MPLS Working Group D.
Frost, Ed.Frost Internet-Draft S. Bryant, Ed.Bryant Intended status: Informational Cisco Systems Expires: April 11,14, 2014 M. Bocci, Ed.Bocci Alcatel-Lucent L. Berger, Ed.Berger LabN Consulting October 11,14, 2013 A Framework for Point-to-Multipoint MPLS in Transport Networks draft-ietf-mpls-tp-p2mp-framework-03draft-ietf-mpls-tp-p2mp-framework-04 Abstract The Multiprotocol Label Switching (MPLS)Transport Profile (MPLS-TP)is the common set of MPLS protocol functions defined to enable the construction and operation of packet transport networks. The MPLS-TP supports both point-to-point and point-to-multipoint transport paths. This document defines the elements and functions of the MPLS-TP architecture applicable specifically to supporting point-to- multipoint transport paths. This document is a product of a joint Internet Engineering Task Force (IETF) / International Telecommunication Union Telecommunication Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS and PWE3 architectures to support the capabilities and functions of a packet transport network.Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on April 11,14, 2014. Copyright Notice Copyright (c) 2013 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 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 32 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2.1. Additional Definitions and Terminology . . . . . . . 3 1.3. Applicability . . . . . . . . . . . . . . . . . . . . . . 3 2. MPLS Transport Profile Point-to-Multipoint Requirements . . . 4 3. Architecture . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. MPLS-TP Encapsulation and Forwarding . . . . . . . . . . 5 4. Operations, Administration and Maintenance (OAM). . . . . . . . . 5 5. Control Plane . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1. Point-to-Multipoint LSP Control Plane . . . . . . . . . . 76 5.2. Point-to-Multipoint PW Control Plane . . . . . . . . . . 7 6. Survivability . . . . . . . . . . . . . . . . . . . . . . . . 7 7. Network Management . . . . . . . . . . . . . . . . . . . . . 87 8. Security Considerations . . . . . . . . . . . . . . . . . . . 8 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 10.1. Normative References . . . . . . . . . . . . . . . . . . 8 10.2. Informative References . . . . . . . . . . . . . . . . . 9 1. Introduction The Multiprotocol Label Switching (MPLS)Transport Profile (MPLS-TP)is the common set of MPLS protocol functions defined to meet the requirements specified in [RFC5654]. The MPLS-TP Framework [RFC5921] provides an overall introduction to the MPLS-TP and defines the general architecture of the Transport Profile, as well as those aspects specific to point-to-pointpoint-to- point transport paths. The purpose of this document is to define the elements and functions of the MPLS-TP architecture applicable specifically to supporting point-to- multipointpoint-to-multipoint transport paths. This document is a product of a joint Internet Engineering Task Force (IETF) / International Telecommunication Union Telecommunication Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS and PWE3 architectures to support the capabilities and functions of a packet transport network.1.1. Scope This document defines the elements and functions of the MPLS-TP architecture related to supporting point-to-multipoint transport paths. The reader is referred to [RFC5921] for those aspects of the MPLS-TP architecture that are generic, or concerned specifically with point-to-point transport paths. 1.2. Terminology Term Definition ------- --------------------------------------------------------------------------------------------- CE Customer Edge GMPLS Generalized MPLS LDP Label Distribution Protocol LSP Label Switched Path MPLS-TP MPLS Transport Profile SDH Synchronous Digital Hierarchy ATM Asynchronous Transfer Mode OTN Optical Transport Network OAM Operations, Administration and Maintenance G-ACh Generic Associated Channel GAL G-AChLSR Label Switching Router MEP Maintenance End Point MIP Maintenance Intermediate Point APS Automatic Protection Switching SCC Signaling Communication Channel MCC Management Communication Channel EMF Equipment Management Function FM Fault Management CM Configuration Management PM Performance Monitoring LSRMPLS Multiprotocol Label Switching RouterMPLS-TE MPLS Traffic Engineering MPLS-TP MPLS Transport Profile OAM Operations, Administration and Maintenance OTN Optical Transport Network P2MP Point-to-multipoint PW Pseudowire RSVP-TE Resource Reservation Protocol - Traffic Engineering SDH Synchronous Digital Hierarchy T-LDP Targeted LDP 1.2.1. Additional Definitions and Terminology Detailed definitions and additional terminology may be found in [RFC5921] and [RFC5654]. 1.3. Applicability The point-to-multipoint connectivity provided by an MPLS-TP network is based on the point-to-multipoint connectivity provided by MPLS networks. P2MP MPLS TE-LSP support is discussed in [RFC4875] and [RFC5332], and P2MP PW support is being developed based on [I-D.ietf-pwe3-p2mp-pw-requirements] and [I-D.ietf-l2vpn-vpms-frmwk-requirements]. MPLS-TP point-to- multipoint connectivity is analogous to that provided by traditional transport technologies such as Optical Transport Network (OTN) point- to-multipointpoint-to- multipoint [G.798] and drop-and-continue [G.780], and thus supports the same class of traditional applications, e.g., video distribution. There is no definition for MPLS TE-LSP support of multipoint-to- multipoint connectivity and none is anticipated. 2. MPLS Transport Profile Point-to-Multipoint Requirements The requirements for MPLS-TP are specified in [RFC5654], [RFC5860], and [RFC5951]. This section provides a brief summary of point-to- multipoint transport requirements as set out in those documents; the reader is referred to the documents themselves for the definitive and complete list of requirements. This summary does not include the [RFC2119] conformance language used in original documents as this document is not authoritative. o MPLS-TP must support unidirectional point-to-multipoint (P2MP)transport paths. o MPLS-TP must support traffic-engineered point-to-multipoint transport paths. o MPLS-TP must be capable of using P2MP server (sub)layer capabilities as well as P2P server (sub)layer capabilities when supporting P2MP MPLS-TP transport paths. o The MPLS-TP control plane must support establishing all the connectivity patterns defined for the MPLS-TP data plane (i.e., unidirectional P2P, associated bidirectional P2P, co-routed bidirectional P2P, unidirectional P2MP) including configuration of protection functions and any associated maintenance functions. o Recovery techniques used for P2P and P2MP should be identical to simplify implementation and operation. o Unidirectional 1+1 and 1:n protection for P2MP connectivity must be supported. o MPLS-TP recovery in a ring must protect unidirectional P2MP transport paths. 3. Architecture The overall architecture of the MPLS Transport Profile is defined in [RFC5921]. The architecture for point-to-multipoint MPLS-TP comprises the following additional elements and functions: o Unidirectional point-to-multipoint Label Switched Paths (LSPs)LSPs o Unidirectional point-to-multipoint pseudowires (PWs)PWs o Optional point-to-multipoint LSP and PW control planes o Survivability, network management, and Operations, Administration and Maintenance (OAM)functions for point-to-multipoint PWs and LSPs The following subsections summarise the encapsulation and forwarding of point-to-multipoint traffic within an MPLS-TP network, and the encapsulation options for delivery of traffic to and from MPLS-TP Customer EdgeCE devices when the network is providing a packet transport service. 3.1. MPLS-TP Encapsulation and Forwarding Packet encapsulation and forwarding for MPLS-TP point-to-multipoint LSPs is identical to that for MPLS-TE point-to-multipoint LSPs. MPLS-TE point-to-multipoint LSPs were introduced in [RFC4875] and the related data-plane behaviour was further clarified in [RFC5332]. MPLS-TP allows for both upstream-assigned and downstream-assigned labels for use with point-to-multipoint LSPs. Packet encapsulation and forwarding for point-to-multipoint PWs has been discussed bywithin the PWE3 Working Group [I-D.raggarwa-pwe3-p2mp-pw-encaps], but such definition is for further study. 4. Operations, Administration and Maintenance (OAM)The overall OAM architecture for MPLS-TP is defined in [RFC6371], and P2MP OAM design considerations are described in Section 3.7 of that RFC. All the traffic sent over a P2MP transport path, including OAM packets generated by a MEP, is sent (multicast) from the root to all the leaves, thus every OAM packet is sent to all leaves, and thus can simultaneously instrumentimpact all the MEs in a P2MP MEG. If an OAM packet is to be processed by only onea specific leaf, it requires information to indicate to all other leaves that the packet must be discarded. To address a packet to an intermediate node in the tree, TTL based addressing is used to set the radius and addressing information in the OAM payload is used to identify the specific destination node. P2MP paths are unidirectional; therefore, any return path to an originating MEP for on-demand transactions will be out-of-band. Out of band return paths are discussed in Section 3.8 of [RFC5921]. Packet Loss and Delay Measurement for MPLS Networks [RFC6374] already considers the P2MP case and it is not thought that anyno change is needed to the MPLS-TP profile of [RFC6375]. A more detailed discussion of P2MP OAM considerations can be found in [I-D.hmk-mpls-tp-p2mp-oam-framework]. 5. Control Plane The framework for the MPLS-TP control plane is provided in [RFC6373]. This document reviews MPLS-TP control plane requirements as well as provides details on how the MPLS-TP control plane satisfies these requirements. Most of the requirements identified in [RFC6373] apply equally to P2P and P2MP transport paths. The key P2MP specific control plane requirements are identified inare: o requirement 6 (P2MP transport paths), o requirement 34 (use P2P sub-layers), o requirement 49 (common recovery solutions for P2P and P2MP), o requirement 59 (1+1 protection), o requirement 62 (1:n protection), o and requirement 65 (1:n shared mesh recovery). [RFC6373] defines the control plane approach used to support MPLS-TP transport paths. It identifies Generalized MPLS (GMPLS)GMPLS as the control plane for MPLS-TP Label Switched Paths (LSPs) and Targeted LDP (T-LDP)MPLS- TP LSPs T-LDP as the control plane for pseudowires (PWs).PWs. MPLS-TP allows that either, or both, LSPs and PWs to be provisioned statically or via a control plane. As noted in [RFC6373]: The PW and LSP control planes, collectively, must satisfy the MPLS-TP control-plane requirements. As with P2P services, when P2MP client services are provided directly via LSPs, all requirements must be satisfied by the LSP control plane. When client services are provided via PWs, the PW and LSP control planes can operate in combination, and some functions may be satisfied via the PW control plane while others are provided to PWs by the LSP control plane. This is particularly noteworthy for P2MP recovery. 5.1. Point-to-Multipoint LSP Control Plane The MPLS-TP control plane for point-to-multipoint LSPs uses GMPLS and is based on Resource Reservation Protocol - Traffic Engineering (RSVP-TE)RSVP-TE for point-to-multipoint LSPs as defined in [RFC4875]. A detailed listing of how GMPLS satisfies MPLS-TP control plane requirements is provided in [RFC6373]. Per [RFC6373], the definitions of P2MP, [RFC4875], and GMPLS recovery, [RFC4872] and [RFC4873], do not explicitly cover their interactions. MPLS-TP requires a formal definition of recovery techniques for P2MP LSPs. Such a formal definition will be based on existing RFCs and may not require any new protocol mechanisms but, nonetheless, should be documented. Protection of P2MP LSPs is also discussed in [RFC6372] Section 4.7.3. 5.2. Point-to-Multipoint PW Control Plane The MPLS-TP control plane for point-to-multipoint PWs should be based on the LDP control protocol used for point-to-point PWs [RFC4447], with updates as required for P2MP applications. A detailed specification of the >control plane for P2MP PWs is for further study. 6. Survivability The overall survivability architecture for MPLS-TP is defined in [RFC6372], and section 4.7.3 in particular describes the application of linear protection to unidirectional P2MP entities using 1+1 and 1:1 protection architecture. For 1+1, the approach is for the root of the P2MP tree to bridge the user traffic to both the working and protection entities. Each sink/leaf MPLS-TP node selects the traffic from one entity according to some predetermined criteria. For 1:1, the source/root MPLS-TP node needs to identify the existence of a fault condition on any of the branches of the network. Fault notification happens from the node identifying the fault to the root node and from the leaves to the root via an out of band path. In either case the root then selects the protection transport path for traffic transfer. More sophisticated survivability approaches such as partial tree protection and 1:n protection are for further study. The IETF has no experience with P2MP PW survivability as yet, and therefore it is proposed that the P2MP PW survivability will initially rely on the LSP survivability. Further work is needed on this subject, particularly if a requirement emerges to provide survivability for P2MP PWs in an MPLS-TP context. 7. Network Management An overview of network management considerations for MPLS-TP can be found in Section 3.14 of "Framework for MPLS in Transport Networks" [RFC5921]. The provided description applies equally to P2MP transport paths. The network management architecture and requirements for MPLS-TP are specified in [RFC5951]. They derive from the generic specifications described in ITU-T G.7710/Y.1701 [G.7710] for transport technologies. They also incorporate the OAM requirements for MPLS Networks [RFC4377] and MPLS-TP Networks [RFC5860] and expand on those requirements to cover the modifications necessary for fault, configuration, performance, and security in a transport network. [RFC5951] covers all MPLS-TP connection types, including P2MP. [RFC6639] provides the MIB-based architecture for MPLS-TP. It reviews the interrelationships between different non MPLS-TP specific MIB modules that can be leveraged for MPLS-TP network management, and identifies areas where additional MIB modules are required. While the document does not consider P2MP transport paths, it does provide a foundation for an analysis of areas where MIB module modification and addition may be needed to fully support P2MP transport paths. There has also been work in the MPLS working group on a P2MP specific MIB, [I-D.ietf-mpls-p2mp-te-mib]. 8. Security Considerations General security considerations for MPLS-TP are covered in [RFC5921]. Additional security considerations for point-to-multipoint LSPs are provided in [RFC4875]. This document introduces no new security considerations beyond those covered in those documents. 9. IANA Considerations IANA considerations resulting from specific elements of MPLS-TP functionalityThere are detailed in the documents specifying that functionality. This document introducesno additionalrequests for IANA considerationsactions in itself.this document. 10. References 10.1. Normative References [RFC4872] Lang, J., Rekhter, Y., and D. Papadimitriou, "RSVP-TE Extensions in Support of End-to-End Generalized Multi- Protocol Label Switching (GMPLS) Recovery", RFC 4872, May 2007. [RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel, "GMPLS Segment Recovery", RFC 4873, May 2007. [RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa, "Extensions to Resource Reservation Protocol - Traffic Engineering (RSVP-TE) for Point-to-Multipoint TE Label Switched Paths (LSPs)", RFC 4875, May 2007. [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP Specification", RFC 5036, October 2007. [RFC5331] Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream Label Assignment and Context-Specific Label Space", RFC 5331, August 2008.[RFC5332] Eckert, T., Rosen, E., Aggarwal, R., and Y. Rekhter, "MPLS Multicast Encapsulations", RFC 5332, August 2008. [RFC5654] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N., and S. Ueno, "Requirements of an MPLS Transport Profile", RFC 5654, September 2009. [RFC5921] Bocci, M., Bryant, S., Frost, D., Levrau, L., and L. Berger, "A Framework for MPLS in Transport Networks", RFC 5921, July 2010. [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay Measurement for MPLS Networks", RFC 6374, September 2011. [RFC6375] Frost, D. and S. Bryant, "A Packet Loss and Delay Measurement Profile for MPLS-Based Transport Networks", RFC 6375, September 2011. 10.2. Informative References [G.7710] ITU-T Recommendation G.7710/Y.1701 (07/2007), "Common equipment management function requirements", 2007. [G.780] ITU-T Recommendation G.780//Y.1351 (07/2010), "Terms and definitions for synchronous digital hierarchy (SDH) networks", 2010. [G.798] ITU-T Recommendation G.798 (10/2010), "Characteristics of optical transport network hierarchy equipment functional blocks", 2010. [I-D.hmk-mpls-tp-p2mp-oam-framework] Koike, Y., Hamano, T., and M. Namiki, "Framework for Point-to-Multipoint MPLS-TP OAM", draft-hmk-mpls-tp-p2mp- oam-framework-02 (work in progress), February 2013. [I-D.ietf-l2vpn-vpms-frmwk-requirements] Kamite, Y., JOUNAY, F., Niven-Jenkins, B., Brungard, D., and L. Jin, "Framework and Requirements for Virtual Private Multicast Service (VPMS)", draft-ietf-l2vpn-vpms- frmwk-requirements-05 (work in progress), October 2012. [I-D.ietf-mpls-p2mp-te-mib] Farrel, A., Yasukawa, S., and T. Nadeau, "Point-to- Multipoint Multiprotocol Label Switching (MPLS) Traffic Engineering (TE) Management Information Base (MIB) module", draft-ietf-mpls-p2mp-te-mib-09 (work in progress), April 2009. [I-D.ietf-pwe3-p2mp-pw-requirements] Bocci, M., Heron, G., and Y. Kamite, "Requirements and Framework for Point-to-Multipoint Pseudowires over MPLS PSNs", draft-ietf-pwe3-p2mp-pw-requirements-05 (work in progress), September 2011. [I-D.ietf-pwe3-p2mp-pw] Sivabalan, S., Boutros, S., and L. Martini, "Signaling Root-Initiated Point-to-Multipoint Pseudowire using LDP", draft-ietf-pwe3-p2mp-pw-04 (work in progress), March 2012.[I-D.raggarwa-pwe3-p2mp-pw-encaps] Aggarwal, R. and F. JOUNAY, "Point-to-Multipoint Pseudo- Wire Encapsulation", draft-raggarwa-pwe3-p2mp-pw-encaps-01 (work in progress), March 2010. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4377] Nadeau, T., Morrow, M., Swallow, G., Allan, D., and S. Matsushima, "Operations and Management (OAM) Requirements for Multi-Protocol Label Switched (MPLS) Networks", RFC 4377, February 2006. [RFC4447] Martini, L., Rosen, E., El-Aawar, N., Smith, T., and G. Heron, "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", RFC 4447, April 2006. [RFC5860] Vigoureux, M., Ward, D., and M. Betts, "Requirements for Operations, Administration, and Maintenance (OAM) in MPLS Transport Networks", RFC 5860, May 2010. [RFC5951] Lam, K., Mansfield, S., and E. Gray, "Network Management Requirements for MPLS-based Transport Networks", RFC 5951, September 2010. [RFC6371] Busi, I. and D. Allan, "Operations, Administration, and Maintenance Framework for MPLS-Based Transport Networks", RFC 6371, September 2011. [RFC6372] Sprecher, N. and A. Farrel, "MPLS Transport Profile (MPLS- TP) Survivability Framework", RFC 6372, September 2011. [RFC6373] Andersson, L., Berger, L., Fang, L., Bitar, N., and E. Gray, "MPLS Transport Profile (MPLS-TP) Control Plane Framework", RFC 6373, September 2011. [RFC6639] King, D. and M. Venkatesan, "Multiprotocol Label Switching Transport Profile (MPLS-TP) MIB-Based Management Overview", RFC 6639, June 2012. [RFC6718] Muley, P., Aissaoui, M., and M. Bocci, "Pseudowire Redundancy", RFC 6718, August 2012.Authors' Addresses Dan Frost (editor)Cisco Systems EMail: email@example.com Stewart Bryant (editor)Cisco Systems EMail: firstname.lastname@example.org Matthew Bocci (editor)Alcatel-Lucent Voyager Place, Shoppenhangers Road Maidenhead, Berks SL6 2PJ United Kingdom EMail: email@example.com Lou Berger (editor)LabN Consulting Phone: +1-301-468-9228 EMail: firstname.lastname@example.org