[86466] in North American Network Operators' Group
Re: BGP terminology question
daemon@ATHENA.MIT.EDU (Tony Li)
Sun Nov 6 14:33:28 2005
In-Reply-To: <655FE506-A389-466F-9314-6416F2C8C2C6@ianai.net>
Cc: NetSecGuy <netsecguy@gmail.com>, nanog@merit.edu
From: Tony Li <tony.li@tony.li>
Date: Sun, 6 Nov 2005 11:32:49 -0800
To: Patrick W.Gilmore <patrick@ianai.net>
Errors-To: owner-nanog@merit.edu
>> 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 unless that route is withdrawn.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
