INTERNET-DRAFT                                              L. Fang, Ed.
Intended Status: Informational                                     Cisco
Expires: June 16, 2013                                          N. Bitar
                                                                R. Zhang
                                                          Alcatel Lucent
                                                              M. Daikoku
                                                                  P. Pan

                                                       December 16, 2012

             MPLS-TP Applicability; Use Cases and Design


   This document provides applicability, use case studies and network
   design considerations for the Multiprotocol Label Switching Transport
   Profile (MPLS-TP). The use cases include Metro Ethernet access and
   aggregation transport, Mobile backhaul, and packet optical transport.

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Copyright and License Notice

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   Copyright (c) 2012 IETF Trust and the persons identified as the
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Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3. MPLS-TP Use Cases . . . . . . . . . . . . . . . . . . . . . . .  5
     3.1. Metro Access and Aggregation  . . . . . . . . . . . . . . .  5
     3.2. Packet Optical Transport  . . . . . . . . . . . . . . . . .  6
     3.3. Mobile Backhaul . . . . . . . . . . . . . . . . . . . . . .  7
       3.3.1. 2G and 3G Mobile Backhaul . . . . . . . . . . . . . . .  7
       3.3.2. 4G/LTE Mobile Backhaul  . . . . . . . . . . . . . . . .  8
   4. Network Design Considerations . . . . . . . . . . . . . . . . .  8
     4.1. The role of MPLS-TP . . . . . . . . . . . . . . . . . . . .  8
     4.2. Provisioning mode . . . . . . . . . . . . . . . . . . . . .  8
     4.3. Standards compliance  . . . . . . . . . . . . . . . . . . .  9
     4.4. End-to-end MPLS OAM consistency . . . . . . . . . . . . . .  9
     4.5. PW Design considerations in MPLS-TP networks  . . . . . . .  9
     4.6. Proactive and on-demand MPLS-TP OAM tools . . . . . . . . . 10
     4.7. MPLS-TP and IP/MPLS Interworking considerations . . . . . . 10
   5. Security Considerations . . . . . . . . . . . . . . . . . . . . 11
   6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 11
   7. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 11
   8. References  . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     8.1. Normative References  . . . . . . . . . . . . . . . . . . . 11
     8.2. Informative References  . . . . . . . . . . . . . . . . . . 12
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
   Contributors' Addresses  . . . . . . . . . . . . . . . . . . . . . 13

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1. Introduction

   This document provides applicability, use case studies and network
   design considerations for the Multiprotocol Label Switching Transport
   Profile (MPLS-TP).

   In recent years, the urgency for moving from traditional transport
   technologies, such as SONET/SDH, TDM, and ATM, to new packet
   technologies has been rising. This is largely due to the fast growing
   demand for bandwidth, which has been fueled by the following factors:
   1) The growth of new services. This includes: the tremendous success
   of data services, such as IPTV and IP Video for content downloading,
   streaming, and sharing; the rapid growth of mobile services, as a
   consequence of the explosion of smart phone applications; the
   continued growth of business VPNs and residential broadband services.
   2) Network infrastructure evolution. As many legacy transport devices
   are approaching end of life, Service Providers transition to new
   packet technologies and evolve their transport network into the next
   generation packet transport.

   As part of MPLS family, MPLS-TP complements existing IP/MPLS
   technologies; it closes the gaps in the traditional access and
   aggregation transport to enable end-to-end packet technology
   solutions in a cost efficient, reliable, and interoperable manner.
   After several years of industry debate on which packet technology to
   use, MPLS-TP has emerged as the next generation transport technology
   of choice for many Service Providers worldwide.

   The Unified MPLS strategy - using MPLS from core to aggregation and
   access (e.g. IP/MPLS in the core, IP/MPLS or MPLS-TP in aggregation
   and access) appear to be very attractive to many SPs. It streamlines
   the operation, reduces the overall complexity, and improves end-to-
   end convergence. It leverages the MPLS experience, and enhances the
   ability to support revenue generating services.

   MPLS-TP is a subset of MPLS functions that meet the packet transport
   requirements defined in [RFC5654]. This subset includes: MPLS data
   forwarding, pseudo-wire encapsulation for circuit emulation, and
   dynamic control plane using GMPLS control for LSP and tLDP for
   pseudo-wire (PW). MPLS-TP also extends previous MPLS OAM functions,
   such as BFD extension for proactive Connectivity Check and
   Connectivity Verification (CC-CV) [RFC6428], and Remote Defect
   Indication (RDI) [RFC6428], LSP Ping Extension for on-demand CC-CV
   [RFC6426], fault allocation, and remote integrity check. New tools
   have been defined for alarm suppression with Alarm Indication Signal
   (AIS) [RFC6427], and switch-over triggering with Link Defect
   Indication (LDI). Note that since the MPLS OAM feature extensions
   defined through the process of MPLS-TP development are part of the

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   MPLS family, the applicability is general to MPLS, and not limited to

   The requirements of MPLS-TP are provided in MPLS-TP Requirements [RFC
   5654], and the architectural framework is defined in MPLS-TP
   Framework [RFC5921]. This document's intent is to provide the use
   case studies and design considerations from a practical point of view
   based on Service Providers deployments plans and actual deployments.

   The most common use cases for MPLS-TP include Metro access and
   aggregation, Mobile Backhaul, and Packet Optical Transport. MPLS-TP
   data plane architecture, path protection mechanisms, and OAM
   functionality are used to support these deployment scenarios.

   The design considerations discussed in this documents include: role
   of MPLS-TP in the network; provisioning options; standards
   compliance; end-to-end forwarding and OAM consistency; compatibility
   with existing IP/MPLS networks; and optimization vs. simplicity
   design trade-offs.

2. Terminology

      Term     Definition
      ------   -------------------------------------------------------
      2G       2nd generation wireless telephone technology
      3G       3rd generation of mobile telecommunications technology
      4G       4th Generation Mobile network: LTE
      ADSL     Asymmetric Digital Subscriber Line
      AIS      Alarm Indication Signal
      ASNGW    Access Service Network Gateway
      ATM      Asynchronous Transfer Mode
      BFD      Bidirectional Forwarding Detection
      BTS      Base Transceiver Station
      CC-CV    Continuity Check and Connectivity Verification
      CDMA     Code Division Multiple Access
      E-LINE   Ethernet point-to-point connectivity
      E-LAN    Ethernet LAN, provides multipoint connectivity
      eNB      Evolved Node B
      E-VLAN   Ethernet Virtual Private LAN
      EVDO     Evolution-Data Optimized
      G-ACh    Generic Associated Channel
      GAL      G-ACh Label
      GMPLS    Generalized Multi-Protocol Label Switching
      GSM      Global System for Mobile Communications
      HSPA     High Speed Packet Access
      IPTV     Internet Protocol television
      L2VPN    Layer 2 Virtual Private Network
      L3VPN    Layer 3 Virtual Private Network

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      LAN      Local Access Network
      LDI      Link Down Indication
      LDP      Label Distribution Protocol
      LSP      Label Switched Path
      LTE      Long Term Evolution
      MEP      Maintenance End Point
      MIP      Maintenance Intermediate Point
      NMS      Network Management System
      MPLS     MultiProtocol Label Switching
      MPLS-TP  MultiProtocol Label Switching Transport Profile
      MS-PW    Multi-Segment Pseudowire
      OAM      Operations, Administration, and Management
      OPEX     Operating Expenses
      PE       Provider-Edge device
      PSW      Packet Data Network Gateway
      RAN      Radio Access Network
      RDI      Remote Defect Indication
      SDH      Synchronous Digital Hierarchy
      SGW      Serving Gateway
      SLA      Service Level Agreement
      SONET    Synchronous Optical Network
      S-PE     PW Switching Provider Edge
      SP       Service Provider
      SRLG     Shared Risk Link Groups
      SS-PW    Single-Segment Pseudowire
      TDM      Time Division Multiplexing
      tLDP     Targeted Label Distribution Protocol
      VPN      Virtual Private Network
      UMTS     Universal Mobile Telecommunications System

3. MPLS-TP Use Cases

3.1. Metro Access and Aggregation

   The use of MPLS-TP for Metro access and aggregation transport is the
   most common deployment scenario observed in the field.

   Some operators are building green-field access and aggregation
   transport infrastructure, while others are upgrading/replacing their
   existing transport infrastructure with new packet technologies. The
   existing legacy access and aggregation networks are usually based on
   TDM or ATM technologies. Some operators are replacing these networks
   with MPLS-TP technologies, since legacy ATM/TDM aggregation and
   access are becoming inadequate to support the rapid business growth
   and too expensive to maintain. In addition, in many cases the legacy
   devices are facing End of Sale and End of Life issues. As operators
   must move forward with the next generation packet technology, the
   adoption of MPLS-TP in access and aggregation becomes a natural

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   choice. The statistical multiplexing in MPLS-TP helps to achieve
   higher efficiency comparing with the time division scheme in the
   legacy technologies. MPLS-TP OAM tools and protection mechanisms help
   to maintain high reliability of transport network and achieve fast

   As most Service Providers core networks are MPLS enabled, extending
   the MPLS technology to the aggregation and access transport networks
   with a Unified MPLS strategy is very attractive to many Service
   Providers. Unified MPLS strategy in this document means having end-
   to-end MPLS technologies through core, aggregation, and access. It
   reduces OPEX by streamlining operation and leveraging the operational
   experience already gained with MPLS technologies; it also improves
   network efficiency and reduces end-to-end convergence time.

   The requirements from the SPs for ATM/TDM aggregation replacement
   often include: i) maintaining the previous operational model, which
   means providing a similar user experience in NMS, ii) supporting the
   existing access network, (e.g., Ethernet, ADSL, ATM, TDM, etc.), and
   connections with the core networks, and iii) supporting the same
   operational capabilities and services (L3VPN, L2VPN, E-LINE/E-LAN/E-
   VLAN, Dedicated Line, etc.). MPLS-TP can meet these requirements and
   in general the requirements defined in [RFC5654] to support a smooth

3.2. Packet Optical Transport

   Many SP's transport networks consist of both packet and optical
   portions. The transport operators are typically sensitive to network
   deployment cost and operational simplicity. MPLS-TP supports both
   static provisioning through NMS and dynamic provisioning via the
   GMPLS control plane. As such, it is viewed as a natural fit in some
   of the transport networks, where the operators can utilize the MPLS-
   TP LSP's (including the ones statically provisioned) to manage user
   traffic as "circuits" in both packet and optical networks, and when
   they are ready, move to dynamic control plane for greater efficiency.

   Among other attributes, bandwidth management, protection/recovery and
   OAM are critical in Packet/Optical transport networks. In the context
   of MPLS-TP, each LSP is expected to be associated with a fixed amount
   of bandwidth in terms of bits-per-second and/or time-slots. OAM is to
   be performed on each individual LSP. For some of the performance
   monitoring (PM) functions, the OAM mechanisms need to be able to
   transmit and process OAM packets at very high frequency. An overview
   of MPLS-TP OAM toolset is found in [RFC6669].

   Protection [RFC6372] is another important element in transport
   networks. Typically, ring and linear protection can be readily

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   applied in metro networks. However, as long-haul networks are
   sensitive to bandwidth cost and tend to have mesh-like topology,
   shared mesh protection is becoming increasingly important.

   In some cases, SPs plan to deploy MPLS-TP from their long haul
   optical packet transport all the way to the aggregation and access in
   their networks.

3.3. Mobile Backhaul

   Wireless communication is one of the fastest growing areas in
   communication worldwide. In some regions, the tremendous mobile
   growth is fueled by the lack of existing land-line and cable
   infrastructure. In other regions, the introduction of smart phones is
   quickly driving mobile data traffic to become the primary mobile
   bandwidth consumer (some SPs have already observed more than 85% of
   total mobile traffic are data traffic). MPLS-TP is viewed as a
   suitable technology for Mobile backhaul.

3.3.1. 2G and 3G Mobile Backhaul

   MPLS-TP is commonly viewed as a very good fit for 2G/3G mobile
   backhaul. 2G (GSM/CDMA) and 3G (UMTS/HSPA/1xEVDO) Mobile Backhaul
   Networks are still currently dominating the mobile infrastructure.

   The connectivity for 2G/3G networks is point to point (P2P). The
   logical connections are hub-and-spoke. Networks are physically
   constructed using a star or ring topology. In the Radio Access
   Network (RAN), each mobile Base Transceiver Station (BTS/Node B) is
   communicating with a Radio Controller (BSC/RNC). These connections
   are often statically set up.

   Hierarchical or centralized architectures are often used for pre-
   aggregation and aggregation layers. Each aggregation network inter-
   connects with multiple access networks. For example, a single
   aggregation ring could aggregate traffic for 10 access rings with
   total 100 base stations.

   The technology used today is largely ATM based. Mobile providers are
   replacing the ATM RAN infrastructure with newer packet technologies.
   IP RAN networks with IP/MPLS technologies are deployed today by many
   SPs with great success. MPLS-TP is another suitable choice for Mobile
   RAN. The P2P connections from base station to Radio Controller can be
   set statically to mimic the operation of today's RAN environments;
   in-band OAM and deterministic path protection can support fast
   failure detection and switch-over to satisfy the SLA agreements.
   Bidirectional LSPs may help to simplify the provisioning process. The
   deterministic nature of MPLS-TP LSP set up can also support packet

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   based synchronization to maintain predictable performance regarding
   packet delay and jitters.

3.3.2. 4G/LTE Mobile Backhaul

   One key difference between LTE and 2G/3G mobile networks is that the
   logical connection in LTE is a mesh, while in 2G/3G is a P2P star. In
   LTE, the base stations eNB/BTS communicate with multiple Network
   controllers (PSW/SGW or ASNGW), and the radio elements communicate
   with one another for signal exchange and traffic offload to wireless
   or wireline infrastructures.

   IP/MPLS has a great advantage in any-to-any connectivity environment.
   Thus, the use of mature IP or L3VPN technologies is particularly
   common in the design of SP's LTE deployment plans.

   The extended OAM functions defined in MPLS-TP, such as in-band OAM
   and path protection mechanisms bring additional advantages to support
   SLAs. The dynamic control-plane with GMPLS signaling is especially
   suited for the mesh environment, to support dynamic topology changes
   and network optimization.

4. Network Design Considerations

4.1. The role of MPLS-TP

   The role of MPLS-TP is to provide a solution to help evolving
   traditional transport towards packet. It is designed to support the
   transport characteristics/behavior described in [RFC5654]. The
   primary use of MPLS-TP is largely to replace legacy transport
   technologies, such as SONET/SDH. MPLS-TP is not designed to replace
   the service support capabilities of IP/MPLS, such as L2VPN, L3VPN,
   IPTV, Mobile RAN, etc.

4.2. Provisioning mode

   MPLS-TP supports two provisioning modes: i) a mandatory static
   provisioning mode, which must be supported without dependency on
   dynamic routing or signaling; and ii) an optional distributed dynamic
   control plane, which is used to enable dynamic service provisioning.

   The decision on which mode to use is largely dependent on the
   operational feasibility and the stage of evolution transition.
   Operators who are accustomed with the transport-centric operational
   model (e.g., NMS configuration without control plane) typically
   prefer the static provisioning mode. This is the most common choice

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   in current deployments. The dynamic provisioning mode can be more
   powerful but it is more suited for operators who are familiar with
   the operation and maintenance of IP/MPLS technologies or ready to
   step up through training and planned transition.

   There may be also cases where operators choose to use the combination
   of both modes. This is appropriate when parts of the network are
   provisioned in a static fashion and other parts are controlled by
   dynamic signaling. This combination may also be used to transition
   from static provisioning to dynamic control plane.

4.3. Standards compliance

   It is generally recognized by SPs that standards compliance is
   important for lowering cost, accelerating product maturity, achieving
   multi-vendor interoperability, and meeting the expectations of their
   enterprise customers.

   MPLS-TP is a joint work between IETF and ITU-T. In April 2008, IETF
   and ITU-T jointly agreed to terminate T-MPLS and progress MPLS-TP as
   joint work [RFC5317]. The transport requirements are provided by ITU-
   T, the protocols are developed in IETF.

4.4. End-to-end MPLS OAM consistency

   End-to-end MPLS OAM consistency is highly desirable in order to
   enable Service Providers to deploy end-to-end MPLS solution with a
   combination of IP/MPLS (for example, in the core including service
   edge) and MPLS-TP (for example, in the aggregation/access networks).
   Using MPLS based OAM in MPLS-TP can help achieving such a goal.

4.5. PW Design considerations in MPLS-TP networks

   In general, PWs in MPLS-TP work the same as in IP/MPLS networks. Both
   Single-Segment PW (SS-PW) and Multi-Segment PW (MS-PW) are supported.
   For dynamic control plane, Targeted LDP (tLDP) is used. In static
   provisioning mode, PW status is a new PW OAM feature for failure
   notification. In addition, both directions of a PW must be bound to
   the same transport bidirectional LSP.

   In the common network topology involving multi-tier rings, the design
   choice is between using SS-PW or MS-PW. This is not a discussion
   unique to MPLS-TP, as it applies to PW design in general, but it is
   relevant here, since MPLS-TP is more sensitive to the operational
   complexities, as noted by operators. If MS-PW is used, Switched PE
   (S-PE) must be deployed to connect the rings. The advantage of this
   choice is that it provides domain isolation, which in turn
   facilitates trouble shooting and allows for faster PW failure

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   recovery. On the other hand, the disadvantage of using S-PE is that
   it adds more complexity. Using SS-PW is simpler, since it does not
   require S-PEs, but less efficient because the paths across primary
   and secondary rings are longer. If operational simplicity is a higher
   priority, some SPs choose the latter.

   Another design trade-off is whether to use PW protection in addition
   to LSP protection or rely solely on LSP protection. By definition,
   MPLS-TP LSPs are protected. If the working LSP fails, the protect LSP
   assures that the connectivity is maintained and the PW is not
   impacted. However, in the case of simultaneous failure of both
   working and protect LSPs, the attached PW would fail. By adding PW
   protection, and attaching the protect PW to a diverse LSP not in the
   same Shared Risk Link Group (SRLG), the PW is protected even when the
   primary PW fails.  Clearly, using PW protection adds considerably
   more complexity and resource usage, and thus operators often may
   choose not to use it, and consider protection against single point of
   failure as sufficient.

4.6. Proactive and on-demand MPLS-TP OAM tools

   MPLS-TP provide both proactive and on-demand OAM Tools. As a
   proactive OAM fault management tool, BFD hellos can be sent at
   regular intervals for Connectivity Check; 3 missed hellos trigger the
   failure protection switch-over. BFD sessions are configured for both
   working and protecting LSPs.

   A design decision is choosing the value of the BFD hello interval.
   The shorter the interval (3.3ms is the minimum allowed interval), the
   faster the detection time is, but also the higher the resource
   utilization is. The proper value depends on the application and the
   service needs.

   As an on-demand OAM fault management mechanism, for example when
   there is a fiber cut, Link Down Indication (LDI) message [RFC6427] is
   generated from the failure point and propagated to the Maintenance
   End Points (MEPs) to trigger immediate switch-over from working to
   protect path. An Alarm Indication Signal (AIS) propagates from the
   Maintenance Intermediate Point (MIP) to the MEPs for alarm

   In general, both proactive and on-demand OAM tools should be enabled
   to guarantee short switch-over times.

4.7. MPLS-TP and IP/MPLS Interworking considerations

   Since IP/MPLS is largely deployed in most SPs' networks, MPLS-TP and
   IP/MPLS interworking is a reality.

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   The interworking issues are addressed in a separate document

5. Security Considerations

   Under the use case of Metro access and aggregation, in the scenario
   where some of the access equipment is placed in facilities not owned
   by the SP, the static provisioning mode of MPLS-TP is often preferred
   over the control plane option because it eliminates the possibility
   of a control plane attack which may potentially impact the whole
   network. This scenario falls into the Security Reference Model 2 as
   described in [MPLS-TP Sec FW].

   Similar location issues apply to the mobile use cases, since
   equipment is often placed in remote and outdoor environment, which
   can increase the risk of un-authorized access to the equipment.

   In general, NMS access can be a common point of attack in all MPLS-TP
   use cases, and attacks to GAL or G-ACh are unique security treats to
   MPLS-TP. The MPLS-TP security considerations are discussed in MPLS-TP
   Security Framework [MPLS-TP Sec FW]. General security considerations
   for MPLS and GMPLS networks are addressed in Security Framework for
   MPLS and GMPLS Networks [RFC5920].

6. IANA Considerations

   This document contains no new IANA considerations.

7. Acknowledgements

   The authors wish to thank Adrian Farrel for his review as Routing
   Area Director, Adrian's detailed comments were of great help for
   improving the quality of this document. The authors would also like
   to thank Loa Andersson for his continued support and guidance.

8. References

8.1. Normative References

   [RFC5317]  Bryant, S., Ed., and L. Andersson, Ed., "Joint Working
              Team (JWT) Report on MPLS Architectural Considerations for
              a Transport Profile", RFC 5317, February 2009.

   [RFC5654]  Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M., Ed.,
              Sprecher, N., and S. Ueno, "Requirements of an MPLS
              Transport Profile", RFC 5654, September 2009.

   [RFC5920]  Fang, L., Ed., "Security Framework for MPLS and GMPLS

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              Networks", RFC 5920, July 2010.

   [RFC6426]  Gray, E., Bahadur, N., Boutros, S., and R. Aggarwal, "MPLS
              On-Demand Connectivity Verification and Route Tracing",
              RFC 6426, November 2011.

   [RFC6427]  Swallow, G., Ed., Fulignoli, A., Ed., Vigoureux, M., Ed.,
              Boutros, S., and D. Ward, "MPLS Fault Management
              Operations, Administration, and Maintenance (OAM)",
              RFC 6427, November 2011.

   [RFC6428]  Allan, D., Ed., Swallow Ed., G., and J. Drake Ed.,
              "Proactive Connectivity Verification, Continuity Check,
              and Remote Defect Indication for the MPLS Transport
              Profile", RFC 6428, November 2011.

8.2. Informative References

   [RFC5921]  Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau,
              L., and L. Berger, "A Framework for MPLS in Transport
              Networks", RFC 5921, July 2010.

   [RFC6372]  Sprecher, N., Ed., and A. Farrel, Ed., "MPLS Transport
              Profile (MPLS-TP) Survivability Framework", RFC 6372,
              September 2011.

   [RFC6669]  Sprecher, N. and L. Fang, "An Overview of the Operations,
              Administration, and Maintenance (OAM) Toolset for MPLS-
              Based Transport Networks", RFC 6669, July 2012.

   [Interworking] Martinotti, R., et al., "Interworking between MPLS-TP
              and IP/MPLS," draft-martinotti-mpls-tp-interworking-
              02.txt, June 2011.

   [MPLS-TP Sec FW] Fang, L. Ed., Niven-Jenkins, B., Ed., Mansfield,
              S., Ed., Graveman, R., Ed., "MPLS-TP Security Framework,"
              draft-ietf-mpls-tp-security-framework-05.txt, October

Authors' Addresses

      Luyuan Fang
      Cisco Systems, Inc.
      111 Wood Ave. South
      Iselin, NJ 08830

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      United States
      Nabil Bitar
      40 Sylvan Road
      Waltham, MA 02145
      United States

      Raymond Zhang
      701 Middlefield Road
      Mountain View, CA 94043
      United States

      Masahiro DAIKOKU
      KDDI corporation
      3-11-11.Iidabashi, Chiyodaku, Tokyo

      Ping Pan
      United States

Contributors' Addresses

      Kam Lee Yap
      XO Communications
      13865 Sunrise Valley Drive,
      Herndon, VA 20171
      United States

      Dan Frost
      Cisco Systems, Inc.
      United Kingdom

      Henry Yu
      TW Telecom
      10475 Park Meadow Dr.
      Littleton, CO 80124
      United States

Fang et al.              Expires June 16, 2013                 [Page 13]

INTERNET DRAFT        MPLS-TP Use Cases and Design     December 16, 2012

      Jian Ping Zhang   China Telecom, Shanghai
      Room 3402, 211 Shi Ji Da Dao
      Pu Dong District, Shanghai

      Lei Wang
      Lime Networks
      Strandveien 30, 1366 Lysaker

      Mach(Guoyi) Chen
      Huawei Technologies Co., Ltd.
      No. 3 Xinxi Road
      Shangdi Information Industry Base
      Hai-Dian District, Beijing 100085

      Nurit Sprecher
      Nokia Siemens Networks
      3 Hanagar St. Neve Ne'eman B
      Hod Hasharon, 45241

Fang et al.              Expires June 16, 2013                 [Page 14]