North American Network Operators Group

Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

Re: BGP terminology question

  • From: Tony Li
  • Date: Sun Nov 06 14:34:43 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A peer should never announce a route it has already announced unless that route is withdrawn.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.