[Babel-users] Babel: news about IPv4 support

[Juliusz Chroboczek]

Dear all,

Since this list has been somewhat silent for the last weeks, this is
a good time to tell you about the work going on.

I've started working on an IPv4 extension to Babel.  The idea is to
keep Babel packets within IPv6, but allow it to distribute IPv4
routes, somewhat in the manner of multi-protocol BGP.

The protocol extension is undocumented.  A new packet type, type 5, is
used for IPv4 addresses, and carries both the IPv4 prefix and the IPv4
next hop; the originating router id is carried by a preceding update
message (type 3), just like for IPv6 prefix messages (type 4).

Internally, IPv4 prefixes are encoded as IPv6-mapped addresses.  Next
hop information is added to the routes.  (This is one of the three
designs that I considered, and it is by far the cleanest and the
simplest.)

The work is almost complete, but the kernel support is missing.  Very
little has been committed at this time, I hope to be able to publish
the code over the Christmas holidays.

There is some other unpublished work going on, but since I haven't
asked the people doing it for permission to announce it, I'll keep
silent for now.

                                        Juliusz