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a different proposal for ipv6 in bgp

At 04:53 PM 1/6/97 -0800, Dave Katz wrote:
>It remains unclear to me why it is desirable to couple multiprotocol
>support and the AS number space increase.  The two functions are
>completely orthogonal and as far as I can tell there is no benefit for
>*mandating* that the two changes be made at the same time.
>Clearly the multiprotocol stuff could be deployed and become useful
>more quickly than the AS number extension, due to the fact that it
>can be done in a backward compatible, pairwise fashion.
I don't believe that this assessment is accurate.  The BGP5 proposal
is as backward compatible (if not more) with BGP4 as the proposed multiprotocol 
extension to BGP4.  I.e., v4 routing information exchanged between BGP5
peers can be fully re-advertised via BGP4 and vise versa.  As you might notice
we even didn't require to immediately extend AS number space for v4
to keep the v4 related changes to a bare minimum.  To support v6, bgp data
structures need to change any way and v6 has no backward compatibility
issue at this point. Thus it only makes sense to get a larger AS space for
v6 now
to avoid another transition later.

>The deployment considerations for multiprotocol support are far less
>onerous than the AS number stuff.
Care elaborate (in light of the BGP5 proposal)? 
>Operators who are concerned about deploying new software twice could
>always wait until BGP5 deployment and turn on both features at the
>same time.  However, I think that the deployment timing for each
>feature is difficult to predict in advance (will IPv6 take off?  Are
>we really under pressure for AS numbers?) so keeping them decoupled
>keeps things more flexible.
>So, what is it that makes it preferable to entwine the changes?
Once again, the way the BGP5 proposal written I don't believe this larger AS
space for v6 introduces more implementation and/or deployment burdens than
yours multiprotocol
stuff does...  unless I miss some vital points. My point is that there is no
additional penalty for the introducing a larger AS number space for v6 now
and,  to boot,  BGP5
provides an optional mechanism to gradually introduce a larger AS number
space for v4
too.  So why not?


>   X-Phone: +1 703 812 3704
>   Date: Mon, 30 Dec 1996 14:05:41 EST
>   From: "John W. Stewart III" <[email protected]>
>   Sender: [email protected]
>   Precedence: bulk
>   attached below is a proposal for a multi-protocol (including
>   ipv6) bgp
>   while there are a number of differences between this one and
>   the bates/chandra/katz/rekhter one, one of the main motivating
>   factors for this one is to support longer-than-two-byte ASs.
>   it is our view that making bgp multi-protocol significantly
>   extends its life.  so, although in a narrow sense the length
>   of the AS is orthogonal to being multi-protocol, the logistics
>   of transitions and the need to adequeately engineer the
>   protocol up-front, to us, suggests the need for longer-than-
>   two-byte ASs
>   /jws