Re: IDR WG Last Call

[Enke Chen <[e-mail]>]

Jeff,

> Date: Mon, 14 Jan 2002 23:21:28 -0500
> From: Jeffrey Haas <[e-mail]>
> To: Enke Chen <[e-mail]>
> Cc: [e-mail]
> Subject: Re: IDR WG Last Call
> Message-ID: <[e-mail]>
> 
> On Mon, Jan 14, 2002 at 04:04:24PM -0800, Enke Chen wrote:
> > It seems that the "SAFI 3" certainly makes the issue at hand much more
> > complicated.
> 
> IMO, SAFI 3 was probably not a very good idea.  Dealing with it can
> be a real pain in the implementation. :-)

So can we clean out "SAFI 3" from MP-BGP spec.? It does not seem to add
much value, but has caused a lot of confusion and complexity. I am not
aware of any depolyment either.

> 
> > As Yakov and Sue pointed out, it is a good idea to discourage
> > having one prefix in multiple fields of an update message. How about the
> > following text:
> > 
> >    An UPDATE message should not include the same address prefix in more than
> >    one of the following fields: WITHDRAWN ROUTES field, Network Reachability
> >    Information fields, MP_REACH_NLRI field, and MP_UNREACH_NLRI field. The
> >    processing of an UPDATE message in this form is un-defined.
> 
> I think that "undefined" is overkill.  I would suggest the following instead:
> 
> An UPDATE message should not include the same address prefix in
> more than one of the following fields: WITHDRAWN ROUTES, Network
> Layer Reachability Information, MP_REACH_NLRI and MP_UNREACH_NLRI.
> An implementation that receives a packet in this form should process
> the Update as if it had processed it in the following order:
> WITHDRAWN ROUTE, MP_UNREACH_NLRI, MP_REACH_NLRI, Network Layer
> Reachability Information.
> 
> The wording could probably use some tightening.
> 
> The intended result is that reachability rules over unreachability.

If we want to define the behavior, I would like to suggest sticking to
the order in the message. That probably would reflect the sender's
intention more closely, and make the processing simpler.

-- Enke