Quoting RFC2860 [Re: I-D Action:draft-azinger-scalable-addressing-00.txt]

Tony Li tony.li at tony.li
Tue Sep 28 18:22:56 CEST 2010

> on the issue of decoupling locator and identifier,  I'm still not really sure that any L/I separation is really going to fix our problems in the long term.  In fact, we already use a form of locator / identifier separation: ASN and prefix.  We could - with some work - implement L/I separation by creating a new BGP / core router model which made routing decisions on the basis of AS identifier only, and not per-prefix.

L/I separation gives us multi-homing without global prefix injection.

We could translate the current model into the AS number space, but then the routing architecture won't scale to route 4 billion ASes.  This just pushes the scalability problem into a different number space.

The only way to resolve the scalability problem is to avoid global scope.

> But I can't help wondering that if we perform our routing decisions based solely on locator (e.g. ASN or other) and not identifier, then we commit ourselves to trashing our current traffic engineering flexibilities.  If we decide we want traffic engineering capabilities again, we need to introduce a routing protocol which also discriminates on the basis of the identifier.  And that's hardly an improvement on what we have right now.

Current traffic engineering is only done based on global distribution of more-specific prefixes.  We can either remove the 'global' aspect, choose something else to engineer on, or give up our current 'traffic engineering' capabilities.  So far, proposals (scoping of prefixes) to fix this have had a 'no thank you'.


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