Re: IDR WG Last Call

[Jeffrey Haas <[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. :-)

> 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    one of the following fields: WITHDRAWN ROUTES field, Network Reachability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more than one of the following fields: WITHDRAWN ROUTES, Network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WITHDRAWN ROUTE, MP_UNREACH_NLRI, MP_REACH_NLRI, Network Layer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.

> -- Enke

-- 
Jeff Haas 
NextHop Technologies