[175858] in North American Network Operators' Group
RE: Default routes on BGP routers with full feeds
daemon@ATHENA.MIT.EDU (Adam Greene)
Wed Nov 5 09:23:06 2014
X-Original-To: nanog@nanog.org
From: "Adam Greene" <maillist@webjogger.net>
To: <nanog@nanog.org>
In-Reply-To: <D05FAF98-D8E1-4ABA-BAA1-3F18CA844480@voipgate.com>
Date: Wed, 5 Nov 2014 09:22:45 -0500
Errors-To: nanog-bounces@nanog.org
We receive full routes and a default so we can perform traffic =
engineering within our network. We have links to multiple carriers, via =
multiple routers. We inject a default route into OSPF from distinct =
segments of our network, based on receiving the default route on that =
segment via eBGP. If the default route goes down, the default injected =
from another segment assumes priority and traffic routes out through =
that segment's carrier. It's easier to manage this kind of failover (for =
us) using default routes, so we don't have to carry full routes on all =
our core routers. We also prefer using a default route over engineering =
things based on some other arbitrary route learned from eBGP.
Thanks,
Adam
-----Original Message-----
From: NANOG [mailto:nanog-bounces+maillist=3Dwebjogger.net@nanog.org] On =
Behalf Of Marc Storck
Sent: Wednesday, November 05, 2014 6:53 AM
To: nanog@nanog.org
Subject: Re: Default routes on BGP routers with full feeds
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Hash: SHA1
On Nov 5, 2014, at 7:49 AM, Andreas Larsen <andreas.larsen@ip-only.se> =
wrote:
There is one setup where you would need default route from your =
provider.
If you have no IBGP between two sites and your prefix is a large /16 on =
side and maybe a /18 from that /16 on another site. These site would not =
be able to talk to each other if you orginate from the same AS.
Other than that I see not harm in having both default and a full table =
since longest prefix match will always win even if you have 2 or more =
transits.
I think in that case you would use =E2=80=9Callowas-in=E2=80=9D.
Regards,
Marc
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