MPLS Working Group M. Bocci, Ed. Internet-Draft Alcatel-Lucent Intended status: Standards Track S. Bryant, Ed. Expires: December 31, 2009 Cisco Systems L. Levrau Alcatel-Lucent June 29, 2009 A Framework for MPLS in Transport Networks draft-ietf-mpls-tp-framework-01 Status of This Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on December 31, 2009. 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Bocci, et al. Expires December 31, 2009 [Page 1] Internet-Draft MPLS TP Framework June 2009 Abstract This document specifies an archiectectural framework for the application of MPLS in transport networks. It describes a profile of MPLS that enables operational models typical in transport networks networks, while providing additional OAM, survivability and other maintenance functions not currently supported by MPLS. Requirements Language Although this document is not a protocol specification, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC2119 [RFC2119] and are to be interpreted as instructions to the protocol designers producing solutions that satisfy the architectural concepts set out in this document.. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Motivation and Background . . . . . . . . . . . . . . . . 3 1.2. Applicability . . . . . . . . . . . . . . . . . . . . . . 4 1.3. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.4. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6 2. Introduction to Requirements . . . . . . . . . . . . . . . . . 6 3. Transport Profile Overview . . . . . . . . . . . . . . . . . . 7 3.1. Packet Transport Services . . . . . . . . . . . . . . . . 7 3.2. Architecture . . . . . . . . . . . . . . . . . . . . . . . 7 3.3. MPLS-TP Forwarding Domain . . . . . . . . . . . . . . . . 10 3.4. MPLS-TP Transport Domain . . . . . . . . . . . . . . . . . 11 3.5. Addressing . . . . . . . . . . . . . . . . . . . . . . . . 11 3.6. Operations, Administration and Maintenance (OAM) . . . . . 13 3.7. Generic Associated Channel (G-ACh) . . . . . . . . . . . . 17 3.8. Control Plane . . . . . . . . . . . . . . . . . . . . . . 20 3.8.1. PW Control Plane . . . . . . . . . . . . . . . . . . . 22 3.8.2. LSP Control Plane . . . . . . . . . . . . . . . . . . 22 3.9. Static Operation of LSPs and PWs . . . . . . . . . . . . . 23 3.10. Survivability . . . . . . . . . . . . . . . . . . . . . . 23 3.11. Network Management . . . . . . . . . . . . . . . . . . . . 24 4. Security Considerations . . . . . . . . . . . . . . . . . . . 25 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 26 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26 7.1. Normative References . . . . . . . . . . . . . . . . . . . 26 7.2. Informative References . . . . . . . . . . . . . . . . . . 29 Bocci, et al. Expires December 31, 2009 [Page 2] Internet-Draft MPLS TP Framework June 2009 1. Introduction 1.1. Motivation and Background This document describes a framework for a Multiprotocol Label Switching Transport Profile (MPLS-TP). It presents the architectural framework for MPLS-TP, definining those elements of MPLS applicable to supporting the requirements in [I-D.ietf-mpls-tp-requirements] and what new protocol elements are required. Bandwidth demand continues to grow worldwide, stimulated by the accelerating growth and penetration of new packet based services and multimedia applications: o Packet-based services such as Ethernet, Voice over IP (VoIP), Layer 2 (L2)/Layer 3 (L3) Virtual Private Networks (VPNs), IP Television (IPTV), Radio Access Network (RAN) backhauling, etc., o Applications with various bandwidth and Quality of Service (QoS) requirements. This growth in demand has resulted in dramatic increases in access rates that are, in turn, driving dramatic increases in metro and core network bandwidth requirements. Over the past two decades, the evolving optical transport infrastructure (Synchronous Optical Networking (SONET)/Synchronous Digital Hierarchy (SDH), Optical Transport Network (OTN)) has provided carriers with a high benchmark for reliability and operational simplicity. To achieve this, these existing transport technologies have been designed with specific characteristics : o Strictly connection-oriented connectivity, which may be long-lived and may be provisioned manually or by network management. o A high level of protection and availability. o Quality of service. o Extended OAM capabilities. Carriers are looking to evolve such transport networks to support packet based services and networks, and to take advantage of the flexibility and cost benefits of packet switching technology. While MPLS is a maturing packet technology that is already playing an important role in transport networks and services, not all of MPLS's capabilities and mechanisms are needed and/or consistent with transport network operations. There are also transport technology Bocci, et al. Expires December 31, 2009 [Page 3] Internet-Draft MPLS TP Framework June 2009 characteristics that are not currently reflected in MPLS. The types of packet transport services delivered by transport networks are very similar to Layer 2 Virtual Private Networks defined by the IETF. 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 create a common set of new functions that are applicable to both MPLS networks in general, and those blonging to the MPLS-TP profile. MPLS-TP therefore defines a profile of MPLS targeted at transport applications and networks. This profile specifies the specific MPLS characteristics and extensions required to meet transport requirements. An equipment conforming to MPLS-TP MUST support this profile. An MPLS-TP conformant equipment MAY support additional MPLS features. A carrier may deploy some of those additional features in the transport layer of their network if they find them to be beneficial. 1.2. Applicability Figure 1 illustrates the range of services that MPLS-TP is intended to address. MPLS-TP is intended to support a range of layer 1, layer 2 and layer 3 services, and is not limited to layer 3 services only. Networks implementing MPLS-TP may choose to only support a subset of these services. Bocci, et al. Expires December 31, 2009 [Page 4] Internet-Draft MPLS TP Framework June 2009 MPLS-TP Solution exists over this spectrum |<-------------------------------->| cl-ps Multi-Service co-cs & co-ps (cl-ps & co-ps) (Label is | | service context) | | | |<------------------------------|--------------------------------->| | | | L3 Only L1, L2, L3 Services L1, L2 Services Pt-Pt, Pt-MP, MP-MP Pt-Pt and Pt-MP Figure 1: MPLS-TP Applicability The diagram above shows the spectrum of services that can be supported by MPLS. MPLS-TP solutions are primarily intended for packet transport applications. These can be deployed using a profile of MPLS that is strictly connection oriented and does not rely on IP forwarding or routing (shown on the right hand side of the figure), or in conjunction with an MPLS network that does use IP forwarding and that supports a broader range of IP services. This is the multi- service solution in the centre of the figure. 1.3. Scope This document describes a framework for a Tranport Profile of Multiprotocol Label Switching (MPLS-TP). It presents the architectural framework for MPLS-TP, definining those elements of MPLS applicable to supporting the requirements in [I-D.ietf-mpls-tp-requirements] and what new protocol elements are required. This document describes the architecture for MPLS-TP when the LSP client is a PW. The transport of IP and MPLS, other than carried over a PW, is outside the scope of this document. This does not preclude the use of LSPs conforming to the MPLS transport profile from being used to carry IP or other MPLS LSPs by general purpose MPLS networks. Bocci, et al. Expires December 31, 2009 [Page 5] Internet-Draft MPLS TP Framework June 2009 1.4. 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, Adminitration 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 Detailed definitions and additional terminology may be found in [I-D.ietf-mpls-tp-requirements]. 2. Introduction to Requirements The requirements for MPLS-TP are specified in [I-D.ietf-mpls-tp-requirements], [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. 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. Any new mechanisms and capabilities added to support transport networks and packet transport services must be able to interoperate with existing MPLS and pseudowire control and forwarding planes. Point to point LSPs MAY be unidirectional or bi-directional, and it MUST be possible to construct congruent Bi-directional LSPs. Point to multipoint LSPs are unidirectional. 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 December 31, 2009 [Page 6] Internet-Draft MPLS TP Framework June 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. Transport Profile Overview 3.1. Packet Transport Services The types of packet transport services provided by existing transport networks are similar to MPLS Layer 2 VPNs. A key characteristic of packet transport services is that the network used to provide the service does not participate in the any IP routing protocols present in the client, or use the IP addresses in client packets to forward those packets. The network is therefore transparent to IP in the client service. MPLS-TP MUST use one of the Layer 2 VPN services defined in [PPVPN architecture] to provide a packet transport service. MPLS-TP LSPs MAY also be used to transport traffic for which the immediate client of the MPLS-TP LSP is not a Layer 2 VPN. However, for the purposes of this document, we do not refer to these traffic types as belonging to a packet transport service. Such clients include IP and MPLS LSPs. 3.2. Architecture The architecture for a transport profile of MPLS (MPLS-TP) is based on the MPLS [RFC3031], pseudowire [RFC3985], and multi-segment pseudowire [I-D.ietf-pwe3-ms-pw-arch] architectures, as illustrated in Figure 2. Bocci, et al. Expires December 31, 2009 [Page 7] Internet-Draft MPLS TP Framework June 2009 |<-------------- Emulated Service ---------------->| | | | |<------- Pseudo Wire ------>| | | | | | | | |<-- PSN Tunnel -->| | | | V V V V | V AC +----+ +----+ AC V +-----+ | | PE1|==================| PE2| | +-----+ | |----------|............PW1.............|----------| | | CE1 | | | | | | | | CE2 | | |----------|............PW2.............|----------| | +-----+ ^ | | |==================| | | ^ +-----+ ^ | +----+ +----+ | | ^ | | Provider Edge 1 Provider Edge 2 | | | | | | Customer | | Customer Edge 1 | | Edge 2 | | | | Native service Native service Figure 2: MPLS-TP Architecture (Single Segment PW) Native |<------------Pseudowire-------------->| Native Service | PSN PSN | Service (AC) | |<--cloud->| |<-cloud-->| | (AC) | V V V V V V | | +----+ +-----+ +----+ | +----+ | |TPE1|===========|SPE1 |==========|TPE2| | +----+ | |------|..... PW.Seg't1.........PW.Seg't3.....|-------| | | CE1| | | | | | | | | |CE2 | | |------|..... PW.Seg't2.........PW.Seg't4.....|-------| | +----+ | | |===========| |==========| | | +----+ ^ +----+ ^ +-----+ ^ +----+ ^ | | | | | TE LSP TE LSP | | | | | |<---------------- Emulated Service ----------------->| MPLS-TP Architecture (Multi-Segment PW) The above figures illustrates the MPLS-TP architecture used to provide a point-to-point packet transport service, or VPWS. In this case, the MPLS-TP forwarding plane is a profile of the MPLS LSP and SS-PW or MS-PW forwarding architecture as detailed in section Bocci, et al. Expires December 31, 2009 [Page 8] Internet-Draft MPLS TP Framework June 2009 Section 3.3. This document describes the architecture for MPLS-TP when the LSP client is a PW. The transport of IP and MPLS, other than carried over a PW, is outside the scope of this document. This does not preclude the use of LSPs conforming to the MPLS transport profile from being used to carry IP or other MPLS LSPs by general purpose MPLS networks. LSP hierarchy MAY be used within the MPLS-TP network, so that more than one LSP label MAY appear in the label stack. +---------------------------+ | PW Native service | /===========================\ H PW Encapsulation H \ <---- PW Control word H---------------------------H \ <---- Normalised client H PW OAM H MPLS-TP channel H---------------------------H / H PW Demux (S=1) H / H---------------------------H \ H LSP OAM H \ H---------------------------H / MPLS-TP Path(s) H LSP Demultiplexer(s) H / \===========================/ | Server | +---------------------------+ Figure 3: Domain of MPLS-TP Layer Network using Pseudowires Figure (Figure 3) illustrates the protocol stack to be used when pseudowires are carried over MPLS-TP LSPs. When providing a VPWS, VPLS, VPMS or IPLS, pseudowires MUST be used to carry a client service. For compatibility with transport nomenclature, the PW may be referred to as the MPLS-TP Channel and the LSP may be referred to as the MPLS-TP Path. Note that in MPLS-TP environments where IP is used for control or OAM purposes, IP MAY be carried over the LSP demultiplexers as per RFC3031 [RFC3031], or directly over the server. PW OAM, PSN OAM and PW client data are mutually exclusive and never exist in the same packet. The MPLS-TP definition applies to the following two domains: Bocci, et al. Expires December 31, 2009 [Page 9] Internet-Draft MPLS TP Framework June 2009 o MPLS-TP Forwarding Domain o MPLS-TP Transport Domain 3.3. MPLS-TP Forwarding Domain A set of client-to-MPLS-TP adaptation functions interface the client to MPLS-TP. For pseudowires, this adaptation function is the PW forwarder shown in Figure 4a of [RFC3985]. The PW label is used for forwarding in this case and is always at the bottom of the label stack. The operation of the MPLS-TP network is independent of the payload carried by the MPLS-TP PW packet. MPLS-TP is itself a client of an underlying server layer. MPLS-TP is thus bounded by a set of adaptation functions to this server layer network. 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 QoS from the MPLS-TP network, which in turn inherits its QoS from the server layer. The server layer must therefore provide the neccesary Quality of Service (QoS) to ensure that the MPLS-TP client QoS commitments are satisfied. MPLS-TP LSPs use the MPLS label switching operations defined in [RFC3031]. These operations are highly optimized for performance and are not modified by the MPLS-TP profile. During forwarding a label is pushed to associate a forwarding equivalence class (FEC) with the LSP or PW. This specifies the processing operaton 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, in which case the packet may be inspected and either discarded or subjected to further processing within the LSR. TTL expiry causes an exception which forces a packet to be further inspected and processed. While this occurs, the forwarding of succeeding packets continues without interruption. Therefore, the only way to cause a P (intermediate) LSR to inspect a packet (for example for OAM purposes) is to set the TTL to expire at that LSR. MPLS-TP PWs support the PW and MS-PW forwarding operations defined in[RFC3985] and [I-D.ietf-pwe3-ms-pw-arch]. The Traffic Class field (formerly the MPLS EXP field) follows the definition and processing rules of [RFC5462] and [RFC3270]. Only the pipe and short-pipe models are supported in MPLS-TP. Bocci, et al. Expires December 31, 2009 [Page 10] Internet-Draft MPLS TP Framework June 2009 The MPLS encapsulation format is as defined in RFC 3032[RFC3032]. Per-platform label space is used for PWs. Either per-platform or per-interface label space may be used for LSPs. Point to point MPLS-TP LSPs can be either unidirectional or bidirectional. Point-to-multipoint MPLS-TP LSPs are unidirectional. Point-to-multipont PWs are currently being defined in the IETF and may be incorporated in MPLS-TP if required. 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. they 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. 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. Both E-LSP and L-LSP are supported in MPLS-TP, as defined in RFC 3270 [RFC3270] 3.4. MPLS-TP Transport Domain This document specifies the architecture when the client of the MPLS-TP LSP is a PW. Note, however, that in MPLS-TP environments where IP is used for control or OAM purposes, IP MAY be carried over the the LSPs or directly over the server, as described in Section 3.2. In this case, the MPLS-TP transport domain consists of the PW encapsulation mechanisms, including the PW control word. 3.5. Addressing Editor's note: This section will be updated after publication of the MPLS-TP Addressing Architecture draft. MPLS-TP distinguishes between adressing used to identify nodes in the network, and identifiers used for demultiplexing and forwarding. This distinction is illustrated in Figure 4. Bocci, et al. Expires December 31, 2009 [Page 11] Internet-Draft MPLS TP Framework June 2009 NMS Control/Signalling ..... ..... [Address]| | [Address] | | +-----+---------+------+ Address = Node | | | | ID in forwarding plane | V V | | | | MEP or MIP | | dmux | | svcid | | src | +--^-------------------+ | OAM: OAM | dmux= [GAL/GACH]........... or ________________________________________ IP (________________________________________) svc context=ID/FEC PWE=ID1 SRC=IP . . IDx Figure 4: Addressing in MPLS-TP Editor's note: The figure above arose from discussions in the MPLS-TP design team. It will be clarified in a future verson of this draft. IPv4 or IPv6 addresses are used to identify MPLS-TP nodes by default for network management and signaling purposes. In the forwarding plane, identfiers are required for the service context (provided by the FEC), and for OAM. OAM requires both a demultiplexer and an address for the source of the OAM packet. For MPLS in general where IP addressing is used, IPv4 or IPv6 is used by default. However, 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. Forwarding based on IP addresses for user or OAM packets is NOT REQUIRED for MPLS-TP. RFC 4379 [RFC4379]and BFD for MPLS LSPs [I-D.ietf-bfd-mpls] have defined alert mechanisms that enable a 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. These mechanisms are the default mechanisms for MPLS networks in general for Bocci, et al. Expires December 31, 2009 [Page 12] Internet-Draft MPLS TP Framework June 2009 identifying MPLS OAM packets when the OAM packets are encapsulated in an IP header. MPLS-TP must not rely on these mechanisms, and thus relies on the GACH/GAL to demultiplex OAM packets. 3.6. Operations, Administration and Maintenance (OAM) MPLS-TP supports a comprehensive set of OAM capabilities for packet transport applications, with equivalent capabilities to those provided in SONET/SDH. MPLS-TP defines mechanisms to differentiate specific packets (e.g. OAM, APS, MCC or SCC) from those carrying user data packets on the same LSP. These mechanisms are described in RFC5586 [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 localization) 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]. 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 (or more) Maintenance End Points (MEPs) (see example in Figure 5 ). The MEPs that form an ME should be configured and managed to limit the OAM responsibilities of an OAM flow within a network or sub- network, or 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. Bocci, et al. Expires December 31, 2009 [Page 13] Internet-Draft MPLS TP Framework June 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 5: Example of MPLS-TP OAM Figure 6 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 December 31, 2009 [Page 14] Internet-Draft MPLS TP Framework June 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........|...PW3...|........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 6: MPLS-TP OAM archtecture 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 December 31, 2009 [Page 15] Internet-Draft MPLS TP Framework June 2009 o An LSP Tandem Connection Maintenance Entity (LTCME), allowing monitoring and management of an LSP Tandem Connection (or LSP Segment) between any LER/LSR along the LSP. o A MS-PW Tandem Connection Maintenance Entity (PTCME), allows monitoring and management of a SS/MS-PW Tandem Connection (or PW Segment) between any T-PE/S-PE along the (MS-)PW. Note that the term Tandem Connection Monitoring has historical significance dating back to the early days of the telephone network, but is equally applicable to the two-level hierarchal architectures commonly employed in todays packet networks. Individual MIPs along the path of an LSP or PW are addressed by setting the appropriate TTL in the label for the OAM packet, as per [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 cases where this is not the case in general MPLS networks e.g. following restoration using a facility bypass LSP. 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. The MPLS-TP OAM architecture support a wide range of OAM functions, including the following o Continuity Check o Connectivity Verification o Performance monitoring (e.g. loss and delay) o Alarm suppression o Remote Integrity These are applicable to any layer defined within MPLS- TP, i.e. MPLS Section, LSP and PW. The MPLS-TP OAM toolset needs to be able to operate without relying on a dynamic control plane or IP functionality in the datapath. In the case of MPLS-TP deployment with IP functionality, all existing IP-MPLS OAM functions, e.g. LSP-Ping, BFD and VCCV, may be used. This does not preculde the use of other OAM tools in an IP addressable network. One use of OAM mechanisms is to detect link failures, node failures Bocci, et al. Expires December 31, 2009 [Page 16] Internet-Draft MPLS TP Framework June 2009 and performance outside the required specification which then may be used to trigger recovery actions, according to the requirements of the service. 3.7. 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 MPSL-TP it is necessary to discriminate between user data payloads and other types of payload. For example the packet may contain a Signaling Communication Channel (SCC), or a channel used for Automatic Protecton Switching (APS) data. Such packetets are carried on a control channel associated to the LSP, Section or PW. 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 it is similar to the Pseudowire Associated Channel [RFC4385], which is used to carry OAM packets across pseudowires. The G-ACH is indicated by a generic associated channel header (ACH), similar to the Pseudowire VCCV control word, and this is present for all Sections, LSPs and PWs making use of FCAPS functions supported by the G-ACH. For pseudowires, the G-ACh use the first nibble of the pseudowire control word to provide the initial discrimination between data packets a packets belonging to the associated channel, as described in[RFC4385]. When the first nibble of a packet, immediately following the label at the bottom of stack, has a value of one, 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 a similar 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 acheived by including a reserved label with a value of 13 in the label stack. This reserved label is referred to as the 'Generic Alert Label (GAL)', and is defined in [RFC5586]. When a GAL is found anywhere within the label stack 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 Bocci, et al. Expires December 31, 2009 [Page 17] Internet-Draft MPLS TP Framework June 2009 forwarding follows the normal MPLS model, and that a GAL is invisible to an LSR unless it is the top label iin 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 arein accordance with [RFC3031] and [RFC3032]. In MPLS-TP, the 'Generic Alert Label (GAL)' always appears at the bottom of the label stack (i.e. S bit set to 1), however this does not preclude its use elsewhere in the label stack in other applications. 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 resticted to those names 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. Since the G-ACh traffic is indistinguishable from the user data traffic at the server layer, bandwidth and QoS commitments apply to the gross traffic on the LSP, PW or section. Protocols using the G-ACh must therefore take into consideration the impact they have on the user data that they are sharing resources with. In addition, protocols using the G-ACh MUST conform to the security and congestion considerations described in [RFC5586]. . Figure 7 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 December 31, 2009 [Page 18] Internet-Draft MPLS TP Framework June 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 7: 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 8 shows the reference model depicting how the control channel is associated with the LSP protocol stack. Bocci, et al. Expires December 31, 2009 [Page 19] Internet-Draft MPLS TP Framework June 2009 +-------------+ +-------------+ | Payload | < Service > | Payload | +-------------+ +-------------+ |Discriminator| < ACH on LSP > |Discriminator| +-------------+ +-------------+ |Demultiplexer| < GAL on LSP > |Demultiplexer| +-------------+ +-------------+ | PSN | < LSP > | PSN | +-------------+ +-------------+ | Physical | | Physical | +-----+-------+ +-----+-------+ | | | ____ ___ ____ | | _/ \___/ \ _/ \__ | | / \__/ \_ | | / \ | +--------| MPLS/MPLS-TP Network |---+ \ / \ ___ ___ __ _/ \_/ \____/ \___/ \____/ Figure 8: MPLS Protocol Stack Reference Model including the LSP Associated Control Channel 3.8. Control Plane MPLS-TP should be capable of being operated with centralized Network Management Systems (NMS). The NMS may be supported by a distributed control plane, but MPLS-TP can operated in the absense of such a control plane. A distributed control plane may be used to enable dynamic service provisioning in multi-vendor and multi-domain environments using standardized protocols that guarantee interoperability. Where the requirements specified in [I-D.ietf-mpls-tp-requirements] can be met, the MPLS transport profile uses existing control plane protocols for LSPs and PWs. Figure 9 illustrates the relationshop 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 December 31, 2009 [Page 20] Internet-Draft MPLS TP Framework June 2009 +------------------------------------------------------------------------+ | | | Network Management System and/or | | | | Control Plane for Point to Point Connections | | | +------------------------------------------------------------------------+ | | | | | | ............|......|..... ....|.......|.... ....|....|............... +---+ | : : +---+ | : : +---+ | : : |OAM| | : : |OAM| | : : |OAM| | : : +---+ | : : +---+ | : : +---+ | : : | | : : | | : : | | : \: +----+ +----------+ : : +----------+ : : +----------+ +----+ :/ --+-|Edge|<->|Forwarding|<---->|Forwarding|<----->|Forwarding|<->|Edge|-+-- /: +----+ | | : : | | : : | | +----+ :\ : +----------+ : : +----------+ : : +----------+ : ''''''''''''''''''''''''' ''''''''''''''''' '''''''''''''''''''''''' 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. Figure 9: 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 LSP signaling for MPLS-TP are based on GMPLS. The distributed MPLS-TP control plane provides 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 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. Bocci, et al. Expires December 31, 2009 [Page 21] Internet-Draft MPLS TP Framework June 2009 The MPLS-TP control plane is capable of activating MPLS-TP OAM functions as described in the OAM section of this document Section 3.6 e.g. for fault detection and localization 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 the survivability section Section 3.10 of this document. Examples of the MPLS-TP data plane connectivity patterns are LSPs utilizing 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 degredations. 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 [I-D.ietf-pwe3-ms-pw-arch] ). 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 nodes 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) 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 signalling o OSPF-TE or ISIS-TE for routing RSVP-TE signaling in support of GMPLS, as defined in [RFC4872], is used for the setup, modification, and release of MPLS-TP transport paths and protection paths. It supports unidirectional, bi- directional and multicast types of LSPs. The route of a transport Bocci, et al. Expires December 31, 2009 [Page 22] Internet-Draft MPLS TP Framework June 2009 path is typically calculated in the ingress node of a domain and the RSVP explicit route object (ERO) is utilized for the setup of the transport path exactly following the given route. GMPLS based MPLS-TP LSPs must be able to interoperate with RSVP-TE based MPLS-TE LSPs, as per [RFC5146] OSPF-TE routing in support of GMPLS as defined in [RFC4203] is used for carrying link state information in a MPLS-TP network. ISIS-TE routing in support of GMPLS as defined in [RFC5307] is used for carrying link state information in a MPLS-TP network. 3.9. Static Operation of LSPs and PWs A PW or LSP may be statically configured without the support of a dynamic control plane. This may be either by direct configuration of the PEs/LSRs, or via a network management system. The colateral damage that loops can cause during the time taken to detect the failure may be severe. When static configuration mechanisms are used, care must be taken to ensure that loops to not form. 3.10. Survivability 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 can not 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 control plane driven protection and restoration mechanisms [RFC4872]. MPLS-TP provides additional protection mechansisms that are optimised for both linear topologies and ring topologies, and that operate in the absense 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, two concurrent traffic paths (1+1), one active and one standby path with guaranteed bandwidth on both paths (1:1) or one active path and a standby path that is 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. Bocci, et al. Expires December 31, 2009 [Page 23] Internet-Draft MPLS TP Framework June 2009 The characteristics of MPLS-TP resiliency mechanisms are listed below. o Optimised for linear, ring or meshed topologies. o Use OAM mechanisms to detect and localize network faults or service degenerations. o Include protection mechanisms to coordinate and trigger protection switching actions in the absense 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 occuring 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 behavior. 3.11. Network Management The network management architecture and requirements for MPLS-TP are specified in [I-D.ietf-mpls-tp-nm-req]. It derives 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 a 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), realized by the G-ACh, provides a logical operations channel between NEs for transferring Management information. For the management interface from a management system to a MPLS-TP NE, there is no restriction on which management protocol should be used. It is used to provision and manage an end-to-end connection across a network where some segments are create/managed, for examples by 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. Bocci, et al. Expires December 31, 2009 [Page 24] Internet-Draft MPLS TP Framework June 2009 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 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. 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 should be capable of operating on-demand or proactively. 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-TP profile are used to support packet transport services, the security considerations of that additional functionality also apply. The security considerations of [RFC3985] and Bocci, et al. Expires December 31, 2009 [Page 25] Internet-Draft MPLS TP Framework June 2009 [I-D.ietf-pwe3-ms-pw-arch] apply. Each MPLS-TP solution must specify the addtional 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 Dieter Beller o Italo Busi o Hing-Kam Lam o Marc Lasserre o Vincenzo Sestito o Martin Vigoureux o Malcolm Betts 7. References 7.1. Normative References [G.7710] "ITU-T Recommendation G.7710/ Y.1701 (07/07), "Common equipment management function requirements"", 2005. [I-D.ietf-mpls-cosfield-def] Andersson, L. and R. Asati, "Multi-Protocol Label Switching (MPLS) label stack entry: "EXP" field renamed to "Traffic Class" field", draft-ietf-mpls-cosfield-def-08 (work in progress), Bocci, et al. Expires December 31, 2009 [Page 26] Internet-Draft MPLS TP Framework June 2009 December 2008. [I-D.ietf-pwe3-ms-pw-arch] Bocci, M. and S. Bryant, "An Architecture for Multi-Segment Pseudowire Emulation Edge-to- Edge", draft-ietf-pwe3-ms-pw-arch-06 (work in progress), February 2009. [I-D.ietf-pwe3-redundancy] Muley, P. and M. Bocci, "Pseudowire (PW) Redundancy", draft-ietf-pwe3-redundancy-01 (work in progress), September 2008. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [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. [RFC3985] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to-Edge Bocci, et al. Expires December 31, 2009 [Page 27] Internet-Draft MPLS TP Framework June 2009 (PWE3) Architecture", RFC 3985, March 2005. [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005. [RFC4201] Kompella, K., Rekhter, Y., and L. Berger, "Link Bundling in MPLS Traffic Engineering (TE)", RFC 4201, October 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, Bocci, et al. Expires December 31, 2009 [Page 28] Internet-Draft MPLS TP Framework June 2009 "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" 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. 7.2. Informative References [I-D.bryant-filsfils-fat-pw] Bryant, S., Filsfils, C., Drafz, U., Kompella, V., Regan, J., and S. Amante, "Flow Aware Transport of MPLS Pseudowires", draft-bryant-filsfils-fat-pw-03 (work in progress), March 2009. [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-nm-req] Mansfield, S. and K. Lam, "MPLS TP Network Management Requirements", draft-ietf-mpls-tp-nm-req-02 (work in progress), June 2009. [I-D.ietf-mpls-tp-oam-framework] Busi, I. and B. Niven-Jenkins, "MPLS-TP OAM Framework and Overview", draft-ietf-mpls-tp- oam-framework-00 (work in progress), March 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-02 (work in progress), June 2009. Bocci, et al. Expires December 31, 2009 [Page 29] Internet-Draft MPLS TP Framework June 2009 [I-D.ietf-mpls-tp-requirements] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N., and S. Ueno, "MPLS-TP Requirements", dr aft-ietf-mpls-tp-requirements-09 (work in progress), June 2009. [I-D.ietf-mpls-tp-survive-fwk] Sprecher, N., Farrel, A., and H. Shah, "Multiprotocol Label Switching Transport Profile Survivability Framework", draft- ietf-mpls-tp-survive-fwk-00 (work in progress), April 2009. [I-D.ietf-pwe3-dynamic-ms-pw] Martini, L., Bocci, M., Bitar, N., Shah, H., Aissaoui, M., and F. Balus, "Dynamic Placement of Multi Segment Pseudo Wires", draft-ietf-pwe3-dynamic-ms-pw-09 (work in progress), March 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-12 (work in progress), June 2009. [RFC4377] Nadeau, T., Morrow, M., Swallow, G., Allan, D., and S. Matsushima, "Operations and Management (OAM) Requirements for Multi-Protocol Label Switched (MPLS) Networks", RFC 4377, February 2006. [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. Bocci, et al. Expires December 31, 2009 [Page 30] Internet-Draft MPLS TP Framework June 2009 Authors' Addresses Matthew Bocci (editor) Alcatel-Lucent Voyager Place, Shoppenhangers Road Maidenhead, Berks SL6 2PJ United Kingdom Phone: +44-207-254-5874 EMail: matthew.bocci@alcatel-lucent.com Stewart Bryant (editor) Cisco Systems 250 Longwater Ave Reading RG2 6GB United Kingdom Phone: +44-208-824-8828 EMail: stbryant@cisco.com Lieven Levrau Alcatel-Lucent 7-9, Avenue Morane Sulnier Velizy 78141 France Phone: +33-6-33-86-1916 EMail: lieven.levrau@alcatel-lucent.com Bocci, et al. Expires December 31, 2009 [Page 31]