:23:39 ART
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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