> If this is not the case, I think the RFC needs to specify what, exactly, > is meant by a "wildcard address". I've always thought of ::/0 as the > wildcard address; and doesn't "default route" also mean "wildcard > route"?
Wow, no. The main purpose of a routing protocol is to carry prefixes. Now prefixes do represent sets of addresses, but that's none of the routing protocol's business -- from the point of view of the protocol, they are just opaque constructs. For example, a request for 2000::/3 requests an update for 2000::/3. If a router has routers for 2000::/4 and 3000::/4 but no route for 2000::/3, it must not use the longer prefixes to satisfy a request for 2000::/3 -- from the router's point of view, there's no relation between the prefixes. AE 0 is used to mean "any" in the following circumstances: - IHU (where it represents "any" interface identifier); - non-seqno request (where it represents "any" prefix); - retraction (where it represents "any" prefix). It is not allowed in any other place -- in other places, RFC 6126 says that AE MUST NOT be 0. (There's an omission in Section 4.4.9, where it only says in what case AE MAY be 0; the implication is that it MUST NOT be 0 in other cases.) If we decide to make an incompatible revision of Babel, I might decide to remove AE 0. While it seemed like a good idea at the time, it's turned out to only be moderately useful -- the retraction case can be handled by announcing a Hell interval of 10ms (which causes the neighbour to drop after 0.16s), and the other uses are not useful. -- Juliusz
