nanog mailing list archives

Re: Partial vs Full tables


From: Chuck Anderson <cra () WPI EDU>
Date: Fri, 5 Jun 2020 13:45:07 -0400

On Fri, Jun 05, 2020 at 10:20:00AM -0700, William Herrin wrote:
On Fri, Jun 5, 2020 at 9:49 AM Saku Ytti <saku () ytti fi> wrote:
The comparison isn't between full or default, the comparison is
between static default or dynamic default. Of course with any default
scenario there are more failure modes you cannot route around. But if
you need default, you should not want to use dynamic default.

It's a little more nuanced than that. You probably don't want to
accept a default from your transit but you may want to pin defaults
(or a set of broad routes as I did) to "representative" routes you do
accept from your transit. By "pin" I mean tell BGP that 0.0.0.0/0 is
reachable by some address inside a representative route you've picked
that is NOT the next hop. That way the default goes away if your
transit loses the representative route and the default pinned to one
of your other transits takes over.

I do the above using routes to *.root-servers.net to contribute to the
aggregate 0/0.


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