--On October 20, 2005 2:31:39 PM -0400 "Howard, W. Lee" <Lee.Howard@stanleyassociates.com> wrote:

...

Imagine instead, a world where Routing Location Identifiers are not coupled to End System Identifiers and Interdomain routing (AS-AS routing) occurred based on Routing Location Identifier, and only Intra-AS routing depended on the End System Identifier.

For example:

Host A connected to ISP X then ISP Y to ISP Z which provides service to Host B.

Today, A, X, Y, Z all need to know how to reach B.

If we separated the RLI from the ESI, then, the fact that B is reached via Z only has to be available information that can be looked up by A, and, X and Y only need to know how to get to Z. Only Z needs to know how to reach B. This allows the amount of data kept by each point along the way to be much smaller.

Interesting. So Host A needs a lookup mechanism. If I'm ISP X, then I'm providing a lookup server? You'd need to figure out how to provide locally-significant lookup results for topologically diverse hosts (A).

No.... ISP X needs to be able to look up a mapping for Host B->Z or B->{G,H,Q,Z} or such. Much like a Name->A record lookup occurs today, but, with a more authenticated/secure protocol. Further, since this is a "What ASs are proper termination points for B?" question, it's not locally significant to A (or locally significant at all).

What if X and Y (or Y and Z) connect at multiple points? Would you hot-potato or cold-potato? Can you provide a TE knob for that?

Yes... This would be router dependent, but, it is do-able. Instead of X knowing how to reach prefix Y.B and prefix Y.C and prefix Y.D, X would know all the ways to reach Y. TE would involve some mechanism for deciding which portions of traffic destined to Y use which path, and, in this case could be based on prefix or on some other method. Specifying the methods is outside of the scope of this proposal, but, examples could include: round robbin, shortest queue, least recently used, prefix hashing, flow hashing, etc.

It would be interesting to see a table showing how often various routes are looked up. I suspect that a significant portion of routes are seldom, if ever, used by most parts of the network, and therefore don't really need to be held and recalculated except on-demand. But

Exactly, and, which significant portion that is is different depending on where on the network you are.

I'm not currently equipped to do that analysis, and it would be completely different depending on where you are in [your | the] network.

Exactly. That is why I think that global knowledge doesn't and can't scale in the long run. Currently, we are approaching routing the same way we used to approach name->IP mapping. (Remember the days when the /etc/hosts file was FTPd from SRI?) DNS is a much more scalable solution for that problem. I think that routing can be done on a similar basis. Owen -- If it wasn't crypto-signed, it probably didn't come from me.