[Babel-users] draft-ietf-babel-rfc6126bis-02

[Juliusz Chroboczek]

Dear all,

I've just published a new version of the Babel protocol specification:

  https://tools.ietf.org/html/draft-ietf-babel-rfc6126bis-02

This version containts some fairly major changes, the most notable being
the addition of mandatory bits to the extension subprotocol.  There have
also been some fairly technical changes to the procedures for sending of
requests, which should not invalidate any existing implementations.

The mandatory bit makes the protocol more easily extensible by making it
possible to explicitly encode the fact that an extension is not backwards
compatible.  It has greatly simplified the packet format of Matthieu
Boutier's source-specific extension [1], and is used by Gwendoline
Chouasne's TOS-specific extension [2].

[1] https://github.com/boutier/babeld/tree/dev
[2] https://github.com/Gwendocg/babeldToS

Both babeld and sbabeld have support for mandatory bits in their
"mandatory" branches.  I'll wait a few days to see if there are any flaws
in this proposal, then merge into trunk.  Please consider implementing
mandatory bits if you have an implementation of Babel.

The backwards compatibility of this change is reasonably strong, but
somewhat weaker than what we at Babel Towers have been doing previously.
More exactly:

  - new implementations of Babel will interoperate with old
    implementations as long as the former don't use any extensions that
    the latter don't understand;
  - new implementations of Babel that use the new extensions (new-style
    source-specific routing, TOS-specific routing) will not interoperate
    with old implementations, and might even create routing loops.

We will refrain from deploying the new extensions until all implementations
have acquired support for mandatory bits.

Please read.  Please think it over.  Please comment.

-- Juliusz