BGP terminology question
Tony Li
tony.li at tony.li
Sun Nov 6 19:32:49 UTC 2005
>> I understand BGP flapping to be announcements followed by
>> withdraws over a short period. I am seeing a peer with a large
>> number of announcements and the normal number of withdraws. Is
>> there a term to describe what I am seeing? I'd like to understand
>> what is happening, but I've been looking for more info and can't
>> seem to find anything. I suspect I am just not using the right
>> words to search.
>>
>> If there isn't a term, why would a peer announce thousands of time
>> an hour with very few withdraws?
>
> There is a term, it's called "broken".
>
> A peer should never announce a route it has already announced
> unless that route is withdrawn. (If the session goes down or is
> reset, that counts as a withdrawal.)
There's another term for that behavior. It's called "compliant".
There are a number of good implementation reasons why it is
reasonable for an implementation to announce a route that it has
already announced (e.g., peer groups). Admittedly announcing
thousands of times an hour does NOT seem reasonable, but 'never' is
not a requirement of the BGP spec either.
Tony
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