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Network Working Group                                       J. De ClercqRequest for Comments: 4659                                       AlcatelCategory: Standards Track                                        D. Ooms                                                              OneSparrow                                                               M. Carugi                                                         Nortel Networks                                                          F. Le Faucheur                                                           Cisco Systems                                                          September 2006BGP-MPLS IP Virtual Private Network (VPN) Extension for IPv6 VPNStatus of This Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2006).Abstract   This document describes a method by which a Service Provider may use   its packet-switched backbone to provide Virtual Private Network (VPN)   services for its IPv6 customers.  This method reuses, and extends   where necessary, the "BGP/MPLS IP VPN" method for support of IPv6.   In BGP/MPLS IP VPN, "Multiprotocol BGP" is used for distributing IPv4   VPN routes over the service provider backbone, and MPLS is used to   forward IPv4 VPN packets over the backbone.  This document defines an   IPv6 VPN address family and describes the corresponding IPv6 VPN   route distribution in "Multiprotocol BGP".   This document defines support of the IPv6 VPN service over both an   IPv4 and an IPv6 backbone, and for using various tunneling techniques   over the core, including MPLS, IP-in-IP, Generic Routing   Encapsulation (GRE) and IPsec protected tunnels.  The inter-working   between an IPv4 site and an IPv6 site is outside the scope of this   document.De Clercq, et al.           Standards Track                     [Page 1]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 2006Table of Contents1. Introduction ....................................................22. The VPN-IPv6 Address Family .....................................43. VPN-IPv6 Route Distribution .....................................53.1. Route Distribution Among PEs by BGP ........................53.2. VPN IPv6 NLRI Encoding .....................................63.2.1. BGP Next Hop encoding ...............................63.2.1.1. BGP Speaker Requesting IPv6 Transport ......73.2.1.2. BGP Speaker Requesting IPv4 Transport ......83.3. Route Target ...............................................83.4. BGP Capability Negotiation .................................84. Encapsulation ...................................................85. Address Types ..................................................106. Multicast ......................................................117. Carriers' Carriers .............................................118. Multi-AS Backbones .............................................119. Accessing the Internet from a VPN ..............................1310. Management VPN ................................................1411. Security Considerations .......................................1412. Quality of Service ............................................1513. Scalability ...................................................1514. IANA Considerations ...........................................1515. Acknowledgements ..............................................1516. References ....................................................1616.1. Normative References .....................................1616.2. Informative References ...................................161.  Introduction   This document describes a method by which a Service Provider may use   its packet-switched backbone to provide Virtual Private Network   services for its IPv6 customers.   This method reuses, and extends where necessary, the "BGP/MPLS IP   VPN" method [BGP/MPLS-VPN] for support of IPv6.  In particular, this   method uses the same "peer model" as [BGP/MPLS-VPN], in which the   customers' edge routers ("CE routers") send their IPv6 routes to the   Service Provider's edge routers ("PE routers").  BGP ("Border Gateway   Protocol", [BGP,BGP-MP]) is then used by the Service Provider to   exchange the routes of a particular IPv6 VPN among the PE routers   that are attached to that IPv6 VPN.  Eventually, the PE routers   distribute, to the CE routers in a particular VPN, the IPv6 routes   from other CE routers in that VPN.  As with IPv4 VPNs, a key   characteristic of this "peer model" is that the (IPv6) CE routers   within an (IPv6) VPN do not peer with each other; there is no   "overlay" visible to the (IPv6) VPN's routing algorithm.De Clercq, et al.           Standards Track                     [Page 2]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 2006   This document adopts the definitions, acronyms, and mechanisms   described in [BGP/MPLS-VPN].  Unless it is stated otherwise, the   mechanisms of [BGP/MPLS-VPN] apply and will not be re-described here.   A VPN is said to be an IPv6 VPN when each site of this VPN is IPv6   capable and is natively connected over an IPv6 interface or sub-   interface to the Service Provider (SP) backbone via a Provider Edge   device (PE).   A site may be both IPv4 capable and IPv6 capable.  The logical   interface on which packets arrive at the PE may determine the IP   version.  Alternatively, the same logical interface may be used for   both IPv4 and IPv6, in which case a per-packet lookup at the Version   field of the IP packet header determines the IP version.   This document only concerns itself with handling of IPv6   communication between IPv6 hosts located on IPv6-capable sites.   Handling of IPv4 communication between IPv4 hosts located on IPv4-   capable sites is outside the scope of this document and is covered in   [BGP/MPLS-VPN].  Communication between an IPv4 host located in an   IPv4- capable site and an IPv6 host located in an IPv6-capable site   is outside the scope of this document.   In a similar manner to how IPv4 VPN routes are distributed in   [BGP/MPLS-VPN], BGP and its extensions are used to distribute routes   from an IPv6 VPN site to all the other PE routers connected to a site   of the same IPv6 VPN.  PEs use "VPN Routing and Forwarding tables"   (VRFs) to maintain the reachability information and forwarding   information of each IPv6 VPN separately.   As is done for IPv4 VPNs [BGP/MPLS-VPN], we allow each IPv6 VPN to   have its own IPv6 address space, which means that a given address may   denote different systems in different VPNs.  This is achieved via a   new address family, the VPN-IPv6 Address Family, in a fashion similar   to that of the VPN-IPv4 address family, defined in [BGP/MPLS-VPN],   which prepends a Route Distinguisher to the IP address.   In addition to its operation over MPLS Label Switched Paths (LSPs),   the IPv4 BGP/MPLS VPN solution has been extended to allow operation   over other tunneling techniques, including GRE tunnels, IP-in-IP   tunnels [2547-GRE/IP], L2TPv3 tunnels [MPLS-in-L2TPv3], and IPsec   protected tunnels [2547-IPsec].  In a similar manner, this document   allows support of an IPv6 VPN service over MPLS LSPs, as well as over   other tunneling techniques.   This document allows support for an IPv6 VPN service over an IPv4   backbone, as well as over an IPv6 backbone.  The IPv6 VPN service   supported is identical in both cases.De Clercq, et al.           Standards Track                     [Page 3]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 2006   The IPv6 VPN solution defined in this document offers the following   benefits:      o From both the Service Provider perspective and the customer        perspective, the VPN service that can be supported for IPv6        sites is identical to the one that can be supported for IPv4        sites.      o From the Service Provider perspective, operations of the IPv6        VPN service require the exact same skills, procedures, and        mechanisms as those for the IPv4 VPN service.      o Where both IPv4 VPNs and IPv6 VPN services are supported over an        IPv4 core, the same single set of MP-BGP peering relationships        and the same single PE-PE tunnel mesh MAY be used for both.      o The IPv6 VPN service is independent of whether the core runs        IPv4 or IPv6.  This is so that the IPv6 VPN service supported        before and after a migration of the core from IPv4 to IPv6 is        undistinguishable to the VPN customer.   Note that supporting IPv4 VPN services over an IPv6 core is not   covered by this document.2.  The VPN-IPv6 Address Family   The BGP Multiprotocol Extensions [BGP-MP] allow BGP to carry routes   from multiple "address families".  We introduce the notion of the   "VPN-IPv6 address family", which is similar to the VPN-IPv4 address   family introduced in [BGP/MPLS-VPN].   A VPN-IPv6 address is a 24-octet quantity, beginning with an 8-octet   "Route Distinguisher" (RD) and ending with a 16-octet IPv6 address.   The purpose of the RD is solely to allow one to create distinct   routes to a common IPv6 address prefix, which is similar to the   purpose of the RD defined in [BGP/MPLS-VPN].  In the same way as it   is possible per [BGP/MPLS-VPN], the RD can be used to create multiple   different routes to the very same system.  This can be achieved by   creating two different VPN-IPv6 routes that have the same IPv6 part   but different RDs.  This allows the provider's BGP to install   multiple different routes to the same system and allows policy to be   used to decide which packets use which route.De Clercq, et al.           Standards Track                     [Page 4]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 2006   Also, if two VPNs were to use the same IPv6 address prefix   (effectively denoting different physical systems), the PEs would   translate these into unique VPN-IPv6 address prefixes using different   RDs.  This ensures that if the same address is ever used in two   different VPNs, it is possible to install two completely different   routes to that address, one for each VPN.   Since VPN-IPv6 addresses and IPv6 addresses belong to different   address families, BGP never treats them as comparable addresses.   A VRF may have multiple equal-cost VPN-IPv6 routes for a single IPv6   address prefix.  When a packet's destination address is matched in a   VRF against a VPN-IPv6 route, only the IPv6 part is actually matched.   The Route Distinguisher format and encoding is as specified in   [BGP/MPLS-VPN].   When a site is IPv4 capable and IPv6 capable, the same RD MAY be used   for the advertisement of IPv6 addresses and IPv4 addresses.   Alternatively, a different RD MAY be used for the advertisement of   the IPv4 addresses and of the IPv6 addresses.  Note, however, that in   the scope of this specification, IPv4 addresses and IPv6 addresses   will always be handled in separate contexts, and that no IPv4-IPv6   interworking issues and techniques will be discussed.3.  VPN-IPv6 Route Distribution3.1.  Route Distribution Among PEs by BGP   As described in [BGP/MPLS-VPN], if two sites of a VPN attach to PEs   that are in the same Autonomous System, the PEs can distribute VPN   routes to each other by means of an (IPv4) internal Border Gateway   Protocol (iBGP) connection between them.  Alternatively, each PE can   have iBGP connections to route reflectors.  Similarly, for IPv6 VPN   route distribution, PEs can use iBGP connections between them or use   iBGP connections to route reflectors.  For IPv6 VPN, the iBGP   connections MAY be over IPv4 or over IPv6.   The PE routers exchange, via MP-BGP [BGP-MP], reachability   information for the IPv6 prefixes in the IPv6 VPNs and thereby   announce themselves as the BGP Next Hop.   The rules for encoding the reachability information and the BGP Next   Hop address are specified in the following sections.De Clercq, et al.           Standards Track                     [Page 5]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 20063.2.  VPN IPv6 NLRI Encoding   When distributing IPv6 VPN routes, the advertising PE router MUST   assign and distribute MPLS labels with the IPv6 VPN routes.   Essentially, PE routers do not distribute IPv6 VPN routes, but   Labeled IPv6 VPN routes [MPLS-BGP].  When the advertising PE then   receives a packet that has this particular advertised label, the PE   will pop this label from the MPLS stack and process the packet   appropriately (i.e., forward it directly according to the label or   perform a lookup in the corresponding IPv6-VPN context).   The BGP Multiprotocol Extensions [BGP-MP] are used to advertise the   IPv6 VPN routes in the MP_REACH Network Layer Reachability   Information (NLRI).  The Address Family Identifier (AFI) and   Subsequent Address Family Identifier (SAFI) fields MUST be set as   follows:      - AFI: 2; for IPv6      - SAFI: 128; for MPLS labeled VPN-IPv6   The NLRI field itself is encoded as specified in [MPLS-BGP].  In the   context of this extension, the prefix belongs to the VPN-IPv6 Address   Family and thus consists of an 8-octet Route Distinguisher followed   by an IPv6 prefix as specified inSection 2, above.3.2.1.  BGP Next Hop encoding   The encoding of the BGP Next Hop depends on whether the policy of the   BGP speaker is to request that IPv6 VPN traffic be transported to   that BGP Next Hop using IPv6 tunneling ("BGP speaker requesting IPv6   transport") or using IPv4 tunneling ("BGP speaker requesting IPv4   transport").   Definition of this policy (to request transport over IPv4 tunneling   or IPv6 tunneling) is the responsibility of the network operator and   is beyond the scope of this document.  Note that it is possible for   that policy to request transport over IPv4 (resp. IPv6) tunneling   while the BGP speakers exchange IPv6 VPN reachability information   over IPv6 (resp. IPv4).  However, in that case, a number of   operational implications are worth considering.  In particular, an   undetected fault affecting the IPv4 (resp. IPv6) tunneling data path   and not affecting the IPv6 (resp. IPv4) data path could remain   undetected by BGP, which in turn may result in black-holing of   traffic.   Control of this policy is beyond the scope of this document and may   be based on user configuration.De Clercq, et al.           Standards Track                     [Page 6]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 20063.2.1.1.  BGP Speaker Requesting IPv6 Transport   When the IPv6 VPN traffic is to be transported to the BGP speaker   using IPv6 tunneling (e.g., IPv6 MPLS LSPs, IPsec-protected IPv6   tunnels), the BGP speaker SHALL advertise a Next Hop Network Address   field containing a VPN-IPv6 address      - whose 8-octet RD is set to zero, and      - whose 16-octet IPv6 address is set to the global IPv6 address of        the advertising BGP speaker.   This is potentially followed by another VPN-IPv6 address      - whose 8-octet RD is set to zero, and      - whose 16-octet IPv6 address is set to the link-local IPv6        address of the advertising BGP speaker.   The value of the Length of the Next Hop Network Address field in the   MP_REACH_NLRI attribute shall be set to 24 when only a global address   is present, and to 48 if a link-local address is also included in the   Next Hop field.   If the BGP speakers peer using only their link-local IPv6 address   (for example, in the case where an IPv6 CE peers with an IPv6 PE,   where the CE does not have any IPv6 global address, and where eBGP   peering is achieved over the link-local addresses), the "unspecified   address" ([V6ADDR]) is used by the advertising BGP speaker to   indicate the absence of the global IPv6 address in the Next Hop   Network Address field.   The link-local address shall be included in the Next Hop field if and   only if the advertising BGP speaker shares a common subnet with the   peer the route is being advertised to [BGP-IPv6].   In all other cases, a BGP speaker shall advertise to its peer in the   Next Hop Network Address field only the global IPv6 address of the   next hop.   As a consequence, a BGP speaker that advertises a route to an   internal peer may modify the Network Address of Next Hop field by   removing the link-local IPv6 address of the next hop.   An example scenario where both the global IPv6 address and the link-   local IPv6 address shall be included in the BGP Next Hop address   field is that where the IPv6 VPN service is supported over a multi-   Autonomous System (AS) backbone with redistribution of labeled VPN-De Clercq, et al.           Standards Track                     [Page 7]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 2006   IPv6 routes between Autonomous System Border Routers (ASBR) of   different ASes sharing a common IPv6 subnet: in that case, both the   global IPv6 address and the link-local IPv6 address shall be   advertised by the ASBRs.3.2.1.2.  BGP Speaker Requesting IPv4 Transport   When the IPv6 VPN traffic is to be transported to the BGP speaker   using IPv4 tunneling (e.g., IPv4 MPLS LSPs, IPsec-protected IPv4   tunnels), the BGP speaker SHALL advertise to its peer a Next Hop   Network Address field containing a VPN-IPv6 address:      - whose 8-octet RD is set to zero, and      - whose 16-octet IPv6 address is encoded as an IPv4-mapped IPv6        address [V6ADDR] containing the IPv4 address of the advertising        BGP speaker.  This IPv4 address must be routable by the other        BGP Speaker.3.3.  Route Target   The use of route target is specified in [BGP/MPLS-VPN] and applies to   IPv6 VPNs.  Encoding of the extended community attribute is defined   in [BGP-EXTCOM].3.4.  BGP Capability Negotiation   In order for two PEs to exchange labeled IPv6 VPN NLRIs, they MUST   use BGP Capabilities Negotiation to ensure that they both are capable   of properly processing such NLRIs.  This is done as specified in   [BGP-MP] and [BGP-CAP], by using capability code 1 (multiprotocol   BGP), with AFI and SAFI values as specified above, inSection 3.2.4.  Encapsulation   The ingress PE Router MUST tunnel IPv6 VPN data over the backbone   towards the Egress PE router identified as the BGP Next Hop for the   corresponding destination IPv6 VPN prefix.De Clercq, et al.           Standards Track                     [Page 8]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 2006   When the 16-octet IPv6 address contained in the BGP Next Hop field is   encoded as an IPv4-mapped IPv6 address (seeSection 3.2.1.2), the   ingress PE MUST use IPv4 tunneling unless explicitly configured to do   otherwise.  The ingress PE MAY optionally allow, through explicit   configuration, the use of IPv6 tunneling when the 16-octet IPv6   address contained in the BGP Next Hop field is encoded as an IPv4-   mapped IPv6 address.  This would allow support of particular   deployment environments where IPv6 tunneling is desired but where   IPv4-mapped IPv6 addresses happen to be used for IPv6 reachability of   the PEs instead of Global IPv6 addresses.   When the 16-octet IPv6 address contained in the BGP Next Hop field is   not encoded as an IPv4-mapped address (seeSection 3.2.1.1), the   ingress PE MUST use IPv6 tunneling.   When a PE receives a packet from an attached CE, it looks up the   packet's IPv6 destination address in the VRF corresponding to that   CE.  This enables it to find a VPN-IPv6 route.  The VPN-IPv6 route   will have an associated MPLS label and an associated BGP Next Hop.   First, this MPLS label is pushed on the packet as the bottom label.   Then, this labeled packet is encapsulated into the tunnel for   transport to the egress PE identified by the BGP Next Hop.  Details   of this encapsulation depend on the actual tunneling technique, as   follows:   As with MPLS/BGP for IPv4 VPNs [2547-GRE/IP], when tunneling is done   using IPv4 tunnels or IPv6 tunnels (resp. IPv4 GRE tunnels or IPv6   GRE tunnels), encapsulation of the labeled IPv6 VPN packet results in   an MPLS-in-IP (resp. MPLS-in-GRE) encapsulated packet as specified in   [MPLS-in-IP/GRE].  When tunneling is done using L2TPv3, encapsulation   of the labeled IPv6 VPN packet results in an MPLS-in-L2TPv3-   encapsulated packet, as specified in [MPLS-in-L2TPv3].   As with MPLS/BGP for IPv4 VPNs, when tunneling is done using an IPsec   secured tunnel [2547-IPsec], encapsulation of the labeled IPv6 VPN   packet results in an MPLS-in-IP- or MPLS-in-GRE-encapsulated packet   [MPLS-in-IP/GRE].  The IPsec Transport Mode is used to secure this   IPv4 or GRE tunnel from ingress PE to egress PE.   When tunneling is done using IPv4 tunnels (whether IPsec secured or   not), the Ingress PE Router MUST use the IPv4 address that is encoded   in the IPv4-mapped IPv6 address field of the BGP next hop field as   the destination address of the prepended IPv4 tunneling header.  It   uses one of its IPv4 addresses as the source address of the prepended   IPv4 tunneling header.De Clercq, et al.           Standards Track                     [Page 9]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 2006   When tunneling is done using IPv6 tunnels (whether IPsec secured or   not), the Ingress PE Router MUST use the IPv6 address that is   contained in the IPv6 address field of the BGP next hop field as the   destination address of the prepended IPv6 tunneling header.  It uses   one of its IPv6 addresses as the source address of the prepended IPv6   tunneling header.   When tunneling is done using MPLS LSPs, the LSPs can be established   using any label distribution technique (LDP [LDP], RSVP-TE [RSVP-TE],   etc.).   When tunneling is done using MPLS LSPs, the ingress PE Router MUST   directly push the LSP tunnel label on the label stack of the labeled   IPv6 VPN packet (i.e., without prepending any IPv4 or IPv6 header).   This pushed label corresponds to the LSP starting on the ingress PE   Router and ending on the egress PE Router.  The BGP Next Hop field is   used to identify the egress PE router and in turn the label to be   pushed on the stack.  When the IPv6 address in the BGP Next Hop field   is an IPv4-mapped IPv6 address, the embedded IPv4 address will   determine the tunnel label to push on the label stack.  In any other   case, the IPv6 address in the BGP Next Hop field will determine the   tunnel label to push on the label stack.   To ensure interoperability among systems that implement this VPN   architecture, all such systems MUST support tunneling using MPLS LSPs   established by LDP [LDP].5.  Address Types   Since Link-local unicast addresses are defined for use on a single   link only, those may be used on the PE-CE link, but they are not   supported for reachability across IPv6 VPN Sites and are never   advertised via MultiProtocol-Border Gateway Protocol (MP-BGP) to   remote PEs.   Global unicast addresses are defined as uniquely identifying   interfaces anywhere in the IPv6 Internet.  Global addresses are   expected to be commonly used within and across IPv6 VPN Sites.  They   are obviously supported by this IPv6 VPN solution for reachability   across IPv6 VPN Sites and advertised via MP-BGP to remote PEs and are   processed without any specific considerations to their global scope.De Clercq, et al.           Standards Track                    [Page 10]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 2006   Quoting from [UNIQUE-LOCAL]: "This document defines an IPv6 unicast   address format that is globally unique and is intended for local   communications [IPv6].  These addresses are called Unique Local IPv6   Unicast Addresses and are abbreviated in this document as Local IPv6   addresses.  They are not expected to be routable on the global   Internet.  They are routable inside of a more limited area such as a   site.  They may also be routed between a limited set of sites."   [UNIQUE-LOCAL] also says in itsSection 4.7: "Local IPv6 addresses   can be used for inter-site Virtual Private Networks (VPN) if   appropriate routes are set up.  Because the addresses are unique   these VPNs will work reliably and without the need for translation.   They have the additional property that they will continue to work if   the individual sites are renumbered or merged."   In accordance with this, Unique Local IPv6 Unicast Addresses are   supported by the IPv6 VPN solution specified in this document for   reachability across IPv6 VPN Sites.  Hence, reachability to such   Unique Local IPv6 Addresses may be advertised via MP-BGP to remote   PEs and processed by PEs in the same way as Global Unicast addresses.   Recommendations and considerations for which of these supported   address types should be used in given IPv6 VPN environments are   beyond the scope of this document.6.  Multicast   Multicast operations are outside the scope of this document.7.  Carriers' Carriers   Sometimes, an IPv6 VPN may actually be the network of an IPv6 ISP,   with its own peering and routing policies.  Sometimes, an IPv6 VPN   may be the network of an SP that is offering VPN services in turn to   its own customers.  IPv6 VPNs like these can also obtain backbone   service from another SP, the "Carrier's Carrier", using the Carriers'   Carrier method described inSection 9 of [BGP/MPLS-VPN] but applied   to IPv6 traffic.  All the considerations discussed in [BGP/MPLS-VPN]   for IPv4 VPN Carriers' Carrier apply for IPv6 VPN, with the exception   that the use of MPLS (including label distribution) between the PE   and the CE pertains to IPv6 routes instead of IPv4 routes.8.  Multi-AS Backbones   The same procedures described inSection 10 of [BGP/MPLS-VPN] can be   used (and have the same scalability properties) to address the   situation where two sites of an IPv6 VPN are connected to different   Autonomous Systems.  However, some additional points should be notedDe Clercq, et al.           Standards Track                    [Page 11]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 2006   when applying these procedures for IPv6 VPNs; these are further   described in the remainder of this section.   Approach (a): VRF-to-VRF connections at the AS (Autonomous System)   border routers.   This approach is the equivalent for IPv6 VPNs to procedure (a) inSection 10 of [BGP/MPLS-VPN].  In the case of IPv6 VPNs, IPv6 needs   to be activated on the inter-ASBR VRF-to-VRF (sub)interfaces.  In   this approach, the ASBRs exchange IPv6 routes (as opposed to VPN-IPv6   routes) and may peer over IPv6 or over IPv4.  The exchange of IPv6   routes MUST be carried out as per [BGP-IPv6].  This method does not   use inter-AS LSPs.   Finally, note that with this procedure, since every AS independently   implements the intra-AS procedures for IPv6 VPNs described in this   document, the participating ASes may all internally use IPv4   tunneling, or IPv6 tunneling; or alternatively, some participating   ASes may internally use IPv4 tunneling while others use IPv6   tunneling.   Approach (b): EBGP redistribution of labeled VPN-IPv6 routes from AS   to neighboring AS.   This approach is the equivalent for IPv6 VPNs to procedure (b) inSection 10 of [BGP/MPLS-VPN].  With this approach, the ASBRs use EBGP   to redistribute labeled VPN-IPv4 routes to ASBRs in other ASes.   In this approach, IPv6 may or may not be activated on the inter-ASBR   links since the ASBRs exchanging VPN-IPv6 routes may peer over IPv4   or IPv6 (in which case, IPv6 obviously needs to be activated on the   inter-ASBR link).  The exchange of labeled VPN-IPv6 routes MUST be   carried out as per [BGP-IPv6] and [MPLS-BGP].  When the VPN-IPv6   traffic is to be transported using IPv6 tunneling, the BGP Next Hop   Field SHALL contain an IPv6 address.  When the VPN-IPv6 traffic is to   be transported using IPv4 tunneling, the BGP Next Hop Field SHALL   contain an IPv4 address encoded as an IPv4-mapped IPv6 address.   This approach requires that there be inter-AS LSPs.  As such, the   corresponding (security) considerations described for procedure (b)   inSection 10 of [BGP/MPLS-VPN] apply equally to this approach for   IPv6.De Clercq, et al.           Standards Track                    [Page 12]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 2006   Finally, note that with this procedure, as with procedure (a), since   every AS independently implements the intra-AS procedures for IPv6   VPNs described in this document, the participating ASes may all   internally use IPv4 tunneling or IPv6 tunneling; alternatively, some   participating ASes may internally use IPv4 tunneling while others use   IPv6 tunneling.   Approach (c): Multihop EBGP redistribution of labeled VPN-IPv6 routes   between source and destination ASes, with EBGP redistribution of   labeled IPv4 or IPv6 routes from AS to neighboring AS.   This approach is equivalent for exchange of VPN-IPv6 routes to   procedure (c) inSection 10 of [BGP/MPLS-VPN] for exchange of VPN-   IPv4 routes.   This approach requires that the participating ASes either all use   IPv4 tunneling or all use IPv6 tunneling.   In this approach, VPN-IPv6 routes are neither maintained nor   distributed by the ASBR routers.  The ASBR routers need not be dual   stack.  An ASBR needs to maintain labeled IPv4 (or IPv6) routes to   the PE routers within its AS.  It uses EBGP to distribute these   routes to other ASes.  ASBRs in any transit ASes will also have to   use EBGP to pass along the labeled IPv4 (or IPv6) routes.  This   results in the creation of an IPv4 (or IPv6) label switch path from   ingress PE router to egress PE router.  Now, PE routers in different   ASes can establish multi-hop EBGP connections to each other over IPv4   or IPv6 and can exchange labeled VPN-IPv6 routes over those EBGP   connections.  Note that the BGP Next Hop field of these distributed   VPN-IPv6 routes will contain an IPv6 address when IPv6 tunneling is   used or an IPv4-mapped IPv6 address when IPv4 tunneling is used.   The considerations described for procedure (c) inSection 10 of   [BGP/MPLS-VPN] with respect to possible use of route-reflectors, with   respect to possible use of a third label, and with respect to LSPs   spanning multiple ASes apply equally to this IPv6 VPN approach.9.  Accessing the Internet from a VPN   The methods proposed by [BGP/MPLS-VPN] to access the global IPv4   Internet from an IPv4 VPN can be used in the context of IPv6 VPNs and   the global IPv6 Internet.  Note, however, that if the IPv6 packets   from IPv6 VPN sites and destined for the global IPv6 Internet need to   traverse the SP backbone, and that if this is an IPv4 only backbone,   these packets must be tunneled through that IPv4 backbone.   Clearly, as is the case outside the VPN context, access to the IPv6   Internet from an IPv6 VPN requires the use of global IPv6 addresses.De Clercq, et al.           Standards Track                    [Page 13]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 2006   In particular, Unique Local IPv6 addresses cannot be used for IPv6   Internet access.10.  Management VPN   The management considerations discussed inSection 12 of   [BGP/MPLS-VPN] apply to the management of IPv6 VPNs.   Where the Service Provider manages the CE of the IPv6 VPN site, the   Service Provider may elect to use IPv4 for communication between the   management tool and the CE for such management purposes.  In that   case, regardless of whether a customer IPv4 site is actually   connected to the CE (in addition to the IPv6 site), the CE is   effectively part of an IPv4 VPN in addition to belonging to an IPv6   VPN (i.e., the CE is attached to a VRF that supports IPv4 in addition   to IPv6).  Considerations presented in [BGP/MPLS-VPN], on how to   ensure that the management tool can communicate with such managed CEs   from multiple VPNs without allowing undesired reachability across CEs   of different VPNs, are applicable to the IPv4 reachability of the VRF   to which the CE attaches.   Where the Service Provider manages the CE of the IPv6 VPN site, the   Service Provider may elect to use IPv6 for communication between the   management tool and the CE for such management purposes.   Considerations presented in [BGP/MPLS-VPN], on how to ensure that the   management tool can communicate with such managed CEs from multiple   VPNs without allowing undesired reachability across CEs of different   VPNs, are then applicable to the IPv6 reachability of the VRF to   which the CE attaches.11.  Security Considerations   The extensions defined in this document allow MP-BGP to propagate   reachability information about IPv6 VPN routes.   Security considerations for the transport of IPv6 reachability   information using BGP are discussed inRFC2545, Section 5, and are   equally applicable for the extensions described in this document.   The extensions described in this document for offering IPv6 VPNs use   the exact same approach as the approach described in [BGP/MPLS-VPN].   As such, the same security considerations apply with regards to Data   Plane security, Control Plane security, and PE and P device security   as described in [BGP/MPLS-VPN],Section 13.De Clercq, et al.           Standards Track                    [Page 14]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 200612.  Quality of Service   Since all the QoS mechanisms discussed for IPv4 VPNs inSection 14 of   [BGP/MPLS-VPN] operate in the same way for IPv4 and IPv6 (Diffserv,   Intserv, MPLS Traffic Engineering), the QoS considerations discussed   in [BGP/MPLS-VPN] are equally applicable to IPv6 VPNs (and this holds   whether IPv4 tunneling or IPv6 tunneling is used in the backbone.)13.  Scalability   Each of the scalability considerations summarized for IPv4 VPNs inSection 15 of [BGP/MPLS-VPN] is equally applicable to IPv6 VPNs.14.  IANA Considerations   This document specifies (seeSection 3.2) the use of the BGP AFI   (Address Family Identifier) value 2, along with the BGP SAFI   (Subsequent Address Family Identifier) value 128, to represent the   address family "VPN-IPv6 Labeled Addresses", which is defined in this   document.   The use of AFI value 2 for IPv6 is as currently specified in the IANA   registry "Address Family Identifier", so IANA need not take any   action with respect to it.   The use of SAFI value 128 for "MPLS-labeled VPN address" is as   currently specified in the IANA registry "Subsequence Address Family   Identifier", so IANA need not take any action with respect to it.15.  Acknowledgements   We would like to thank Gerard Gastaud and Eric Levy-Abegnoli, who   contributed to this document.   In Memoriam   The authors would like to acknowledge the valuable contribution to   this document from Tri T. Nguyen, who passed away in April 2002 after   a sudden illness.De Clercq, et al.           Standards Track                    [Page 15]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 200616.  References16.1.  Normative References   [BGP/MPLS-VPN]   Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual                    Private Networks (VPNs)",RFC 4364, February 2006.   [BGP-EXTCOM]     Sangli, S., Tappan, D., and Y. Rekhter, "BGP                    Extended Communities Attribute",RFC 4360, February                    2006.   [BGP-MP]         Bates, T., Rekhter, Y., Chandra, R., and D. Katz,                    "Multiprotocol Extensions for BGP-4",RFC 2858, June                    2000.   [IPv6]           Deering, S. and R. Hinden, "Internet Protocol,                    Version 6 (IPv6) Specification",RFC 2460, December                    1998.   [MPLS-BGP]       Rekhter, Y. and E. Rosen, "Carrying Label                    Information in BGP-4",RFC 3107, May 2001.   [BGP-CAP]        Chandra, R. and J. Scudder, "Capabilities                    Advertisement with BGP-4",RFC 3392, November 2002.   [LDP]            Andersson, L., Doolan, P., Feldman, N., Fredette,                    A., and B. Thomas, "LDP Specification",RFC 3036,                    January 2001.   [BGP-IPv6]       Marques, P. and F. Dupont, "Use of BGP-4                    Multiprotocol Extensions for IPv6 Inter-Domain                    Routing",RFC 2545, March 1999.16.2.  Informative References   [V6ADDR]         Hinden, R. and S. Deering, "IP Version 6 Addressing                    Architecture",RFC 4291, February 2006.   [UNIQUE-LOCAL]   Hinden, R. and B. Haberman, "Unique Local IPv6                    Unicast Addresses",RFC 4193, October 2005.   [2547-GRE/IP]    Rekhter and Rosen, "Use of PE-PE GRE or IP inRFC2547 VPNs", Work in Progress.   [2547-IPsec]     Rosen, De Clercq, Paridaens, T'Joens, Sargor, "Use                    of PE-PE IPsec inRFC2547 VPNs", Work in Progress,                    August 2005.De Clercq, et al.           Standards Track                    [Page 16]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 2006   [RSVP-TE]        Awduche, D., Berger, L., Gan, D., Li, T.,                    Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions                    to RSVP for LSP Tunnels",RFC 3209, December 2001.   [MPLS-in-IP/GRE] Worster, T., Rekhter, Y., and E. Rosen,                    "Encapsulating MPLS in IP or Generic Routing                    Encapsulation (GRE)",RFC 4023, March 2005.   [MPLS-in-L2TPv3] Townsley, M., et al., "Encapsulation of MPLS over                    Layer-2 Tunneling Protocol Version 3", Work in                    Progress, February 2006.   [BGP]            Rekhter, Y., Li, T., and S. Hares, "A Border Gateway                    Protocol 4 (BGP-4)",RFC 4271, January 2006.Authors' Addresses   Jeremy De Clercq   Alcatel   Copernicuslaan 50, 2018 Antwerpen, Belgium   EMail: jeremy.de_clercq@alcatel.be   Dirk Ooms   OneSparrow   Belegstraat 13, 2018 Antwerpen, Belgium   EMail: dirk@onesparrow.com   Marco Carugi   Nortel Networks S.A.   Parc d'activites de Magny-Les Jeunes Bois CHATEAUFORT   78928 YVELINES Cedex 9 - France   EMail: marco.carugi@nortel.com   Francois Le Faucheur   Cisco Systems, Inc.   Village d'Entreprise Green Side - Batiment T3   400, Avenue de Roumanille   06410 Biot-Sophia Antipolis   France   EMail: flefauch@cisco.comDe Clercq, et al.           Standards Track                    [Page 17]

RFC 4659         BGP-MPLS IP VPN Extension for IPv6 VPN   September 2006Full Copyright Statement   Copyright (C) The Internet Society (2006).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at   ietf-ipr@ietf.org.Acknowledgement   Funding for the RFC Editor function is provided by the IETF   Administrative Support Activity (IASA).De Clercq, et al.           Standards Track                    [Page 18]