From: Victor Cappuccio (cvictor@protokolgroup.com)
Date: Fri May 19 2006 - 15:20:08 ART
Jerry, look at this Email from one of the experts in this list..
-----Mensaje original-----
De: nobody@groupstudy.com [mailto:nobody@groupstudy.com] En nombre de
Godswill Oletu
Enviado el: Viernes, 19 de Mayo de 2006 09:53 a.m.
Para: Koen Zeilstra; ccielab@groupstudy.com
Asunto: Re: ip event dampening parameters
Koen,
Without going into alot of calculations, the answer to your original
question was straight forward and you were actually on the right path, but
instead of using a half life of 15 sec; a half life of 30 sec will do the
job..ie instead of:
>dampening 15 1000 3000 60
Using ....
!
interface fa0/0
dampening 30 1000 3000 60
!
Will be just fine...
The penalty for each flag is 1000 and that does not change and there is no
configurable parameter to change it. The above dampenning policy simply
means:
* 1st flap, interface will get a penalty of 1000
* 2nd flap, the penalty will be 2000
* 3rd flap, the penalty will be 3000 and the interface will be dampened.
If the 2nd or 3rd flap occurred after 30 sec, the culmulative penalty will
be less than 3000 and the interface will not be dampened.
***Note, the original question states that "dampen the interface if it flaps
3 times in 30 sec. period"
You see that, there will be no need to dampen the interface unless all three
flagings occur within 30 sec and since the half life is pegged at 30 sec, a
penalty of 3000 accessed against 3 flaps is the key to answering your
original question.
You might want to say..."What if the 3rd flap happens at the 30th sec.?,
well this is open to a wide variety of interpretation, which, I believe the
question does not want to exploit, because if a flap took place at the 30th
sec, two things will happen; a penalty of 1000 will be accessed, and the
cumulative penalty will be cut in half, now which will take place first
(accessing a penalty of 1000 or cutting the culmulative penalty by half)? As
you can see, this is another thread of its own.
So 'dampening 30 1000 3000 60' is good enough, you can adjust the reuse and
max suppress vlaues, since the question is silent about them.
HTH
Godswill Oletu
-----Mensaje original-----
De: nobody@groupstudy.com [mailto:nobody@groupstudy.com] En nombre de Ram
Shummoogum
Enviado el: Viernes, 19 de Mayo de 2006 02:04 p.m.
Para: jerry.montgomery@eds.com
CC: ccielab@groupstudy.com; nobody@groupstudy.com
Asunto: Re: Interface Flapping Question
Have a look at Dampening
"Montgomery,
Jerry"
<jerry.montgomery To
@eds.com> <ccielab@groupstudy.com>
Sent by: cc
nobody@groupstudy
.com Subject
Interface Flapping Question
05/19/2006 01:38
PM
Please respond to
"Montgomery,
Jerry"
<jerry.montgomery
@eds.com>
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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