[76250] in North American Network Operators' Group
Re: 16-bit ASN kludge
daemon@ATHENA.MIT.EDU (Edward B. Dreger)
Fri Dec 3 19:32:05 2004
Date: Sat, 4 Dec 2004 00:30:39 +0000 (GMT)
From: "Edward B. Dreger" <eddy+public+spam@noc.everquick.net>
To: Owen DeLong <owen@delong.com>
Cc: John Dupuy <jdupuy-list@socket.net>, <nanog@merit.edu>
In-Reply-To: <2147483647.1102085116@[172.17.1.152]>
Errors-To: owner-nanog-outgoing@merit.edu
OD> Date: Fri, 03 Dec 2004 14:45:17 -0800
OD> From: Owen DeLong <owen@delong.com>
OD> I think the original proposal was to still go with 32 bit ASNs, but, adapt
OD> a range of 32 bit ASNs for the assignment to "NON-TRANSIT" ASNs leaving
OD> the entire 16 bit range reserved for "TRANSIT" ASNs.
Correct. BGP would still carry traditional 16-bit ASNs, which would be
used strictly by transit networks. Leaf ASes would use the "new" 32-bit
ASNs, which would be carried as BGP attributes.
It's similar to a transit provider with a downstream connected to
multiple POPs: $transit_provider assigns all downstreams a private AS,
which is stripped from outbound advertisements.
OD> I think there's merit to the idea, but, I think that it could use some
OD> refinement. I agree there will be many more non-transit than transit ASNs
No disagreement re needing refinement. I lack the clout to push BGPv8
on the world. ;-)
OD> (non-transit is an ASN that does not provide transit, transit is an
OD> ASN that provides transit).
OD>
OD> I think it would make more sense to put the boundary somewhere around 12
OD> bits or so. If we reserved the first meg 1024k ASNs for transit providers
OD> (excepting the Private ASN reservation already in place), and, allowed the
OD> remaining ASNs to be assigned to non-transit ASNs, this functionality could
OD> be implemented relatively easily with maximum backward compatibility.
Part of the kludge intent was to create something that standard routers
would carry. Hence 16-bit traditional ASNs, with extended information
as an attribute. It certainly would be possible to reserve 2^20 "new"
ASNs, though, for when BGP5 (or whatever) had native 32-bit support.
Eddy
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