From: Heiko Liedtke (heiko.liedtke@gmx.net)
Date: Sat Nov 18 2006 - 15:17:38 ART
Dear group,
I think I found something like a "Rule of thumb" for the dampening stuff...
The time periods will always start with a flap and we have to wait for
a second or third one within the given period to suppress the interface.
A second or third flap
after the period sould not suppress the interface.
There is the assumption that we start with 0 penalty at the beginning of
the calculation.
===============================
Scenario 1 ----> 2 flaps whithin 15 sec
===============================
With a half-life time of 15 sec, the first flap has decreased its
penalty to 500.
If the second flap occurs after 15 sec, the penalty would be now 1500
and the interface
is dampened.
If the second flap happens 16 sec after the first flap, the penalty of
the first flap would be < 500
and the total penalty would be < 1500 and the interface will not suppressed.
Solution:
Suppress limit 1500
Half-life time 15 sec
==============================
Scenarion 2 ----> 3 flaps whithin 30 sec
==============================
A 3rd flap after 31 sec should not suppress the interface.
After 30 sec the penalty of the first and second flap is at least 1000.
(doesnt
matter at what time the second flap occured(
If the 3rd flap occurs after 30 sec, the penalty would be 2000, if the
3rd flap
comes after 31 sec the penalty would be less than 2000 and the
suppression would
not happen.
Solution:
Suppress limit 2000 (there is a 0% chance that two interface flaps
happen at the same time ;-)
Half-life time 30 sec
For 4 flaps in 30 sec I would configure a suppress value of 2500 and so
on....
Any comments on this would be helpfull, maybe I forgot something
important...
heiko
Ivan schrieb:
>My vote suppress-value 1001.
>Reason of this is after first flap interface must keep alive and after second
>flap no mater "when" inside given interval interface must be suppresed. If
>value above 1000 it will suppress.
>In this solution there is another issue time interval what if second flap
>appear after 16 second. Interface will be suppressed also. I think that
>half-life time must be about 7 or 8 second.
>
>On Friday 17 November 2006 19:36, Salman Abbas wrote:
>
>
>>Hi guys,
>>
>>I want RIP to stop interface e0/0 on my router from participating in
>>routing if it flaps 2 times in a *15* second period. what dampening values
>>will I have to set to achieve this?
>>
>>interface e0/0
>>dampening *15* 1000 __ 60. I think the answer would fit at the third place
>>(value to start supressing an interface) in the dampening command. However,
>>Im not sure. Please help.
>>
>>
>>Thanks a bunch in advance!!!
>>
>>Cheers!
>>
>>Salman
>>
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