hooray .
it looks like as thought i was right about the term flap..just wrong about
BGP ......thanks for the info
chhers
steve
>From: Andy Prima
>To: "'Stephen Skinner'" , [EMAIL PROTECTED]
>Subject: RE: BGP Dampening, What is a flap? [7:1128]
>Date: Thu, 19 Apr 2001 16:19:26 +0700
>
>
>Please let me quote from sitamoth.com:
>
>Route dampening is a BGP feature designed to minimize the propagation of
>flapping routes across an internetwork. A route is considered to be
>flapping
>when it is repeatedly available, then unavailable, then available then
>unavailable..and so on.
>A route that is flapping receives a penalty of 1000 for each flap. When the
>accumulated pelanlty reaches a configurable limit, BGP surpresses
>advertisement of the route EVEN if the route is UP.
>The accumulated penalty is decremented by the half-life time. When the
>accumulated penalty is less than the reuse limit, the route is advertised
>again (if it is still UP).
>
>
>Hope this can help :)
>
>Andy
>
>-----Original Message-----
>From: Stephen Skinner [mailto:[EMAIL PROTECTED]]
>Sent: Thursday, April 19, 2001 3:53 PM
>To: [EMAIL PROTECTED]
>Subject: Re: BGP Dampening, What is a flap? [7:1128]
>
>
>I always thought of a "Flap" as a generic term ....meaning when a
>route/interface/serial-line goes full-circle.....regardless of protocol
>i use the term interchangeably with OSPF,PpP,LEASED lines,BGP,ISDN
>
>from:- working----down----initialising----up
>
>i have always treated the "whole" as one flap?????
>
>Am i going mad.....
>
>Cheers
>
>steve
>
>"my mum always said ....it`s only an exam.......PAH...what the heck do she
>know"
>
>
> >From: "Priscilla Oppenheimer"
> >Reply-To: "Priscilla Oppenheimer"
> >To: [EMAIL PROTECTED]
> >Subject: Re: BGP Dampening, What is a flap? [7:1128]
> >Date: Wed, 18 Apr 2001 18:09:50 -0400
> >
> >I think from BGP's point of view a flap is a withdrawal and announcement
>of
> >a routing prefix. Howard Berkowitz will know for sure. Did you check his
> >BGP papers at http://www.certificationzone.com. Also there's a good paper
> >here:
> >
> >http://www.ripe.net/ripe/docs/ripe-178.html
> >
> >Cisco often uses the word "flapping" in a generic sense for a route or
> >interface going up and down repeatedly. That could be cause for some
> >confusion. In your class, you might want to be clear about whether you
>are
> >using the term generically or with reference to parameters to route
> >dampening commands.
> >
> >Good luck. Let us know what you find out for sure! Thanks.
> >
> >Priscilla
> >
> >At 03:35 PM 4/18/01, Tom Pruneau wrote:
> > >Greetings All
> > >
> > >I am in the process of writing a BGP class, at present I am
>specifically
> > >working on a section covering dampening.
> > >
> > >My question is "what is a flap"
> > >
> > >The two possible answers are:
> > >
> > >
> > >Answer one
> > >A flap is whenever path information changes for a route. By this
> >definition
> > >if a route goes away, that would be a flap. When the route comes back,
> >that
> > >would be another flap.
> > >So a route going away then coming back would be 2 flaps.
> > >
> > >
> > >Answer two
> > >A flap is a route transition from up to down back to up. So a route
>going
> > >away then coming back would count as one flap.
> > >
> > >
> > >
> > >I am mucking with this in my lab and the lab would seem to indicate
>that
> > >answer two is the correct one, but when I read the Sam Halabi copyright
> > >1997 internet routing architectures book, page 440 and 441 it says the
> > >answer is Answer one.
> > >
> > >I am at best confused
> > >
> > >Any help?
> > >Tom Pruneau
> > >Trainer Network Operations
> > >
> > >GENUITY
> > >3 Van de Graff Drive Burlington Ma. 01803
> > >24 Hr. Network Operations Center 800-436-8489
> > >If you need to get a hold of me my hours are 8AM-4PM ET Mon-Fri
> > >
> >
>
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> >
>
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> > >
> > >"Once in a while you get shown the light
> > >in the strangest of places if you look at it right"
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> >
> >________________________
> >
> >Priscilla Oppenheimer
> >http://www.priscilla.com
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