Excerpts from Brian E Carpenter on Tue, Dec 02, 2008 12:02:25PM +1300: > 1. We know of no alternative to a longest-match based approach to > routing lookup for the inter-AS routing system (commonly known as > the DFZ). > > 2. To control the long-term scaling of that approach, we need to > control the long-term size of the lookup table and the long-term > rate of dynamic updates to that table. > > 3. We assume there will be continued unbounded growth in the number > of sites requiring multihoming, but today each site that requires > multihoming thereby requires its own entry in the DFZ lookup table. > In the long term, this is unsustainable. [Digression about numbers > and dates omitted.] > > 4. The known solutions to this all require some mechanism for > aggregating site prefixes into ISP prefixes. [There's space for a > digression about the related advantages of separating the transport > ID from the network address, and about the application layer's view > of all this, but that doesn't affect what I just said.] > > 5. One solution to that is a multi-prefix model (a site runs > multiple prefixes), which is of course the IPv6 design assumption. > Another solution is a map-and-encap model. A third solution is a > map-and-translate model. There are many variants of all these > models, but I don't know of a fourth one. All solutions have > advantages and disadvantages. All good but > IMHO the reason we're hearing about NAT66 is because people > still find the IPv6 multi-prefix model unfamiliar and there is > no consensus-based map-and-encap solution yet. So it's natural > to look at map-and-translate, and NAT66 is one of the solutions > in that category. My suspicion is that it's seen as easier to deploy, right now. Show me your IPv6 multiprefix deployments, now show me your NAT deployments. And NAT66 is just NAT, right? Scott _______________________________________________ Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf