[28778] in North American Network Operators' Group
Re: "Simple" Multi-Homing ? (was Re: CIDR Report)
daemon@ATHENA.MIT.EDU (Chris Williams)
Tue May 16 11:20:26 2000
Message-ID: <228F0747.E93FBDC6@third-rail.net>
Date: Mon, 16 May 1988 11:14:15 -0400
From: Chris Williams <chris.williams@third-rail.net>
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To: Todd Sandor <tsandor@home.com>
Cc: nanog@merit.edu
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In the last year I worked for a company which had multihomed /24s and we
never had any problem with parts of the internet being unreachable when
our primary provider was down, at least not that anyone noticed. I
suspect this is because of which providers were upstream -- the
configuration was that we were directly peered with C&W, using C&W
address space, and our backup was a tier 2 who peered with UUnet and
Sprint.
My theory is that when our connection to C&W was down, networks which
filtered our /24 advertisement would send traffic destined for us to C&W
(who was still advertising large aggregates which our /24s were under),
and then once it reached C&W, C&W would use its own peering connections
with UUnet and/or Sprint to deliver the traffic. Does this sound
plausible, or am I missing something? Do a lot of multihomed /24ers get
away with it by this principle? In what situations would something like
this _not_ happen, aside from peering directly with a primary provider
who would not accept advertisements for your small address block from
outside? (which would be kind of pointless, anyway..)
