nanog mailing list archives
Re: Confussion over multi-homing
From: Patrick Evans <pre () pre org>
Date: Fri, 15 Sep 2000 10:00:22 +0100 (BST)
On Thu, 14 Sep 2000, John Fraizer wrote:
They won't see it even if their /20 announcement is being filtered as long as their upstream is listening to it. (Upstream being the carrier they obtained the /20 from.) This is because even though some ISP/NSPs may not listen to the specific /20 announcement, I haven't found any who will ignore a /19 or /17 announcement for the master block. As long as they know how to get to that block, and teh "upstream" knows how to get to the /20, the route filtering isn't going to be apparent at all... Until the time that the "upstream" has connectivity issues.
So the general picture is... I advertise a /22 to ISPs A and B, my upstream providers, using space allocated from provider A's assignment. ISP A's connection to the world (okay, ISP A might not exactly be UUNet) goes tits up at which point the world ceases to see any announcements because the aggregate with the shorter prefix has vanished, and they're filtering the longer prefix announced via ISP B. The whole thing seems to be dependent on ISP A not having problems connecting to external ASes. Or am I missing something big? If multi-homing still leaves me dependent on one of my upstreams being alive, there would appear to be something very wrong... -- Patrick Evans - Sysadmin, bran addict and couch potato pre at pre dot org www.pre.org/pre
Current thread:
- Re: Confussion over multi-homing, (continued)
- Re: Confussion over multi-homing jlewis (Sep 14)
- RE: Confussion over multi-homing Roeland M.J. Meyer (Sep 14)
- RE: Confussion over multi-homing Tony Tauber (Sep 14)
- Re: Confussion over multi-homing Austin Schutz (Sep 15)
- RE: Confussion over multi-homing Tony Tauber (Sep 14)
- RE: Confussion over multi-homing Richard Welty (Sep 14)
- RE: Confussion over multi-homing Paul Froutan (Sep 14)
- Re: Confussion over multi-homing Brantley Jones (Sep 14)
- Re: Confussion over multi-homing dan (Sep 15)
- Re: Confussion over multi-homing Sean Donelan (Sep 14)
- Re: Confussion over multi-homing John Fraizer (Sep 14)
- Re: Confussion over multi-homing Patrick Evans (Sep 15)
- Re: Confussion over multi-homing John Fraizer (Sep 15)
- Re: Confussion over multi-homing John Fraizer (Sep 14)
- RE: Confussion over multi-homing Roeland M.J. Meyer (Sep 15)
- RE: Confussion over multi-homing Dmitri Krioukov (Sep 15)
- Re: Confussion over multi-homing David Lott (Sep 15)
- Re: Confussion over multi-homing Alex Pilosov (Sep 15)
- RE: Confussion over multi-homing Dmitri Krioukov (Sep 15)
- RE: Confussion over multi-homing Alex Pilosov (Sep 15)
- RE: Confussion over multi-homing Dmitri Krioukov (Sep 15)
- RE: Confussion over multi-homing Dmitri Krioukov (Sep 15)