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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________________________
Priscilla Oppenheimer
http://www.priscilla.com
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