Ofer Inbar wrote: > ... > I think today's implied identity of "private address space" > and "locally scoped addresses" is really muddying the > discussion. If we have a world where anyone who asks can get > a unique address block assigned to them to use for their > private network... THEN what are the remaining reasons why > people would want to use site-local addresses? First, http://www.ietf.org/internet-drafts/draft-hain-ipv6-sitelocal-00.txt is offered with the intent to grow into an answer to the last part. Second, the IPv6 SL mechanism exposed the fundamental architectural discrepancy between the traditional application world viewpoint that an address was a valid identifier, and the deployed network where addresses are topology locators and have different visibility in different regions (aka: scopes). Almost all of the complaints against SL will persist even with a non-ambiguous address space (the exception being connecting to the wrong node, which was arguably unlikely to begin with given mac based IIDs). At their core, these complaints are about bringing apps (actually every process that resolves a data structure into a topology locator) into the world of reality where they need to recognize that various members in a list of potential addresses for a node may not be equally accessible from every other node in the network. The fact that IPv6 nodes can simultaneously have addresses of mixed scopes makes the problem more acute, but it is no different than a multi-homed IPv4 node where one or more of its addresses are not visible in the same scope of the routing system, or there are different access controls placed on the set by the network manager. The system as a whole needs to be revisited in the context of making sure every node can resolve a given data structure into a topologically appropriate locator. The IPv6 WG discussion about a specific prefix is probably best dealt with there, but the broader issue about assumptions of a flat routed space vs. the reality of limited topology scopes is something the IETF as a whole needs to deal with, because it exposes many historically invalid assumptions. Tony