Network Working Group R. Aggarwal Internet Draft Juniper Networks Expiration Date: September 2006 C. Kodeboniya Juniper Networks Y. Rekhter Juniper Networks E. Rosen Cisco Systems, Inc. T. Morin France Telecom March 2006 BGP Encodings for Multicast in MPLS/BGP IP VPNs draft-raggarwa-l3vpn-2547bis-mcast-bgp-01.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract This document describes the BGP encodings for signaling the information elements required by Multicast in MPLS/BGP IP VPNs, as specified in [MVPN]. Table of Contents 1. Specification of requirements The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 2. Terminology In the context of this document we will refer to the MVPN auto- discovery/binding information carried in BGP as "auto-discovery routes". For a given MVPN there are three types of auto-discovery routes: + intra-AS auto-discovery route (auto-discovery route); + inter-AS auto-discovery route; + intra-AS segment leaf auto-discovery route (leaf auto-discovery route). In the context of this document we will refer to the MVPN customers multicast routing information carried in BGP as "C-multicast routes". For a given MVPN there are three types of C-Multicast routes: + shared tree join route; + source tree join route; + prune source from shared tree route. For each MVPN present on a PE, the PE maintains a Tree Information Base (MVPN-TIB). This is the same as TIB defined in [PIM-SM], except that instead of a single TIB a PE maintains multiple MVPN-TIBs, one per each MVPN. 3. Introduction This document describes the BGP encodings for exchanging the information elements required by Multicast in MPLS/BGP IP VPNs, as specified in [MVPN]. This document assumes a thorough familiarity with procedures, concepts and terms described in [MVPN]. This document defines a new NLRI, MCAST-VPN NLRI. The MCAST-VPN NLRI is used for MVPN auto-discovery, advertising MVPN - Inclusive tunnel binding, VPN customer multicast routing information exchange among PEs, S-PMSI signaling, choosing a single forwarder PE, and for anycast RP procedures required to home a C-RP on a PE. This document also specifies new BGP attribute, P-Multicast Service Interface Tunnel (PMSI Tunnel) attribute. 4. MCAST-VPN NLRI This document defines a new BGP NLRI, called the MCAST-VPN NLRI. This NLRI is carried in BGP using BGP Multiprotocol Extensions [RFC2858bis]. Following is the format of the MCAST-VPN NLRI: +-----------------------------------+ | Length (1 octet) | +-----------------------------------+ | Route Type (1 octet) | +-----------------------------------+ | Route Type specific (variable) | +-----------------------------------+ The Length field indicates the length in octets of MCAST-VPN NLRI, excluding the Length field itself. The Route Type field defines encoding of the rest of MCAST-VPN NLRI (Route Type specific MCAST-VPN NLRI). This document defines the following Route Types for auto-discovery routes: + 1 - Intra-AS auto-discovery route (or just auto-discovery route); + 2 - Inter-AS auto-discovery route; + 3 - Intra-AS segment leaf auto-discovery route (or just leaf auto-discovery route). This document defines the following Route Types for C-multicast routes: + 4 - Shared Tree Join route; + 5 - Source Tree Join route; + 6 - Prune Source from Shared Tree route. The following describes the format of the Route Type specific MCAST- VPN NLRI for various Route Types defined in this document. 4.1. Intra-AS auto-discovery route An intra-AS auto-discovery route type specific MCAST-VPN NLRI consists of the following: +-----------------------------------+ | RD (8 octets) | +-----------------------------------+ | Originating Router's IP Addr | +-----------------------------------+ | Multicast Source Length (1 octet) | +-----------------------------------+ | Multicast Source (Variable) | +-----------------------------------+ | Multicast Group Length (1 octet) | +-----------------------------------+ | Multicast Group (Variable) | +-----------------------------------+ The RD is encoded as described in [RFC4364]. If the Multicast Source field is empty (not present), then the value of the Multicast Source Length field is 0. If the Multicast Source field contains an IPv4 address, then the value of the Multicast Source Length field is 32. If the Multicast Source field contains an IPv6 address, then the value of the Multicast Source Length field is 128. The Source Address field, if present, contains the C-S address. If the Multicast Group field is empty (not present), then the value of the Multicast Group Length field is 0. If the Multicast Group field contains an IPv4 address, then the value of the Multicast Group Length field is 32. If the Multicast Group field contains an IPv6 address, then the value of the Multicast Group Length field is 128. The Group Address field, if present, contains the C-G address. 4.2. Inter-AS auto-discovery route An inter-AS auto-discovery route type specific MCAST-VPN NLRI consists of the following: +-----------------------------------+ | RD (8 octets) | +-----------------------------------+ | Multicast Source Length (1 octet) | +-----------------------------------+ | Multicast Source (Variable) | +-----------------------------------+ | Multicast Group Length (1 octet) | +-----------------------------------+ | Multicast Group (Variable) | +-----------------------------------+ The RD is encoded as described in [RFC4364]. An inter-AS auto-discovery route contains the autonomous system number (AS number) of the ASBR that originates the route. This AS number is encoded in the RD field of the MCAST-VPN NLRI of the route. If the Multicast Source field is empty (not present), then the value of the Multicast Source Length field is 0. If the Multicast Source field contains an IPv4 address, then the value of the Multicast Source Length field is 32. If the Multicast Source field contains an IPv6 address, then the value of the Multicast Source Length field is 128. The Source Address field, if present, contains the C-S address. If the Multicast Group field is empty (not present), then the value of the Multicast Group Length field is 0. If the Multicast Group field contains an IPv4 address, then the value of the Multicast Group Length field is 32. If the Multicast Group field contains an IPv6 address, then the value of the Multicast Group Length field is 128. The Group Address field, if present, contains the C-G address. 4.3. Leaf auto-discovery route A leaf auto-discovery route type specific MCAST-VPN NLRI has the same format as an intra-AS auto-discovery route type specific MCAST-VPN NLRI. 4.4. C-Multicast Route A shared tree join route, a source tree join route, and a prune source from shared tree route have the following encoding: +-----------------------------------+ | RD (8 octets) | +-----------------------------------+ | Multicast Source Length (1 octet) | +-----------------------------------+ | Multicast Source (Variable) | +-----------------------------------+ | Multicast Group Length (1 octet) | +-----------------------------------+ | Multicast Group (Variable) | +-----------------------------------+ The RD is encoded as described in [RFC4364]. If the Multicast Source field contains an IPv4 address, then the value of the Multicast Source Length field is 32. If the Multicast Source field contains an IPv6 address, then the value of the Multicast Source Length field is 128. The Source Address field contains the C-S address. If the Multicast Group field contains an IPv4 address, then the value of the Multicast Group Length field is 32. If the Multicast Group field contains an IPv6 address, then the value of the Multicast Group Length field is 128. The Group Address field contains the C-G address. 5. P-Multicast Service Interface Tunnel (PMSI Tunnel) attribute This document defines and uses a new BGP attribute, called P- Multicast Service Interface Tunnel (PMSI Tunnel) attribute. This is an optional transitive BGP attribute. The format of this attribute is defined as follows: +---------------------------------+ | Tunnel Type (2 octets) | +---------------------------------+ | MPLS Label (3 octets) | +---------------------------------+ | Tunnel Identifier (variable) | +---------------------------------+ The Tunnel Type identifies the type of the tunneling technology used to establish the PMSI tunnel. The type determines the syntax and semantics of the Tunnel Identifier field. This document defines the following Tunnel Types: + 1 - RSVP-TE P2MP LSP + 2 - LDP P2MP LSP + 3 - PIM-SSM Tree + 4 - PIM-SM Tree + 5 - PIM-Bidir Tree + 6 - Ingress Replication + 7 - LDP MP2MP LSP If the MPLS Label field is non-zero, then it contains an MPLS label encoded as 3 octets, where the high-order 20 bits contain the label value. Absence of MPLS Label is indicated by setting the MPLS Label field to zero. When the type is set to RSVP-TE P2MP LSP, the Tunnel Identifier contains the RSVP-TE P2MP LSP's SESSION Object and optionally the RSVP-TE P2MP LSP's SENDER_TEMPLATE Object. When the type is set to LDP P2MP LSP, the Tunnel Identifier is . When the type is set to PIM-SM Tree, the Tunnel Identifier MUST include P-Multicast Group address, and MAY include P-RP Node Address. When the type is set to PIM-SSM Tree, the Tunnel Identifier is . When the type is set to PIM-Bidir Tree, the Tunnel Identifier MUST include P-Multicast Group address, and MAY include P-RP Node Address. When the type is set to Ingress Replication the Tunnel Identifier carries the unicast tunnel endpoint. When the type is set to LDP MP2MP LSP, the Tunnel Identifier is . If LDP MP2MP LSPs are used as PMSI tunnels, the router that transmitted a given packet into the tunnel cannot be identified. As a result, LDP MP2MP LSPs do not support aggregation, and therefore can only be used as unaggregated tunnels. Support of aggregation with LDP MP2MP LSPs is a matter for further study. In addition, if an LDP MP2MP LSP is used within a given AS as an intra-AS segment of an inter-AS tunnel, a single ASBR within that AS must be chosen to be the one which transmits packets to and from the upstream segment of the inter-AS tunnel. In the absence of the procedures for doing this, LDP MP2MP LSPs can not be used for intra-AS segments of inter-AS tunnels. Procedures for choosing a single ASBR are a matter for further study. Finally, use of LDP MP2MP LSPs makes choosing a single forwarder PE (see section "Choosing a single forwarder PE") mandatory. 6. Source AS Extended Community This document defines a new extended community called Source AS. The Source AS is an AS specific extended community. The Source AS extended community is of an extended type, and is transitive across AS boundaries. To support MVPN a PE that originates a (unicast) route to VPN-IPv4 addresses MUST include in the BGP Update message that carries this route the Source AS extended community. The Global Administrator field of this community MUST be set to the autonomous system number of the PE. The Local Administrator field of this community SHOULD be set to 0. 7. Route Import Extended Community This document defines a new extended community called Route Import. The Route Import is an IPv4 address specific extended community. The Route Import is of an extended type, and is transitive across AS boundaries. To support MVPN in addition to the import/export Route Target(s) used by the unicast routing, each VRF MUST have an import Route Target that is unique to this VRF. This Route Target MUST be IP address specific. The Global Administrator field of this Route Target MUST be set to the IP address used for the Next Hop in (unicast) VPN-IPv4 address advertisements for that VRF. The Local Administrator field of this Route Target should contain a 2 octets long number that uniquely identifies that VRF within the PE that contains the VRF (procedures for assigning such number are purely local to the PE, and outside the scope of this document). A PE that originates a route to VPN-IPv4 addresses MUST include in the BGP Updates message that carries this route the Route Import extended community that has the value of this Route Target. If a PE uses Route Target Constrain [RT-CONSTRAIN], the PE SHOULD advertise all such import Route Targets using Route Target Constrains (note that doing this requires just a single Route Target Constraint advertisement by the PE). This allows each C-multicast route to reach only the relevant PE, rather than all the PEs participating the an MVPN. 8. MVPN Auto-Discovery/Binding This section specifies procedures for the autodiscovery of MVPN memberships and the distribution of information used to instantiate I-PMSIs. MVPN auto-discovery/binding consists of two components: intra-AS and inter-AS. The former provides MVPN auto-discovery/binding within a single AS. The latter provides MVPN auto-discovery/binding across multiple ASes. Note that the inter-AS component applies only to the ASes that use either option (b) or (c) for unicast inter-AS operations, as specified in Section "Multi-AS Backbones" of [BGP-VPN]. ASes that use option (a) need only the intra-AS component. 8.1. MVPN Auto-Discovery/Binding - Intra AS Operations This section describes exchanges of auto-discovery routes originated/received by PEs within the same AS. 8.1.1. Originating auto-discovery/binding To participate in the MVPN auto-discovery/binding a PE router that has a given VRF of a given MVPN originates an auto-discovery route and advertises this route in IBGP. The route is constructed as follows. The route carries a single MCAST-VPN NLRI constructed as follows: + The RD in this NLRI is set to the RD of the VRF. + The Originating Router's IP Address is set to the IP address of the PE that generates the advertisement. This address doesn't have to be a routable IP address. Note that the tuple results in an address that uniquely identifies a given multicast VRF. + The Multicast Source Length field and the Multicast Group Length field MUST both be set to 0. If a P-Multicast Tree is used to instantiate the provider tunnel for the MVPN on the PE, and either (a) this tree exists at the time of discovery, or (b) the PE doesn't need to know the leaves of the tree beforehand in order to advertise the P-Multicast tree identifier, then the advertising PE SHOULD advertise the type and the identity of the P-Multicast tree in the PMSI Tunnel attribute of the route. If a P-Multicast Tree is used to instantiate the provider tunnel for the MVPN on the PE, and in order to advertise the P-Multicast tree identifier the advertising PE needs to know the leaves of the tree beforehand, the PE first discovers the leaves using the Auto- Discovery procedures, as described above. It then advertises the binding of the tree to the MVPN using the same route as the one used for the auto-discovery, with the addition of carrying in the route the PMSI Tunnel attribute that contains the type and the identity of the P-Multicast tree. In other words, in the first phase the PE advertises an auto-discovery route, but with no binding, and receives auto-discovery routes from other PEs. Once this is done, in the second phase the PE advertises binding based on the information acquired in the first phase. If at some later point a new PE advertises participation in the same MVPN, the initial binding PMSI Tunnel binding information SHOULD NOT change (though the leaves of the corresponding P-multicast tree may change). When multiple MVPNs are aggregated onto the same P-multicast tree, advertised in the PMSI Tunnel attribute, the PMSI Tunnel attribute MUST carry a MPLS upstream assigned label [MPLS-UPSTREAM] that is associated with the MVPN. If the PE that originates the advertisement uses ingress replication to instantiate the provider tunnel for the MVPN, the route MUST include the PMSI Tunnel attribute with the Tunnel Type set to Ingress Replication and Tunnel Identifier set to a routable address of the PE. The PMSI Tunnel attribute MUST carry a downstream assigned MPLS label. This label is used to demultiplex the MVPN traffic received over a unicast tunnel by the PE. The Next Hop field of the MP_REACH_NLRI attribute is set to a routable IP address of the PE. Discovery of PE capabilities in terms of what tunnels types they support is outside the scope of this document. Within a given AS PEs participating in an MVPN are expected to advertise tunnel bindings whose tunnel types are supported by all other PEs, that are participating in this MVPN and are part of the same AS. By default the distribution of the auto-discovery routes is controlled by the same Route Targets as the ones used for the distribution of VPN-IPv4 unicast routes. That is, by default the auto-discovery route MUST carry the export Route Target used by the unicast routing. If any other PE has one of these Route Targets configured for a VRF, it treats the advertising PE as a member in the MVPN to which the VRF belongs. The default could be modified via configuration by having a set of Route Targets used for the auto- discovery routes being distinct from the ones used for the VPN-IPv4 unicast routes (see also section "Non-congruent Unicast and Multicast Connectivity"). To constrain distribution of the intra-AS membership/binding information to the AS of the advertising PE the BGP Update message originated by the advertising PE SHOULD carry the NO_EXPORT Community ([RFC1997]). 8.1.2. Receiving auto-discovery/binding When a PE receives a BGP Update message that carries an auto- discovery route such that (a) the route was originated by some other PE within the same AS as the local PE, (b) one of the Route Targets of the route matches one of the import Route Targets configured for a particular VRF on the local PE, (c) the BGP route selection determines that this is the best route with respect to the NLRI carried by the route, and (d) the route carries the PMSI Tunnel attribute, the PE performs the following. If the Tunnel Type in the PMSI Tunnel attribute is set to Ingress Replication, then the MPLS label and the address carried in the Tunnel Identifier field of the PMSI Tunnel attribute should be used when the local PE sends multicast traffic to the PE that originated the route. If the Tunnel Type in the PMSI Tunnel attribute is set to LDP P2MP LSP, or PIM-SSM tree, or PIM-SM tree, or PIM-Bidir tree, the PE SHOULD join the P-Multicast tree whose identity is carried in the Tunnel Identifier. If the Tunnel Type in the PMSI Tunnel attribute is set to RSVP-TE P2MP LSP, the receiving PE has to establish the appropriate state to properly handle the traffic received over that LSP. The PE that originated the route MUST establish an RSVP-TE P2MP LSP with the local PE as a leaf. This LSP MAY have been established before the local PE receives the route. If the PMSI Tunnel attribute does not carry a label, then all packets that are received on the P-Multicast tree, as identified by the PMSI Tunnel attribute, are forwarded using the VRF that has the import Route Target that matches one of the Route Targets of the received auto-discovery route. If the PMSI Tunnel attribute has the Tunnel Type set to LDP P2MP LSP, or PIM-SSM tree, or PIM-SM tree, or PIM- Bidir tree, or RSVP-TE P2MP LSP, and the attribute also carries an MPLS label, then this is an upstream label, and all packets that are received on this tree with that upstream label are forwarded using the matching VRF. 8.2. MVPN Auto-Discovery/Binding - Inter-AS Operations An Autonomous System Border Router (ASBR) may be configured to support a particular MVPN as follows: + An ASBR MUST be be configured with a set of (import) RTs that would specify the set of MVPNs supported by the ASBR. These RTs would control acceptance of intra-AS/inter-AS auto-discovery routes by the ASBR. As long as unicast and multicast connectivity are congruent, this could be the same set of RTs as the ones used for supporting unicast. + The ASBR MUST be configured with an import RT that is IP address specific. The Global Administrator field of this community MUST be set to the IP address carried in the Next Hop of the auto- discovery routes advertised by this ASBR (if the ASBR uses different Next Hops, then the ASBR MUST be configured with multiple import RTs, one per each such Next Hop). The Local Administrator field of this community MUST be set to 0. If the ASBR uses Route Target Constrain [RT-CONSTRAIN], the ASBR SHOULD advertise this import Route Target using Route Target Constrains. Note, that this RT is used by both the auto-discovery routes and C-multicast routes (see Section "VPN C-Multicast Routing Information Exchange among PEs"). + The ASBR MUST be configured with the tunnel type for the intra-AS segments of the MVPNs supported by the ASBR, as well as (depending on the tunnel type) the information needed to create the PMSI attribute. + If the ASBR originates an inter-AS auto-discovery route for a particular MVPN within its own AS, the ASBR MUST be configured with the AS-specific RD for that MVPN. This RD MUST be of Type 0, and MUST embed the autonomous system number of the AS. The Assigned Number field of the RD contains a number that MUST uniquely identify that MVPN within that AS (however, for a given MVPN each AS may assign this number on its own, without coordination with other ASes). As a result, for a given MVPN and a given AS all the ASBRs within that AS that originate the inter- AS auto-discovery route for that MVPN would be configured with the same RD for that MVPN. Note also that ASBRs in a pure transit AS need not originate any inter-AS auto-discovery route. If an ASBR is configured to support a particular MVPN, the ASBR MUST participate in the intra-AS MVPN auto-discovery/binding procedures for that MVPN within the AS that the ASBR belongs to, as defined in this document. Moreover, in addition to the above the ASBR performs the following procedures. 8.2.1. Originating Inter-AS MVPN Auto-Discovery Information For a given MVPN configured on an ASBR when the ASBR determines (using the intra AS auto-discovery procedures) that at least one of the PEs of its own AS has (directly) connected site(s) of the MVPN, the ASBR originates an inter-AS auto-discovery route and advertises it in EBGP. The route is constructed as follows. The route carries a single MCAST-VPN NLRI constructed as follows: + The RD MUST be set to the RD configured for that MVPN on the ASBR. + The Multicast Source Length field and the Multicast Group Length field MUST both be set to 0. The Next Hop field of the MP_REACH_NLRI attribute is set to a routable IP address of the ASBR. By default the BGP Update message MUST carry the export Route Target used by the unicast routing of that VPN. The default could be modified via configuration by having a set of Route Targets used for the inter-AS auto-discovery routes being distinct from the ones used by the unicast routing of that VPN (see also section "Non-congruent Unicast and Multicast Connectivity"). An inter-AS auto-discovery route for a given indicates presence of the MVPN sites connected to one or more PEs of the AS. An inter-AS auto-discovery route originated by an ASBR aggregates auto-discovery routes originated within the ASBR's own AS. Thus while the auto-discovery routes originated within an AS are at the granularity of within that AS, outside of that AS the (aggregated) inter-AS auto-discovery routes are at the granularity of . 8.2.2. Propagating Inter-AS MVPN Auto-Discovery Information An inter-AS auto-discovery route for a given MVPN, originated by an ASBR within a given AS, is propagated via BGP to other ASes. The precise rules for distributing and processing the inter-AS auto- discovery routes are given in subsequent sections. Suppose that an ASBR A installs an inter-AS auto-discovery route for MVPN V that originated at a particular AS, AS1. The BGP next hop of that route becomes A's "upstream neighbor" on a multicast distribution tree for V that is rooted at AS1. When the inter-AS auto-discovery routes have been distributed to all the necessary ASes, they define a "reverse path" from any AS that supports MVPN V back to AS1. For instance, if AS2 supports MVPN V, then there will be a reverse path for MVPN V from AS2 to AS1. This path is a sequence of ASBRs, the first of which is in AS2, and the last of which is in AS1. Each ASBR in the sequence is the BGP next hop of the previous ASBR in the sequence on the given inter-AS auto-discovery route. This reverse path information can be used to construct a unidirectional multicast distribution tree for MVPN V, containing all the ASes that support V, and having AS1 at the root. We call such a tree an "inter-AS tree". Multicast data originating in given AS will travel downstream along the tree which is rooted at that AS. The path along an inter-AS tree is a sequence of ASBRs; it is still necessary to specify how the multicast data gets from a given ASBR to the set of ASBRs which are immediately downstream of the given ASBR along the tree. This is done by creating "segments". ASBRs in adjacent ASes will be connected by inter-AS segments. ASBRs in the same AS will be connected by "intra-AS segments". An ASBR originates creation of an intra-AS segment when the ASBR receives an inter-AS auto-discovery route from an EBGP neighbor. Creation of the segment is completed as a result of distributing via IBGP this route within the ASBR's own AS. For a given inter-AS tunnel each of its intra-AS segments could be constructed by its own independent mechanism. Moreover, by using upstream labels within a given AS multiple intra-AS segments of different inter-AS tunnels of either the same or different MVPNs may share the same P-Multicast Tree. If the multicast tunnel instantiating a particular segment of an inter-AS tunnel is created by a multicast control protocol that uses receiver-initiated joins (e.g, mLDP, any PIM variant), then all the information needed to create that segment will be present in the inter-AS auto-discovery routes. But if the multicast tunnel instantiating the segment is created by a protocol that does not use receiver-initiated joins (e.g., RSVP-TE, ingress unicast replication), then it is also necessary to use "leaf auto-discovery" routes. The precise conditions under which leaf auto-discover routes need to be used are described in subsequent sections. Since (aggregated) inter-AS auto-discovery routes have granularity of , an MVPN that is present in N ASes would have total of N inter-AS tunnels. Thus for a given MVPN the number of inter-AS tunnels is independent of the number of PEs that have this MVPN. The following sections specify procedures for propagation of (aggregated) inter-AS auto-discovery routes across ASes. 8.2.2.1. Inter-AS Auto-Discovery Route received via EBGP When an ASBR receives from one of its EBGP neighbors a BGP Update message that carries an inter-AS auto-discovery route, if (a) at least one of the Route Targets carried in the message matches one of the import Route Targets configured on the ASBR, and (b) the ASBR determines that the received route is the best route to the destination carried in the NLRI of the route, the ASBR re-advertises this auto-discovery route to other PEs and ASBRs within its own AS. When re-advertising an inter-AS auto-discovery route the ASBR MUST NOT modify the NLRI of the route. When re-advertising an inter-AS auto-discovery route the ASBR MUST set the Next Hop field of the MP_REACH_NLRI attribute to a routable IP address of the ASBR. If the ASBR uses ingress replication to instantiate the intra-AS segment of the inter-AS tunnel, the re-advertised route SHOULD carry the PMSI Tunnel attribute with the Tunnel Type set to Ingress Replication, but no MPLS labels. If a P-Multicast Tree is used to instantiate the intra-AS segment of the inter-AS tunnel, and in order to advertise the P-Multicast tree identifier the ASBR does not need to know the leaves of the tree beforehand, then the advertising ASBR SHOULD advertise the type and the identity of the P-Multicast tree in the PMSI Tunnel attribute of the route. This, in effect, creates a binding between the inter-AS auto-discovery route and the P-Multicast Tree. If a P-Multicast Tree is used to instantiate the intra-AS segment of the inter-AS tunnel, and in order to advertise the P-Multicast tree identifier the advertising ASBR needs to know the leaves of the tree beforehand, the ASBR first discovers the leaves using the Auto- Discovery procedures, as specified further down. It then advertises the binding of the tree to the inter-AS auto-discovery route using the original inter-AS auto-discovery route with the addition of carrying in the route the PMSI Tunnel attribute that contains the type and the identity of the tree. In other words, in the first phase the ASBR advertises inter-AS auto-discovery routes, but with no binding. Once this is done, in the second phase the ASBR advertises binding based on the information acquired in the first phase. When multiple inter-AS auto-discovery routes are bound onto the same P-multicast tree advertised in the PMSI Tunnel attribute, the PMSI Tunnel attribute MUST carry a MPLS upstream assigned label [MPLS- UPSTREAM] that is associated with the inter-AS auto-discovery route. In addition the ASBR MUST send to the EBGP neighbor, from whom it receives the inter-AS auto-discovery route, a BGP Update message that carries a leaf auto-discovery route constructed as follows. The route carries a single MCAST-VPN NLRI constructed as follows: + The RD in this NLRI is set to the RD carried in the inter-AS auto-discovery route received from that neighbor. + The Multicast Source Length field and the Multicast Group Length field MUST both be set to 0. + The Originating Router's IP address is set to the IP address of the ASBR. The leaf auto-discovery route MUST include the PMSI Tunnel attribute with the Tunnel Type set to Ingress Replication, and the Tunnel Identifier set to a routable address of the advertising router. The PMSI Tunnel attribute MUST carry a downstream assigned MPLS label that is used to demultiplex the MVPN traffic received over a unicast tunnel by the advertising router. The leaf auto-discovery route MUST carry the same set of Route Target communities as was carried in the received inter-AS auto-discovery route. The Next Hop field of the MP_REACH_NLRI attribute of the route is set to a routable IP address of the ASBR. To constrain the distribution scope of this route the route SHOULD carry the NO_ADVERTISE BGP community ([RFC1997]). 8.2.2.2. Leaf Auto-Discovery Route received via EBGP When an ASBR receives via EBGP a leaf auto-discovery route, the ASBR finds an inter-AS auto-discovery route that has the same RD as the leaf auto-discovery route. The MPLS label carried in the PMSI Tunnel attribute of the leaf auto-discovery route is used to stitch a one hop ASBR-ASBR LSP to the tail of the intra-AS tunnel segment associated with the inter-AS auto-discovery route. 8.2.2.3. Inter-AS Auto-Discovery Route received via IBGP In the context of this section we use the term "PE/ASBR router" to denote either a PE or an ASBR router. If a given inter-AS auto-discovery route is advertised within an AS by multiple ASBRs of that AS, the BGP best route selection performed by other PE/ASBR routers within the AS does not require all these PE/ASBR routers to select the route advertised by the same ASBR - to the contrary different PE/ASBR routers may select routes advertised by different ASBRs. When a PE/ASBR router receives from one of its IBGP neighbors a BGP Update message that carries an inter-AS auto-discovery route, if (a) the route was originated outside of the router's own AS, (b) at least one of the Route Targets carried in the message matches one of the import Route Targets configured on the PE/ASBR, and (c) the PE/ASBR determines that the received route is the best route to the destination carried in the NLRI of the route, the PE/ASBR performs the following operations. If the router is an ASBR then the ASBR propagates the route to its EBGP neighbors. When propagating the route to the EBGP neighbors the ASBR MUST set the Next Hop field of the MP_REACH_NLRI attribute to a routable IP address of the ASBR. If the received inter-AS auto-discovery route carries the PMSI Tunnel attribute with the Tunnel Type set to LDP P2MP LSP, or PIM-SSM tree, or PIM-SM tree, or PIM-Bidir tree, the PE/ASBR SHOULD join the P- Multicast tree whose identity is carried in the Tunnel Identifier. If the received inter-AS auto-discovery route carries the PMSI Tunnel attribute with the Tunnel Identifier set to RSVP-TE P2MP LSP, then the ASBR that originated the route MUST establish an RSVP-TE P2MP LSP with the local PE/ASBRas a leaf. This LSP MAY have been established before the local PE/ASBR receives the route. If the received inter-AS auto-discovery route carries the PMSI Tunnel attribute with the Tunnel Type set to LDP P2MP LSP, or RSVP-TE P2MP LSP, or PIM-SSM, or PIM-SM tree, or PIM-Bidir tree, but the attribute does not carry a label, then the P-Multicast tree, as identified by the PMSI Tunnel Attribute, is an intra-AS LSP segment that is part of the inter-AS Tunnel for the MVPN advertised by the inter-AS auto- discovery route and rooted at the AS that originated the inter-AS auto-discovery route. If the PMSI Tunnel attribute carries a (upstream) label, then a combination of this tree and the label identifies the intra-AS segment. If the received router is an ASBR, this intra-AS segment may further be stitched to ASBR-ASBR inter-AS segment of the inter-AS tunnel. If the PE/ASBR has local receivers in the MVPN, packets received over the intra-AS segment must be forwarded to the local receivers using the local VRF. If the received inter-AS auto-discovery route either does not carry the PMSI Tunnel attribute, or carries the PMSI Tunnel attribute with the Tunnel Type set to ingress replication, then the PE/ASBR originates a new leaf auto-discovery route as follows. The route carries a single MCAST-VPN NLRI constructed as follows: + The RD in the NLRI is set to the RD of the received inter-AS auto-discovery route. + The Multicast Source Length field and the Multicast Group Length field MUST both be set to 0. + The Originating Router's IP Address is set to the IP address of the ASBR. This address doesn't have to be a routable IP address. If the received inter-AS auto-discovery route carries the PMSI Tunnel attribute with the Tunnel Type set to ingress replication, the leaf auto-discovery route MUST carry the PMSI Tunnel attribute with the Tunnel Type set to Ingress Replication. The Tunnel Identifier MUST carry a routable address of the PE/ASBR. The PMSI Tunnel attribute MUST carry a downstream assigned MPLS label that is used to demultiplex the MVPN traffic received over a unicast tunnel by the PE/ASBR. The PE/ASBR constructs an IP-based Route Target community by placing the next hop of the received inter-AS auto-discovery route in the Global Administrator field of the community, with the Local Administrator field of this community set to 0, and adds this community to the Extended Community attribute of the leaf auto- discovery route. The route MUST carry the NO_EXPORT Community. Once the leaf auto-discovery route is constructed, the PE/ASBR advertises this route into IBGP. 8.2.2.4. Leaf Auto-Discovery route received via IBGP When an ASBR receives via IBGP a leaf auto-discovery route, the ASBR finds an inter-AS auto-discovery route that has the same RD as the leaf auto-discovery route. If the received route does not carry the PMSI Tunnel attribute, the ASBR uses the information from the received route to determine the leaves of the P-tree rooted at the ASBR that would be used for the intra-AS segment associated with the inter-AS auto-discovery route. If the received route carries the PMSI Tunnel attribute with the Tunnel Type set to Ingress Replication the ASBR uses the information carried by the route to construct the intra-AS segment with ingress replication. 9. Non-congruent Unicast and Multicast Connectivity If the multicast connectivity of a MVPN is congruent to its unicast connectivity, the VRF of that MVPN, as referred to by this document, means the VRF of that VPN used for unicast routing. If the multicast connectivity of a MVPN is non-congruent to its unicast connectivity, the VRF of that MVPN, as referred to by this document, means the VRF that is distinct from the VRF of that VPN used for unicast routing. On a given PE such a VRF may have its own import and export Route Targets, different from the ones used by the VRF used for unicast routing. These Route Targets are used for the auto-discovery routes. The export Route Targets are added to the Route Targets used for unicast routing when originating VPN-IPv4 routes. The export Route Targets control the set of sites that could receive multicast traffic originated by the sources within the local site. The import Route Targets associated with a given VRF are used to determine which of the received VPN-IPv4 routes should be accepted into the VRF. The import Route Targets control the set of sites that contain sources of multicast traffic that could be received within the local site. If an MVPN site is single-homed to a PE, then on this PE the VRF associated with the site should use the same RD as the one used by the VRF used for unicast routing of that VPN. If an MVPN site is multi-homed to several PEs, then to support non-congruent unicast and multicast connectivity on each of these PEs the VRF of the MVPN should use its own distinct RD (although on a given PE the RD used by the VRF of the MVPN should be the same as the one used by the VRF used for unicast routing of that VPN). If for a given MVPN all of its sites connected to a given PE are known a priori to have no multicast sources, then this PE is NOT REQUIRED to originate an auto-discovery route for that MVPN at all, unless either (a) some other PEs that have VRFs in that MVPN use RSVP TE P2MP LSPs, in which case the PE originates an auto-discovery route, but with no PMSI Tunnel attribute, or (b) the PE uses ingress replication for incoming multicast traffic, in which case the PE originates an auto-discovery route with the PMSI Tunnel attribute indicating ingress replication. 10. VPN C-Multicast Routing Information Exchange among PEs VPN C-Multicast Routing Information is exchanged among PEs by using C-multicast routes that are carried using MCAST-VPN NLRI. These routes are originated and propagated as follows. 10.1. Originating C-Multicast Routes by a PE 10.1.1. Constructing MCAST-VPN NLRI Procedures for constructing MCAST-VPN NLRI depend on the multicast routing protocol between CE and PE (C-multicast protocol). 10.1.1.1. PIM as the C-Multicast protocol The following specifies construction of MCAST-VPN NLRI of C-multicast routes for the case where the C-multicast protocol is PIM. These C- multicast routes are originated as a result of updates in or or or state learnt by a PE via the C-multicast protocol. Whenever a PE creates a new state in one of its MVPN-TIBs, if C-S is reachable through some other PE the local PE originates a C-multicast route. The source address in the MCAST-VPN NLRI of the route is set to C-S, the group address is set of C-G. The MCAST-VPN NLRI is carried as a source tree join route type. The semantics of the route is that the PE has one or more receivers for in the sites connected to the PE (the route has the (C-S, C-G) Join semantics). Whenever a PE deletes a previously created state that had resulted in originating a C-multicast route, the PE withdraws the route (the withdrawn route has the (C-S, C-G) Prune semantics). The MCAST-VPN NLRI of the withdrawn route is carried in the MP_UNREACH_NLRI attribute. Whenever a PE creates a new state in one of its MVPN-TIBs, if the C-RP for C-G is reachable through some other PE the local PE originates a C-multicast route. The source address in the MCAST-VPN NLRI of the route is set to the C-RP address. The MCAST-VPN NLRI of the route is carried as the shared tree join route type. The semantics of the route is that the PE has one or more receivers for in the sites connected to the PE (the route has the (C-*, C-G) Join semantics). Whenever a PE deletes a previously created state that had resulted in originating a C-multicast route, the PE withdraws the route (the withdrawn route has the (C-*, C-G) Prune semantics). The MCAST-VPN NLRI of the withdrawn route is carried in the MP_UNREACH_NLRI attribute. Whenever a PE creates a new state in one of its MVPN-TIBs (this state is created whenever the PE that has an existing state switches from the C-RP based tree to the C-S based tree for C-G), if the C-RP is reachable through some other PE the local PE originates a C-multicast route. The source address in the MCAST-VPN NLRI of the route is set to C-S and the group address is set to C-G. The MCAST-VPN NLRI of the route is carried as the prune source from shared tree route type. The semantics of the route is to indicate that the receivers for no longer want to receive traffic via the C-RP based tree (the route has the (C-S,C- G, RPT) Prune semantics). If later on the PE deletes a previously created state, the PE withdraws the route (the semantics of the withdrawn route is to indicate that traffic should be carried via the C-RP-based tree). The MCAST-VPN NLRI of the withdrawn route is carried in the MP_UNREACH_NLRI attribute. Whenever a PE creates a state in one of its MVPN-TIBs, if the C-RP is reachable through some other PE the local PE originates a C-multicast route. The source address in the MCAST-VPN NLRI of the route is set to the C-RP address. The group address in the NLRI MUST be set to a wildcard i.e. 0. The MCAST-VPN NLRI of the route is carried as the shared tree join route type. Whenever a PE deletes a previously created state that had resulted in originating a C-multicast route, the PE withdraws the route (the withdrawn route has the (C-*, C-*) Prune semantics). The MCAST-VPN NLRI of the withdrawn route is carried in the MP_UNREACH_NLRI attribute. 10.1.2. Constructing the rest of the route The rest of the C-multicast route is constructed as follows. The (local) PE uses its VRF to determine (a) the autonomous system number of the (remote) PE that originates the (unicast) route to C- S/C-RP, and (b) the import Route Target community associated with the VRF on the remote PE which was used to originate the route (this information is available from the Route Import extended community carried in the unicast VPN-IPv4 routing advertisements by the remote PE). Note that for a C-multicast route that the PE originates in response to creating a state, the remote PE is the PE that originates the route to C-RP, not to C-S. Irrespective of whether the local and the remote PE are in the same or different ASes, the Extended Community attribute of the route MUST include the import Route Target community associated with the VRF on the remote PE. If the local and the remote PEs are in the same AS, then the RD of the advertised MCAST-VPN NLRI is set to the RD of the VPN-IPv4 route that contains C-S/C-RP. The route is then advertised into IBGP. If the local and the remote PEs are in different ASes, then the local PE finds in its VRF an inter-AS auto-discovery route whose RD embeds the autonomous system number of the remote PE. The RD of this route is used as the RD of the advertised MCAST-VPN NLRI. The local PE constructs an IP-based Route Target community by placing the next hop of this route in the Global Administrator field of an community, with the Local Administrator field of this community set to 0, and adds this community to the Extended Community attribute of the route. The Next Hop field of the MP_REACH_NLRI attribute is set to a routable IP address of the local PE. If the next hop of the auto-discovery route is an EBGP neighbor of the local PE, then the PE advertises this route to that neighbor. If the next hop of the route is within the same AS as the local PE, then the PE advertises the route into IBGP. 10.1.3. Unicast Route Changes Whenever unicast route used for determining PE connected to C-S/C-RP changes, the local PE updates and re-originates the previously originated C-multicast routes, as appropriate. 10.2. Propagating C-Multicast routes by an ASBR When an ASBR receives a BGP Update message that carries a C-multicast route the ASBR first checks if it already has one or more C-multicast routes that have the same MCAST-VPN NLRI as the newly received route. If such route(s) already exists, the ASBR keeps the newly received route, but SHALL not re-advertise the newly received route. Otherwise, the ASBR re-advertises the route, as described further down. When an ASBR receives a BGP Update message that carries a withdraw of a previously advertised C-multicast route, the ASBR first checks if it already has at least one C-multicast route that has the same MCAST-VPN NLRI. If such a route already exists, the ASBR processes the withdrawn route, but SHALL not re-advertise the withdrawn route. Otherwise, the ASBR re-advertise the withdraw of a previously advertised C-multicast route, as described below. When an ASBR receives a BGP Update message that carries a C-multicast route, if at least one of the Route Targets of the route matches one of the import Route Targets configured on the ASBR, the ASBR finds an auto-discovery route whose RD matches the RD carried in the C- multicast route. If the next hop for the found auto-discovery route is an EBGP neighbor of the ASBR, then the ASBR re-advertises the C-multicast route to that neighbor. If the next hop for the found auto-discovery route is an IBGP neighbor of the ASBR, the ASBR re-advertises the route into IBGP. If it is the ASBR that originated the found auto- discovery route in the first place, then the ASBR just re-advertises this route into IBGP. Before re-advertising the C-Multicast route, the ASBR modifies the Extended Community attribute of the route as follows. If the Route Target of the route that matches one of the import Route Targets configured on the ASBR is an IP-based Route Target with the Global Administrator field set to the IP address of ASBR, then the ASBR replaces this Route Target with a newly constructed IP-based Route Target that has the Global Administrator field set to the Next Hop of the found auto-discovery route, and Local Administrator field of this community set to 0. The rest of the Extended Community attribute of the route is passed unmodified. The Originating Router's IP Address is set to 0. The Next Hop field of the MP_REACH_NLRI attribute is set to a routable IP address of the ASBR. 10.3. Receiving C-Multicast Routes by a PE Procedures for a PE to process received C-multicast routes depend on the multicast routing protocol between CE and PE (C-multicast protocol). 10.3.1. PIM as the C-Multicast protocol When a PE receives a C-multicast route the PE checks if any of the Route Target communities carried in the Extended Community attribute of the route match any of the import Route Target communities associated with the VRFs maintained by the PE. If no match is found the PE, as a local choice, may keep the route, but does not perform any further processing of the route. If a match is found then the PE proceeds as follows. If the received route has the route type set to source tree join, then the PE creates a new state in its MVPN-TIB from the source address and group address fields in the MCAST-VPN NLRI of the route, if such a state does not already exist. If there is no S-PMSI for then the PE adds an I-PMSI to the outgoing interface list of the state if it is not already there. If there is an S-PMSI for then the PE add S-PMSI to the outgoing interface list of the state if it is not already there. If the received route has the route type set to shared tree join, then the PE creates a new state in its MVPN-TIB with the RP address for that state taken from the source address, and C-G for that state taken from the group address field of the MCAST-VPN NLRI of the route, if such a state does not already exist. The PE adds I- PMSI to the outgoing interface list of the state if it is not already there. If the received route has the route type set to prune source from shared tree, then the PE creates a new state in its MVPN-TIB from the source address and group address fields in the MCAST-VPN NLRI of the route, if such a state does not already exist. The PE adds I-PMSI to the outgoing interface list of the state if it is not already there. 11. Switching to S-PMSI Section 7.3.2 if [MVPN] describes a BGP based protocol for switching to S-PMSI. Auto-discovery routes are used for this purpose. The procedures are described in section 7.3.2 of [MVPN]. The C-multicast streams for which the S-PMSI is being instantiated are advertised using the same procedures as the MVPN auto-discovery/binding procedures (both intra-AS and inter-AS) specified in this document with the following modifications: 1. The Multicast Source field MUST contain the source address associated with the C-multicast stream, and the Multicast Source Length field is set appropriately to reflect this; 2. The Multicast Group field MUST contain the group address associated with the C-multicast stream, and the Multicast Group Length field is set appropriately to reflect this. The above two points apply to both the inter-AS auto-discovery routes and to the leaf auto-discovery routes. 12. Choosing a single forwarder PE In certain cases it may be necessary to choose a single forwarder PE to avoid packet duplication. Choosing of a single consistent upstream PE as described in [MVPN] may not suffice. An example is a to switch. Consider a set of PEs {PE2, PE4, PE6} that are on the C-RP tree for and have chosen a consistant upstream PE, as described in [MVPN], for state. Further this upstream PE, say PE1, is using an MI-PMSI for . If a site attached to one of these PEs, say PE2, switches to the C-S tree for , PE2 generates a C-Multicast route towards the upstream PE that is on the path to C-S, say PE3. PE3 also uses an MI-PMSI for . This results in {PE2, PE4, PE6} receiving duplicate traffic for - both on the C-RP tree (from PE1) and C-S tree (from PE3). If it is desirable to suppress receiving duplicate traffic then it is necessary to choose a single forwarder PE for . The following text describes how this is achieved. Whenever a PE creates an state as a result of receiving a C-multicast route for from some other PE, the PE that creates the state SHOULD originate an auto-discovery route. The route is being advertised using the same procedures as the MVPN auto- discovery/binding (both intra-AS and inter-AS) specified in this document with the following modifications: 1. The Multicast Source field MUST be set to C-S. The Multicast Source Length field is set appropriately to reflect this. 2. The Multicast Group field MUST be set to C-G. The Multicast Group Length field is set appropriately to reflect this. The above two points apply to both the inter-AS auto-discovery routes and to the leaf auto-discovery routes. The route goes to all the PEs of the MVPN. When a PE receives this route, it checks whether there are any receivers in the MVPN sites attached to the PE for the group carried in the route. If yes, then it generates a C-multicast route indicating Join for . This forces all the PEs to switch to the C-S tree for from the C-RP tree. Whenever the PE deletes the state that was previousely created as a result of receiving a C-multicast route for from some other PE, the PE that deletes the state also withdraws the auto-discovery route that was advertised when the state was created. 13. Co-locating C-RPs on a PE Section 9 of [MVPN] describes two models for co-locating C-RPs on a PE. 13.1. Anycast RP Based on C-(*, G) Advertisements When the first model of anycast RP based on (*, C-G) advertisements is used, (C-*, C-G) information is advertised using MCAST-VPN SAFI as per the procedures of section 9.1.2 in [MVPN]. This information is sent to all PEs in the MVPN. Further details will be described in the future revision of this document. 13.2. Anycast RP Based on Propagating Active Sources The second model of anycast RP is based on advertising active sources. 13.2.1. Source Within a Site - Active Source Advertisement When a PE receives a PIM-Register message from one of its directly connected CEs that belong to a given MVPN, the PE follows the normal PIM procedures. In addition the PE advertises the source and the group of the multicast data packet caried in PIM-Register message using an auto-discovery route. The route is being instantiated and handled using the same procedures as the MVPN auto-discovery/binding (both intra-AS and inter-AS) specified in this document with the following modifications: 1. The Multicast Source field MUST be set to the source IP address of the multicast data packet carried in the PIM-Register message. The Multicast Source Length field is set appropriately to reflect this. 2. The Multicast Group field MUST be set to the group address of the multicast data packet carried in the PIM-Register message. The Multicast Group Length field is set appropriately to reflect this. The above two points apply to both the inter-AS auto-discovery routes and to the leaf auto-discovery routes. The route goes to all the PEs of the MVPN. When a PE receives this route, it checks whether there are any receivers in the MVPN sites attached to the PE for the group carried in the route. If yes, then it generates an advertisement for as specified in the next section. 13.2.2. Receiver(s) Within a Site A PE which receives C-Join for or from one of its connected CEs that belong to a given MVPN does not send the information that it has receiver(s) for C-G until it receives an auto-discovery route from some other PE indicating that there are active sources for that G. On receiving an auto-discovery route (described in the previous section), the downstream PE will respond with a C-multicast route indicating Join for . The route is constructed as described in Section "Originating C-Multicast Routes by a PE". 14. Scalability Considerations A PE should use Route Target Constrain [RT-CONSTRAIN] to advertise the Route Targets that the PE uses for the Route Imports extended community (note that doing this requires just a single Route Target Constraint advertisement by the PE). This allows each C-multicast route to reach only the relevant PE, rather than all the PEs participating the an MVPN. To keep the intra-AS membership/binding information within the AS of the advertising router the BGP Update message originated by the advertising router SHOULD carry the NO_EXPORT Community ([RFC1997]). An inter-AS auto-discovery route originated by an ASBR aggregates auto-discovery routes originated within the ASBR's own AS. Thus while the auto-discovery routes originated within an AS are at the granularity of within that AS, outside of that AS the (aggregated) inter-AS auto-discovery routes are at the granularity of . An inter-AS auto-discovery route for a given indicates the presence of or or more sites of the MVPN connected to the PEs of the AS. For a given inter-AS tunnel each of its intra-AS segments could be constructed by its own mechanism. Moreover, by using upstream labels within a given AS multiple intra-AS segments of different inter-AS tunnels of either the same or different MVPNs may share the same P- Multicast Tree. Since (aggregated) inter-AS auto-discovery routes have granularity of , an MVPN that is present in N ASes would have total of N inter-AS tunnels. Thus for a given MVPN the number of inter-AS tunnels is independent of the number of PEs that have this MVPN. Within each Autonomous System BGP Route reflectors can be partitioned among MVPNs present in that Autonomous System so that each partition carries routes for only a subset of the MVPNs supported by the Service Provider. Thus no single Route Reflector is required to maintain routes for all MVPNs. Moreover, Route Reflectors used for MVPN do not have to be used for VPN-IPv4 routes (although they may be used for VPN-IPv4 routes as well). C-multicast routes for a given (S,G) of a given MVPN originated by PEs that are clients of a given Route Reflector are aggregated by the Route Reflector. Therefore, even if within a Route Reflector cluster there are multiple C-multicast routes for a given (S,G) of a given MVPN, outside of the cluster all these routes are aggregated into a single C-multicast route. Additional aggregation of C-multicast routes occurs at ASBRs, where an ASBR aggregates all the received C- multicast routes for a given (S,G) of a given MVPN into a single C- multicast route. Moreover, both Route Reflectors and ASBRs maintain C-multicast routes only in the control plane, but not in the data plane. 15. IANA Consideration This document defines a new BGP Extended Community called Source AS. This community is 2-octet AS specific, of an extended type, and is transitive. This document defines a new BGP Extended Community called Route Import. This community is IPv4 address specific, of an extended type, and is transitive. This document defines a new NLRI, called MCAST-VPN, to be carried in BGP using multiprotocol extensions. It is assigned its own SAFI. This document defines a new BGP optional transitive attribute, called PMSI Tunnel. 16. Security Considerations The mechanisms described in this document could re-use the existing BGP security mechanisms. 17. References 17.1. Normative References [MVPN] E. Rosen, R. Aggarwal [Editors], "Multicast in MPLS/BGP IP VPNs", draft-ietf-l3vpn-2547bis-mcast-01.txt, [RFC2119] "Key words for use in RFCs to Indicate Requirement Levels.", Bradner, March 1997 [RFC4364] E. Rosen, Y. Rekhter, "BGP/MPLS IP Virtual Private Networks (VPNs)", RFC4364, February 2006 17.2. Informative References [MPLS-UPSTREAM] R. Aggrwal, Y. Rekhter, E. Rosen, " MPLS Upstream Label Assignment and Context Specific Label Space", draft-raggarwa- mpls-upstream-label-01.txt [PIM-SM] B. Fenner et. al., "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)", draft-ietf-pim-sm- v2-new-11.txt [RT-CONSTRAIN] P. Marques et. al., ",Constrained VPN Route Distribution" draft-ietf-l3vpn-rt-constrain-02 18. Author Information Rahul Aggarwal Juniper Networks 1194 North Mathilda Ave. Sunnyvale, CA 94089 Email: rahul@juniper.net Chaitanya Kodeboniya Juniper Networks 1194 North Mathilda Ave. Sunnyvale, CA 94089 Email: ck@juniper.net Yakov Rekhter Juniper Networks 1194 North Mathilda Ave. Sunnyvale, CA 94089 Email: yakov@juniper.net Eric C. Rosen Cisco Systems, Inc. 1414 Massachusetts Avenue Boxborough, MA, 01719 E-mail: erosen@cisco.com Thomas Morin France Telecom R & D 2, avenue Pierre-Marzin 22307 Lannion Cedex France Email: thomas.morin@francetelecom.com 19. 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