On 12/01/2011 22:07, Ted Hardie wrote: > No, I think that premise is mis-stated. Premise 1: There exists > equipment that can't handle identical addresses on the interior and > exterior interface. Premise 2: it may be deployed now or in the future > for customers using any part of the RFC 1918 allocation *because those > using the RFC 1918 allocations had no prior warning that this might > create a collision*. Conclusion: You cannot avoid identical addresses > on the interior and exterior interface by using any part of the RFC 1918 > allocation. But doesn't that same line of reasoning apply to any new allocation that's made for this purpose? You can fix the problem for today, but you can't fix it for the future because you can't prohibit customers from using the new allocation on the inside of their network. Therefore, making the allocation is a pointless waste of resources that can be better utilized elsewhere. Step 1: Determine the most popular inside prefixes for CPEs Step 2: Use the least popular RFC 1918 prefix for the CGN network Step 3: If your customer has somehow chosen the same prefix, tell them they can't do that. And yes, I realize that Step 3 is going to be incredibly unpopular for the ISPs, but they created the problem, so they should have to live with the results. Doug -- "We could put the whole Internet into a book." "Too practical." Breadth of IT experience, and depth of knowledge in the DNS. Yours for the right price. :) http://SupersetSolutions.com/ _______________________________________________ Ietf mailing list Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf