nanog mailing list archives

Re: BGP Path Attribute Filtering, YES or NO?


From: Mark Tinka <mark.tinka () seacom mu>
Date: Wed, 8 Jan 2020 17:14:32 +0200



On 8/Jan/20 16:52, James Jun wrote:

I see.  LOCAL_PREF and RFC 1998 style of community attributes however are
 not the right tool for signalling exit locations -- it does not scale.
Sure, it's a useful hammer to hard enforce a baseline mode of preference
on given route (e.g. route of last resort, backup or equalize to same
baseline level as peer-learned routes, etc), but for signalling optimal
exit locations at scale, MED is exactly the right tool for that job (and
networks would typically derive MED values using IGP metrics).

Two solutions, two methods, same result, IMHO.

It's been scaling very well for us, and offers customers explicit
control that comes with a flip-switch cover over the, well, switch :-).

If you know of any reason why LOCAL_PREF doesn't scale, I'd like to hear
it, since I'd imagine that if closely maintaining exit paths is
important to you, you don't want to leave it to chance anyway.

Mark.


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