[130275] in North American Network Operators' Group
Re: BGP next-hop
daemon@ATHENA.MIT.EDU (Franck Martin)
Thu Sep 30 18:00:25 2010
X-Barracuda-Envelope-From: franck@genius.com
Date: Thu, 30 Sep 2010 15:00:08 -0700 (PDT)
From: Franck Martin <franck@genius.com>
To: Randy Bush <randy@psg.com>
In-Reply-To: <m239sqzzdk.wl%randy@psg.com>
Cc: North American Network Operators Group <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Because the path was broken everytime the bgp session was established and rewriting the routing table with more specific routes?
----- Original Message -----
From: "Randy Bush" <randy@psg.com>
To: "North American Network Operators Group" <nanog@nanog.org>
Sent: Thursday, 30 September, 2010 2:37:43 PM
Subject: Re: BGP next-hop
i was recently bitten by a cousin of this
research router getting an ebgp multi-hop full feed from 147.28.0.1
(address is relevant)
it is on a lan with a default gateway 42.666.77.11 (address not
relevant), so it has
ip route 0.0.0.0 0.0.0.0 42.666.77.11
massive flapping results.
it seems it gets the bgp route for 147.28.0.0/16 and then can not
resolve the next hop. it would not recurse to the default exit.
of course it was solved by
ip route 147.28.0.0 255.255.0.0 42.666.77.11
but i do not really understand in my heart why i needed to do this.
randy
