From: Salman Abbas (dukelondon@gmail.com)
Date: Sat Nov 18 2006 - 05:22:35 ART
Hi Anthony,
Sorry, I didnt read the thread immediately after the one you sent me. That
thread has the answer.
Thanks and Regards,
Salman
On 11/18/06, anthony.sequeira@thomson.com <anthony.sequeira@thomson.com>
wrote:
>
> I labbed this one up as this post suggests and learned that he was indeed
> correct about how the penalty moves.I am so sorry that I do not have time
> right now to research the definitive answer <again> - but I think you
should
> have all the info you need now to ensure that you will get the dampening
> behavior required given certain values.
>
>
>
> I suggest you lab this up. With "dampen 30 1000 3000 60" the interface
>
> will not dampen in 30 seconds with 3 flaps..
>
>
>
> True, the half life is when the value is decayed by half its original
>
> penalty. But since its an exponentially decaying algorithm, the penalty
>
> begins decaying IMMEDIATELY.
>
>
>
> What this means is, if you flap the interface with dampening (dampen 30
>
> 1000 3000 60) you will see the penalty at 1000 immediately, but then
>
> querying the dampening for the interface again will indicate another
>
> value like 893. And again, 773, etc. until at 30 seconds the value will
>
> be 500 for the first flap.
>
>
>
> If you flap it a second time then the penalty will be the original
>
> decayed penalty value at that moment PLUS the new penalty value (e.g.
>
> 1000). And the exponential decay begins again. Query the interface and
>
> you will see the penalty between 500 and 1500 and decaying fast. The
>
> same holds true for a third flap.
>
>
>
> In short, a suppress value of 3000, as configured, will not dampen the
>
> interface with 3 flaps in 30 seconds because the cumulative penalty will
>
> be < 3000 at the half-life; guaranteed!
>
>
>
>
> ------------------------------
>
> *From:* Salman Abbas [mailto:dukelondon@gmail.com]
> *Sent:* Saturday, November 18, 2006 1:40 AM
> *To:* Sequeira, Anthony (NETg)
> *Cc:* hitesh@att.com; ccielab@groupstudy.com
> *Subject:* Re: IP Event Dampening
>
>
>
> Hi Hitesh,
>
>
>
> Thanks a bunch bro.
>
>
> Hi Anthony,
>
>
>
> Thanks for the thread but what should the answer be, taking Hitesh's reply
> and the thread into consideration?
>
> I mean dampening 15 1000 ___ 60 .
>
>
>
> Pls advise,
>
>
>
> Thanks and Regards,
>
>
> Salman
>
>
>
> On 11/18/06, *anthony.sequeira@thomson.com* <anthony.sequeira@thomson.com >
> wrote:
>
> Careful - this feature does not work like you think - here is an
> excellent thread from the archives on the subject. . . note that the
> biggest surprise is how the feature uses an exponentially decaying
> algorithm - jeez.....
>
> http://adserver.groupstudy.com/archives/ccielab/200605/msg01011.html
>
> Anthony J. Sequeira
> #15626
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com ] On Behalf Of
> SAVJANI, HITESH, WWCS
> Sent: Friday, November 17, 2006 2:54 PM
> To: Salman Abbas; ccie >> Cisco certification;
> Duane.Fletcher@morganstanley.com
> Subject: RE: IP Event Dampening
>
> Salman,
>
> Default value for the penalty is 1000 which can not be changed. Yes, it
> increases by 1000 every time it flaps. You are probably looking at the
> default suppress value which is 2000 also. However you can configure the
> suppress-threshold value which will decide when to suppress a route. You
> can read more about it on the following link
>
> http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123tcr/1
> 23tip2r/ip2_c1gt.htm#wp1093971
>
> I am sure someone else on the group can add to this.
>
> HTH,
>
> Hitesh Savjani
> CCIE # 17151
>
>
> ________________________________
>
> From: Salman Abbas [mailto: dukelondon@gmail.com]
> Sent: Friday, November 17, 2006 1:57 PM
> To: SAVJANI, HITESH, WWCS; ccie >> Cisco certification;
> Duane.Fletcher@morganstanley.com
> Subject: Re: IP Event Dampening
>
>
> Hi Fletcher,
>
> I'm not the Sal Abbas who used to work at AT&T.
>
> Hi Hitesh,
>
> Thanks a bunch for your reply. The default value for "value to start
> suppressing an interface" is 2000. I've checked that on the router.
> When you say in 2 flaps, it'll become 2000, do you mean it increases by
> 1000 every time theres a flap? Is this a documented value somewhere or
> can I see this on the router? If it starts from 0, why do I always see a
> value of 2000 in my sh dampening interface output?What do you think the
> answer should be in the light of this fact?
>
> Regards,
>
> Salman
>
>
> On 11/18/06, SAVJANI, HITESH, WWCS <hitesh@att.com> wrote:
>
>
> Salman,
>
> I think if you want your interface to be suppressed after two
> flaps then
> you should set the value to be 2000.
> Reason for that is it will start from 0 penalty & in 2 flaps
> will bring
> it to 2000.
>
> HTH,
>
> Hitesh Savjani
> CCIE # 17151
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> Behalf Of
> Salman Abbas
> Sent: Friday, November 17, 2006 11:36 AM
> To: ccie >> Cisco certification
> Subject: IP Event Dampening
>
> 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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