[54111] in North American Network Operators' Group
Re: FW: /8s and filtering
daemon@ATHENA.MIT.EDU (bmanning@vacation.karoshi.com)
Tue Dec 10 15:12:09 2002
From: bmanning@vacation.karoshi.com
To: hnarayan@cs.ucsd.edu (Harsha Narayan)
Date: Tue, 10 Dec 2002 11:47:25 -0800 (PST)
Cc: ejay.hire@isdn.net (Ejay Hire), nanog@merit.edu
In-Reply-To: <Pine.GSO.4.32.0212101112390.13597-100000@gradlab.ucsd.edu> from "Harsha Narayan" at Dec 10, 2002 11:14:33 AM
Errors-To: owner-nanog-outgoing@merit.edu
>
>
> Hello,
> No, this is not the case. I enquired and it seems multihoming is not a
> justification for a /24 in any RIR.
>
> Does a network have to be able to fully utilize a /26 (25% of /24) in
> order to multihome?
>
> Harsha.
You do err, not knowing the scripture.
To multihome, you need to get (at least) two other providers to listen
to your routing announcement(s). Wango'z'tango! multihoming done.
Your announcement can be as small as a /32 (although there was a
time when at least one /33 was delegated...)
What's that? you want everyone running IP to reach your gopher
server? Tough luck. then you must somehow meet/pass the
byzantine filtering rules (unpublished sometimes) that parties
which are three and four hops away from your edge will impose on
whatever announcements you happen to propogate. The dead hand of
the CIDR mafia will eat your lunch and you'll have no recourse.
So, whats a poor'lil player todo? Some say that this works:
) build a rich peering mesh. (reduces your dependence
on any one transit provider)
) buy transit (where you -MUST-) and insist that you
understand BGP, peering, and how to prevent leakage.
Demand that they accept your announcement(s).
[ note that this may turn transit into peering, which
may trigger other unpleasent SOPs from the salesdroids
but hey, multihoming is -worth- the effort...]
as usual, YMMV.
--bill (who is earning the sobriquet "grumpy" today)
