Subject: Re: [lisp] Can I get opinions?

From: Olivier Bonaventure <[email-masked]>
Date: Mon, 01 Jun 2009 11:04:02 +0200

Dino,

> Since the list has brought up packet formats, I would like to suggest
> this packet format change for draft-ietf-lisp-02.txt (about to release
> draft-ietf-lisp-01.txt):
> 
>       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>   L / |                      Locator Reach Bits                       |
>   I   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>   S \ |S|E|rsvd-flags |               Nonce                           |
>   P   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> 
> The E-bit is for the echo-nonce idea that Andrew Partan and Noel Chiappa
> came up with. We will document it relatively soon. I'm doing an
> implementation of it right now to see how it works.
> 
> What we get from the previous version:
> 
> 1) 32 loc-reach-bits rather than 31.

31 or 32 bits is the same. I'm still in favor of the versioning solution
proposed by Luigi. The locator reach bits only cover the case where
mapping changes when a RLOC becomes unreachable. The versionning
approach is more generic as it is applicable also for other changes in
the mapping.

> 2) Set aside flag bits for future use.

This is important for the evolution of the protocol.

> 3) Settling for a 24-bit nonce rather than a 32-bit nonce. But this is
> only in the data packet header and not in the nonce that is carried in
> UDP port 4342. That nonce remains at 32 bits.

We still need to document the exact usage of the 24 bits nonce in data
encapsulated packets.

Olivier
-- 
http://inl.info.ucl.ac.be , UCLouvain, Belgium