Subject: Protocol Action: 'Constrained VPN Route Distribution' to Proposed Standard

From: The IESG <[email-masked]>
Date: Mon, 17 Apr 2006 13:45:15 -0400

The IESG has approved the following document:

- 'Constrained VPN Route Distribution '
   <draft-ietf-l3vpn-rt-constrain-02.txt> as a Proposed Standard

This document is the product of the Layer 3 Virtual Private Networks Working 
Group. 

The IESG contact persons are Mark Townsley and Margaret Wasserman.

A URL of this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-l3vpn-rt-constrain-02.txt

Technical Summary
 
This document addresses scaling issues for VPN routing information maintained
atroute reflectors. It extends the RFC2547bis approach using “Cooperative
Route
Filtering” between router reflectors for support multiple autonomous systems
and asymmetric VPN topologies such as hub-and-spoke. The solution uses MP-BGP
UPDATE messages to propagate Route Target membership information. Received
RouteTarget membership information can then be used to restrict advertisement
ofVPN
NLRI to peers that have advertised their respective Route Targets, effectively
building a route distribution graph. In this model, VPN NLRI routing
informationflows in the inverse direction of Route Target membership
information.

This mechanism is applicable to any BGP NLRI that controls the distribution of
routing information based on Route Targets, such as BGP L2VPNs [L2VPN] and VPLS
[VPLS].

Working Group Summary

There were several detailed issued which were raised when the document was
submitted to the WG. Constructive comments led to modifications to the document
which addressed the concerns that were raised.
 
Protocol Quality
   
   In addition to L3VPN review, this document was reviewed by the IDR WG 
   where it received review comments from Rick Wilder, Chandrashekhar Appanna,
   and Jeff Haas. Multiple implementations exist.

Note to RFC Editor

The upper left hand corner of the title page should include: "Updates:
draft-ietf-l3vpn-rfc2547bis-03"

In section 2, please replace "proposal" with "document" in the following text:

  > This proposal extends the RFC2547bis [3] ORF work to include support
  > for multiple autonomous systems, and asymmetric VPN topologies such
  > as hub-and-spoke. 

Also in section 2, please remove the [?] reference, new text is:

>  This mechanism is applicable to any BGP NLRI that controls the
>  distribution of routing information based on Route Targets such
>  as VPLS [9].

Please change the title to:

"Constrained Route Distribution for BGP/MPLS IP VPNs"

Please replace the Abstract with:
 
This document defines Multi-Protocol BGP (MP-BGP) procedures that allow
BGP speakers to exchange Route Target reachability information.  This
information can be used to build a route distribution graph in order to
limit the propagation of Virtual Private Network (VPN) Network Layer
Reachability Information (NLRI) between different autonomous systems or
distinct clusters of the same autonomous system. This document updates
draft-ietf-l3vpn-rfc2547bis-03. [RFC Editor: please replace this Internet-Draft
reference with an RFC number when it is assigned.]"

Please add a Terminology Section with the following acronyms expanded and
defined and the informational reference to RFC4026:

This document uses a number of terms and acronyms specific to
Provider-Provisioned VPNs, including those specific to L2VPNs, L3VPNs and BGP.
Definitions for many of these terms may be found in the VPN terminology
document [RFC4026]. This section also includes some brief acronym expansion and
terminology to aid the reader.

AFI - Address Family Identifier (a BGP address type)

BGP - Border Gateway Protocol

BGP/MPLS VPN - A Layer 3 VPN implementation based upon BGP and MPLS. 

CE - Customer Edge (router)

iBGP - Internal BGP; i.e., a BGP peering session that connects two
routers within an autonomous system

L2VPN - Layer 2 Virtual Private Network

L3VPN - Layer 3 Virtual Private Network

MP-BGP - Multi-Protocol Border Gateway Protocol

MPLS - Multi-Protocol Label Switching

NLRI - Network Layer Reachability Information

ORF - Outbound Route Filtering

PE - Provider Edge (router)

RT - Route Target (i.e., a BGP extended community that conditions
network layer reachability information with VPN membership)

SAFI - Subsequence Address Family Identifier (a BGP address sub-type)

VPLS - Virtual Private LAN Service

VPN - Virtual Private Network

Editor: Please include an informational reference to RFC 4026 in the referencessection.

Please change the following text in section 6 From:

   A BGP speaker should generate the minimum set of BGP VPN route
   updates necessary to transition between the previous and current
   state of the route distribution graph that is derived from Route
   Target membership information. 

To:

   A BGP speaker should generate the minimum set of BGP VPN route
   updates (advertisements and/or withdrawls) necessary to transition 
   between the previous and current state of the route distribution 
   graph that is derived from Route Target membership information.