Network Working Group I. Wijnands (Editor) Internet-Draft T. Eckert Intended status: Standards Track Cisco Systems, Inc. Expires: April 27, 2010 N. Leymann Deutsche Telekom M. Napierala AT&T Labs October 24, 2009 mLDP based in-band signaling for Point-to-Multipoint and Multipoint-to- Multipoint Label Switched Paths draft-wijnands-mpls-mldp-in-band-signaling-02 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. 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. This Internet-Draft will expire on April 27, 2010. Copyright Notice Wijnands (Editor), et al. Expires April 27, 2010 [Page 1] Internet-Draft In-band signaling with mLDP October 2009 Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract When an IP multicast tree needs to pass through an MPLS domain, it is advantageous to map the tree to a Point-to-Multipoint or Multipoint- to-Multipoint Label Switched Path. This document specifies a way to provide a one-one mapping between IP multicast trees and Label Switched Paths using mLDP signaling. The IP multicast control messages are translated into MPLS control messages when they enter the MPLS domain, and are translated back into IP multicast control messages at the far end of the MPLS domain. The IP multicast control information is coded into the MPLS control information in such a way as to ensure that a single Multipoint Label Switched Path gets set up for each IP multicast tree. Wijnands (Editor), et al. Expires April 27, 2010 [Page 2] Internet-Draft In-band signaling with mLDP October 2009 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Conventions used in this document . . . . . . . . . . . . 4 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 2. In-band signaling for MP LSPs . . . . . . . . . . . . . . . . 5 2.1. Transiting IP multicast source trees . . . . . . . . . . . 6 2.2. Transiting IP multicast bidirectional trees . . . . . . . 6 2.3. Transiting IP multicast shared Trees . . . . . . . . . . . 7 3. LSP opaque encodings . . . . . . . . . . . . . . . . . . . . . 7 3.1. Transit IPv4 Source TLV . . . . . . . . . . . . . . . . . 7 3.2. Transit IPv6 Source TLV . . . . . . . . . . . . . . . . . 8 3.3. Transit IPv4 bidir TLV . . . . . . . . . . . . . . . . . . 8 3.4. Transit IPv6 bidir TLV . . . . . . . . . . . . . . . . . . 9 4. Security Considerations . . . . . . . . . . . . . . . . . . . 10 5. IANA considerations . . . . . . . . . . . . . . . . . . . . . 10 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 7. Contributing authors . . . . . . . . . . . . . . . . . . . . . 10 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 8.1. Normative References . . . . . . . . . . . . . . . . . . . 11 8.2. Informative References . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Wijnands (Editor), et al. Expires April 27, 2010 [Page 3] Internet-Draft In-band signaling with mLDP October 2009 1. Introduction The mLDP specification [I-D.ietf-mpls-ldp-p2mp] describes mechanisms for creating point-to-multipoint (P2MP) and multipoint-to-multipoint MP2MP LSPs. These LSPs are typically used for transporting enduser multicast packets. However, the mLDP specification [I-D.ietf-mpls-ldp-p2mp] does not provide any rules for associating particular enduser multicast packets with any particular LSP. Other drafts, like [I-D.ietf-l3vpn-2547bis-mcast], describe applications in which out-of-band signaling protocols, such as PIM and BGP, are used to establish the mapping between an LSP and the multicast packets that need to be forwarded over the LSP. This draft describes an application in which the information needed to establish the mapping between an LSP and the set of multicast packets to be forwarded over it is carried in the "opaque value" field of an mLDP FEC element. When an IP multicast tree (either a source-specific tree or a bidirectional tree) enters the MPLS network, the IP multicast control messages used to set up the tree are translated into mLDP messages. The (S,G) or (*,G) information from the IP multicast control messages is carried in the opaque value field of the mLDP FEC message. As the tree leaves the MPLS network, this information is extracted from the FEC element and used to build the IP multicast control messages that are sent outside the MPLS domain. Note that although the IP multicast control messages are sent periodically, the mLDP messages are not. Each IP multicast tree is mapped one-to-one to a P2MP or MP2MP LSP in the MPLS network. This type of service works well if the number of LSPs that are created is under control of the MPLS network operator, or if the number of LSPs for a particular service are known to be limited in number. 1.1. Conventions used in this document 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 RFC 2119 [RFC2119]. 1.2. Terminology IP multicast tree : An IP multicast distribution tree identified by an source IP address and/or IP multicast destination address, also refered to as (S,G) and (*,G). Wijnands (Editor), et al. Expires April 27, 2010 [Page 4] Internet-Draft In-band signaling with mLDP October 2009 mLDP : Multicast LDP. Transit LSP : An P2MP or MP2MP LSP whose FEC element contains the (S,G) or (*,G) identifying a particular IP multicast distribution tree. In-band signaling : Using the opaque value of a mLDP FEC element to signal multicast route information. P2MP LSP: An LSP that has one Ingress LSR and one or more Egress LSRs. MP2MP LSP: An LSP that connects a set of leaf nodes, acting indifferently as ingress or egress. MP LSP: A multipoint LSP, either a P2MP or an MP2MP LSP. Ingress LSR: Source of the P2MP LSP, also referred to as root node. Egress LSR: One of potentially many destinations of an LSP, also referred to as leaf node in the case of P2MP and MP2MP LSPs. Transit LSR: An LSR that has one or more directly connected downstream LSRs. 2. In-band signaling for MP LSPs Suppose an LSR, call it D, is attached to a network that is capable of MPLS multicast and IP multicast, and D has the desire to create IP multicast tree due to a certain IP multicast event, like a PIM Join, MSDP Source Announcement (SA) [RFC3618] or RP discovery. Suppose that D can determine that the IP multicast tree needs to travel through the MPLS network until it reaches some other LSR, U. For instance, when D looks up the route to the Source or Rendezvous Point (RP) [RFC4601] of the IP multicast tree, it may discover that the route is a BGP route with U as the BGP next hop. Then D may chose to set up a P2MP or MP2MP LSP, with U as root, and to make that LSP become part of the IP multicast distribution tree. Note that other methods are possible to determine that an IP multicast tree is to be Wijnands (Editor), et al. Expires April 27, 2010 [Page 5] Internet-Draft In-band signaling with mLDP October 2009 transported across an MPLS network using P2MP or MP2MP LSPs, these methods are outside the scope of this document. Source or RP addresses that are reachable in a VPN context are outside the scope of this document. In order to send the multicast stream via a P2MP or MP2MP LSP using in-band signaling the source and the group will be encoded into an mLDP opaque TLV encoding [I-D.ietf-mpls-ldp-p2mp]. The type of encoding depends on the IP version. The tree type (P2MP or MP2MP) depends on whether this is a source specific or a bidirectional multicast stream. The root of the tree is the BGP next-hop that was found during the route lookup on the source or RP. Using this information a mLDP FEC is created and the LSP is build towards the root of the LSP. When an LSR receives a label mapping or withdraw and discovers it is the root of the identified P2MP or MP2MP LSP, then the following procedure will be executed. If the opaque encoding of the FEC indicates this is an Transit LSP (indicated by the opaque type), the opaque TLV will be decoded and the multicast source and group is passed to the multicast code. If the multicast tree information was received via a label mapping, the multicast code will effectively treat this as a positif indication to create a IP multicast tree based on the received information. If it was due to a label withdraw, the multicast code will effectively treat this as having received a negative indication and it will remove the tree indentified by the encoded information. From this point on normal PIM processing will occur. 2.1. Transiting IP multicast source trees IP multicast source trees can either be created via PIM operating in SSM mode [RFC4607] or ASM mode [RFC4601] (for example via last hop behavior or MSDP [RFC3618]) and MUST be transporting across the MPLS network using a P2MP LSP. A Transit LSP may be setup to forward the IP multicast traffic across an MPLS core. If the multicast source is reachable in a global table the source and group addresses are encoded into the a transit TLV. Depending on the IP version it is either Section 3.1 or Section 3.2. 2.2. Transiting IP multicast bidirectional trees Bidirectional IP multicast trees [RFC5015] MUST be transported across a MPLS network using MP2MP LSPs. A bidirectional tree does not have a specific source address; only the group address and subnet mask are relevant for multicast forwarding. The RP for the group already known by IP multicast is used to select the ingress PE and root of Wijnands (Editor), et al. Expires April 27, 2010 [Page 6] Internet-Draft In-band signaling with mLDP October 2009 the LSP. The group address is encoded in either Section 3.3 or Section 3.4, depending on the IP version. The subnet mask associated with the bidirectional group is encoded in the Transit TLV. There are two types of bidirection states in IP multicast, the group specific state and the RPA state. The first type is typlically created due to receiving a PIM join and has a subnet mask of 32 for IPv4 and 128 for IPv6, the latter is typically created via the RP mapping protocol and has a variable subnet mask. The RPA state is used to build a tree to the RP and used for sender only branches. Please see [RFC5015] for more details. 2.3. Transiting IP multicast shared Trees Nothing prevents PIM shared trees from being transported across a MPLS core. However, it is not possible to prune of individual sources from the shared tree without the use of an additional out-of- band signaling protocol, like PIM. For that reason transiting Shared Trees across a Transit LSP is outside the scope of this draft. 3. LSP opaque encodings This section documents the different transit opaque encodings. 3.1. Transit IPv4 Source TLV 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Source +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Group +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: 2 (to be assigned by IANA). Length: 8 Wijnands (Editor), et al. Expires April 27, 2010 [Page 7] Internet-Draft In-band signaling with mLDP October 2009 Source: IPv4 multicast source address, 4 octets. Group: IPv4 multicast group address, 4 octets. 3.2. Transit IPv6 Source TLV 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Source ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ | Group ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: 3 (to be assigned by IANA). Length: 32 Source: IPv6 multicast source address, 16 octets. Group: IPv6 multicast group address, 16 octets. 3.3. Transit IPv4 bidir TLV 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Mask Len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RP | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Group | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Wijnands (Editor), et al. Expires April 27, 2010 [Page 8] Internet-Draft In-band signaling with mLDP October 2009 Type: 4 (to be assigned by IANA). Length: 9 Mask Len: The number of contiguous one bits that are left justified and used as a mask, 1 octet. RP: Rendezvous Point (RP) IPv4 address used for encoded Group, 4 octets. Group: IPv4 multicast group address, 4 octets. 3.4. Transit IPv6 bidir TLV 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Mask Len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RP ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Group ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: 4 (to be assigned by IANA). Length: 33 Mask Len: The number of contiguous one bits that are left justified and used as a mask, 1 octet. Wijnands (Editor), et al. Expires April 27, 2010 [Page 9] Internet-Draft In-band signaling with mLDP October 2009 RP: Rendezvous Point (RP) IPv6 address used for encoded group, 16 octets. Group: IPv6 multicast group address, 16 octets. 4. Security Considerations The same security considerations apply as for the base LDP specification, as described in [RFC5036]. 5. IANA considerations This document requires allocation from the LDP MP Opaque Value Element type name space managed by IANA. The values requested are: Transit IPv4 Source TLV type - requested 2 Transit IPv6 Source TLV type - requested 3 Transit IPv4 Bidir TLV type - requested 4 Transit IPv6 Bidir TLV type - requested 5 6. Acknowledgments Thanks to Eric Rosen for his valuable comments on this draft. Also thanks to Yakov Rekhter, Adrial Farrel and Uwe Joorde for providing comments on this draft. 7. Contributing authors Below is a list of the contributing authors in alphabetical order: Toerless Eckert Cisco Systems, Inc. 170 Tasman Drive San Jose, CA, 95134 USA E-mail: eckert@cisco.com Wijnands (Editor), et al. Expires April 27, 2010 [Page 10] Internet-Draft In-band signaling with mLDP October 2009 Nicolai Leymann Deutsche Telekom Winterfeldtstrasse 21 Berlin, 10781 Germany E-mail: n.leymann@telekom.de Maria Napierala AT&T Labs 200 Laurel Avenue Middletown, NJ 07748 USA E-mail: mnapierala@att.com IJsbrand Wijnands Cisco Systems, Inc. De kleetlaan 6a 1831 Diegem Belgium E-mail: ice@cisco.com 8. References 8.1. Normative References [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP Specification", RFC 5036, October 2007. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [I-D.ietf-mpls-ldp-p2mp] Minei, I., "Label Distribution Protocol Extensions for Point-to-Multipoint and Multipoint-to-Multipoint Label Switched Paths", draft-ietf-mpls-ldp-p2mp-05 (work in progress), June 2008. 8.2. Informative References [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)", RFC 4601, August 2006. [RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for IP", RFC 4607, August 2006. Wijnands (Editor), et al. Expires April 27, 2010 [Page 11] Internet-Draft In-band signaling with mLDP October 2009 [RFC5015] Handley, M., Kouvelas, I., Speakman, T., and L. Vicisano, "Bidirectional Protocol Independent Multicast (BIDIR- PIM)", RFC 5015, October 2007. [RFC3618] Fenner, B. and D. Meyer, "Multicast Source Discovery Protocol (MSDP)", RFC 3618, October 2003. [I-D.ietf-l3vpn-2547bis-mcast] Aggarwal, R., Bandi, S., Cai, Y., Morin, T., Rekhter, Y., Rosen, E., Wijnands, I., and S. Yasukawa, "Multicast in MPLS/BGP IP VPNs", draft-ietf-l3vpn-2547bis-mcast-07 (work in progress), July 2008. Authors' Addresses IJsbrand Wijnands Cisco Systems, Inc. De kleetlaan 6a Diegem 1831 Belgium Email: ice@cisco.com Toerless Eckert Cisco Systems, Inc. 170 Tasman Drive San Jose CA, 95134 USA Email: eckert@cisco.com Nicolai Leymann Deutsche Telekom Winterfeldtstrasse 21 Berlin 10781 Germany Email: nicolai.leymann@t-systems.com Wijnands (Editor), et al. Expires April 27, 2010 [Page 12] Internet-Draft In-band signaling with mLDP October 2009 Maria Napierala AT&T Labs 200 Laurel Avenue Middletown NJ 07748 USA Email: mnapierala@att.com Wijnands (Editor), et al. Expires April 27, 2010 [Page 13]