16-bit ASN kludge

John Dupuy jdupuy-list at socket.net
Fri Dec 3 22:36:39 UTC 2004


Along these lines, one could leave the transit AS networks alone if a 
parallel 16 bit ASN space were created. Essentially, any non-transit 
network would have it's non-public ASN retranslated NAT-style by upstream 
transit network border routers. Only the border routers would have to be 
changed. They would have to differentiate between public ASN X and 
non-public ASN X (same number) based on the which side of the router the 
ASN was learned from.

This would essentially double the ASN numbers available.

All that being said, I'd much rather see 32-bit ASNs.

John

At 10:48 AM 12/3/2004, Edward B. Dreger wrote:

>Perhaps transit networks should receive 16-bit ASNs.  Leaf networks
>would use { a special ASN | I'm still brainstorming | who knows } and
>carry an "available upstreams" BGP tag for each upstream.
>
>Metrics are calculated for each transit AS.  Those metrics are then
>combined with <as yet unspecified intelligence in "available upstreams"
>tag> for each leaf ASN.
>
>BGP loop detection might present a problem if all leaf ASNs use, say,
>16-bit AS65535.  If existing allowas-in is too coarse, refer to "32-bit
>ASN" BGP attribute for fine-grained control.
>
>In short: I'm trying to think up a mechanism that performs full Dijkstra
>calculations _only_ for transit networks, and uses some cheaper version
>for the degenerate case of a leaf network.
>
>
>Eddy
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