Re: [Idr] Fwd: New Version Notification for draft-scudder-idr-rt-constrain-lite-00

[Robert Raszuk <raszuk at cisco.com>]

Hello John,

Let me share with you two observations:

Observation #1:

Let's notice that original RFC4684 already well defines rt-constrain 
lite in it's published text:

   "A BGP speaker MAY participate in the distribution of Route Target
   information without using the learned information for purposes of VPN
   NLRI output route filtering, although this is discouraged."

As RT-constrain lite draft does exactly the above paragraph it is at 
least redundant.

Observation #2:

The original RFC4684 says:

   "A VPN NLRI route should be advertised to a peer that participates in
   the exchange of Route Target membership information if that peer has
   advertised either the default Route Target membership NLRI or a Route
   Target membership NLRI containing any of the targets contained in the
   extended communities attribute of the VPN route in question."

RT-C lite says:

   "Specifically, the PE need only implement the ability to send Route
   Target Membership NLRI; it need not have the ability to receive,
   store and filter upon such information."

That directly violates RFC4684 as quoted above. After exchanged the 4684 
capabilities the PE should wait for the default rt filter or atomic one 
before it starts any VPN route advertisement.

The same for the RR side ... RR may expect after negotiating RFC4684 
capability not to receive any routes from a peer until it has send 
default rt NLRI or an atomic one. That may be used for peer 
prioritization as an example.

Conclusion of the observation #2 above leads me to believe that 
reception and parsing of at least default rt-filter by RT-Constrain lite 
is required.

But I am more interested to find out what is missing today in RFC4684 in 
the light of the first observation.

Cheers,
R.


> FYI.
>
> --John
>
> Begin forwarded message:
>
> > From: IETF I-D Submission Tool <idsubmission at ietf.org>
> > Date: June 25, 2009 2:30:20 PM GMT-04:00
> > To: John Scudder <jgs at juniper.net>
> > Cc: "uttaro at att.com" <uttaro at att.com>, "pmohapat at cisco.com" 
> > <pmohapat at cisco.com>
> > Subject: New Version Notification for 
> > draft-scudder-idr-rt-constrain-lite-00
> >
> >
> > A new version of I-D, draft-scudder-idr-rt-constrain-lite-00.txt has 
> > been successfuly submitted by John Scudder and posted to the IETF 
> > repository.
> >
> > Filename:     draft-scudder-idr-rt-constrain-lite
> > Revision:     00
> > Title:         RT-Constrain Lite for Provider Edge Routers
> > Creation_date:     2009-06-25
> > WG ID:         Independent Submission
> > Number_of_pages: 5
> >
> > Abstract:
> > RFC 4684, "Constrained Route Distribution for Border Gateway
> > Protocol/MultiProtocol Label Switching (BGP/MPLS) Internet Protocol
> > (IP) Virtual Private Networks (VPNs)" provides a powerful and general
> > means for BGP speakers to exchange and propagate Route Target
> > reachability information which is used for cooperative route
> > filtering.  However, the complexity of implementing the entire
> > specification may have impeded its widespread deployment.  This
> > document specifies the subset of functionality which is required for
> > a provider edge router ("PE") to originate Route Target NLRI.  Such
> > PEs need not implement any filtering functionality.
> >
> >
> >
> > The IETF Secretariat.
>
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