I think all the meaningful parties have already pretty much agreed on 32bit ASNs in BGP4. I think that will be coded in the routers well before any attribute-based thing for 32bit ASNs is. As such, I don't see much point to kludging this instead of just going for it assuming a 32bit world. Owen --On Saturday, December 4, 2004 0:30 +0000 "Edward B. Dreger" <eddy+public+spam@noc.everquick.net> wrote:
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.
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