Communities BCP [was: RE: BGP Path Filtering]
deepak at ai.net
Fri May 16 18:50:09 UTC 2003
> I like using BGP communities:
> o filter announcements you receive from downstreams based on your
> criteria of choice
> o set a specific BGP community (yourAS:whatever) on
> announcements which
> are to be propagated to various places (upstream providers, etc.)
> o do output filtering based on the communities you set
> Make sure you clear yourAS:whatever in announcements from your BGP peers.
> You can use this same technique for prefixes you originate, so
> that all your
> outbound BGP filtering is based on communities.
I am hijacking this thread a bit. Setting communities is excellent advice
especially if you are just starting out with downstream ASes.
The question is that changing your communities down the road might be a big
headache depending on whether you'll come to need more advanced ways of
filtering your announcements than coarse communities allow. Especially when
going (through growth or acquisition) from a single metro network to a
multi-metro or national/international one.
What criteria does the community think should be used when specifying
communities. IMO, overspecificity [sp?] doesn't hurt, but others may (and
have) disagreed. What's the BCP?
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