Network Working Group R. Aggarwal (Editor) Internet Draft Juniper Networks Category: Standards Track Expiration Date: December 2008 Y. Kamite NTT Communications L. Fang Cisco Systems, Inc June 02, 2008 Multicast in VPLS draft-ietf-l2vpn-vpls-mcast-04.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 a solution for overcoming a subset of the limitations of existing VPLS multicast solutions. It describes procedures for VPLS multicast that utilize multicast trees in the sevice provider (SP) network. One such multicast tree can be shared between multiple VPLS instances. Procedures by which a single multicast tree in the SP network can be used to carry traffic Raggarwa, Kamite & Fang [Page 1] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 belonging only to a specified set of one or more IP multicast streams from one or more VPLSs are also described. Raggarwa, Kamite & Fang [Page 2] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 Table of Contents 1 Specification of requirements ......................... 4 2 Contributors .......................................... 4 3 Terminology ........................................... 5 4 Introduction .......................................... 5 5 Existing Limitations of VPLS Multicast ................ 5 6 Overview .............................................. 6 6.1 Inclusive and Selective Multicast Trees ............... 6 6.2 BGP-Based VPLS Membership Auto-Discovery .............. 7 6.3 IP Multicast Group Membership Discovery ............... 8 6.4 Advertising P-Tree to VPLS / C-Multicast Binding ...... 8 6.5 Aggregation ........................................... 9 6.6 Inter-AS VPLS Multicast ............................... 9 7 Intra-AS Inclusive Multicast Tree A-D/Binding ......... 10 7.1 Originating (intra-AS) auto-discovery routes .......... 11 7.2 Receiving (intra-AS) auto-discovery routes ............ 12 8 Demultiplexing Multicast Tree Traffic ................. 13 8.1 One Multicast Tree - One VPLS Mapping ................. 13 8.2 One Multicast Tree - Many VPLS Mapping ................ 13 9 Establishing Multicast Trees .......................... 14 9.1 RSVP-TE P2MP LSPs ..................................... 14 9.1.1 P2MP TE LSP - VPLS Mapping ............................ 15 9.1.2 Demultiplexing C-Multicast Data Packets ............... 15 9.2 Receiver Initiated MPLS Trees ......................... 16 9.2.1 P2MP LSP - VPLS Mapping ............................... 16 9.2.2 Demultiplexing C-Multicast Data Packets ............... 16 9.3 Encapsulation of the Aggregate Inclusive and Selective Tree 17 10 Inter-AS Inclusive Multicast Tree A-D/Binding ......... 17 10.1 VSIs on the ASBRs ..................................... 17 10.1.1 Option (a) ............................................ 18 10.1.2 Option (e) ............................................ 18 10.2 Option (b) - Segmented Inter-AS Trees ................. 18 10.2.1 Segmented Inter-AS Trees VPLS Inter-AS A-D/Binding .... 19 10.2.2 Propagating VPLS BGP A-D routes to other ASes - Overview ..19 10.2.2.1 Propagating Intra-AS VPLS A-D routes in E-BGP ......... 21 10.2.2.2 A-D route received via E-BGP .......................... 21 10.2.2.3 Leaf A-D Route received via E-BGP ..................... 23 10.2.2.4 Inter-AS A-D Route received via I-BGP ................. 23 10.3 Option (c) ............................................ 25 11 Optimizing Multicast Distribution via Selective Trees . 25 11.1 Protocol for Switching to Selective Trees ............. 27 Raggarwa, Kamite & Fang [Page 3] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 11.2 Advertising C-(S, G) Binding to a Selective Tree using BGP 27 11.2.1 Explicit Tracking ..................................... 28 11.3 Inter-AS Selective Tree ............................... 29 11.3.1 VSIs on the ASBRs ..................................... 29 11.3.1.1 VPLS Inter-AS Selective Tree A-D Binding .............. 29 11.3.2 Inter-AS Segmented Selective Trees .................... 29 11.3.3 Inter-AS Non-Segmented Selective Trees ................ 31 12 BGP Extensions ........................................ 32 12.1 Inclusive Tree/Selective Tree Identifier .............. 32 12.2 MCAST-VPLS NLRI ....................................... 33 12.2.1 Selective Tree auto-discovery route ................... 34 12.2.2 Leaf auto-discovery route ............................. 35 13 Aggregation Methodology ............................... 35 14 Data Forwarding ....................................... 36 14.1 MPLS Tree Encapsulation ............................... 36 15 VPLS Multicast/Broadcast/Unknown Unicast Data Packet Treatment 37 16 Security Considerations ............................... 38 17 IANA Considerations ................................... 38 18 Acknowledgments ....................................... 39 19 Normative References .................................. 39 20 Informative References ................................ 39 21 Author's Address ...................................... 40 22 Intellectual Property Statement ....................... 41 23 Full Copyright Statement .............................. 42 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. Contributors Rahul Aggarwal Yakov Rekhter Juniper Networks Yuji Kamite NTT Communications Luyuan Fang AT&T Chaitanya Kodeboniya Raggarwa, Kamite & Fang [Page 4] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 3. Terminology This document uses terminology described in [RFC4761] and [RFC4762]. 4. Introduction [RFC4761] and [RFC4762] describe a solution for VPLS multicast that relies on ingress replication. This solution has certain limitations for certain VPLS multicast traffic profiles. This document describes procedures for overcoming the limitations of existing VPLS multicast solutions. It describes procedures for VPLS multicast that utilize multicast trees in the Sevice Provider (SP) network. The procedures described in this document are applicable to both [RFC4761] and [RFC4762]. It provides mechanisms that allow a single multicast distribution tree in the Service Provider (SP) network to carry all the multicast traffic from one or VPLS sites connected to a given PE, irrespective of whether these sites belong to the same or different VPLSs. Such a tree is referred to as an "Inclusive Tree" and more specifically as an "Aggregate Inclusive Tree" when the tree is used to carry multicast traffic from more than one VPLS. This document also provides procedures by which a single multicast distribution tree in the SP network can be used to carry traffic belonging only to a specified set of IP multicast streams, originated in one or more VPLS sites connected to a given PE, irrespective of whether these sites belong to the same or different VPLSs. Such a tree is referred to as a "Selective Tree" and more specifically as an "Aggregate Selective Tree" when the IP multicast streams belong to different VPLSs. So traffic from most multicast streams could be carried by an Inclusive Tree, while traffic from, e.g., high bandwidth streams could be carried in one of the "Selective Trees". 5. Existing Limitations of VPLS Multicast One of the limitations of existing VPLS multicast solutions described in [RFC4761] and [RFC4762] is that they rely on ingress replication. Thus the ingress PE replicates the multicast packet for each egress PE and sends it to the egress PE using a unicast tunnel. This is a reasonable model when the bandwidth of the multicast traffic is low or/and the number of replications performed on an average on each outgoing interface for a particular customer VPLS multicast packet is small. If this is not the case it is desirable to Raggarwa, Kamite & Fang [Page 5] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 utilize multicast trees in the SP network to transmit VPLS multicast packets [MCAST-VPLS-REQ]. Note that unicast packets that are flooded to each of the egress PEs, before the ingress PE performs learning for those unicast packets, MAY still use ingress replication. 6. Overview This document describes procedures for using multicast trees in the SP network to transport VPLS multicast data packets. RSVP-TE P2MP LSPs described in [RFC4875] are an example of such multicast trees. The use of multicast trees in the SP network can be beneficial when the bandwidth of the multicast traffic is high or when it is desirable to optimize the number of copies of a multicast packet transmitted by the ingress. This comes at a cost of state in the SP network to build multicast trees and overhead to maintain this state. This document describes procedures for using multicast trees for VPLS multicast when the provider tunneling technology is either P2MP RSVP- PE or mLDP [MLDP]. The protocol architecture described herein is considered to be flexible to support other P-tunneling technologies as well. This document uses the prefix 'C' to refer to the customer control or data packets and 'P' to refer to the provider control or data packets. An IP (multicast source, multicast group) tuple is abbreviated to (S, G). 6.1. Inclusive and Selective Multicast Trees Multicast trees used for VPLS can be of two types: 1. Inclusive Trees. A single multicast distribution tree in the SP network is used to carry all the multicast traffic from a specified set of VPLS sites connected to a given PE. A particular multicast distribution tree can be set up to carry the traffic originated by sites belonging to a single VPLS, or to carry the traffic originated by sites belonging to different VPLSs. The ability to carry the traffic of more than one VPLS on the same tree is termed 'Aggregation'. The tree will include every PE that is a member of any of the VPLSs that are using the tree. This implies that a PE may receive multicast traffic for a multicast stream even if it doesn't have any receivers on the path of that stream. An Inclusive tree as defined in this document is a source tree. A source tree is used to carry traffic only for VPLS sites that are connected to the PE that is the root. Raggarwa, Kamite & Fang [Page 6] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 2. Selective Trees. A Selective Tree is used by a PE to send IP multicast traffic for one or IP more multicast streams, originated within sites connected to the PE, that belong to the same or different VPLSs, to a subset of the PEs that belong to those VPLSs. Each of the PEs in the subset should be on the path to a receiver of one or more multicast streams that are mapped onto the tree. The ability to use the same tree for multicast streams that belong to different VPLSs is termed have the ability to create separate SP multicast trees for high bandwidth multicast groups. This allows traffic for these multicast groups to reach only those PE routers that have receivers in these groups. This avoids flooding other PE routers in the VPLS. A SP can use both Inclusive Trees and Selective Trees or either of them for a given VPLS on a PE, based on local configuration. Inclusive Trees can be used for both IP and non-IP data multicast traffic, while Selective Trees can be used only for IP multicast data traffic. A variety of transport technologies may be used in the SP network. For inclusive trees, these transport technologies include point-to- multipoint LSPs created by RSVP-TE or mLDP. For selective trees, only unicast PE-PE tunnels (using MPLS or IP/GRE encapsulation) and unidirectional single-source trees are supported, and the supported tree signaling protocols are RSVP-TE, and mLDP. This document also describes the data plane encapsulations for supporting the various SP multicast transport options. 6.2. BGP-Based VPLS Membership Auto-Discovery In order to establish Inclusive P-trees for one or more VPLSs, when Aggregation is performed or when the tunneling technology is P2MP RSVP-TE, the root of the tree must be able to discover the other PEs that have membership in one or more of these VPLSs. This document uses the BGP-based procedures described in [RFC4761] and [L2VPN-SIG] for discovering the VPLS membership of all PEs. The leaves of the Inclusive P-trees must also be able to auto- discover the identifier of the tree. This is described in section 6.4. Raggarwa, Kamite & Fang [Page 7] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 6.3. IP Multicast Group Membership Discovery The setup of a Selective P-tree for one or more IP multicast (S, G)s, when aggregation is used or when the tunneling technology is P2MP RSVP-TE, requires the ingress PE to learn the PEs that have receivers in one or more of these (C-S, C-G)s. For discovering the IP multicast group membership, procedures described in [VPLS-CTRL] should be used. Procedures in [VPLS-CTRL] can also be used with ingress replication to send traffic for an IP multicast stream to only those PEs that are on the path to receivers for that stream. The leaves of the Selective P-trees must also be able to discover the identifier of the tree. This is described in section 6.4. 6.4. Advertising P-Tree to VPLS / C-Multicast Binding This document also describes procedures based on BGP VPLS Auto- Discovery (A-D) that are used by the root of an Aggregate Tree to advertise the Inclusive or Selective tree binding and the de- multiplexing information to the leaves of the tree. This document uses the PMSI Tunnel Attribute [BGP-MVPN] for this purpose. Once a PE decides to bind a set of VPLSes or customer multicast groups to an Inclusive Tree or a Selective Tree, it needs to announce this binding to other PEs in the network. This procedure is referred to as Inclusive Tree or Selective Tree binding distribution and is performed using BGP. For an Inclusive Tree this discovery implies announcing the binding of all VPLSs bound to the Inclusive Tree. The inner label assigned by the ingress PE for each VPLS MUST be included, if more than one VPLS is bound to the same tree. The Inclusive Tree Identifier MUST be included. For a Selective Tree this discovery implies announcing all the specific entries bound to this tree along with the Selective Tree Identifier. The inner label assigned for each MUST be included if s from different VPLSes are bound to the same tree. The labels MUST be distinct on a per VPLS basis and MAY be distinct on a per basis. The Selective Tree Identifier MUST be included. Raggarwa, Kamite & Fang [Page 8] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 6.5. Aggregation As described above the ability to carry the traffic of more than one VPLS on the same tree is termed 'Aggregation'. Both Inclusive and Selective trees support aggregation. Aggregation enables the SP to place a bound on the amount of multicast tree forwarding and control plane state which the P routers must have. Let us call the number of VPLSes aggregated onto a single P-tree as the "Aggregation Factor". When Inclusive source trees are used the number of trees that a PE is the root of is proportional to: + (Number of VPLSes on the PE / Aggregation Factor). In this case the state maintained by a P router, is proportional to: + ((Average number of VPLSes on a PE / Aggregation Factor) * number of PEs) / (Average number of trees that transit a given P router) Thus the state does not grow linearly with the number of VPLSes. Aggregation requires a mechanism for the egresses of the tree to demultiplex the multicast traffic received over the tree. This document describes how upstream-assigned labels can be assigned and distributed by the root of aggregate tree and then used by the egresses to perform this demultiplexing. 6.6. Inter-AS VPLS Multicast This document supports three models of inter-AS VPLS service, option (a), (b) and (c) which are very similar conceptually to option (a), (b) and (c) specified in [RFC4364] for IP VPNs. The three options described here are also similar to the three options described in in [RFC4761], which in turn extends the concepts of [RFC4364] to inter- AS VPLS. For option (a) and option (b) support this document specifies a model where Inter-AS VPLS service can be offered without requiring a single P-multicast tree to span multiple ASes. There are two variants of this model. In the first variant, the Autonomous System Border Routers (ASBRs) perform a MAC lookup, in addition to any MPLS lookups, to determine the forwarding decision on a VPLS packet. In this variant the multicast trees are confined to an AS. Hence each AS may use a Raggarwa, Kamite & Fang [Page 9] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 different P-tunneling technology. An ASBR on receiving a VPLS packet from another ASBR is required to perform a MAC lookup to determine how to forward the packet. Thus an ASBR is required to keep a VPLS Switching Instance (VSI) for the VPLS. This variant is applicable to option (a). In the case of option (a) an ASBR in one AS treats an adjoining ASBR in another AS as a CE and determines the VSI for packets received from another ASBR based on the incoming ethernet interface. It is possible to extend this model by using a PW, per VPLS instance, to interconnect the adjoining ASBRs in what is called as option (e). In the second variant, an inter-AS multicast tree, rooted at a particular PE for a particular VPLS instance, consists of a number of "segments", one per AS, which are stitched together at Autonomous System Border Routers (ASBRs). These are known as "segmented inter-AS trees". Each segment of a segmented inter-AS tree may use a different multicast transport technology. In this variant, an ASBR is not required to keep a a VSI for the VPLS and is not required to perform a MAC lookup in order to forward the VPLS packet. This variant is applicable to option (b) as in the case of option (b) the BGP-VPLS NLRIs or A-D routes are redistributed by the ASBRs. For option (c) support this document specifies a model where Inter-AS VPLS service is offered by requiring a single P-multicast tree to span multiple ASs. This is because in the case of option (c) the ASBRs do not exchange BGP-VPLS NLRIs or A-D routes. 7. Intra-AS Inclusive Multicast Tree A-D/Binding This section specifies procedures for the intra-AS auto-discovery (A- D) of VPLS membership and the distribution of information used to instantiate P-Multicast Tunnels. VPLS auto-discovery/binding consists of two components: intra-AS and inter-AS. The former provides VPLS auto-discovery/binding within a single AS. The latter provides VPLS auto-discovery/binding across multiple ASes. Inter-AS auto-discovery/binding is described in section 11. VPLS auto-discovery using BGP as described in [RFC4761, L2VPN-SIG] enables a PE to learn the VPLS membership of other PEs. A PE that belongs to a particular VPLS announces a BGP Network Layer Reachability Information (NLRI) that identifies the Virtual Switch Instance (VSI). This NLRI is constructed from the tuple. The NLRI defined in [RFC4761] comprises the tuple and label Raggarwa, Kamite & Fang [Page 10] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 blocks for PW signaling. The VE-ID in this case is a two octet number. The NLRI defined in [L2VPN-SIG] comprises only the where the VE-ID is a four octet number. The procedures for constructing Inclusive intra-AS and inter-AS trees as specified in this document require the BGP A-D NLRI to carry only the . Hence these procedures can be used for both BGP-VPLS and LDP-VPLS with BGP A-D. 7.1. Originating (intra-AS) auto-discovery routes To participate in the VPLS auto-discovery/binding a PE router that has a given VSI of a given VPLS originates an auto-discovery route and advertises this route in I-BGP. The route is constructed as described in [RFC4761] and [L2VPN-SIG]. The route carries a single L2VPN NLRI with the RD set to the RD of the VSI, and the VE-ID set to the VE-ID of the VSI. If a P-Multicast tree is used to instantiate the provider tunnel for VPLS multicast 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 before hand in order to advertise the P-Multicast tree identifier, then the advertising PE MUST advertise the type and the identity of the P-Multicast tree in the the PMSI Tunnel attribute [BGP-MVPN]. This attribute is described in section 13.1. If a P-Multicast tree is used to instantiate the provider tunnel for VPLS multicast 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, then the PE obtains this information from the intra- AS auto-discovery routes received from other PEs. Once the PE obtains the information about the leaves (this information is obtained from the auto-discovery routes received by the PE), the PE then advertises the binding of the tree to the VPLS 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. If at some later point a new PE advertises participation in the same VPLS, the initial binding P- Tunnel binding information SHOULD NOT change (though the leaves of the corresponding P-Multicast tree may change). A PE that uses a P-Multicast tree to instantiate the provider tunnel MAY aggregate two or more VPLSs present on the PE onto the same tree. If the PE already advertises intra-AS auto-discovery routes for these VPLSs, then aggregation requires the PE to re-advertise these routes. The re-advertised routes MUST be the same as the original ones, Raggarwa, Kamite & Fang [Page 11] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 except for the PMSI Tunnel attribute. If the PE has not previously advertised intra-AS auto-discovery routes for these VPLSs, then the aggregation requires the PE to advertise (new) intra-AS auto- discovery routes for these VPLSs. The P-Tunnel attribute in the newly advertised/re-advertised routes MUST carry the identity of the P-Multicast tree that aggregates the VPLSs, as well as an MPLS upstream-assigned label [MPLS-UPSTREAM]. Each re-advertised route MUST have a distinct label. 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 a VPLS are expected to advertise tunnel bindings whose tunnel types are supported by all other PEs that are participating in this VPLS and are part of the same AS. 7.2. Receiving (intra-AS) auto-discovery routes When a PE receives a BGP Update message that carries an A-D route such that (a) the route was originated by some other PE within the same AS as the local PE, (b) at least one of the Route Targets of the route matches one of the import Route Targets configured for a particular VSI 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 route carries the PMSI Tunnel attribute then: + If the Tunnel Type in the PMSI Tunnel attribute is set to LDP P2MP LSP, the PE SHOULD join the P-Multicast tree whose identity is carried in the PMSI Tunnel Attribute. + 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 VSI that has at least one of its import Route Targets that matches one of the Route Targets of the received auto-discovery route. Raggarwa, Kamite & Fang [Page 12] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 + If the PMSI Tunnel attribute has the Tunnel Type set to LDP P2MP LSP or RSVP-TE P2MP LSP, and the attribute also carries an MPLS label, then the egress PE MUST treat this as an upstream-assigned label, and all packets that are received on the P-Multicast tree, as identified by the PMSI Tunnel attribute, with that upstream label are forwarded using the VSI that has at least one of its import Route Target that matches one of the Route Targets of the received auto-discovery route. If the local PE uses RSVP-TE P2MP LSP for sending (multicast) traffic, originated by VPLS sites connected to the PE, to the sites attached to other PEs, then the local PE uses the Originating Router's IP address information carried in the Intra- AS A-D route to add the PE that originated the route as a leaf node to the LSP. This is done irrespective of whether the received Intra-AS A-D route carries the PMSI Tunnel attribute or not. 8. Demultiplexing Multicast Tree Traffic Demultiplexing received VPLS traffic requires the receiving PE to determine the VPLS instance the packet belongs to. The egress PE can then perform a VPLS lookup to further forward the packet. It also requires the egress PE to determine the identity of the ingress PE for MAC learning, as described in section 7. 8.1. One Multicast Tree - One VPLS Mapping When a multicast tree is mapped to only one VPLS, determining the tree on which the packet is received is sufficient to determine the VPLS instance on which the packet is received. The tree is determined based on the tree encapsulation. If MPLS encapsulation is used, eg: RSVP-TE P2MP LSPs, the outer MPLS label is used to determine the tree. Penultimate-hop-popping MUST be disabled on the MPLS LSP (RSVP- TE P2MP LSP or LDP P2MP LSP). 8.2. One Multicast Tree - Many VPLS Mapping As traffic belonging to multiple VPLSs can be carried over the same tree, there is a need to identify the VPLS the packet belongs to. This is done by using an inner label that determines to the VPLS for which the packet is intended. The ingress PE uses this label as the inner label while encapsulating a customer multicast data packet. Each of the egress PEs must be able to associate this inner label with the same VPLS and use it to demultimplex the traffic received Raggarwa, Kamite & Fang [Page 13] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 over the Aggregate Inclusive Tree or the Aggregate Selective Tree. This document requires the use of upstream label assignment by the ingress PE [MPLS-UPSTREAM]. Hence the inner label is assigned by the ingress PE. When the egress PE receives a packet over an Aggregate Tree, the outer encapsulation [in the case of MPLS P2MP LSPs, the outer MPLS label] specifies the label space to perform the inner label lookup. The same label space MUST be used by the egress PE for all P-multicast trees that have the same root [MPLS-UPSTREAM]. If the tree uses MPLS encapsulation the outer MPLS label and the incoming interface provides the label space of the label beneath it. This assumes that penultimate-hop-popping is disabled. An example of this is RSVP-TE P2MP LSPs. The outer label and incoming interface effectively identifies the Tree [MPLS-UPSTREAM, MPLS-MCAST]. The ingress PE informs the egress PEs about the inner label as part of the tree binding procedures described in section 12. 9. Establishing Multicast Trees This document does not place any fundamental restrictions on the multicast technology used to setup P-multicast trees. However specific procedures are specified currently only for RSVP-TE P2MP LSPs and LDP P2MP LSPs. An implementation that supports this document MUST support RSVP-TE P2MP LSPs and MAY support LDP P2MP LSPs. The P-multicast trees supported in this document are source trees. A source tree is used to carry traffic originated in sites connected to the PE which is the root of the tree, irrespective of whether these sites belong to the same or different VPLSs. 9.1. RSVP-TE P2MP LSPs This section describes procedures that are specific to the usage of RSVP-TE P2MP LSPs for instantiating a multicast tree. Procedures in [RFC4875] are used to signal the P2MP LSP. The LSP is signaled after the root of the P2MP LSP discovers the leaves. The egress PEs are discovered using the procedures described in section 9. Aggregation as described in this document is supported. Raggarwa, Kamite & Fang [Page 14] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 9.1.1. P2MP TE LSP - VPLS Mapping P2MP TE LSP to VPLS mapping is learned at the egress PEs using BGP based advertisements of the P2MP TE LSP - VPLS mapping. They require that the root of the tree include the P2MP TE LSP identifier as the tunnel identifier in the BGP advertisements. This identifier contains the following information elements: - The type of the tunnel is set to RSVP-TE P2MP LSP - RSVP-TE P2MP LSP's SESSION Object This Tunnel Identifier is described in section 13.1. 9.1.2. Demultiplexing C-Multicast Data Packets Demultiplexing the C-multicast data packets at the egress PE requires that the PE must be able to determine the P2MP TE LSP that the packets are received on. This enables the egress PE to determine the VPLS that the packet belongs to. To achieve this the LSP MUST be signaled with penultimate-hop-popping (PHP) off as described in section 9. In other words an egress PE MUST NOT advertise IMPLICIT NULL or EXPLICIT NULL for a RSVP-TE P2MP LSP that is carrying traffic for one or more VPLSs. This is because the egress PE needs to rely on the MPLS label, that it advertises to its upstream neighbor, to determine the P2MP LSP that a C-multicast data packet is received on. The egress PE also needs to identify the ingress PE to perform MAC learning. When P2MP LSPs are used as source trees, determining the P2MP LSP that the packets are received on, is sufficient to determine the ingress PE. This is because the ingress PE is the root of the P2MP LSP. The egress PE relies on receiving the PMSI Tunnel Attribute in BGP to determine the VPLS instance to P2MP TE LSP mapping. Once the egress PE receives this mapping: + If the egress PE already has RSVP-TE state for the P2MP TE LSP, it MUST begin to assign a MPLS label from the non-reserved label range, for the P2MP TE LSP and signal this to the previous hop of the P2MP TE LSP. Further it MUST create forwarding state to forward packets received on the P2MP LSP. + If the egress PE does not have RSVP-TE state for the P2MP TE LSP, it MUST retain this mapping. Subsequently when the egress PE receives the RSVP-TE P2MP signaling message, it creates the RSVP- TE P2MP LSP state. It MUST then assign a MPLS label from the non-reserved label range, for the P2MP TE LSP, and signal this to Raggarwa, Kamite & Fang [Page 15] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 the previous hop of the P2MP TE LSP. Note that if the signaling to set up an RSVP-TE P2MP LSPis completed before a given egress PE learns, via a PMSI Tunnel attribute, of the VPLS or set of VPLSs to which the LSP is bound, the PE MUST discard any traffic received on that LSP until the binding is received. In order for the egress PE to be able to discard such traffic it needs to know that the LSP is associated with one or more VPLSs and that the A-D route that binds the LSP to a VPLS has not yet been received. This is provided by extending [RFC4875] with [RSVP-OBB]. 9.2. Receiver Initiated MPLS Trees Receiver initiated MPLS trees can also be used. An example of such trees are LDP setup P2MP MPLS Trees [MLDP]. Procedures in [MLDP] are used to signal the LSP. The LSP is signaled once the leaves receive the LDP FEC for the tree from the root. The egress PEs are discovered using the procedures described in section 9. Aggregation as described in this document is supported. 9.2.1. P2MP LSP - VPLS Mapping P2MP LSP to VPLS mapping is learned at the egress PEs using BGP based advertisements of the P2MP LSP - VPLS mapping. They require that the root of the tree include the P2MP LSP identifier as the tunnel identifier in the BGP advertisements. This identifier contains the following information elements: - The type of the tunnel is set to LDP P2MP LSP - LDP P2MP FEC which includes an identifier generated by the root. Each egress PE "joins" the P2MP MPLS tree by sending LDP label mapping messages for the LDP P2MP FEC, that was learned in the BGP advertisement, using procedures described in [MLDP]. 9.2.2. Demultiplexing C-Multicast Data Packets This follows the same procedures described above for RSVP-TE P2MP LSPs. Raggarwa, Kamite & Fang [Page 16] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 9.3. Encapsulation of the Aggregate Inclusive and Selective Tree An Aggregate Inclusive Tree or an Aggregate Selective Tree MUST use a MPLS encapsulation. The protocol type in the data link header is as described in [MPLS-MCAST]. 10. Inter-AS Inclusive Multicast Tree A-D/Binding This document supports three models of inter-AS VPLS service, option (a), (b) and (c) which are very similar conceptually to option (a), (b) and (c) specified in [RFC4364] for IP VPNs. The three options described here are also similar to the three options described in [RFC4761], which in turn extends the concepts of [RFC4364] to inter- AS VPLS. An implementation MUST support all three of these models. When there are multiple options for implementing one of these models, this section specifies which option is mandatory. For option (a) and option (b) support this section specifies a model where inter-AS VPLS service can be offered without requiring a single P-multicast tree to span multiple ASes. This allows individual ASes to potentially use different P-tunneling technologies.There are two variants of this model. One that requires MAC lookup on the ASBRs and another that does not require MAC lookup on the ASBRs and instead builds segmented inter-AS trees. This applies to both Inclusive and Selective trees. For option (c) support this document specifies a model where Inter-AS VPLS service is offered by requiring a single Inclusive P-multicast tree to span multiple ASs. This is referred to as a non-segmented P- multicast tree. This is because in the case of option (c) the ASBRs do not exchange BGP-VPLS NLRIs or A-D routes. Selective inter-AS trees for option (c) support may be segmented or non-segmented. 10.1. VSIs on the ASBRs In this variant, the ASBRs MUST perform a MAC lookup, in addition to any MPLS lookups, to determine the forwarding decision on a VPLS packet. The multicast trees are confined to an AS. An ASBR on receiving a VPLS packet from another ASBR is required to perform a MAC lookup to determine how to forward the packet. Thus an ASBR is required to keep a VSI for the VPLS and MUST be configured with its own VE ID for the VPLS. In this variant the BGP A-D routes generated by PEs in an AS MUST NOT be propagated outside the AS. Raggarwa, Kamite & Fang [Page 17] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 10.1.1. Option (a) When this variant is used with option (a) an ASBR in one AS treats an adjoining ASBR in another AS as a CE and determines the VSI for packets received from another ASBR based on the incoming ethernet interface. In the case of option (a) the ASBRs do not exchange A-D routes. An implementation MUST support this variant for option (a). 10.1.2. Option (e) The VSIs on the ASBRs variant can be used such that the interconnect between the ASBRs is a PW and MPLS encapsulation is used between the ASBRs. An ASBR in one AS treats an adjoining ASBR in another AS as a CE and determines the VSI for packets received from another ASBR based on the incoming MPLS encapsulation. The only A-D routes that are propagated outside the AS are the ones originated by ASBRs. This MPLS PW connects the VSIs on the ASBRs and MUST be signaled using the procedures defined in [RFC4761] or [RFC4762]. The multicast trees for a VPLS are confined to each AS and the VPLS auto-discovery/binding MUST follow the intra-AS procedures described in section 8. 10.2. Option (b) - Segmented Inter-AS Trees In this variant, an inter-AS multicast tree, rooted at a particular PE for a particular VPLS instance, consists of a number of "segments", one per AS, which are stitched together at ASBRs. These are known as "segmented inter-AS trees". Each segment of a segmented inter-AS tree may use a different multicast transport technology. In this variant, an ASBR is not required to keep a VSI for the VPLS and is not required to perform a MAC lookup in order to forward the VPLS packet. This implies that an ASBR is not required to be configured with a VE ID for the VPLS. This variant is applicable to option (b). An implementation MUST support this variant. The construction of segmented Inter-AS trees requires the BGP-VPLS A- D NLRI described in [RFC4761, RFC4762]. A BGP-VPLS A-D route for a tuple advertised outside the AS, to which the originating PE belongs, will be referred to as an inter-AS auto-discovery route (Though this route is originated by a PE as an intra-AS route and is referred to as an inter-AS route outside the AS). In addition to this, segmented inter-AS trees require support for the Raggarwa, Kamite & Fang [Page 18] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 PMSI Tunnel Attribute described in section 13.1. They also require additional procedures in BGP to signal leaf A-D routes between ASBRs as explained in subsequent sections. 10.2.1. Segmented Inter-AS Trees VPLS Inter-AS A-D/Binding This section specifies the procedures for inter-AS VPLS A-D/binding for segmented inter-AS trees. An ASBR must be configured to support a particular VPLS as follows: + An ASBR MUST be be configured with a set of (import) Route Targets (RTs) that specifies the set of VPLSes supported by the ASBR. These Route Targets control acceptance of BGP VPLS auto- discovery routes by the ASBR. Note that instead of being configured, the ASBR MAY obtain this set of (import) Route Targets (RTs) by using Route Target Constrain [RFC4684]. + The ASBR MUST be configured with the tunnel types for the intra- AS segments of the VPLSes supported by the ASBR, as well as (depending on the tunnel type) the information needed to create the PMSI Tunnel attribute for these tunnel types. Note that instead of being configured, the ASBR MAY derive the tunnel types from the intra-AS auto-discovery routes received by the ASBR from the PEs in its own AS. If an ASBR is configured to support a particular VPLS, the ASBR MUST participate in the intra-AS VPLS auto-discovery/binding procedures for that VPLS within the ASBR's own AS, as defined in this document. Moreover, in addition to the above the ASBR performs procedures specified in the next section. 10.2.2. Propagating VPLS BGP A-D routes to other ASes - Overview An auto-discovery route for a given VPLS, 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 receives and installs an auto-discovery route for VPLS "X" and VE ID "V" that originated at a particular PE, PE1. The BGP next hop of that received route becomes A's "upstream Raggarwa, Kamite & Fang [Page 19] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 neighbor" on a multicast distribution tree for (X, V) that is rooted at PE1. When the auto-discovery routes have been distributed to all the necessary ASes, they define a "reverse path" from any AS that supports VPLS X and VE ID V back to PE1. For instance, if AS2 supports VPLS X, then there will be a reverse path for VPLS X and VE ID 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 auto-discovery route. This reverse path information can be used to construct a unidirectional multicast distribution tree for VPLS X and VE ID V, containing all the ASes that support X, and having PE1 at the root. We call such a tree an "inter-AS tree". Multicast data originating in VPLS sites for VPLS X connected to PE1 will travel downstream along the tree which is rooted at PE1. 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". For a given inter-AS tree and a given AS there MUST be only one ASBR within that AS that accepts traffic flowing on that tree. Further for a given inter-AS tree and a given AS there MUST be only one ASBR in that AS that sends the traffic flowing on that tree to a particular adjacent AS. The precise rules for accomplishing this are given in subsequent sections. An ASBR initiates creation of an intra-AS segment when the ASBR receives an auto-discovery route from an E-BGP neighbor. Creation of the segment is completed as a result of distributing, via I-BGP, 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-assigned labels within a given AS multiple intra-AS segments of different inter-AS tunnels of either the same or different VPLSs may share the same P-Multicast tree. If the P-Multicast tree instantiating a particular segment of an inter-AS tunnel is created by a multicast control protocol that uses receiver-initiated joins (e.g, mLDP), and this P-Multicast tree does not aggregate multiple segments, then all the information needed to create that segment will be present in the inter-AS auto-discovery routes received by the ASBR from the neighboring ASBR. But if the P- Raggarwa, Kamite & Fang [Page 20] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 Multicast tree instantiating the segment is created by a protocol that does not use receiver-initiated joins (e.g., RSVP-TE, ingress unicast replication), or if this P-Multicast tree aggregates multiple segments (irrespective of the multicast control protocol used to create the tree), then the ASBR needs to learn the leaves of the segment. These leaves are learned from A-D routes received from other PEs in the AS, for the same VPLS (i.e. same VE-ID) as the one that the segment belongs to. The following sections specify procedures for propagation of auto- discovery routes across ASes in order to construct inter-AS segmented trees. 10.2.2.1. Propagating Intra-AS VPLS A-D routes in E-BGP For a given VPLS configured on an ASBR when the ASBR receives intra- AS A-D routes originated PEs in its own AS, the ASBR MUST propagate each of these route in E-BGP. This procedure MUST be performed for each of the VPLSs configurd on the ASBR. Each of these routes is constructed as follows: + The route carries a single BGP VPLS A-D NLRI with the RD and VE ID being the same as the NLRI in the received intra-AS A-D route. + The Next Hop field of the MP_REACH_NLRI attribute is set to a routable IP address of the ASBR. + The route carries the PMSI Tunnel attribute with the Tunnel Type set to Ingress Replication; the attribute carries no MPLS labels. + The route MUST carry the export Route Target used by the VPLS. 10.2.2.2. A-D route received via E-BGP When an ASBR receives from one of its E-BGP neighbors a BGP Update message that carries an 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. The best route selection procedures MUST ensure that for the same destination, all ASBRs in an AS pick the same route as the best route. This ensures that if multiple ASBRs, in an AS, receive the same inter-AS A-D route from their E-BGP neighbors, only one of these ASBRs propagates this route in I-BGP. This ASBR becomes the root of the intra-AS segment of Raggarwa, Kamite & Fang [Page 21] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 the inter-AS tree and ensures that this is the only ASBR that accepts traffic into this AS from the inter-AS tree. 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. Depending on the type of a P-Multicast tree used to instantiate the intra-AS segment of the inter-AS tunnel, the PMSI Tunnel attribute of the re-advertised inter-AS auto-discovery route is constructed as follows: + If the ASBR uses ingress replication to instantiate the intra-AS segment of the inter-AS tunnel, the re-advertised route MUST NOT carry the PMSI Tunnel attribute. + If the ASBR uses a P-Multicast tree to instantiate the intra-AS segment of the inter-AS tunnel, the PMSI Tunnel attribute MUST contain the identity of the tree that is used to instantiate the segment (note that the ASBR could create the identity of the tree prior to the actual instantiation of the segment). If in order to instantiate the segment the ASBR needs to know the leaves of the tree, then the ASBR obtains this information from the auto- discovery routes received from other PEs/ASBRs in ASBR's own AS. + An ASBR that uses a P-Multicast tree to instantiate the intra-AS segment of the inter-AS tunnel MAY aggregate two or more VPLSs present on the ASBR onto the same tree. If the ASBR already advertises inter-AS auto-discovery routes for these VPLSs, then aggregation requires the ASBR to re-advertise these routes. The re-advertised routes MUST be the same as the original ones, except for the PMSI Tunnel attribute. If the ASBR has not previously advertised inter-AS auto-discovery routes for these VPLSs, then the aggregation requires the ASBR to advertise (new) inter-AS auto-discovery routes for these VPLSs. The PMSI Tunnel attribute in the newly advertised/re-advertised routes MUST carry the identity of the P-Multicast tree that aggregates the VPLSs, as well as an MPLS upstream-assigned label [MPLS-UPSTREAM]. Each re-advertised route MUST have a distinct label. In addition the ASBR MUST send to the E-BGP neighbor, from whom it receives the inter-AS auto-discovery route, a BGP Update message that carries a "leaf auto-discovery route". The exact encoding of this route is described in section 13. This route contains the following information elements: Raggarwa, Kamite & Fang [Page 22] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 + The route carries a single NLRI with the Route Key field set to the tuple of the BGP VPLS A-D NLRI of the inter-AS auto-discovery route received from that neighbor. The NLRI also carries the IP address of the ASBR (this MUST be a routable IP address). + 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 VPLS traffic received over a unicast tunnel by the advertising router. + The Next Hop field of the MP_REACH_NLRI attribute of the route SHOULD be set to the same IP address as the one carried in the Originating Router's IP Address field of the route. + To constrain the distribution scope of this route the route MUST carry the NO_ADVERTISE BGP community ([RFC1997]). + The Route Targets associated with the VPLS MUST be included in the route. 10.2.2.3. Leaf A-D Route received via E-BGP When an ASBR receives via E-BGP a leaf auto-discovery route, the ASBR accepts the route only if 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. If the ASBR accepts the leaf auto-discovery route, the ASBR finds an auto-discovery route whose BGP-VPLS A-D NLRI has the same value as the field of the 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 found auto- discovery route. 10.2.2.4. Inter-AS A-D Route received via I-BGP In the context of this section we use the term "PE/ASBR router" to denote either a PE or an ASBR router. Raggarwa, Kamite & Fang [Page 23] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 Note that a given inter-AS auto-discovery route is advertised within a given AS by only one ASBR as described above. When a PE/ASBR router receives from one of its I-BGP 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 PE/ASBR, and (b) 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 E- BGP neighbors. When propagating the route to the E-BGP 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, the PE/ASBR SHOULD join the P-Multicast tree whose identity is carried in the PMSI Tunnel Attribute. 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, or MAY be established after the local PE 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, 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 advertised by the inter-AS auto-discovery route and rooted at the PE that originated the auto-discovery route. If the PMSI Tunnel attribute carries a (upstream-assigned) 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 VPLS, packets received over the intra-AS segment must be forwarded to the local receivers using the local VSI. Raggarwa, Kamite & Fang [Page 24] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 10.3. Option (c) In this method, there is a multi-hop E-BGP peering between the PEs (or a Route Reflector) in one AS and the PEs (or Route Reflector) in another AS. The PEs exchange BGP-VPLS NLRI or BGP-VPLS A-D NLRI, along with PMSI Tunnel Attribute, as in the intra-AS case described in section 8. An implementation MUST support this method. The PEs in different ASs use a non-segmented inter-AS P2MP tunnel for VPLS multicast. A non-segmented inter-AS tunnel is a single tunnel which spans AS boundaries. The tunnel technology cannot change from one point in the tunnel to the next, so all ASes through which the tunnel passes must support that technology. In essence, AS boundaries are of no significance to a non-segmented inter-AS This method requires no VPLS information (in either the control or the data plane) on the ASBRs. The ASBRs only need to participate in the non-segmented P2MP tunnel setup in the control plane, and do MPLS label forwarding in the data plane. The setup of non-segmented inter-AS P2MP tunnels MAY require the P- routers in one AS to have IP reachability to the loopback addresses of the PE routers in another AS, depending on the tunneling technology chosen. If this is the case, reachability to the loopback addresses of PE routers in one AS MUST be present in the IGP in another AS. The data forwarding in this model is the same as in the intra-AS case described in section 8. 11. Optimizing Multicast Distribution via Selective Trees Whenever a particular multicast stream is being sent on an Inclusive Tree, it is likely that the data of that stream is being sent to PEs that do not require it as the sites connected to these PEs may have no receivers for the stream. If a particular stream has a significant amount of traffic, it may be beneficial to move it to a Selective Tree which has at its leaves only those PEs, connected to sites that have receivers for the multicast stream (or at least includes fewer PEs that are attached to sites with no receivers compared to an Inclusive tree). A PE connected to the multicast source of a particular multicast stream may be performing explicit tracking i.e. it may know the PEs that have receivers in the multicast stream. Section 12.2.1 describes procedures that enable explicit tracking. If this is the case Selective Trees can also be triggered on other criteria. For instance Raggarwa, Kamite & Fang [Page 25] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 there could be a "pseudo wasted bandwidth" criteria: switching to a Selective Tree would be done if the bandwidth multiplied by the number of uninterested PEs (PE that are receiving the stream but have no receivers) is above a specified threshold. The motivation is that (a) the total bandwidth wasted by many sparsely subscribed low- bandwidth groups may be large, and (b) there's no point to moving a high-bandwidth group to a Selective Tree if all the PEs have receivers for it. Switching a (C-S, C-G) stream to a Selective Tree may require the root of the tree to determine the egress PEs that need to receive the (C-S, C-G) traffic. This is true in the following cases: + If the tunnel is a source initiated tree, such as a RSVP-TE P2MP Tunnel, the PE needs to know the leaves of the tree before it can instantiate the Selective Tree. + If a PE decides to send traffic for multicast streams, belonging to different VPLSs, using one P-multicast Selective Tree, such a tree is termed an Aggregate Tree with a selective mapping. The setting up of such an Aggregate Tree requires the ingress PE to know all the other PEs that have receivers for multicast groups that are mapped onto the tree. For discovering the IP multicast group membership, for the above two cases, procedures described in [VPLS-CTRL] SHOULD be used. These cases require that explicit tracking be done for the (C-S, C-G) stream. The root of the Selective P-tree MAY decide to do explicit tracking of this stream only after it has determined to move the stream to a Selective tree, or it MAY have been doing explicit tracking all along. The PE at the root of the tree MUST signal the leaves of the tree that the (C-S, C-G) stream is now bound to the to the Selective Tree. Note that the PE could create the identity of the P- multicast tree prior to the actual instantiation of the tunnel. If the Selective Tree is instantiated by a source-initiated P- multicast tree (e.g., an RSVP-TE P2MP tunnel), the PE at the root of the tree MUST establish the source-initiated P-multicast tree to the leaves. This tree MAY have been established before the leaves receive the Selective Tree binding, or MAY be established after the leaves receives the binding. The leaves MUST not switch to the Selective Tree until they receive both the binding and the tree signaling message. Raggarwa, Kamite & Fang [Page 26] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 11.1. Protocol for Switching to Selective Trees Selective Trees provide a PE the ability to create separate P- multicast trees for certain streams. The source PE, that originates the Selective Tree, and the egress PEs, MUST switch to the Selective Tree for the streams that are mapped to it. Once a source PE decides to setup an Selective Tree, it MUST announce the mapping of the streams (which may be in different VPLSs) that are mapped to the tree to the other PEs using BGP. Depending on the P-multicast technology used, this announcement may be done before or after setting up the Selective Tree. After the egress PEs receive the announcement they setup their forwarding path to receive traffic on the Selective Tree if they have one or more receivers interested in the streams mapped to the tree. Setting up the forwarding path requires setting up the demultiplexing forwarding entries based on the top MPLS label (if there is no inner label) or the inner label (if present) as described in section 9. The egress PEs may perform this switch to the Selective Tree once the advertisement from the ingress PE is received or wait for a preconfigured timer to do so. A source PE MUST use the following approach to decide when to start transmitting data on the Selective tree. A certain pre-configured delay after advertising the streams mapped to an Selective Tree, the source PE begins to send traffic on the Selective Tree. At this point it stops to send traffic for the streams, that are mapped on the Selective Tree, on the Inclusive Tree. This traffic is instead transmitted on the Selective Tree. 11.2. Advertising C-(S, G) Binding to a Selective Tree using BGP The ingress PE informs all the PEs that are on the path to receivers of the C-(S, G) of the binding of the Selective Tree to the C-(S, G). The BGP announcement is done by sending update for the MCAST-VPLS address family. A Selective Tree A-D route is used, containing the following information: + a) IP address of the originating PE b) The RD configured locally for the MVPN. This is required to uniquely identify the as the addresses could overlap between different VPLSs. This is the same RD value used in the VPLS auto-discovery process. c) The C-Source address. Raggarwa, Kamite & Fang [Page 27] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 d) The C-Group address. e) A PE MAY aggregate two or more (C-S, C-G)s originated by the PE onto the same P-Multicast tree. If the PE already advertises Selective Tree auto-discovery routes for these Selective Trees, then aggregation requires the PE to re-advertise these routes. The re-advertised routes MUST be the same as the original ones, except for the PMSI tunnel attribute. If the PE has not previously advertised Selective Tree auto-discovery routes for these (C-S, C-G)s, then the aggregation requires the PE to advertise (new) Selective Tree auto-discovery routes for these (C-S, C-G)s. The PMSI Tunnel attribute in the newly advertised/re-advertised routes MUST carry the identity of the P- Multicast tree that aggregates the (C-S, C-G)s. If at least some of the (C-S, C-G)s aggregated onto the same P-Multicast tree belong to different VPLSs, then all these routes MUST carry an MPLS upstream assigned label [MPLS-UPSTREAM]. If all these aggregated (C-S, C-G)s belong to the same VPLS, then the routes MAY carry an MPLS upstream assigned label [MPLS-UPSTREAM]. The labels MUST be distinct on a per VPLS basis, and MAY be distinct on a per route basis. When a PE distributes this information via BGP, it must include the following: + 1. A PMSI Tunnel Attribute to identify the Selective Tree to which the stream is bound. + Route Target Extended Communities attribute. This is used as described in section 8. 11.2.1. Explicit Tracking If the PE wants to enable explicit tracking for the specified flow, it also indicates this in the A-D route it uses to bind the flow to a particular Selective Tree. Then any PE which receives the A-D route will respond with a "Leaf A-D Route" in which it identifies itself as a receiver of the specified flow. The Leaf A-D route will be withdrawn when the PE is no longer a receiver for the flow. If the PE needs to enable explicit tracking for a flow before binding the flow to an Selective Tree, it can do so by sending an A-D route identifying the flow but not specifying an Selective Tree. This will elicit the Leaf A-D Routes. This is useful when the PE needs to know the receivers before selecting an Selective Tree. Raggarwa, Kamite & Fang [Page 28] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 11.3. Inter-AS Selective Tree Inter-AS Selective Trees support all three models of inter-AS VPLS service, option (a), (b) and (c), that are supported by Inter-AS Inclusive Trees. They are constructed in a manner that is very similar to Inter-AS Inclusive Trees. For option (a) and option (b) support inter-AS Selective Trees are constructed without requiring a single P-multicast tree to span multiple ASes. This allows individual ASes to potentially use different P-tunneling technologies.There are two variants of this model. One that requires MAC and IP multicast lookup on the ASBRs and another that does not require MAC/IP multicast lookup on the ASBRs and instead builds segmented inter-AS Selective trees. Segmented Inter-AS Selective trees can also be used with option (c) unlike Segmented Inter-AS Inclusive trees. This is because the Selective tree A-D routes can be exchanged via ASBRs (even though BGP-VPLS NLRI or A-D routes are not exchanged via ASBRs). In the case of Option (c) an Inter-AS Selective tree may also be a non-segmented P-multicast tree that spans multiple ASs. 11.3.1. VSIs on the ASBRs The requirements on ASBRs in this model include the requirements presented in section 11. The source ASBR (that receives traffic from another AS) may independently decide whether it wishes to use Selective Trees or not. If it uses Selective Trees the source ASBR MUST perform an IP multicast lookup to determine the Selective Tree to forward the VPLS packet on. 11.3.1.1. VPLS Inter-AS Selective Tree A-D Binding The mechanisms for propagating Selective Tree A-D routes are the same as the intra-AS case described in section 12.2. The BGP Selective Tree A-D routes generated by PEs in an AS MUST NOT be propagated outside the AS. 11.3.2. Inter-AS Segmented Selective Trees Inter-AS Segmented Selective trees MUST be used when option (b) is used to provide the inter-AS VPLS service. They MAY be used when option (c) is used to provide the inter-AS VPLS service. Raggarwa, Kamite & Fang [Page 29] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 A Segmented inter-AS Selective Tunnel is constructed similar to an inter-AS Segmented Inclusive Tunnel. Namely, such a tunnel is constructed as a concatenation of tunnel segments. There are two types of tunnel segments: an intra-AS tunnel segment (a segment that spans ASBRs within the same AS), and inter-AS tunnel segment (a segment that spans adjacent ASBRs in adjacent ASes). ASes that are spanned by a tunnel are not required to use the same tunneling mechanism to construct the tunnel - each AS may pick up a tunneling mechanism to construct the intra-AS tunnel segment of the tunnel, in its AS. The PE that decides to set up a Selective Tree, advertises the Selective Tree to (C-S, C-G) binding using a Selective Tree A-D route as per procedures in section 12.2, to the routers in its own AS. A Selective Tree A-D route advertised outside the AS, to which the originating PE belongs, will be referred to as an inter-AS Selective Tree A-D route (Although this route is originated by a PE as an intra-AS route it is referred to as an inter-AS route outside the AS). An ASBR that receives the information from its upstream ASBR using E- BGP sends back a tunnel binding for AS information 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. If the ASBR instantiates a Selective Tree for the AS it sends back a downstream label that is used to forward the packet along its intra-AS Selective Tree segment for . However, in the case of option (b) the ASBR may decide to use an AS Inclusive Tree segment instead, in which case it sends back the same label that it advertised for the AS-AS segment of the inter-AS segmented Inclusive tree. (This is not possible in option (c) as in option (c) the ASBRs do not participate in inter-AS Inclusive tree setup). If the downstream ASBR instantiates a Selective Tree, it further propagates the Selective Tree A-D route to its downstream ASes. An AS can instantiate an intra-AS Selective Tree segment for the inter-AS Selective tunnel only if the upstream AS instantiates a Selective Tree. The procedures allow each AS to determine whether it wishes to setup a Selective Tree or not and the AS is not forced to setup a Selective Tree just because the upstream AS decides to do so. Raggarwa, Kamite & Fang [Page 30] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 The leaves of an intra-AS Selective Tree will be the PEs that have local receivers that are interested in and the ASBRs that have received VPLS control information for . The C-multicast data traffic is sent on the Selective Tree by the originating PE. When it reaches an ASBR that is on the spanning tree, it is delivered to local receivers, if any, and is also forwarded to the neighbor ASBR after being encapsulated in the label advertised by the neighbor. The neighbor ASBR either transports this packet on the Selective Tree segment for the multicast stream or an Inclusive Tree segment, delivering it to the ASBRs in its own AS. These ASBRs in turn repeat the procedures of the origin AS ASBRs and the multicast packet traverses the spanning tree. The (C-S, C-G) membership for which the Selective Tree is instantiated, is propagated inter-AS using procedures in [VPLS-CTRL]. 11.3.3. Inter-AS Non-Segmented Selective Trees Inter-AS Non-segmented Selective trees may be used in the case of option (c). In this method, there is a multi-hop E-BGP peering between the PEs (or a Route Reflector) in one AS and the PEs (or Route Reflector) in another AS. The PEs exchange BGP Selective tree A-D routes, along with PMSI Tunnel Attribute, as in the intra-AS case described in section 12.2. The PEs in different ASs use a non-segmented Selective inter-AS P2MP tunnel for VPLS multicast. This method requires no VPLS information (in either the control or the data plane) on the ASBRs. The ASBRs only need to participate in the non-segmented P2MP tunnel setup in the control plane, and do MPLS label forwarding in the data plane. The data forwarding in this model is the same as in the intra-AS case described in section 9. Raggarwa, Kamite & Fang [Page 31] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 12. BGP Extensions This section describes the encoding of the BGP extensions required by this document. 12.1. Inclusive Tree/Selective Tree Identifier Inclusive Tree and Selective Tree advertisements carry the Tree identifier. This document defines and uses a new BGP attribute, called PMSI Tunnel Attribute. This is an optional transitive BGP attribute. The format of this attribute is defined as follows: +---------------------------------+ | Flags (1 octet) | +---------------------------------+ | Tunnel Type (1 octets) | +---------------------------------+ | MPLS Label (3 octets) | +---------------------------------+ | Tunnel Identifier (variable) | +---------------------------------+ The Flags field has the following format: 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ | reserved |L| +-+-+-+-+-+-+-+-+ This document defines the following flags: + Leaf Information Required (L) The Tunnel Type identifies the type of the tunneling technology used to establish the P-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 + 6 - Ingress Replication 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 Raggarwa, Kamite & Fang [Page 32] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 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. When the type is set to LDP P2MP LSP, the Tunnel Identifier is . When the type is set to Ingress Replication the Tunnel Identifier carries the unicast tunnel endpoint. 12.2. MCAST-VPLS NLRI This document defines a new BGP NLRI, called the MCAST-VPLS NLRI. Following is the format of the MCAST-VPLS NLRI: +-----------------------------------+ | Route Type (1 octet) | +-----------------------------------+ | Length (1 octet) | +-----------------------------------+ | Route Type specific (variable) | +-----------------------------------+ The Route Type field defines encoding of the rest of MCAST-VPLS NLRI (Route Type specific MCAST-VPLS NLRI). The Length field indicates the length in octets of the Route Type specific field of MCAST-VPLS NLRI. This document defines the following Route Types for auto-discovery routes: + 3 - Selective Tree auto-discovery route; + 4 - Leaf auto-discovery route. The MCAST-VPLS NLRI is carried in BGP using BGP Multiprotocol Extensions [RFC4760] with an AFI of 25 (L2VPN AFI), and an SAFI of MCAST-VPLS. The NLRI field in the MP_REACH_NLRI/MP_UNREACH_NLRI attribute contains the MCAST-VPLS NLRI (encoded as specified above). In order for two BGP speakers to exchange labeled MCAST-VPLS NLRI, they must use BGP Capabilities Advertisement to ensure that they both are capable of properly processing such NLRI. This is done as specified in [RFC4760], by using capability code 1 (multiprotocol Raggarwa, Kamite & Fang [Page 33] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 BGP) with an AFI of 25 and an SAFI of MCAST-VPLS. The following describes the format of the Route Type specific MCAST- VPLS NLRI for various Route Types defined in this document. 12.2.1. Selective Tree auto-discovery route An Selective Tree A-D route type specific MCAST-VPLS NLRI consists of the following: +-----------------------------------+ | RD (8 octets) | +-----------------------------------+ | Multicast Source Length (1 octet) | +-----------------------------------+ | Multicast Source (Variable) | +-----------------------------------+ | Multicast Group Length (1 octet) | +-----------------------------------+ | Multicast Group (Variable) | +-----------------------------------+ | Originating Router's IP Addr | +-----------------------------------+ The RD is encoded as described in [RFC4364]. The Multicast Source field contains the C-S address. 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 Multicast Group field contains the C-G 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. Usage of Selective Tree auto-discovery routes is described in Section 12. Raggarwa, Kamite & Fang [Page 34] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 12.2.2. Leaf auto-discovery route A leaf auto-discovery route type specific MCAST-VPLS NLRI consists of the following: +-----------------------------------+ | Route Key (variable) | +-----------------------------------+ | Originating Router's IP Addr | +-----------------------------------+ Usage of Leaf auto-discovery routes is described in sections "Inter- AS Inclusive Multicast Tree A-D/Binding" and "Optimizing Multicast Distribution via Selective Trees". 13. Aggregation Methodology In general the herustics used to decide which VPLS instances or entries to aggregate is implementation dependent. It is also conceivable that offline tools can be used for this purpose. This section discusses some tradeoffs with respect to aggregation. The "congruency" of aggregation is defined by the amount of overlap in the leaves of the client trees that are aggregated on a SP tree. For Aggregate Inclusive Trees the congruency depends on the overlap in the membership of the VPLSs that are aggregated on the Aggregate Inclusive Tree. If there is complete overlap aggregation is perfectly congruent. As the overlap between the VPLSs that are aggregated reduces, the congruency reduces. If aggregation is done such that it is not perfectly congruent a PE may receive traffic for VPLSs to which it doesn't belong. As the amount of multicast traffic in these unwanted VPLSs increases aggregation becomes less optimal with respect to delivered traffic. Hence there is a tradeoff between reducing state and delivering unwanted traffic. An implementation should provide knobs to control the congruency of aggregation. This will allow a SP to deploy aggregation depending on the VPLS membership and traffic profiles in its network. If different PEs or shared roots' are setting up Aggregate Inclusive Trees this will also allow a SP to engineer the maximum amount of unwanted VPLSs that a particular PE may receive traffic for. The state/bandwidth optimality trade-off can be further improved by having a versatile many-to-many association between client trees and provider trees. Thus a VPLS can be mapped to multiple Aggregate Raggarwa, Kamite & Fang [Page 35] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 Trees. The mechanisms for achieving this are for further study. Also it may be possible to use both ingress replication and an Aggregate Tree for a particular VPLS. Mechanisms for achieving this are also for further study. 14. Data Forwarding 14.1. MPLS Tree Encapsulation The following diagram shows the progression of the VPLS IP multicast packet as it enters and leaves the SP network when MPLS trees are being used for multiple VPLS instances. RSVP-TE P2MP LSPs are examples of such trees. Packets received Packets in transit Packets forwarded at ingress PE in the service by egress PEs provider network +---------------+ |MPLS Tree Label| +---------------+ | VPLS Label | ++=============++ ++=============++ ++=============++ ||C-Ether Hdr || || C-Ether Hdr || || C-Ether Hdr || ++=============++ >>>>> ++=============++ >>>>> ++=============++ || C-IP Header || || C-IP Header || || C-IP Header || ++=============++ >>>>> ++=============++ >>>>> ++=============++ || C-Payload || || C-Payload || || C-Payload || ++=============++ ++=============++ ++=============++ The receiver PE does a lookup on the outer MPLS tree label and determines the MPLS forwarding table in which to lookup the inner MPLS label. This table is specific to the tree label space. The inner label is unique within the context of the root of the tree (as it is assigned by the root of the tree, without any coordination with any other nodes). Thus it is not unique across multiple roots. So, to unambiguously identify a particular VPLS one has to know the label, and the context within which that label is unique. The context is provided by the outer MPLS label [MPLS-UPSTREAM]. The outer MPLS label is stripped. The lookup of the resulting MPLS label determines the VSI in which the receiver PE needs to do the C- multicast data packet lookup. It then strips the inner MPLS label and Raggarwa, Kamite & Fang [Page 36] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 sends the packet to the VSI for multicast data forwarding. 15. VPLS Multicast/Broadcast/Unknown Unicast Data Packet Treatment If the destination MAC address of a VPLS packet received by a PE from a VPLS site is a multicast adddress, a multicast tree SHOULD be used to transport the packet, if possible. If the packet is an IP multicast packet and a Selective tree exists for that multicast stream, the Selective tree SHOULD be used. Else if an Inclusive tree exists for the VPLS, it SHOULD be used. If the destination MAC address of a VPLS packet is a broadcast address, it is flooded. If Inclusive tree is already established, PE SHOULD flood over it. If Inclusive Tree cannot be used for some reason, PE MUST flood over multiple PWs, based on [RFC4761] or [RFC4762]. If the destination MAC address of a packet is a unicast address and it has not been learned, the packet MUST be sent to all PEs in the VPLS. Inclusive multicast trees SHOULD be used for sending unknown unicast MAC packets to all PEs. When this is the case the receiving PEs MUST support the ability to perform MAC address learning for packets received on a multicast tree. In order to perform such learning, the receiver PE MUST be able to determine the sender PE when a VPLS packet is received on a multicast tree. This further implies that the MPLS multicast tree technology MUST allow the egress PE to determine the sender PE from the received MPLS packet. When a receiver PE receives a VPLS packet with a source MAC address, that has not yet been learned, on a multicast tree, the receiver PE determines the PW to the sender PE. The receiver PE then creates forwarding state in the VPLS instance with a destination MAC address being the same as the source MAC address being learned, and the PW being the PW to the sender PE. It should be noted that when a sender PE that is sending packets destined to an unknown unicast MAC address over a multicast tree learns the PW to use for forwarding packets destined to this unicast MAC address, it might immediately switch to transport such packets over this particular PW. Since the packets were initially being forwarded using a multicast tree, this could lead to packet reordering. This constraint should be taken into consideration if unknown unicast frames are forwarded using a Inclusive Tree, instead of multiple PWs based on [RFC4761] or [RFC4762]. An implementation MUST support the ability to transport unknown unicast traffic over Inclusive multicast trees. Further an Raggarwa, Kamite & Fang [Page 37] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 implementation MUST support the ability to perform MAC address learning for packets received on a multicast tree. 16. Security Considerations Security considerations discussed in [RFC4761] and [RFC4762] apply to this document. This section describes additional considerations. As mentioned in [RFC4761], there are two aspects to achieving data privacy in a VPLS: securing the control plane and protecting the forwarding path. Compromise of the control plane could result in a PE sending multicast data belonging to some VPLS to another VPLS, or blackholing VPLS multicast data, or even sending it to an eavesdropper; none of which are acceptable from a data privacy point of view. The mechanisms in this document use BGP for the control plane. Hence techniques such as in [RFC2385] help authenticate BGP messages, making it harder to spoof updates (which can be used to divert VPLS traffic to the wrong VPLS) or withdraws (denial-of- service attacks). In the multi-AS methods (b) and (c) described in Section 11, this also means protecting the inter-AS BGP sessions, between the ASBRs, the PEs, or the Route Reflectors. Note that [RFC2385] will not help in keeping MPLS labels, associated with P2MP LSPs or the upstream MPLS labels used for aggregation, private -- knowing the labels, one can eavesdrop on VPLS traffic. However, this requires access to the data path within a Service Provider network. One of the requirements for protecting the data plane is that the MPLS labels are accepted only from valid interfaces. This applies both to MPLS labels associated with P2MP LSPs and also applies to the upstream assigned MPLS labels. For a PE, valid interfaces comprise links from P routers. For an ASBR, a valid interface is a link from another ASBR in an AS that is part of a given VPLS. It is especially important in the case of multi-AS VPLSs that one accept VPLS packets only from valid interfaces. 17. IANA Considerations This document defines a new NLRI, called MCAST-VPLS, to be carried in BGP using multiprotocol extensions. It requires assignment of a new SAFI. This is to be assigned by IANA. This document defines a BGP optional transitive attribute, called PMSI Attribute. This is the same attribute as the one defined in [BGP-MVPN] and the code point for this attribute has already been Raggarwa, Kamite & Fang [Page 38] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 assigned by IANA as 22 [BGP-IANA]. Hence no further action is required from IANA regarding this attribute. 18. Acknowledgments Many thanks to Thomas Morin for his support of this work. We would also like to thank authors of [BGP-MVPN] and [MVPN] as the details of the inter-AS segmented tree procedures in this document have benefited from those in [BGP-MVPN] and [MVPN]. 19. Normative References [RFC2119] "Key words for use in RFCs to Indicate Requirement Levels.", Bradner, March 1997 [RFC4761] K. Kompella, Y. Rekther, "Virtual Private LAN Service", draft-ietf-l2vpn-vpls-bgp-02.txt [RFC4762] M. Lasserre, V. Kompella, "Virtual Private LAN Services over MPLS", draft-ietf-l2vpn-vpls-ldp-03.txt [RFC4760] T. Bates, et. al., "Multiprotocol Extensions for BGP-4", January 2007 [MPLS-UPSTREAM] R. Aggarwal, Y. Rekhter, E. Rosen, "MPLS Upstream Label Assignment and Context Specific Label Space", draft-ietf-mpls- upstream-label-00.txt 20. Informative References [VPLS-CTRL] R. Aggarwal, Y. Kamite, L. Fang, "Propagation of VPLS IP Multicast Group Membership Information", draft-raggarwa-l2vpn-vpls- mcast-ctrl-00.txt [L2VPN-SIG] E. Rosen et. al., "Provisioning, Autodiscovery, and Signaling in L2VPNs", draft-ietf-l2vpn-signaling-08.txt [MPLS-MCAST] T. Eckert, E. Rosen, R. Aggarwal, Y. Rekhter, "MPLS Multicast Encapsulations", draft-ietf-mpls-multicast-encaps-00.txt [MVPN] E. Rosen, R. Aggarwal, "Multicast in 2547 VPNs", draft-ietf- l3vpn-2547bis-mcast-05.txt" [BGP-MVPN] R. Aggarwal, E. Rosen, Y. Rekhter, T. Morin, C. Kodeboniya. "BGP Encodings for Multicast in 2547 VPNs", draft-ietf- Raggarwa, Kamite & Fang [Page 39] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 l3vpn-2547bis-mcast-bgp-03.txt [RFC4875] R. Aggarwal et. al, "Extensions to RSVP-TE for Point to Multipoint TE LSPs", draft-ietf-mpls-rsvp-te-p2mp-07.txt [RSVP-OBB] Z. Ali, G. Swallow, R. Aggarwal, "Non PHP behavior and out-of-band mapping for RSVP-TE LSPs", draft-ietf-mpls-rsvp-te-no- php-obb-mapping-00.txt [MLDP] I. Minei et. al, "Label Distribution Protocol Extensions for Point-to-Multipoint and Multipoint-to-Multipoint Label Switched Paths", draft-ietf-mpls-ldp-p2mp-02.txt [RFC4364] "BGP MPLS VPNs", E. Rosen, Y.Rekhter, February 2006 [MCAST-VPLS-REQ] Y. kamite, et. al., "Requirements for Multicast Support in Virtual Private LAN Services", draft-ietf-l2vpn-vpls- mcast-reqts-05.txt [RFC1997] R. Chandra, et. al., "BGP Communities Attribute", August 1996 [BGP-IANA] http://www.iana.org/assignments/bgp-parameters [RFC4684] P. Marques et. al., "Constrained Route Distribution for Border Gateway Protocol/MultiProtocol Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual Private Networks (VPNs)", RFC 4684, November 2006 [RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5 Signature Option", RFC 2385, August 1998. 21. Author's Address Rahul Aggarwal Juniper Networks 1194 North Mathilda Ave. Sunnyvale, CA 94089 USA Phone: +1-408-936-2720 Email: rahul@juniper.net Yuji Kamite NTT Communications Corporation Tokyo Opera City Tower 3-20-2 Nishi Shinjuku, Shinjuku-ku, Tokyo 163-1421, Raggarwa, Kamite & Fang [Page 40] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 Japan Email: y.kamite@ntt.com Luyuan Fang Cisco Systems 300 Beaver Brook Road BOXBOROUGH, MA 01719 USA Email: lufang@cisco.com Yakov Rekhter Juniper Networks 1194 North Mathilda Ave. Sunnyvale, CA 94089 USA Email: yakov@juniper.net Chaitanya Kodeboniya 22. Intellectual Property Statement 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 in BCP 78 and BCP 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 at http://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. Raggarwa, Kamite & Fang [Page 41] Internet Draft draft-ietf-l2vpn-vpls-mcast-04.txt June 2008 23. Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 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, THE IETF TRUST 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. Raggarwa, Kamite & Fang [Page 42]