Movatterモバイル変換

[RFC Home] [TEXT|PDF|HTML] [Tracker] [IPR] [Info page]

INFORMATIONAL

Internet Engineering Task Force (IETF) D. FrostRequest for Comments: 7167 Blue SunCategory: Informational S. BryantISSN: 2070-1721 Cisco Systems M. Bocci Alcatel-Lucent L. Berger LabN Consulting April 2014A Framework for Point-to-Multipoint MPLS in Transport NetworksAbstract The Multiprotocol Label Switching 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 that are applicable specifically to supporting point-to- multipoint transport paths.Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; seeSection 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc7167.Frost, et al. Informational [Page 1]

RFC 7167          MPLS Transport Profile P2MP Framework       April 2014Copyright Notice   Copyright (c) 2014 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 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 Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .31.1.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . .31.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .32.  Applicability . . . . . . . . . . . . . . . . . . . . . . . .43.  MPLS-TP P2MP Requirements . . . . . . . . . . . . . . . . . .44.  Architecture  . . . . . . . . . . . . . . . . . . . . . . . .64.1.  MPLS-TP Encapsulation and Forwarding  . . . . . . . . . .65.  Operations, Administration, and Maintenance . . . . . . . . .66.  Control Plane . . . . . . . . . . . . . . . . . . . . . . . .76.1.  P2MP LSP Control Plane  . . . . . . . . . . . . . . . . .86.2.  P2MP PW Control Plane . . . . . . . . . . . . . . . . . .87.  Survivability . . . . . . . . . . . . . . . . . . . . . . . .88.  Network Management  . . . . . . . . . . . . . . . . . . . . .99.  Security Considerations . . . . . . . . . . . . . . . . . . .910. References  . . . . . . . . . . . . . . . . . . . . . . . . .910.1.  Normative References . . . . . . . . . . . . . . . . . .910.2.  Informative References . . . . . . . . . . . . . . . . .10Frost, et al.                 Informational                     [Page 2]

RFC 7167          MPLS Transport Profile P2MP Framework       April 20141.  Introduction   The Multiprotocol Label Switching 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 the aspects   specific to point-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-   multipoint transport paths.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 the aspects of the   MPLS-TP architecture that are generic or are concerned specifically   with point-to-point transport paths.1.2.  Terminology   Term    Definition   ------- ---------------------------------------------------   CE      Customer Edge   LSP     Label Switched Path   LSR     Label Switching Router   MEG     Maintenance Entity Group   MEP     Maintenance Entity Group End Point   MIP     Maintenance Entity Group Intermediate Point   MPLS-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   tLDP    Targeted LDP   Detailed definitions and additional terminology may be found in   [RFC5921] and [RFC5654].Frost, et al.                 Informational                     [Page 3]

RFC 7167 MPLS Transport Profile P2MP Framework April 20142. Applicability The point-to-multipoint connectivity provided by an MPLS-TP network is based on the point-to-multipoint connectivity provided by MPLS networks. Traffic Engineered P2MP LSP support is discussed in [RFC4875] and [RFC5332], and P2MP PW support is being developed based on [P2MP-PW-REQS] and [VPMS-FRMWK-REQS]. MPLS-TP point-to-multipoint connectivity is analogous to that provided by traditional transport technologies such as Optical Transport Network point-to-multipoint [G.798] and drop-and-continue [G.780], and thus supports the same class of traditional applications, e.g., video distribution. The scope of this document is limited to point-to-multipoint functions and it does not discuss multipoint-to-multipoint support.3. MPLS-TP P2MP 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 theRFC2119 [BCP14] conformance language used in the original documents as this document is not authoritative. From [RFC5654]: o MPLS-TP must support traffic-engineered point-to-multipoint transport paths. o MPLS-TP must support unidirectional 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.Frost, et al. Informational [Page 4]

RFC 7167          MPLS Transport Profile P2MP Framework       April 2014   o  MPLS-TP recovery in a ring must protect unidirectional P2MP      transport paths.   From [RFC5860]:   o  The protocol solution(s) developed to perform the following OAM      functions must also apply to point-to-point associated      bidirectional LSPs, point-to-point unidirectional LSPs, and point-      to-multipoint LSPs:      *  Continuity Check      *  Connectivity Verification, proactive      *  Lock Instruct      *  Lock Reporting      *  Alarm Reporting      *  Client Failure Indication      *  Packet Loss Measurement      *  Packet Delay Measurement   o  The protocol solution(s) developed to perform the following OAM      functions may also apply to point-to-point associated      bidirectional LSPs, point-to-point unidirectional LSPs, and point-      to-multipoint LSPs:      *  Connectivity Verification, on-demand      *  Route Tracing      *  Diagnostic Tests      *  Remote Defect Indication   From [RFC5951]:   o  For unidirectional (P2P and point-to-multipoint (P2MP))      connection, proactive measurement of packet loss and loss ratio is      required.   o  For a unidirectional (P2P and P2MP) connection, on-demand      measurement of delay measurement is required.Frost, et al.                 Informational                     [Page 5]

RFC 7167 MPLS Transport Profile P2MP Framework April 20144. Architecture The overall architecture of the MPLS-TP is defined in [RFC5921]. The architecture for point-to-multipoint MPLS-TP comprises the following additional elements and functions: o Unidirectional point-to-multipoint LSPs o Unidirectional point-to-multipoint PWs o Optional point-to-multipoint LSP and PW control planes o Survivability, network management, and Operations, Administration, and Maintenance functions for point-to-multipoint PWs and LSPs. The following subsection summarises 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 CE devices when the network is providing a packet transport service.4.1. 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 within the PWE3 Working Group [P2MP-PW-ENCAPS], but such definition is for further study.5. Operations, Administration, and Maintenance The requirements for MPLS-TP OAM are specified in [RFC5860]. The overall OAM architecture for MPLS-TP is defined in [RFC6371], and P2MP OAM design considerations are described inSection 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 towards all the leaves, and thus may be processed by all the MIPs and MEPs associated with a P2MP MEG. If an OAM packet is to be processed by only a 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, Time-to-Live-based addressing is used to set the radius and additional information in the OAM payloadFrost, et al. Informational [Page 6]

RFC 7167 MPLS Transport Profile P2MP Framework April 2014 is used to identify the specific destination. It is worth noting that a MIP and MEP may be instantiated on a single node when it is both a branch and leaf 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 inSection 3.8 of [RFC5921]. A more detailed discussion of P2MP OAM considerations can be found in [MPLS-TP-P2MP-OAM].6. 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: 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), and o requirement 65 (1:n shared mesh recovery). [RFC6373] defines the control-plane approach used to support MPLS-TP transport paths. It identifies GMPLS as the control plane for MPLS- TP LSPs and tLDP as the control plane for PWs. MPLS-TP allows that either, or both, LSPs and PWs to be provisioned statically or via a control plane. Quoting from [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.Frost, et al. Informational [Page 7]

RFC 7167 MPLS Transport Profile P2MP Framework April 20146.1. P2MP LSP Control Plane The MPLS-TP control plane for P2MP LSPs uses GMPLS and is based on RSVP-TE for P2MP LSPs as defined in [RFC4875]. A detailed listing of how GMPLS satisfies MPLS-TP control-plane requirements is provided in [RFC6373]. [RFC6373] notes that recovery techniques for traffic engineered P2MP LSPs are not formally defined, and that such a definition is needed. A formal definition will be based on existing RFCs and may not require any new protocol mechanisms but, nonetheless, should be documented. GMPLS recovery is defined in [RFC4872] and [RFC4873]. Protection of P2MP LSPs is also discussed in[RFC6372] Section 4.7.3.6.2. P2MP PW Control Plane The MPLS-TP control plane for P2MP 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.7. Survivability The overall survivability architecture for MPLS-TP is defined in [RFC6372], andSection 4.7.3 of that RFC 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 impacting delivery to any of the leaves. Fault notification happens from the node identifying the fault to the root node via an out-of-band path. 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; 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.Frost, et al. Informational [Page 8]

RFC 7167 MPLS Transport Profile P2MP Framework April 20148. Network Management An overview of network management considerations for MPLS-TP can be found inSection 3.14 of [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 MIB modules that are not MPLS-TP specific and 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, [MPLS-TE-P2MP-MIB].9. Security Considerations General security considerations for MPLS-TP are covered in [RFC5921]. Additional security considerations for P2MP LSPs are provided in [RFC4875]. This document introduces no new security considerations beyond those covered in those documents.10. References10.1. 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.Frost, et al. Informational [Page 9]

RFC 7167          MPLS Transport Profile P2MP Framework       April 2014   [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",RFC5921, July 2010.10.2.  Informative References   [BCP14]    Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119, March 1997.   [G.7710]   ITU-T, "Common equipment management function              requirements", ITU-T G.7710/Y.1701, July 2007.   [G.780]    ITU-T, "Terms and definitions for synchronous digital              hierarchy (SDH) networks", ITU-T G.780/Y.1351, July 2010.   [G.798]    ITU-T, "Characteristics of optical transport network              hierarchy equipment functional blocks", ITU-T G.798,              December 2012.   [MPLS-TE-P2MP-MIB]              Farrel, A., Yasukawa, S., and T. Nadeau, "Point-to-              Multipoint Multiprotocol Label Switching (MPLS) Traffic              Engineering (TE) Management Information Base (MIB)              module", Work in Progress, April 2009.   [MPLS-TP-P2MP-OAM]              Arai, K., Koike, Y., Hamano, T., and M. Namiki, "Framework              for Point-to-Multipoint MPLS-TP OAM", Work in Progress,              January 2014.   [P2MP-PW-ENCAPS]              Aggarwal, R. and F. Jounay, "Point-to-Multipoint Pseudo-              Wire Encapsulation", Work in Progress, March 2010.   [P2MP-PW-REQS]              Jounay, F., Kamite, Y., Heron, G., and M. Bocci,              "Requirements and Framework for Point-to-Multipoint              Pseudowires over MPLS PSNs", Work in Progress, February              2014.Frost, et al.                 Informational                    [Page 10]

RFC 7167          MPLS Transport Profile P2MP Framework       April 2014   [RFC4377]  Nadeau, T., Morrow, M., Swallow, G., Allan, D., and S.              Matsushima, "Operations and Management (OAM) Requirements              for Multi-Protocol Label Switched (MPLS) Networks",RFC4377, 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.   [VPMS-FRMWK-REQS]              Kamite, Y., Jounay, F., Niven-Jenkins, B., Brungard, D.,              and L. Jin, "Framework and Requirements for Virtual              Private Multicast Service (VPMS)", Work in Progress,              October 2012.Frost, et al.                 Informational                    [Page 11]

RFC 7167          MPLS Transport Profile P2MP Framework       April 2014Authors' Addresses   Dan Frost   Blue Sun   EMail: frost@mm.st   Stewart Bryant   Cisco Systems   EMail: stbryant@cisco.com   Matthew Bocci   Alcatel-Lucent   Voyager Place, Shoppenhangers Road   Maidenhead, Berks  SL6 2PJ   United Kingdom   EMail: matthew.bocci@alcatel-lucent.com   Lou Berger   LabN Consulting   Phone: +1-301-468-9228   EMail: lberger@labn.netFrost, et al.                 Informational                    [Page 12]

[8]ページ先頭