MPLS Working Group M. Bocci, Ed. Internet-Draft Alcatel-Lucent Intended status: Informational S. Bryant, Ed. Expires: June 25, 2010 D. Frost Cisco Systems L. Levrau Alcatel-Lucent L. Berger LabN December 22, 2009 A Framework for MPLS in Transport Networks draft-ietf-mpls-tp-framework-07 Abstract This document specifies an architectural framework for the application of Multiprotocol Label Switching (MPLS) to the construction of packet-switched equivalents of traditional circuit- switched carrier networks. It describes a common set of protocol functions - the MPLS Transport Profile (MPLS-TP) - that supports the operational models and capabilities typical of such networks, including signaled or explicitly provisioned bi-directional connection-oriented paths, protection and restoration mechanisms, comprehensive Operations, Administration and Maintenance (OAM) functions, and network operation in the absence of a dynamic control plane or IP forwarding support. Some of these functions are defined in existing MPLS specifications, while others require extensions to existing specifications to meet the requirements of the MPLS-TP. This document defines the subset of the MPLS-TP applicable in general and to point-to-point paths. The remaining subset, applicable specifically to point-to-multipoint paths, are out of scope of this document. This document is a product of a joint Internet Engineering Task Force (IETF) / International Telecommunications Union Telecommunications Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS and PWE3 architectures to support the capabilities and functionalities of a packet transport network as defined by the ITU-T. Status of This Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Bocci, et al. Expires June 25, 2010 [Page 1] Internet-Draft MPLS Transport Profile Framework December 2009 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 June 25, 2010. Copyright Notice 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 (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 BSD License. Bocci, et al. Expires June 25, 2010 [Page 2] Internet-Draft MPLS Transport Profile Framework December 2009 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Motivation and Background . . . . . . . . . . . . . . . . 4 1.2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6 1.3.1. Transport Network . . . . . . . . . . . . . . . . . . 6 1.3.2. MPLS Transport Profile . . . . . . . . . . . . . . . . 7 1.3.3. MPLS-TP Section . . . . . . . . . . . . . . . . . . . 7 1.3.4. MPLS-TP Label Switched Path . . . . . . . . . . . . . 7 1.3.5. MPLS-TP Label Switching Router (LSR) and Label Edge Router (LER) . . . . . . . . . . . . . . . . . . 7 1.3.6. Customer Edge (CE) . . . . . . . . . . . . . . . . . . 8 1.3.7. Additional Definitions and Terminology . . . . . . . . 8 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 8 2. MPLS Transport Profile Requirements . . . . . . . . . . . . . 11 3. MPLS Transport Profile Overview . . . . . . . . . . . . . . . 12 3.1. Packet Transport Services . . . . . . . . . . . . . . . . 12 3.2. Scope of the MPLS Transport Profile . . . . . . . . . . . 13 3.3. Architecture . . . . . . . . . . . . . . . . . . . . . . . 14 3.3.1. MPLS-TP Client Adaptation Functions . . . . . . . . . 14 3.3.2. MPLS-TP Forwarding Functions . . . . . . . . . . . . . 15 3.4. MPLS-TP Native Services . . . . . . . . . . . . . . . . . 16 3.4.1. MPLS-TP Client/Server Relationship . . . . . . . . . . 17 3.4.2. Pseudowire Adaptation . . . . . . . . . . . . . . . . 17 3.4.3. Network Layer Adaptation . . . . . . . . . . . . . . . 20 3.5. Identifiers . . . . . . . . . . . . . . . . . . . . . . . 24 3.6. Generic Associated Channel (G-ACh) . . . . . . . . . . . . 24 3.7. Operations, Administration and Maintenance (OAM) . . . . . 27 3.7.1. OAM Architecture . . . . . . . . . . . . . . . . . . . 28 3.7.2. OAM Functions . . . . . . . . . . . . . . . . . . . . 31 3.8. Control Plane . . . . . . . . . . . . . . . . . . . . . . 32 3.8.1. PW Control Plane . . . . . . . . . . . . . . . . . . . 34 3.8.2. LSP Control Plane . . . . . . . . . . . . . . . . . . 34 3.9. Static Operation of LSPs and PWs . . . . . . . . . . . . . 35 3.10. Survivability . . . . . . . . . . . . . . . . . . . . . . 35 3.11. Network Management . . . . . . . . . . . . . . . . . . . . 37 4. Security Considerations . . . . . . . . . . . . . . . . . . . 38 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 38 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 38 7. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 39 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 40 8.1. Normative References . . . . . . . . . . . . . . . . . . . 40 8.2. Informative References . . . . . . . . . . . . . . . . . . 42 Bocci, et al. Expires June 25, 2010 [Page 3] Internet-Draft MPLS Transport Profile Framework December 2009 1. Introduction 1.1. Motivation and Background This document describes an architectural framework for the application of MPLS to the construction of packet-switched transport networks. It specifies the common set of protocol functions that meet the requirements in [RFC5654], and that together constitute the MPLS Transport Profile (MPLS-TP) for point-to-point paths. The remaining MPLS-TP functions, applicable specifically to point-to- multipoint paths, are out of scope of this document. Historically the optical transport infrastructure - Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) and Optical Transport Network (OTN) - has provided carriers with a high benchmark for reliability and operational simplicity. To achieve this, transport technologies have been designed with specific characteristics: o Strictly connection-oriented connectivity, which may be long-lived and may be provisioned manually (i.e. configuration of the node via a command line interface) or by network management. o A high level of availability. o Quality of service. o Extensive OAM capabilities. Carriers wish to evolve such transport networks to take advantage of the flexibility and cost benefits of packet switching technology and to support packet based services more efficiently. While MPLS is a maturing packet technology that already plays an important role in transport networks and services, not all MPLS capabilities and mechanisms are needed in or consistent with the transport network operational model. There are also transport technology characteristics that are not currently reflected in MPLS. There are thus two objectives for MPLS-TP: 1. To enable MPLS to be deployed in a transport network and operated in a similar manner to existing transport technologies. 2. To enable MPLS to support packet transport services with a similar degree of predictability to that found in existing transport networks. In order to achieve these objectives, there is a need to define a Bocci, et al. Expires June 25, 2010 [Page 4] Internet-Draft MPLS Transport Profile Framework December 2009 common set of MPLS protocol functions - an MPLS Transport Profile - for the use of MPLS in transport networks and applications. Some of the necessary functions are provided by existing MPLS specifications, while others require additions to the MPLS tool-set. Such additions should, wherever possible, be applicable to MPLS networks in general as well as those that conform strictly to the transport network model. This document is a product of a joint Internet Engineering Task Force (IETF) / International Telecommunications Union Telecommunications Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS and PWE3 architectures to support the capabilities and functionalities of a packet transport network as defined by the ITU-T. 1.2. Scope This document describes an architectural framework for the application of MPLS to the construction of packet-switched transport networks. It specifies the common set of protocol functions that meet the requirements in [RFC5654], and that together constitute the MPLS Transport Profile (MPLS-TP) for point-to-point MPLS-TP transport paths. The remaining MPLS-TP functions, applicable specifically to point-to-multipoint transport paths, are out of scope of this document. Bocci, et al. Expires June 25, 2010 [Page 5] Internet-Draft MPLS Transport Profile Framework December 2009 1.3. Terminology Term Definition ---------- ---------------------------------------------------------- LSP Label Switched Path MPLS-TP MPLS Transport Profile SDH Synchronous Digital Hierarchy ATM Asynchronous Transfer Mode OTN Optical Transport Network cl-ps Connectionless - Packet Switched co-cs Connection Oriented - Circuit Switched co-ps Connection Oriented - Packet Switched OAM Operations, Administration and Maintenance G-ACh Generic Associated Channel GAL Generic Alert Label 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 Management LSR Label Switching Router MPLS-TP PE MPLS-TP Provider Edge LSR MPLS-TP P MPLS-TP Provider LSR PW Pseudowire Adaptation The mapping of client information into a format suitable for transport by the server layer Native The traffic belonging to the client of the MPLS-TP network Service T-PE PW Terminating Provider Edge S-PE PW Switching provider Edge 1.3.1. Transport Network A Transport Network provides transparent transmission of client user plane traffic between attached client devices by establishing and maintaining point-to-point or point-to-multipoint connections between such devices. The architecture of networks supporting point to multipoint connections is out of scope of this document. A Transport Network is independent of any higher-layer network that may exist between clients, except to the extent required to supply this transmission service. In addition to client traffic, a Transport Network may carry traffic to facilitate its own operation, such as that required to support connection control, network management, and Operations, Administration and Maintenance (OAM) functions. Bocci, et al. Expires June 25, 2010 [Page 6] Internet-Draft MPLS Transport Profile Framework December 2009 See also the definition of Packet Transport Service in Section 3.1. 1.3.2. MPLS Transport Profile The MPLS Transport Profile (MPLS-TP) is the subset of MPLS functions that meet the requirements in [RFC5654]. Note that MPLS is defined to include any present and future MPLS capability specified by the IETF, including those capabilities specifically added to support transport network requirements [RFC5654]. 1.3.3. MPLS-TP Section An MPLS-TP Section is defined in Section 1.2.2 of [RFC5654]. 1.3.4. MPLS-TP Label Switched Path An MPLS-TP Label Switched Path (MPLS-TP LSP) is an LSP that uses a subset of the capabilities of an MPLS LSP in order to meet the requirements of an MPLS transport network as set out in [RFC5654]. The characteristics of an MPLS-TP LSP are primarily that it: 1. Uses a subset of the MPLS OAM tools defined as described in [I-D.ietf-mpls-tp-oam-framework]. 2. Supports 1+1, 1:1, and 1:N protection functions. 3. Is traffic engineered. 4. May be established and maintained via the management plane, or using GMPLS protocols when a control plane is used. 5. Is either point-to-point or point-to-multipoint. Multipoint to point and multipoint to multipoint LSPs are not permitted. Note that an MPLS LSP is defined to include any present and future MPLS capability, including those specifically added to support the transport network requirements. 1.3.5. MPLS-TP Label Switching Router (LSR) and Label Edge Router (LER) Editor's Note: These terms are here for clarity - but this is not the authoritative definition - (need to find a definition) An MPLS-TP Label Switching Router (LSR) is either an MPLS-TP Provider Edge (PE) router or an MPLS-TP Provider (P) router for a given LSP, as defined below. The terms MPLS-TP PE router and MPLS-TP P router describe logical functions; a specific node may undertake only one of these roles on a given LSP. Bocci, et al. Expires June 25, 2010 [Page 7] Internet-Draft MPLS Transport Profile Framework December 2009 Note that the use of the term "router" in this context is historic and neither requires nor precludes the ability to perform IP forwarding. 1.3.5.1. MPLS-TP Provider Edge (PE) Router An MPLS-TP Provider Edge (PE) router is an MPLS-TP LSR that adapts client traffic and encapsulates it to be transported over an MPLS-TP LSP. Encapsulation may be as simple as pushing a label, or it may require the use of a pseudowire. An MPLS-TP PE exists at the interface between a pair of layer networks. For an MS-PW, an MPLS-TP PE may be either an S-PE or a T-PE, as defined in [RFC5659]. A layer network is defined in [G.805]. 1.3.5.2. MPLS-TP Provider (P) Router An MPLS-TP Provider router is an MPLS-TP LSR that does not provide MPLS-TP PE functionality for a given LSP. An MPLS-TP P router switches LSPs which carry client traffic, but does not adapt client traffic and encapsulate it to be carried over an MPLS-TP LSP. 1.3.6. Customer Edge (CE) A Customer Edge (CE) is the client function sourcing or sinking native service traffic to or from the MPLS-TP network. CEs on either side of the MPLS-TP network are peers and view the MPLS-TP network as a single point-to-point or point-to-multipoint link. 1.3.7. Additional Definitions and Terminology Detailed definitions and additional terminology may be found in [RFC5654]. 1.4. Applicability MPLS-TP can be used to construct packet transport networks and is therefore applicable in any packet transport network context. It is also applicable to subsets of a packet network where the transport network operational model is deemed attractive. The following are examples of MPLS-TP applicability models: 1. MPLS-TP provided by a network that only supports MPLS-TP LSPs and PWs (i.e. Only MPLS-TP LSPs and PWs exist between the PEs or LSRs), acting as a server for other layer 1, layer 2 and layer 3 networks (Figure 1). Bocci, et al. Expires June 25, 2010 [Page 8] Internet-Draft MPLS Transport Profile Framework December 2009 2. MPLS-TP provided by a network that also supports non-MPLS-TP LSPs and PWs (i.e. both LSPs and PWs that conform to the transport profile and those that do not, exist between the PEs), acting as a server for other layer 1, layer 2 and layer 3 networks (Figure 2). 3. MPLS-TP as a server layer for client layer traffic of IP or MPLS networks which do not use functions of the MPLS transport profile. For MPLS traffic, the MPLS-TP server layer network uses PW switching or LSP stitching at the PE that terminates the MPLS-TP server layer (Figure 3). - See notes in word document - ref = rfc5150 These models are not mutually exclusive. MPLS-TP LSP, provided by a network that only supports MPLS-TP, acting as a server for other layer 1, layer 2 and layer 3 networks. |<-- L1/2/3 -->|<-- MPLS-TP-->|<-- L1/2/3 -->| Only MPLS-TP +---+ LSP +---+ +---+ Client | |----------| | Client +---+ |CE1|==Traffic=|PE2|==========|PE3|=Traffic==|CE1| +---+ | |----------| | +---+ +---+ +---+ Example a) [Ethernet] [Ethernet] [Ethernet] layering [ PW ] [-TP LSP ] b) [ IP ] [ IP ] [ IP ] [ Demux ] [-TP LSP ] Figure 1: MPLS-TP Server Layer Example Bocci, et al. Expires June 25, 2010 [Page 9] Internet-Draft MPLS Transport Profile Framework December 2009 MPLS-TP LSP, provided by a network that also supports non-MPLS-TP functions, acting as a server for other layer 1, layer 2 and layer 3 networks. |<-- L1/2/3 -->|<-- MPLS -->|<-- L1/2/3 -->| MPLS-TP +---+ LSP +---+ +---+ Client | |----------| | Client +---+ |CE1|==Traffic=|PE2|==========|PE3|=Traffic==|CE1| +---+ | |----------| | +---+ +---+ +---+ Example a) [Ethernet] [Ethernet] [Ethernet] layering [ PW ] [-TP LSP ] b) [ IP ] [ IP ] [ IP ] [ Demux ] [-TP LSP ] Figure 2: MPLS-TP in MPLS Network Example Bocci, et al. Expires June 25, 2010 [Page 10] Internet-Draft MPLS Transport Profile Framework December 2009 MPLS-TP as a server layer for client layer traffic of IP or MPLS networks which do not use functions of the MPLS transport profile. |<-- MPLS ---->|<-- MPLS-TP-->|<--- MPLS --->| Only +---+ +----+ Non-TP +----+ MPLS-TP +----+ Non-TP +----+ +---+ |CE1|---|T-PE|====LSP===|S-PE|====LSP===|S-PE|====LSP===|S-PE|---|CE2| +---+ +----+ +----+ +----+ +----+ +---+ (PW switching) (PW switching) (a) [ Eth ] [ Eth ] [ Eth ] [ Eth ] [ Eth ] [PW Seg't] [PW Seg't] [PW Seg't] [ LSP ] [-TP LSP ] [ LSP ] |<-- MPLS ---->|<-- MPLS-TP-->|<--- MPLS --->| Only +---+ +----+ Non-TP +----+ MPLS-TP +----+ Non-TP +----+ +---+ |CE1|---| PE |====LSP===| PE |====LSP===| PE |====LSP===| PE |---|CE2| +---+ +----+ +----+ +----+ +----+ +---+ (LSP stitching) (LSP stitching) (b) [ IP ] [ IP ] [ IP ] [ IP ] [ IP ] [ LSP ] [-TP LSP ] [ LSP ] Figure 3: MPLS-TP Transporting Client Service Traffic 2. MPLS Transport Profile Requirements The requirements for MPLS-TP are specified in [RFC5654], [I-D.ietf-mpls-tp-oam-requirements], and [I-D.ietf-mpls-tp-nm-req]. This section provides a brief reminder to guide the reader and is therefore not normative. It is not intended as a substitute for these documents. MPLS-TP must not modify the MPLS forwarding architecture and must be based on existing pseudowire and LSP constructs. Point to point LSPs may be unidirectional or bi-directional, and it must be possible to construct congruent Bi-directional LSPs. MPLS-TP LSPs do not merge with other LSPs at an MPLS-TP LSR and it must be possible to detect if a merged LSP has been created. Bocci, et al. Expires June 25, 2010 [Page 11] Internet-Draft MPLS Transport Profile Framework December 2009 It must be possible to forward packets solely based on switching the MPLS or PW label. It must also be possible to establish and maintain LSPs and/or pseudowires both in the absence or presence of a dynamic control plane. When static provisioning is used, there must be no dependency on dynamic routing or signaling. OAM, protection and forwarding of data packets must be able to operate without IP forwarding support. It must be possible to monitor LSPs and pseudowires through the use of OAM in the absence of control plane or routing functions. In this case information gained from the OAM functions is used to initiate path recovery actions at either the PW or LSP layers. 3. MPLS Transport Profile Overview 3.1. Packet Transport Services One objective of MPLS-TP is to enable MPLS networks to provide packet transport services with a similar degree of predictability to that found in existing transport networks. Such packet transport services inherit a number of characteristics, defined in [RFC5654]: o In an environment where an MPLS-TP layer network is supporting a client layer network, and the MPLS-TP layer network is supported by a server layer network then operation of the MPLS-TP layer network must be possible without any dependencies on either the server or client layer network. o The service provided by the MPLS-TP network to the client is guaranteed not to fall below the agreed level regardless of other client activity. o The control and management planes of any client network layer that uses the service is isolated from the control and management planes of the MPLS-TP layer network, where the client network layer is considered to be the native service of the MPLS-TP network. o Where a client network makes use of an MPLS-TP server that provides a packet transport service, the level of co-ordination required between the client and server layer networks is minimal (preferably no co-ordination will be required). o The complete set of packets generated by a client MPLS(-TP) layer network using the packet transport service, which may contain packets that are not MPLS packets (e.g. IP or CNLS packets used by the control/management plane of the client MPLS(-TP) layer Bocci, et al. Expires June 25, 2010 [Page 12] Internet-Draft MPLS Transport Profile Framework December 2009 network), are transported by the MPLS-TP server layer network. o The packet transport service enables the MPLS-TP layer network addressing and other information (e.g. topology) to be hidden from any client layer networks using that service, and vice-versa. These characteristics imply that a packet transport service does not support a connectionless packet-switched forwarding mode. However, this does not preclude it carrying client traffic associated with a connectionless service. Such packet transport services are very similar to Layer 2 Virtual Private Networks as defined by the IETF. 3.2. Scope of the MPLS Transport Profile Figure 4 illustrates the scope of MPLS-TP. MPLS-TP solutions are primarily intended for packet transport applications. MPLS-TP is a strict subset of MPLS, and comprises only those functions that are necessary to meet the requirements of [RFC5654]. This includes MPLS functions that were defined prior to [RFC5654] but that meet the requirements of [RFC5654], together with additional functions defined to meet those requirements. Some MPLS functions defined before [RFC5654] such as Equal Cost Multi-Path, LDP signaling used in such a way that it creates multipoint-to-point LSPs, and IP forwarding in the data plane are explicitly excluded from MPLS-TP by that requirements specification. Note that MPLS as a whole will continue to evolve to include additional functions that do not conform to the MPLS Transport Profile or its requirements, and thus fall outside the scope of MPLS-TP. |<============================== MPLS ==============================>| |<============= Pre-RFC5654 MPLS ================>| { ECMP } { LDP/non-TE LSPs } { IP fwd } |<================ MPLS-TP ====================>| { Additional } { Transport } { Functions } Bocci, et al. Expires June 25, 2010 [Page 13] Internet-Draft MPLS Transport Profile Framework December 2009 Figure 4: Scope of MPLS-TP 3.3. Architecture MPLS-TP comprises the following architectural elements: o Sections, LSPs and PWs that provide a packet transport service for a client network. o Proactive and on-demand Operations, Administration and Maintenance (OAM) functions to monitor and diagnose the MPLS-TP network, such as connectivity check, connectivity verification, performance monitoring and fault localisation. o Optional control planes for LSPs and PWs, as well as support for static provisioning and configuration. o Optional path protection mechanisms to ensure that the packet transport service survives anticipated failures and degradations of the MPLS-TP network. o Network management functions. The MPLS-TP architecture for LSPs and PWs includes the following two sets of functions: o MPLS-TP client adaptation o MPLS-TP forwarding The adaptation functions interface the native service to MPLS-TP. This includes the case where the native service is an MPLS-TP LSP. The forwarding functions comprise the mechanisms required for forwarding the encapsulated client traffic over an MPLS-TP server layer network, for example PW and LSP labels. 3.3.1. MPLS-TP Client Adaptation Functions The MPLS-TP native service adaptation functions interface the client service to MPLS-TP. For pseudowires, these adaptation functions are the payload encapsulation described in Section 4.4 of [RFC3985] and Section 6 of [RFC5659]. For network layer client services, the adaptation function uses the MPLS encapsulation format as defined in [RFC3032]. The purpose of this encapsulation is to abstract the client service data plane from the MPLS-TP data plane, thus contributing to the Bocci, et al. Expires June 25, 2010 [Page 14] Internet-Draft MPLS Transport Profile Framework December 2009 independent operation of the MPLS-TP network. MPLS-TP is itself a client of an underlying server layer. MPLS-TP is thus also bounded by a set of adaptation functions to this server layer network, which may itself be MPLS-TP. These adaptation functions provide encapsulation of the MPLS-TP frames and for the transparent transport of those frames over the server layer network. The MPLS-TP client inherits its Quality of Service (QoS) from the MPLS-TP network, which in turn inherits its QoS from the server layer. The server layer must therefore provide the necessary QoS to ensure that the MPLS-TP client QoS commitments can be satisfied. 3.3.2. MPLS-TP Forwarding Functions The forwarding functions comprise the mechanisms required for forwarding the encapsulated client over an MPLS-TP server layer network, for example PW and LSP labels. MPLS-TP LSPs use the MPLS label switching operations and TTL processing procedures defined in [RFC3031] and [RFC3032]. These operations are highly optimised for performance and are not modified by the MPLS-TP profile. In addition, MPLS-TP PWs use the SS-PW and MS-PW forwarding operations defined in [RFC3985] and [RFC5659]. The PW label is processed by a PW forwarder and is always at the bottom of the label stack for a given MPLS-TP layer network. Per-platform label space is used for PWs. Either per-platform, per- interface or other context-specific label space [RFC5331] may be used for LSPs. MPLS-TP forwarding is based on the label that identifies the transport path (LSP or PW). The label value specifies the processing operation to be performed by the next hop at that level of encapsulation. A swap of this label is an atomic operation in which the contents of the packet after the swapped label are opaque to the forwarder. The only event that interrupts a swap operation is TTL expiry. This is a fundamental architectural construct of MPLS to be taken into account when designing protocol extensions that require packets (e.g. OAM packets) to be sent to an intermediate LSR. Further processing to determine the context of a packet occurs when a swap operation is interrupted in this manner, or a pop operation exposes a specific reserved label at the top of the stack. Otherwise the packet is forwarded according to the procedures in [RFC3032]. Point-to-point MPLS-TP LSPs can be either unidirectional or Bocci, et al. Expires June 25, 2010 [Page 15] Internet-Draft MPLS Transport Profile Framework December 2009 bidirectional. It must be possible to configure an MPLS-TP LSP such that the forward and backward directions of a bidirectional MPLS-TP LSP are co-routed, i.e. follow the same path. The pairing relationship between the forward and the backward directions must be known at each LSR or LER on a bidirectional LSP. In normal conditions, all the packets sent over a PW or an LSP follow the same path through the network and those that belong to a common ordered aggregate are delivered in order. For example per-packet equal cost multi-path (ECMP) load balancing is not applicable to MPLS-TP LSPs. Penultimate hop popping (PHP) is disabled on MPLS-TP LSPs by default. MPLS-TP supports Quality of Service capabilities via the MPLS Differentiated Services (DiffServ) architecture [RFC3270]. Both E-LSP and L-LSP MPLS DiffServ modes are supported. The Traffic Class field (formerly the EXP field) of an MPLS label follows the definition and processing rules of [RFC5462] and [RFC3270]. Note that packet reordering between flows belonging to different traffic classes may occur if more than one traffic class is supported on a single LSP. Only the Pipe and Short Pipe DiffServ tunnelling and TTL processing models described in [RFC3270] and [RFC3443] are supported in MPLS-TP. 3.4. MPLS-TP Native Services This document specifies the architecture for two types of native service adaptation: o A PW: PW Demultiplexer and PW encapsulation o An MPLS Label A PW can carry any emulated service defined by the IETF to be provided by a PW, for example Ethernet, Frame Relay, or PPP/HDLC. A registry of PW types is maintained by IANA. When the client adaptation is via a PW, the mechanisms described in Section 3.4.2 are used. An MPLS LSP Label can also be used as the adaptation, in which case any network layer client supported by MPLS is allowed, for example an MPLS LSP, PW, or IP. When the client adaptation is via an MPLS label, the mechanisms described in Section 3.4.3 are used. Bocci, et al. Expires June 25, 2010 [Page 16] Internet-Draft MPLS Transport Profile Framework December 2009 3.4.1. MPLS-TP Client/Server Relationship The relationship of MPLS-TP to its clients is illustrated in Figure 5. PW-Based MPLS Labelled Services Services Emulated PW LSP IP Service +------------+ | PW Payload | +------------+ +------------+ +------------+ (CLIENTS) | PW Payload | |PW Lbl(S=1) | | IP | ~~~~~~~~~~~~~~~~~ +------------+ +------------+ +------------+ |PW Lbl (S=1)| | |LSP Lbl(S=0)| |LSP Lbl(S=1)| | IP | +------------+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |LSP Lbl(S=0)| |LSP Lbl(S=0)| |LSP Lbl(S=0)| |LSP Lbl(S=1)| +------------+ +------------+ +------------+ +------------+ (MPLS-TP) ~~~~~~~~~~~ = Client - MPLS-TP layer boundary Figure 5: MPLS-TP - Client Relationship The data plane behaviour of MPLS-TP is the same as the best current practise for MPLS. This includes the setting of the S-Bit. In each case, the S-bit is set to indicate the bottom (i.e. inner-most) label in the label stack that is contiguous between the MPLS-TP server and the client layer. Note that this best current practise differs slightly from [RFC3032] which uses the S-bit to identify when MPLS label processing stops and network layer processing starts. Note that the label stacks shown above are those inside MPLS-TP network. They illustrate the smallest number of labels possible. These label stacks could also include more labels. 3.4.2. Pseudowire Adaptation The architecture for an MPLS-TP client adaptation that uses PWs is based on the MPLS [RFC3031] and pseudowire [RFC3985] architectures. If multi-segment pseudowires are used to provide a packet transport service, motivated by, for example, the requirements specified in [RFC5254], then the MS-PW architecture [RFC5659] also applies. Bocci, et al. Expires June 25, 2010 [Page 17] Internet-Draft MPLS Transport Profile Framework December 2009 Figure 6 shows the architecture for an MPLS-TP network using single- segment PWs. |<--------------- Emulated Service ----------------->| | | | |<-------- Pseudowire -------->| | | | encapsulated packet | | | | transport service | | | | | | | | |<------ LSP ------->| | | | V V V V | V AC +----+ +-----+ +----+ AC V +-----+ | | PE1|=======\ /========| PE2| | +-----+ | |----------|.......PW1.| \ / |............|----------| | | CE1 | | | | | X | | | | | CE2 | | |----------|.......PW2.| / \ |............|----------| | +-----+ ^ | | |=======/ \========| | | ^ +-----+ ^ | +----+ +-----+ +----+ | ^ | | Provider Edge 1 ^ Provider Edge 2 | | | | | | | Customer | P Router | Customer Edge 1 | | Edge 2 | | | | Native service Native service Figure 6: MPLS-TP Architecture (Single Segment PW) Figure 7 shows the architecture for an MPLS-TP network when multi- segment pseudowires are used. Note that as in the SS-PW case, P-routers may also exist. Bocci, et al. Expires June 25, 2010 [Page 18] Internet-Draft MPLS Transport Profile Framework December 2009 |<----------- Pseudowire encapsulated ------------->| | packet transport service | | | | | | | AC | |<-------- LSP1 -------->| |<--LSP2-->| | AC | V V V V V V | | +----+ +-----+ +----+ +----+ | +---+ | |TPE1|===============\ /=====|SPE1|==========|TPE2| | +---+ | |---|......PW.Seg't1... | \ / | ......X...PW.Seg't3.....|---| | |CE1| | | | | X | | | | | | |CE2| | |---|......PW.Seg't2... | / \ | ......X...PW.Seg't4.....|---| | +---+ | | |===============/ \=====| |==========| | | +---+ ^ +----+ ^ +-----+ +----+ ^ +----+ ^ | | ^ | | | TE LSP | TE LSP | | P-router | | | |<-------------------- Emulated Service ------------------->| Figure 7: MPLS-TP Architecture (Multi-Segment PW) The corresponding domain of the MPLS-TP protocol stack including PWs is shown in Figure 8. +-------------------+ | Client Layer | /===================\ /===================\ H PW Encap H H PW OAM H H-------------------H H-------------------H /===================\ H PW Demux (S=1) H H PW Demux (S=1) H H LSP OAM H H-------------------H H-------------------H H-------------------H H LSP Demux(s) H H LSP Demux(s) H H LSP Demux(s) H \===================/ \===================/ \===================/ | Server Layer | | Server Layer | | Server Layer | +-------------------+ +-------------------+ +-------------------+ User Traffic PW OAM LSP OAM Note: Transport Service Layer = PW Demux Transport Path Layer = LSP Demux Figure 8: MPLS-TP Layer Network using Pseudowires When providing a Virtual Private Wire Service (VPWS), Virtual Private Local Area Network Service (VPLS), Virtual Private Multicast Service Bocci, et al. Expires June 25, 2010 [Page 19] Internet-Draft MPLS Transport Profile Framework December 2009 (VPMS) or Internet Protocol Local Area Network Service (IPLS), pseudowires must be used to carry the client service. [Editors' note add references for the terms in this para]. PWs and their underlying labels may be configured or signaled. See Section 3.9 for additional details related to configured service types. See Section 3.8 for additional details related to signaled service types. 3.4.3. Network Layer Adaptation MPLS-TP LSPs can be used to transport network layer clients. Any network layer protocol can be transported between service interfaces. Examples of network layer protocols include IP, MPLS and MPLS-TP. Support for network layer clients follows the MPLS architecture for support of network layer protocols as defined in [RFC3031] and supported in [RFC3032]. With network layer adaptation, the MPLS-TP domain provides a bidirectional point-to-point connection between two PEs in order to deliver a packet transport service to attached customer edge (CE) nodes. For example, a CE may be an IP, MPLS or MPLS-TP node. As shown in Figure 9, there is an attachment circuit between the CE node on the left and its corresponding provider edge (PE) node which provides the service interface, a bidirectional LSP across the MPLS-TP network to the corresponding PE node on the right, and an attachment circuit between that PE node and the corresponding CE node for this service. Bocci, et al. Expires June 25, 2010 [Page 20] Internet-Draft MPLS Transport Profile Framework December 2009 |<------------- Client Network Layer-------------->| | | | |<---- Pkt Xport Service --->| | | | | | | |<-- PSN Tunnel -->| | | | V V V V | V AC +----+ +---+ +----+ AC V +-----+ | |PE1 | | | |PE2 | | +-----+ | | |LSP | | | | | | | | | | CE1 |----------| |========X=========| |----------| CE2 | | | ^ |IP | | ^ | | ^ | | | ^ | | +-----+ | | | | | | | | | | | | +-----+ ^ | +----+ | +---+ | +----+ | | ^ | | Provider | ^ | Provider | | | | Edge | | | Edge | | Customer | 1 | P-router | 2 | Customer Edge 1 | TE TE | Edge 2 | LSP LSP | | | Native service Native service Figure 9: MPLS-TP Architecture for Network Layer Clients At the ingress service interface, the PE pushes one or more labels onto the ingress packets which are label switched over the transport network, and similarly the corresponding service interface at the egress PE pops any labels added by the MPLS-TP networks and delivers the packets to the attached CE. The attachment circuits may be heterogeneous (e.g., any combination of SDH, PPP, Frame Relay, etc.) and network layer protocol payloads arrive at the service interface encapsulated in the Layer1/Layer2 encoding defined for that access link type. It should be noted that the set of network layer protocols includes MPLS and hence MPLS encoded packets with an MPLS label stack (the client MPLS stack), may appear at the service interface. Bocci, et al. Expires June 25, 2010 [Page 21] Internet-Draft MPLS Transport Profile Framework December 2009 +-------------------+ | Client Layer | /===================\ /===================\ H Encap Label H H SvcLSP OAM H H-------------------H H-------------------H /===================\ H SvcLSP Demux H H SvcLSP Demux (S=1)H H LSP OAM H H-------------------H H-------------------H H-------------------H H LSP Demux(s) H H LSP Demux(s) H H LSP Demux(s) H \===================/ \===================/ \===================/ | Server Layer | | Server Layer | | Server Layer | +-------------------+ +-------------------+ +-------------------+ User Traffic Service LSP OAM LSP OAM Note: Transport Service Layer = SvcLSP Demux Transport Path Layer = LSP Demux Note that the functions of the Encap label and the Service Label may be represented by a single label or omitted. Additionally, the S-bit will always be zero when the client layer is MPLS labelled. Figure 10: Domain of MPLS-TP Layer Network for IP and LSP Clients Within the MPLS-TP transport network, the network layer protocols are carried over the MPLS-TP network using a logically separate MPLS label stack (the server stack). The server stack is entirely under the control of the nodes within the MPLS-TP transport network and it is not visible outside that network. Figure 10 shows how a client network protocol stack (which may be an MPLS label stack and payload) is carried over a network layer client service over an MPLS-TP transport network. A label per network layer protocol payload type that is to be transported is required. Such labels are referred to as "Encapsulation Labels", one of which is shown in Figure 10. Encapsulation Label is either configured or signaled. A Service Label should be used when a particular packet transport service is supporting more than one network layer protocol payload type (and more than one Encapsulation Label is used). An example Service Label is shown in Figure 10. A Service Label may be omitted when only one encapsulation label is used in support of a particular service. For example, if only MPLS labelled packets are carried over a service, then a single Encapsulation Label would be used to provide both payload type indication and service identification. Alternatively, if both IP and MPLS is to be carried, as shown in Figure 9, then two Encapsulation Labels could be mapped on to a common Service Label. Bocci, et al. Expires June 25, 2010 [Page 22] Internet-Draft MPLS Transport Profile Framework December 2009 Service labels are typically carried over an MPLS-TP edge-to-edge (or transport path layer) LSP, which is also shown in Figure 10. The use of an edge-to-edge LSP is recommended when more than one service exists between two PEs. An edge-to-edge LSP may be omitted when only one service label is used in between two PEs. For example, if only one service is carried between two PEs then a single Service Label could be used to provided both service indication and the MPLS-TP edge-to-edge LSP. Alternatively, if multiple services exist between a pair of PEs then a per-client Service Label would be mapped on to a common MPLS-TP edge-to-edge LSP. As noted above, the layer 2 and layer 1 protocols used to carry the network layer protocol over the attachment circuits are not transported across the MPLS-TP network. This enables the use of different layer 2 and layer 1 protocols on the two attachment circuits. At each service interface, Layer 2 addressing must be used to ensure the proper delivery of a network layer packet to the adjacent node. This is typically only an issue for LAN media technologies (e.g., Ethernet) which have Media Access Control (MAC) addresses. In cases where a MAC address is needed, the sending node must set the destination MAC address to an address that ensures delivery to the adjacent node. That is the CE sets the destination MAC address to an address that ensures delivery to the PE, and the PE sets the destination MAC address to an address that ensures delivery to the CE. The specific address used is technology type specific and is not covered in this document. In some technologies the MAC address will need to be configured (Examples for the Ethernet case include a configured unicast MAC address for the adjacent node, or even using the broadcast MAC address when the CE-PE service interface is dedicated. The configured address is then used as the MAC destination address for all packets sent over the service interface.) Note that when the two CEs operating over the network layer transport service are running a routing protocol such as IS-IS or OSPF some care should be taken to configure the routing protocols to use point- to-point adjacencies. The specifics of such configuration is outside the scope of this document. See [RFC5309] for additional details. The CE to CE service types and corresponding labels may be configured or signaled. See Section 3.9 for additional details related to configured service types. See Section 3.8 for additional details related to signaled service types. Bocci, et al. Expires June 25, 2010 [Page 23] Internet-Draft MPLS Transport Profile Framework December 2009 3.5. Identifiers Identifiers are used to uniquely distinguish entities in an MPLS-TP network. These include operators, nodes, LSPs, pseudowires, and their associated maintenance entities. [I-D.ietf-mpls-tp-identifiers] defines a set of identifiers that are compatible with existing MPLS control plane identifiers, as well as a set of identifiers that may be used when no IP control plane is available. 3.6. Generic Associated Channel (G-ACh) For correct operation of the OAM it is important that the OAM packets fate-share with the data packets. In addition in MPLS-TP it is necessary to discriminate between user data payloads and other types of payload. For example, a packet may be associated with a Signaling Communication Channel (SCC), or a channel used for Automatic Protection Switching (APS) data. This is achieved by carrying such packets on a generic control channel associated to the LSP, PW or section. MPLS-TP makes use of such a generic associated channel (G-ACh) to support Fault, Configuration, Accounting, Performance and Security (FCAPS) functions by carrying packets related to OAM, APS, SCC, MCC or other packet types in-band over LSPs or PWs. The G-ACh is defined in [RFC5586] and is similar to the Pseudowire Associated Channel [RFC4385], which is used to carry OAM packets over pseudowires. The G-ACh is indicated by a generic associated channel header (ACH), similar to the Pseudowire VCCV control word; this header is present for all Sections, LSPs and PWs making use of FCAPS functions supported by the G-ACh. For pseudowires, the G-ACh uses the first four bits of the pseudowire control word to provide the initial discrimination between data packets and packets belonging to the associated channel, as described in [RFC4385]. When this first nibble of a packet, immediately following the label at the bottom of stack, has a value of '1', then this packet belongs to a G-ACh. The first 32 bits following the bottom of stack label then have a defined format called an associated channel header (ACH), which further defines the content of the packet. The ACH is therefore both a demultiplexer for G-ACh traffic on the PW, and a discriminator for the type of G-ACh traffic. When the OAM or other control message is carried over an LSP, rather than over a pseudowire, it is necessary to provide an indication in the packet that the payload is something other than a user data packet. This is achieved by including a reserved label with a value of 13 in the label stack. This reserved label is referred to as the Bocci, et al. Expires June 25, 2010 [Page 24] Internet-Draft MPLS Transport Profile Framework December 2009 'Generic Alert Label (GAL)', and is defined in [RFC5586]. When a GAL is found, it indicates that the payload begins with an ACH. The GAL is thus a demultiplexer for G-ACh traffic on the LSP, and the ACH is a discriminator for the type of traffic carried on the G-ACh. Note however that MPLS-TP forwarding follows the normal MPLS model, and that a GAL is invisible to an LSR unless it is the top label in the label stack. The only other circumstance under which the label stack may be inspected for a GAL is when the TTL has expired. Any MPLS-TP component that intentionally performs this inspection must assume that it is asynchronous with respect to the forwarding of other packets. All operations on the label stack are in accordance with [RFC3031] and [RFC3032]. In MPLS-TP, the 'G-ACh Alert Label (GAL)' always appears at the bottom of the label stack (i.e. S bit set to 1). The G-ACh must only be used for channels that are an adjunct to the data service. Examples of these are OAM, APS, MCC and SCC, but the use is not restricted to these services. The G-ACh must not be used to carry additional data for use in the forwarding path, i.e. it must not be used as an alternative to a PW control word, or to define a PW type. At the server layer, bandwidth and QoS commitments apply to the gross traffic on the LSP, PW or section. Since the G-ACh traffic is indistinguishable from the user data traffic, protocols using the G-ACh must take into consideration the impact they have on the user data that they are sharing resources with. Conversely, capacity must be made available for important G-ACh uses such as protection and OAM. In addition, protocols using the G-ACh must conform to the security and congestion considerations described in [RFC5586]. Figure 11 shows the reference model depicting how the control channel is associated with the pseudowire protocol stack. This is based on the reference model for VCCV shown in Figure 2 of [RFC5085]. Bocci, et al. Expires June 25, 2010 [Page 25] Internet-Draft MPLS Transport Profile Framework December 2009 +-------------+ +-------------+ | Payload | < Service / FCAPS > | Payload | +-------------+ +-------------+ | Demux / | < CW / ACH for PWs > | Demux / | |Discriminator| |Discriminator| +-------------+ +-------------+ | PW | < PW > | PW | +-------------+ +-------------+ | PSN | < LSP > | PSN | +-------------+ +-------------+ | Physical | | Physical | +-----+-------+ +-----+-------+ | | | ____ ___ ____ | | _/ \___/ \ _/ \__ | | / \__/ \_ | | / \ | +--------| MPLS/MPLS-TP Network |---+ \ / \ ___ ___ __ _/ \_/ \____/ \___/ \____/ Figure 11: PWE3 Protocol Stack Reference Model including the G-ACh PW associated channel messages are encapsulated using the PWE3 encapsulation, so that they are handled and processed in the same manner (or in some cases, an analogous manner) as the PW PDUs for which they provide a control channel. Figure 12 shows the reference model depicting how the control channel is associated with the LSP protocol stack. Bocci, et al. Expires June 25, 2010 [Page 26] Internet-Draft MPLS Transport Profile Framework December 2009 +-------------+ +-------------+ | Payload | < Service > | Payload | +-------------+ +-------------+ |Discriminator| < ACH on LSP > |Discriminator| +-------------+ +-------------+ |Demultiplexer| < GAL on LSP > |Demultiplexer| +-------------+ +-------------+ | PSN | < LSP > | PSN | +-------------+ +-------------+ | Physical | | Physical | +-----+-------+ +-----+-------+ | | | ____ ___ ____ | | _/ \___/ \ _/ \__ | | / \__/ \_ | | / \ | +--------| MPLS/MPLS-TP Network |---+ \ / \ ___ ___ __ _/ \_/ \____/ \___/ \____/ Figure 12: MPLS Protocol Stack Reference Model including the LSP Associated Control Channel 3.7. Operations, Administration and Maintenance (OAM) MPLS-TP must be able to operate in environments where IP is not used in the forwarding plane. Therefore, the default mechanism for OAM demultiplexing in MPLS-TP LSPs and PWs is the Generic Associated Channel (Section 3.6). Forwarding based on IP addresses for user or OAM packets is not required for MPLS-TP. [RFC4379] and BFD for MPLS LSPs [I-D.ietf-bfd-mpls] have defined alert mechanisms that enable an MPLS LSR to identify and process MPLS OAM packets when the OAM packets are encapsulated in an IP header. These alert mechanisms are based on TTL expiration and/or use an IP destination address in the range 127/8 for IPv4 and that same range embedded as IPv4 mapped IPv6 addresses for IPv6 [RFC4379]. When the OAM packets are encapsulated in an IP header, these mechanisms are the default mechanisms for MPLS networks in general for identifying MPLS OAM packets. MPLS-TP must be able to operate in an environments where IP forwarding is not supported, and thus the GACH/GAL is the default mechanism to demultiplex OAM packets in MPLS-TP. MPLS-TP supports a comprehensive set of OAM capabilities for packet transport applications, with equivalent capabilities to those provided in SONET/SDH. Bocci, et al. Expires June 25, 2010 [Page 27] Internet-Draft MPLS Transport Profile Framework December 2009 MPLS-TP defines mechanisms to differentiate specific packets (e.g. OAM, APS, MCC or SCC) from those carrying user data packets on the same transport path (i.e. section, LSP or PW). These mechanisms are described in [RFC5586]. MPLS-TP requires [I-D.ietf-mpls-tp-oam-requirements] that a set of OAM capabilities is available to perform fault management (e.g. fault detection and localisation) and performance monitoring (e.g. packet delay and loss measurement) of the LSP, PW or section. The framework for OAM in MPLS-TP is specified in [I-D.ietf-mpls-tp-oam-framework]. MPLS-TP OAM packets share the same fate as their corresponding data packets, and are identified through the Generic Associated Channel mechanism [RFC5586]. This uses a combination of an Associated Channel Header (ACH) and a Generic Alert Label (GAL) to create a control channel associated to an LSP, Section or PW. 3.7.1. OAM Architecture OAM and monitoring in MPLS-TP is based on the concept of maintenance entities, as described in [I-D.ietf-mpls-tp-oam-framework]. A Maintenance Entity can be viewed as the association of two Maintenance End Points (MEPs) (see example in Figure 13 ). Another OAM construct is referred to as Maintenance Entity Group (MEG), which is a collection of one or more MEs that belongs to the same transport path and that are maintained and monitored as a group. The MEPs that form an ME should be configured and managed to limit the OAM responsibilities of an OAM flow within the domain of a transport path or segment, in the specific layer network that is being monitored and managed. Each OAM flow is associated with a single ME. Each MEP within an ME resides at the boundaries of that ME. An ME may also include a set of zero or more Maintenance Intermediate Points (MIPs), which reside within the Maintenance Entity. Maintenance End Points (MEPs) are capable of sourcing and sinking OAM flows, while Maintenance Intermediate Points (MIPs) can only sink or respond to OAM flows from within a MEG, or originate notifications as a result of specific network conditions. Bocci, et al. Expires June 25, 2010 [Page 28] Internet-Draft MPLS Transport Profile Framework December 2009 ========================== End to End LSP OAM ========================== ..... ..... ..... ..... -----|MIP|---------------------|MIP|---------|MIP|------------|MIP|----- ''''' ''''' ''''' ''''' |<-------- Carrier 1 --------->| |<--- Carrier 2 ----->| ---- --- --- ---- ---- --- ---- NNI | | | | | | | | NNI | | | | | | NNI -----| PE |---| P |---| P |----| PE |--------| PE |---| P |---| PE |---- | | | | | | | | | | | | | | ---- --- --- ---- ---- --- ---- ==== Segment LSP OAM ====== == Seg't == === Seg't LSP OAM === (Carrier 1) LSP OAM (Carrier 2) (inter-carrier) ..... ..... ..... .......... .......... ..... ..... |MEP|---|MIP|---|MIP|--|MEP||MEP|---|MEP||MEP|--|MIP|----|MEP| ''''' ''''' ''''' '''''''''' '''''''''' ''''' ''''' <------------ ME ----------><--- ME ----><------- ME --------> Note: MEPs for End-to-end LSP OAM exist outside of the scope of this figure. Figure 13: Example of MPLS-TP OAM showing end-to-end and segment OAM Figure 14 illustrates how the concept of Maintenance Entities can be mapped to sections, LSPs and PWs in an MPLS-TP network that uses MS- PWs. Bocci, et al. Expires June 25, 2010 [Page 29] Internet-Draft MPLS Transport Profile Framework December 2009 Native |<-------------------- PW15 --------------------->| Native Layer | | Layer Service | |<-PSN13->| |<-PSN3X->| |<-PSNXZ->| | Service (AC1) V V LSP V V LSP V V LSP V V (AC2) +----+ +-+ +----+ +----+ +-+ +----+ +---+ |TPE1| | | |SPE3| |SPEX| | | |TPEZ| +---+ | | | |=========| |=========| |=========| | | | |CE1|------|........PW1.....X..|...PW3...|.X......PW5........|-----|CE2| | | | |=========| |=========| |=========| | | | +---+ | 1 | |2| | 3 | | X | |Y| | Z | +---+ +----+ +-+ +----+ +----+ +-+ +----+ |<- Subnetwork 123->| |<- Subnetwork XYZ->| .------------------- PW15 PME -------------------. .---- PW1 PTCME ----. .---- PW5 PTCME ---. .---------. .---------. PSN13 LME PSNXZ LME .--. .--. .--------. .--. .--. Sec12 SME Sec23 SME Sec3X SME SecXY SME SecYZ SME TPE1: Terminating Provider Edge 1 SPE2: Switching Provider Edge 3 TPEX: Terminating Provider Edge X SPEZ: Switching Provider Edge Z .---. ME . MEP ==== LSP .... PW SME: Section Maintenance Entity LME: LSP Maintenance Entity PME: PW Maintenance Entity Figure 14: MPLS-TP OAM architecture showing PWs, LSPs and Sections The following MPLS-TP MEs are specified in [I-D.ietf-mpls-tp-oam-framework]: o A Section Maintenance Entity (SME), allowing monitoring and management of MPLS-TP Sections (between MPLS LSRs). o A LSP Maintenance Entity (LME), allowing monitoring and management of an end-to-end LSP (between LERs). o A PW Maintenance Entity (PME), allowing monitoring and management of an end-to-end SS/MS-PWs (between T-PEs). Bocci, et al. Expires June 25, 2010 [Page 30] Internet-Draft MPLS Transport Profile Framework December 2009 o An LSP Tandem Connection Maintenance Entity (LTCME). A G-ACH packet may be directed to an individual MIP along the path of an LSP or MS-PW by setting the appropriate TTL in the label for the G-ACH packet, as per the traceroute mode of LSP Ping [RFC4379] and the vccv-trace mode of[I-D.ietf-pwe3-segmented-pw]. Note that this works when the location of MIPs along the LSP or PW path is known by the MEP. There may be circumstances where this is not the case, e.g. following restoration using a facility bypass LSP. In these cases, tools to trace the path of the LSP may be used to determine the appropriate setting for the TTL to reach a specific MIP. Within an LSR or PE, MEPs and MIPs can only be placed where MPLS layer processing is performed on a packet. The architecture mandates that this must occur at least once. MEPs may only act as a sink of OAM packets when the label associated with the LSP or PW for that ME is popped. MIPs can only be placed where an exception to the normal forwarding operation occurs. A MEP may act as a source of OAM packets wherever a label is pushed or swapped. For example, on an MS-PW, a MEP may source OAM within an S-PE or a T-PE, but a MIP may only be associated with a S-PE and a sink MEP can only be associated with a T-PE. 3.7.2. OAM Functions The MPLS-TP OAM architecture supports a wide range of OAM functions, including the following: o Continuity Check o Connectivity Verification o Performance Monitoring (e.g. packet loss and delay measurement) o Alarm Suppression o Remote Integrity These functions are applicable to any layer defined within MPLS-TP, i.e. to MPLS-TP Sections, LSPs and PWs. The MPLS-TP OAM tool-set must be able to operate without relying on a dynamic control plane or IP functionality in the datapath. In the case of an MPLS-TP deployment in a network in which IP functionality is available, all existing IP/MPLS OAM functions, e.g. LSP-Ping, BFD and VCCV, may be used. Bocci, et al. Expires June 25, 2010 [Page 31] Internet-Draft MPLS Transport Profile Framework December 2009 One use of OAM mechanisms is to detect link failures, node failures and performance outside the required specification which then may be used to trigger recovery actions, according to the requirements of the service. 3.8. Control Plane Editors note: This section will be updated based on text supplied by the control plane framework draft editors. A distributed dynamic control plane may be used to enable dynamic service provisioning in an MPLS-TP network. Where the requirements specified in [RFC5654] can be met, the MPLS Transport Profile uses existing standard control plane protocols for LSPs and PWs. Note that a dynamic control plane is not required in an MPLS-TP network. See Section 3.9 for further details on statically configured and provisioned MPLS-TP services. Figure 15 illustrates the relationship between the MPLS-TP control plane, the forwarding plane, the management plane, and OAM for point- to-point MPLS-TP LSPs or PWs. Bocci, et al. Expires June 25, 2010 [Page 32] Internet-Draft MPLS Transport Profile Framework December 2009 +------------------------------------------------------------------+ | | | Network Management System and/or | | | | Control Plane for Point to Point Connections | | | +------------------------------------------------------------------+ | | | | | | .............|.....|... ....|.....|.... ....|.....|............ : +---+ | : : +---+ | : : +---+ | : : |OAM| | : : |OAM| | : : |OAM| | : : +---+ | : : +---+ | : : +---+ | : : | | : : | | : : | | : \: +----+ +--------+ : : +--------+ : : +--------+ +----+ :/ --+-|Edge|<->|Forward-|<---->|Forward-|<----->|Forward-|<->|Edge|-+-- /: +----+ |ing | : : |ing | : : |ing | +----+ :\ : +--------+ : : +--------+ : : +--------+ : ''''''''''''''''''''''' ''''''''''''''' ''''''''''''''''''''''' Note: 1) NMS may be centralised or distributed. Control plane is distributed. 2) 'Edge' functions refers to those functions present at the edge of a PSN domain, e.g. NSP or classification. 3) The control plane may be transported over the server layer, an LSP or a G-ACh. Figure 15: MPLS-TP Control Plane Architecture Context The MPLS-TP control plane is based on a combination of the LDP-based control plane for pseudowires [RFC4447] and the RSVP-TE-based control plane for MPLS-TP LSPs [RFC3471]. Some of the RSVP-TE functions that are required for MPLS-TP LSP signaling are based on Generalized MPLS (GMPLS) ([RFC3945], [RFC3471], [RFC3473]). The distributed MPLS-TP control plane may provide the following functions: o Signaling o Routing o Traffic engineering and constraint-based path computation In a multi-domain environment, the MPLS-TP control plane supports different types of interfaces at domain boundaries or within the domains. These include the User-Network Interface (UNI), Internal Bocci, et al. Expires June 25, 2010 [Page 33] Internet-Draft MPLS Transport Profile Framework December 2009 Network Node Interface (I-NNI), and External Network Node Interface (E-NNI). Note that different policies may be defined that control the information exchanged across these interface types. The MPLS-TP control plane is capable of activating MPLS-TP OAM functions as described in the OAM section of this document Section 3.7, e.g. for fault detection and localisation in the event of a failure in order to efficiently restore failed transport paths. The MPLS-TP control plane supports all MPLS-TP data plane connectivity patterns that are needed for establishing transport paths, including protected paths as described in Section 3.10. Examples of the MPLS-TP data plane connectivity patterns are LSPs utilising the fast reroute backup methods as defined in [RFC4090] and ingress-to-egress 1+1 or 1:1 protected LSPs. The MPLS-TP control plane provides functions to ensure its own survivability and to enable it to recover gracefully from failures and degradations. These include graceful restart and hot redundant configurations. Depending on how the control plane is transported, varying degrees of decoupling between the control plane and data plane may be achieved. 3.8.1. PW Control Plane An MPLS-TP network provides many of its transport services using single-segment or multi-segment pseudowires, in compliance with the PWE3 architecture ([RFC3985] and [RFC5659]). The setup and maintenance of single-segment or multi-segment pseudowires uses the Label Distribution Protocol (LDP) as per [RFC4447] and extensions for MS-PWs ([I-D.ietf-pwe3-segmented-pw] and [I-D.ietf-pwe3-dynamic-ms-pw]). 3.8.2. LSP Control Plane MPLS-TP Provider Edge LSRs aggregate multiple pseudowires and carry them across the MPLS-TP network through MPLS-TP tunnels (MPLS-TP LSPs). Applicable functions from the Generalized MPLS (GMPLS) ([RFC3945]) protocol suite supporting packet-switched capable (PSC) technologies are used as the control plane for MPLS-TP transport paths (LSPs). The LSP control plane includes: o RSVP-TE for signaling o OSPF-TE or ISIS-TE for routing Bocci, et al. Expires June 25, 2010 [Page 34] Internet-Draft MPLS Transport Profile Framework December 2009 RSVP-TE signaling in support of GMPLS, as defined in [RFC3473], is used for the setup, modification, and release of MPLS-TP transport paths and protection paths. It supports unidirectional and bidirectional point-to-point LSPs as well as unidirectional point-to- multipoint LSPs. The architecture for MPLS-TP supporting point-to- multipoint packet transport services is out of scope of this document. The route of a transport path is typically calculated in the ingress node of a domain and the RSVP explicit route object (ERO) is utilised for the setup of the transport path exactly following the given route. GMPLS-based MPLS-TP LSPs must be able to inter-operate with RSVP-TE-based MPLS-TE LSPs, as per [RFC5146] OSPF and IS-IS for GMPLS ([RFC4203] and [RFC5307]) are used for carrying link state routing information in an MPLS-TP network. 3.9. Static Operation of LSPs and PWs An MPLS-TP LSP or PW may be statically configured without the support of a dynamic control plane. This may be either by direct configuration of the LSRs, or via a network management system. Static operation is independent of a specific PW or LSP instance - for example it should be possible for a PW to be statically configured, while the LSP supporting it setup by a dynamic control plane. Persistent forwarding loops can cause significant additional resource utilisation, above that budgeted for the transport path. Therefore, when static configuration mechanisms are used, care must be taken to ensure that loops do not form. 3.10. Survivability Editors note: This section will be updated based on text supplied by the survivability draft editors. Survivability requirements for MPLS-TP are specified in [I-D.ietf-mpls-tp-survive-fwk]. A wide variety of resiliency schemes have been developed to meet the various network and service survivability objectives. For example, as part of the MPLS/PW paradigms, MPLS provides methods for local repair using back-up LSP tunnels ([RFC4090]), while pseudowire redundancy [I-D.ietf-pwe3-redundancy] supports scenarios where the protection for the PW cannot be fully provided by the PSN layer (i.e. where the backup PW terminates on a different target PE node than the working PW). Additionally, GMPLS provides a well known set of Bocci, et al. Expires June 25, 2010 [Page 35] Internet-Draft MPLS Transport Profile Framework December 2009 control plane driven protection and restoration mechanisms [RFC4872]. MPLS-TP provides additional protection mechanisms that are optimised for both linear topologies and ring topologies, and that operate in the absence of a dynamic control plane. These are specified in [I-D.ietf-mpls-tp-survive-fwk]. Different protection schemes apply to different deployment topologies and operational considerations. Such protection schemes may provide different levels of resiliency, for example: o Two concurrent traffic paths (1+1). o one active and one standby path with guaranteed bandwidth on both paths (1:1). o one active path and a standby path the resources or which are shared by one or more other active paths (shared protection). The applicability of any given scheme to meet specific requirements is outside the current scope of this document. The characteristics of MPLS-TP resiliency mechanisms are as follows: o Optimised for linear, ring or meshed topologies. o Use OAM mechanisms to detect and localise network faults or service degenerations. o Include protection mechanisms to coordinate and trigger protection switching actions in the absence of a dynamic control plane. This is known as an Automatic Protection Switching (APS) mechanism. o MPLS-TP recovery schemes are applicable to all levels in the MPLS-TP domain (i.e. MPLS section, LSP and PW), providing segment and end-to-end recovery. o MPLS-TP recovery mechanisms support the coordination of protection switching at multiple levels to prevent race conditions occurring between a client and its server layer. o MPLS-TP recovery mechanisms can be data plane, control plane or management plane based. o MPLS-TP supports revertive and non-revertive behaviour. Bocci, et al. Expires June 25, 2010 [Page 36] Internet-Draft MPLS Transport Profile Framework December 2009 3.11. Network Management The network management architecture and requirements for MPLS-TP are specified in [I-D.ietf-mpls-tp-nm-framework] and [I-D.ietf-mpls-tp-nm-req]. These derive from the generic specifications described in ITU-T G.7710/Y.1701 [G.7710] for transport technologies. It also incorporates the OAM requirements for MPLS Networks [RFC4377] and MPLS-TP Networks [I-D.ietf-mpls-tp-oam-requirements] and expands on those requirements to cover the modifications necessary for fault, configuration, performance, and security in a transport network. The Equipment Management Function (EMF) of an MPLS-TP Network Element (NE) (i.e. LSR, LER, PE, S-PE or T-PE) provides the means through which a management system manages the NE. The Management Communication Channel (MCC), realised by the G-ACh, provides a logical operations channel between NEs for transferring Management information. For the management interface from a management system to an MPLS-TP NE, there is no restriction on which management protocol is used. The MCC is used to provision and manage an end-to- end connection across a network where some segments are created/ managed by, for example, Netconf or SNMP and other segments by XML or CORBA interfaces. Maintenance operations are run on a connection (LSP or PW) in a manner that is independent of the provisioning mechanism. An MPLS-TP NE is not required to offer more than one standard management interface. In MPLS-TP, the EMF must be capable of statically provisioning LSPs for an LSR or LER, and PWs for a PE, as well as any associated MEPs and MIPs, as per Section 3.9. Fault Management (FM) functions within the EMF of an MPLS-TP NE enable the supervision, detection, validation, isolation, correction, and alarm handling of abnormal conditions in the MPLS-TP network and its environment. FM must provide for the supervision of transmission (such as continuity, connectivity, etc.), software processing, hardware, and environment. Alarm handling includes alarm severity assignment, alarm suppression/aggregation/correlation, alarm reporting control, and alarm reporting. Configuration Management (CM) provides functions to control, identify, collect data from, and provide data to MPLS-TP NEs. In addition to general configuration for hardware, software protection switching, alarm reporting control, and date/time setting, the EMF of the MPLS-TP NE also supports the configuration of maintenance entity identifiers (such as MEP ID and MIP ID). The EMF also supports the configuration of OAM parameters as a part of connectivity management to meet specific operational requirements. These may specify whether the operational mode is one-time on-demand or is periodic at a specified frequency. Bocci, et al. Expires June 25, 2010 [Page 37] Internet-Draft MPLS Transport Profile Framework December 2009 The Performance Management (PM) functions within the EMF of an MPLS-TP NE support the evaluation and reporting of the behaviour of the NEs and the network. One particular requirement for PM is to provide coherent and consistent interpretation of the network behaviour in a hybrid network that uses multiple transport technologies. Packet loss measurement and delay measurements may be collected and used to detect performance degradation. This is reported via fault management to enable corrective actions to be taken (e.g. protection switching), and via performance monitoring for Service Level Agreement (SLA) verification and billing. Collection mechanisms for performance data should be capable of operating on- demand or pro-actively. 4. Security Considerations The introduction of MPLS-TP into transport networks means that the security considerations applicable to both MPLS and PWE3 apply to those transport networks. Furthermore, when general MPLS networks that utilise functionality outside of the strict MPLS Transport Profile are used to support packet transport services, the security considerations of that additional functionality also apply. For pseudowires, the security considerations of [RFC3985] and [RFC5659] apply. Packets that arrive on an interface with a given label value should not be forwarded unless that label value is assigned to an LSP or PW to a peer LSR or PE that is reachable via that interface. Each MPLS-TP solution must specify the additional security considerations that apply. 5. IANA Considerations IANA considerations resulting from specific elements of MPLS-TP functionality will be detailed in the documents specifying that functionality. This document introduces no additional IANA considerations in itself. 6. Acknowledgements The editors wish to thank the following for their contribution to this document: o Rahul Aggarwal Bocci, et al. Expires June 25, 2010 [Page 38] Internet-Draft MPLS Transport Profile Framework December 2009 o Dieter Beller o Malcolm Betts o Italo Busi o John E Drake o Hing-Kam Lam o Marc Lasserre o Vincenzo Sestito o Martin Vigoureux o The participants of ITU-T SG15 7. Open Issues This section contains a list of issues that must be resolved before last call. o There is some text missing from the network layer clients section. Text is invited covering the use of out of band signaling associated with the AC. o Need text to address how the LSR next hop MAC address is determined for Ethernet link layers when no IP (i.e. ARP) is available. If statically configured, what is the default? 181209: this will be addressed in the normative data plane draft o Need to add section (Appendix) describing stack optizations for LSP and PWs o Add a section clarify what options are used for interdomain operation e.g. inter-AS TE LSPs, MS-PW, LSP stitching, back-to- back ACs o Text reduction for the OAM, survivability and NM sections. o Include summarised PST text 8. References Bocci, et al. Expires June 25, 2010 [Page 39] Internet-Draft MPLS Transport Profile Framework December 2009 8.1. Normative References [G.7710] "ITU-T Recommendation G.7710/ Y.1701 (07/07), "Common equipment management function requirements"", 2005. [G.805] "ITU-T Recommendation G.805 (11/95), "Generic Functional Architecture of Transport Networks"", November 1995. [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", RFC 3031, January 2001. [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Encoding", RFC 3032, January 2001. [RFC3270] Le Faucheur, F., Wu, L., Davie, B., Davari, S., Vaananen, P., Krishnan, R., Cheval, P., and J. Heinanen, "Multi-Protocol Label Switching (MPLS) Support of Differentiated Services", RFC 3270, May 2002. [RFC3471] Berger, L., "Generalized Multi- Protocol Label Switching (GMPLS) Signaling Functional Description", RFC 3471, January 2003. [RFC3473] Berger, L., "Generalized Multi- Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. [RFC3985] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture", RFC 3985, March 2005. Bocci, et al. Expires June 25, 2010 [Page 40] Internet-Draft MPLS Transport Profile Framework December 2009 [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005. [RFC4203] Kompella, K. and Y. Rekhter, "OSPF Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4203, October 2005. [RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson, "Pseudowire Emulation Edge-to- Edge (PWE3) Control Word for Use over an MPLS PSN", RFC 4385, 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. [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. [RFC5085] Nadeau, T. and C. Pignataro, "Pseudowire Virtual Circuit Connectivity Verification (VCCV): A Control Channel for Pseudowires", RFC 5085, December 2007. [RFC5307] Kompella, K. and Y. Rekhter, "IS-IS Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 5307, October 2008. [RFC5462] Andersson, L. and R. Asati, "Multiprotocol Label Switching (MPLS) Label Stack Entry: "EXP" Bocci, et al. Expires June 25, 2010 [Page 41] Internet-Draft MPLS Transport Profile Framework December 2009 Field Renamed to "Traffic Class" Field", RFC 5462, February 2009. [RFC5586] Bocci, M., Vigoureux, M., and S. Bryant, "MPLS Generic Associated Channel", RFC 5586, June 2009. 8.2. Informative References [I-D.ietf-bfd-mpls] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow, "BFD For MPLS LSPs", draft-ietf-bfd-mpls-07 (work in progress), June 2008. [I-D.ietf-mpls-tp-identifiers] Bocci, M. and G. Swallow, "MPLS-TP Identifiers", draft- ietf-mpls-tp-identifiers-00 (work in progress), November 2009. [I-D.ietf-mpls-tp-nm-framework] Mansfield, S., Gray, E., and H. Lam, "MPLS-TP Network Management Framework", draft-ietf-mpls-tp- nm-framework-02 (work in progress), November 2009. [I-D.ietf-mpls-tp-nm-req] Mansfield, S. and K. Lam, "MPLS TP Network Management Requirements", draft-ietf-mpls-tp-nm-req-06 (work in progress), October 2009. [I-D.ietf-mpls-tp-oam-framework] Allan, D., Busi, I., and B. Niven-Jenkins, "MPLS-TP OAM Framework", draft-ietf-mpls-tp- oam-framework-04 (work in progress), December 2009. [I-D.ietf-mpls-tp-oam-requirements] Vigoureux, M., Ward, D., and M. Betts, "Requirements for OAM in MPLS Transport Networks", draft- ietf-mpls-tp-oam-requirements-04 (work in progress), December 2009. [I-D.ietf-mpls-tp-survive-fwk] Sprecher, N. and A. Farrel, Bocci, et al. Expires June 25, 2010 [Page 42] Internet-Draft MPLS Transport Profile Framework December 2009 "Multiprotocol Label Switching Transport Profile Survivability Framework", draft-ietf-mpls-tp- survive-fwk-03 (work in progress), November 2009. [I-D.ietf-pwe3-dynamic-ms-pw] Martini, L., Bocci, M., Balus, F., Bitar, N., Shah, H., Aissaoui, M., Rusmisel, J., Serbest, Y., Malis, A., Metz, C., McDysan, D., Sugimoto, J., Duckett, M., Loomis, M., Doolan, P., Pan, P., Pate, P., Radoaca, V., Wada, Y., and Y. Seo, "Dynamic Placement of Multi Segment Pseudo Wires", draft-ietf-pwe3-dynamic-ms-pw-10 (work in progress), October 2009. [I-D.ietf-pwe3-redundancy] Muley, P. and V. Place, "Pseudowire (PW) Redundancy", draft-ietf-pwe3-redundancy-02 (work in progress), October 2009. [I-D.ietf-pwe3-segmented-pw] Martini, L., Nadeau, T., Metz, C., Duckett, M., Bocci, M., Balus, F., and M. Aissaoui, "Segmented Pseudowire", draft-ietf-pwe3-segmented-pw-13 (work in progress), August 2009. [RFC3443] Agarwal, P. and B. Akyol, "Time To Live (TTL) Processing in Multi-Protocol Label Switching (MPLS) Networks", RFC 3443, January 2003. [RFC3945] Mannie, E., "Generalized Multi- Protocol Label Switching (GMPLS) Architecture", RFC 3945, October 2004. [RFC4377] Nadeau, T., Morrow, M., Swallow, G., Allan, D., and S. Matsushima, "Operations and Management (OAM) Requirements Bocci, et al. Expires June 25, 2010 [Page 43] Internet-Draft MPLS Transport Profile Framework December 2009 for Multi-Protocol Label Switched (MPLS) Networks", RFC 4377, February 2006. [RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures", RFC 4379, February 2006. [RFC5146] Kumaki, K., "Interworking Requirements to Support Operation of MPLS-TE over GMPLS Networks", RFC 5146, March 2008. [RFC5254] Bitar, N., Bocci, M., and L. Martini, "Requirements for Multi-Segment Pseudowire Emulation Edge-to-Edge (PWE3)", RFC 5254, October 2008. [RFC5309] Shen, N. and A. Zinin, "Point- to-Point Operation over LAN in Link State Routing Protocols", RFC 5309, October 2008. [RFC5331] Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream Label Assignment and Context-Specific Label Space", RFC 5331, 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. [RFC5659] Bocci, M. and S. Bryant, "An Architecture for Multi-Segment Pseudowire Emulation Edge-to- Edge", RFC 5659, October 2009. Bocci, et al. Expires June 25, 2010 [Page 44] Internet-Draft MPLS Transport Profile Framework December 2009 Authors' Addresses Matthew Bocci (editor) Alcatel-Lucent Voyager Place, Shoppenhangers Road Maidenhead, Berks SL6 2PJ United Kingdom Phone: EMail: matthew.bocci@alcatel-lucent.com Stewart Bryant (editor) Cisco Systems 250 Longwater Ave Reading RG2 6GB United Kingdom Phone: EMail: stbryant@cisco.com Dan Frost Cisco Systems Phone: Fax: EMail: danfrost@cisco.com URI: Lieven Levrau Alcatel-Lucent 7-9, Avenue Morane Sulnier Velizy 78141 France Phone: EMail: lieven.levrau@alcatel-lucent.com Bocci, et al. Expires June 25, 2010 [Page 45] Internet-Draft MPLS Transport Profile Framework December 2009 Lou Berger LabN Phone: +1-301-468-9228 Fax: EMail: lberger@labn.net URI: Bocci, et al. Expires June 25, 2010 [Page 46]