Constrained Route Distribution for Border Gateway Protocol/MultiProtocol Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual Private Networks (VPNs)
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From: The IESG <email@example.com> To: IETF-Announce <firstname.lastname@example.org> Cc: Internet Architecture Board <email@example.com>, RFC Editor <firstname.lastname@example.org>, l3vpn mailing list <email@example.com>, l3vpn chair <firstname.lastname@example.org> Subject: Protocol Action: 'Constrained VPN Route Distribution' to Proposed Standard The IESG has approved the following document: - 'Constrained VPN Route Distribution ' <draft-ietf-l3vpn-rt-constrain-03.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 Ross Callon. A URL of this Internet-Draft is: http://www.ietf.org/internet-drafts/draft-ietf-l3vpn-rt-constrain-03.txt
Technical Summary This document addresses scaling issues for VPN routing information maintained atroute reflectors. It extends the RFC2547bis approach using â€œCooperative Route Filteringâ€? 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  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 . 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.