[Babel-users] Version 1.6.0

[Juliusz Chroboczek]

> 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