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Versions: 00 01 02 RFC 7625

Network Working Group                                          J. T. Hao
Internet-Draft                              Huawei Technologies Co., Ltd
Intended status: Informational                             P. Maheshwari
Expires: November 13, 2015                            Bharti Airtel Ltd.
                                                                R. Huang
                                                            L. Andersson
                                                                 M. Chen
                                            Huawei Technologies Co., Ltd
                                                            May 12, 2015


          Architecture of MPLS/IP Network with Hardened Pipes
                   draft-hao-mpls-ip-hard-pipe-02.txt

Abstract

   This document is intended to become an Informational RFC on the
   independent stream.  The document does not specify any new protocol
   or procedures.  It does explain how the MPLS standards
   implementation, has been deployed and operated to meet the
   requirements from operators that offer traditional Virtual Leased
   Line services.

   This document describes an MPLS/IP network that has an infrastructure
   that can be separated into two or more strata.  For the
   implementation described in this document the infrastructure has been
   separated into two strata.  One for the 'Hard Pipes', called the
   'Hard Pipe Stratum".  And one for the normal IP/MPLS traffic - called
   the 'Normal IP/MPLS stratum'.

   This document introduces the concept of "Hard Pipes", a Hard Pipe is
   an MPLS Label Switched Path (LSP) or a Pseudowire (PW) with a
   bandwidth that is guaranteed and can neither be exceeded nor
   infringed upon.

   The Hard Pipe stratum does not use statistical multiplexing, for the
   LSPs and PWs setup within this stratum the bandwidth are guaranteed
   end to end.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.



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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 13, 2015.

Copyright Notice

   Copyright (c) 2015 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
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.2.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   4
   2.  The strata network  . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  The Physical Network  . . . . . . . . . . . . . . . . . .   5
     2.2.  The Hard Pipe stratum . . . . . . . . . . . . . . . . . .   6
     2.3.  The Normal IP/MPLS stratum  . . . . . . . . . . . . . . .   7
     2.4.  Stratum Networks  . . . . . . . . . . . . . . . . . . . .   8
   3.  Configuring the Leased Lines in Hard Pipe Stratum . . . . . .   8
   4.  Efficient State Management  . . . . . . . . . . . . . . . . .  10
     4.1.  State in the Forwarding Plane . . . . . . . . . . . . . .  10
     4.2.  State in the NMS  . . . . . . . . . . . . . . . . . . . .  10
     4.3.  Annotations for Configuring Leased Lines  . . . . . . . .  10
   5.  Setting Up Leased Lines . . . . . . . . . . . . . . . . . . .  12
   6.  Leased Line protection  . . . . . . . . . . . . . . . . . . .  13
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   10. Informative References  . . . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15







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1.  Introduction

   IP leased line services, Ethernet Private Line (EPL) and Time
   Division Multiplex (TDM) leased line services are commonly offered by
   operators worldwide.

   There are customers, e.g. many enterprises, which insist on TDM
   leased line services.  They do so regardless of the fact that the
   same operators often offer IP leased line services, and EPL services,
   at a lower price and with a guaranteed bandwidth.

   Today we see a trend that the TDM (in particular SDH/SONET) networks
   gradually carries less and less traffic, and many operators want to
   shut their TDM networks down to save cost.

   The vendors and operators that build and deploy the Hard Pipe service
   described in this document do so recognizing the trends outlined
   above.  A way to introduce leased line service with the same
   characteristics as TDM leased line services in IP/MPLS networks was
   created.

   Even if Leased Line has been the initially motivation to define the
   Hard pipe technology, the Hard Pipe is by no means limited to support
   Leased Line services.  When guaranteed bandwidth is the priority
   Virtual Private Wire Services (VPWS), Virtual Private LAN Services
   (VPLS) L3 Virtual Private Networks (L3VPN) and IP only Private LAN
   Services can be mapped to a tunnel in the Hard Pipe stratum.

   EPL and EPLAN (Ethernet Private LAN) are out of scope for this
   document.

   The Virtual Leased Line (VLL) service is used for the examples
   throughout this document.

   The solution soon to be deployed has an Ethernet infrastructure,
   which has been split into two parallel logical networks - two
   parallel strata.  The first stratum - the Hard Pipe stratum - does
   not use statistical multiplexing, and bandwidth is guaranteed end to
   end.  The second stratum - Normal IP/MPLS stratum - works as a normal
   IP/MPLS network.  The two strata share the same physical network,
   i.e. routers and links.  But the resource reserved for the Hard Pipe
   stratum will never be preempted by the Normal IP/MPLS stratum.

   The routers will handle the traffic belonging to one stratum
   different from how traffic the other stratum is handled.  This
   separation in traffic handling is based on support in hardware.





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   The reader of this document is assumed to be familiar with RFC 3031
   [RFC3031] and RFC 5921 [RFC5921].

1.1.  Scope

   This document has the following purposes:

   o  To introduce a two strata MPLS/IP network, the purpose of one of
      the strata is to provide capabilities for services that are from a
      customer's point of view functionally identical to TDM like leased
      lines.

   o  To indicate how a router differentiates the traffic of the two
      strata.

1.2.  Abbreviations

   CC, Continuity Check

   CV, Connection Verification

   L-label, Leased Line label

   LSP, Label Switched Path

   LSR, Label Switching Router

   MPLS-TP, MPLS Transport Profile

   NMS, Network Management System

   OAM, Operation, Administration and Maintenance

   P, Provider Router

   PE, Provider Edge Router

   PW, Pseudowire

   T-label, Tunnel label

   TDM, Time Division Multiplexing

   tLDP, Targeted LDP

   VLL, Virtual Leased Line

   VPLS, Virtual Private LAN Service



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   VPWS, Virtual Private Wire Service


2.  The strata network

   The concept of stratified or strata networks has been around for some
   time.  It appears to have different meaning in different contexts.
   The way we use the concept is that we logically assign certain
   characteristics to part of the network.  The part of the network that
   has the special characteristics form one stratum and the "remainder "
   a second stratum.  The network described in this document uses a
   single link layer technology, Ethernet.

   In many cases, a whole physical interface is assigned to a single
   hard stratum.  Especially in the scenario that there are many
   physical links between two nodes.

   This document does not address the network configuration
   possibilities for Hard Pipe and IP/MPLS strata in detail.  There are
   configuration options, the basic configuration is that one Hard Pipe
   stratum and one IP/MPLS stratum are provisioned.

   However it is also possible to provision more than one Hard Pipe
   stratum, e.g. if customers want enhanced separation for their leased
   line.  Even though the main driver for the Hard Pipe technology is
   the leased lines, any service for which an operator does not want to
   use statistical multiplexing will benefit from using the Hard Pipes.

2.1.  The Physical Network

   Consider a network with 10 routers and all the links between are 10G
   Ethernet, such as shown in Figure 1.  This is the network topology
   we've used for this model, and also (with topology variations) in our
   first deployment.

















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           +---+     10G   +---+    10G    +---+   10G    +---+
       +---| B |-----------| C |-----------| D |----------| E |---+
   10G |   +---+           +---+           +---+          +---+   | 10G
       |     |               |               |              |     |
     +---+   |  10G     10G  |          10G  |         10G  |   +---+
   --| F |   |               |               |              |   | G |--
     +---+   |               |               |              |   +---+
       |     |               |               |              |     |
   10G |   +---+           +---+           +---+          +---+   | 10G
       +---| H |-----------| J |-----------| K |----------| L |---+
           +---+      10G  +---+  10G      +---+   10G    +---+



                                 Figure 1

   In this document we use the term traffic matrix or estimated traffic
   matrix to indicate an estimate of how much traffic that will flow
   between the ingress and egress (PE) nodes.  This may be translated
   into how much bandwidth is needed per link in the Hard Pipe stratum.

2.2.  The Hard Pipe stratum

   When the intention is to define a Hard Pipe stratum, it is for
   example possible to start from an estimated traffic matrix to
   estimate how much bandwidth to reserve on the links of the Ethernet
   Link Layer network for the Hard Pipes.

   Note that the implication is that the normal traffic gets the
   remainder of the available bandwidth.  Thus the link layer network
   will be split into two logical networks, or two strata.  One stratum
   to be used for the hardened pipe network, the other for the "normal"
   IP and MPLS traffic.  This is shown in Figure 2 and Figure 3.


















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      The Hard Pipe Stratum:

           +---+    2G     +---+                          +---+
       +---| B |-----------| C |                          | E |---+
    1G |   +---+           +---+                          +---+   |  2G
       |                     |                              |     |
     +---+              2G   |                          1G  |   +---+
   --| F |                   |                              |   | G |--
     +---+                   |                              |   +---+
       |                     |                              |     |
    1G |   +---+           +---+           +---+          +---+   | 2G
       +---| H |-----------| J |-----------| K |----------| L |---+
           +---+      2G   +---+   4G      +---+    4G    +---+



                                 Figure 2

   It is worth noting that even if the figures in this document are
   drawn to indicate "bandwidth on the link", the only bandwidth
   information that the nodes have available is the bandwidth assigned
   to the Hard Pipe stratum and the Normal IP/MPLS stratum.  All other
   information is kept on the NMS.  The NMS keeps a global bandwidth
   resource table for the Hard Pipe stratum.

2.3.  The Normal IP/MPLS stratum

   Given that the starting point is the physical network in Figure 1 and
   the Hard Pipe stratum as defined in in Figure 2, the Normal IP/MPLS
   stratum will look as in Figure 3:





















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      The Normal IP/MPLS Stratum:


           +---+      8G   +---+    10G    +---+   10G    +---+
       +---| B |-----------| C |-----------| D |----------| E |---+
    9G |   +---+           +---+           +---+          +---+   |   8G
       |     |               |               |              |     |
     +---+   |  10G      8G  |          10G  |          9G  |   +---+
   --| F |   |               |               |              |   | G |--
     +---+   |               |               |              |   +---+
       |     |               |               |              |     |
    9G |   +---+           +---+           +---+          +---+   |   9G
       +---| H |-----------| J |-----------| K |----------| L |---+
           +---+       8G  +---+   6G      +---+    6G    +---+



                                 Figure 3

2.4.  Stratum Networks

   Stratum networks the way we use the concept can be seen as two
   basically parallel logical networks with strictly separated
   resources.  Traffic sent over one stratum network can not infringe on
   traffic in the other stratum network.

   In the case described here, all the traffic in the Hard Pipe stratum
   is MPLS-encapsulated.  A number of the labels have been set aside so
   other applications can't allocate them and so the routers recognize
   them as belonging to the Hard Pipe application.

3.  Configuring the Leased Lines in Hard Pipe Stratum

   When the strata are provisioned the IP/MPLS stratum is set up exactly
   as any other IP/MPLS network.  The one small difference between
   provisioning the Hard Pipe stratum and the IP/MPLS stratum is that no
   overbooking is done for the Hard Pipe stratum.

   Overbooking and/or congestion in the IP/MPLS stratum can not effect
   the Hard Pipe stratum.

   All labels used for the Hard Pipe stratum are "Configured Labels",
   i.e.  labels that are provisioned and reclaimed by management
   actions.  These management actions can be by manual actions or by an
   NMS or a centralized controller.  For the size of network being
   deployed manual configuration is not practical, we are doing both
   provisioning and reclaiming a labels from an NMS.




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   o  If an operator want to set up a leased line it is first checked if
      there is a path available in the Hard Pipe stratum that matches
      the criteria (e.g. bandwidth) for the requested leased line.

      *  if such a path does exist, it is checked if there is a matching
         MPLS tunnel available over that path.

         +  if such a tunnel exists, it is used to establish the leased
            line by adding L-labels forming an LSP that are carried by
            the tunnel.  L-labels are known only by the ingress and
            egress LSRs.  They are local to the end points the same way
            as the label signalled by Targeted LDP (tLDP) [RFC5036] are
            local the end points of a targeted session LSP.

            At the same time the available bandwidth in the Hard Pipe
            stratum is decremented by the bandwidth that is needed for
            the leased line for every hop across this stratum in the
            global resource table (for the Hard Pipe stratum).

         +  if such a tunnel does not exist, it can be established so
            that the leased line can be set up as above.



      *  If the path does not exist (not enough bandwidth in Hard Pipe
         stratum for the leased line), available bandwidth on the links
         is checked to see if the stratum can be expanded to accommodate
         such a path.

         +  If the Hard Pipe stratum can be expanded, this is done and
            the tunnel for the leased line is established as described
            above.

            It is likely that other modifications of the Hard Pipe
            stratum, e.g. consolidating already set up Hard IP tunnels
            on to existing links so that room for new Leased Lines are
            created may have implication that goes well outside the
            Leased Line service, and it is currently not viewed as a
            fully automated operation.

         +  If it is not possible to expand the Hard Pipe stratum to
            accommodate the new path, set up of the leased line will
            need to be declined.

   Thus, given the existence of a viable Hard Pipe stratum, Leased Lines
   are configured in two very simple steps.  First, establish a hop-by-
   hop tunnel (T-labels), and second configure the leased lines




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   (L-labels).  The T-labels need to be configured on both PE and P
   routers, while L-Labels only need to be configured on the PE routers.

   Note that L labels may be used for normal IP service [RFC3031], BGP/
   MPLS VPNs [RFC4364] or PWs [RFC3985].

4.  Efficient State Management

   The system as described here generates a very small amount of state,
   and most of it is kept in the NMS.

4.1.  State in the Forwarding Plane

   The only configured information that is actually kept on the LSRs is

   o  the information needed for the label swapping procedures, i.e.
      incoming label to outgoing label and port, and whether the label
      belongs to the set of labels that are set aside for the Hard Pipe
      stratum tunnels.

   o  the bandwidth available for the Hard Pipe stratum and the Normal
      IP/MPLS stratum

4.2.  State in the NMS

   The following state needs to be kept in the NMS

   o  the topology and bandwidth resources available in the Hard Pipe
      network, see Figure 2.

   o  the total and available bandwidth per link in the Hard Pipe
      network see Figure 4.

   o  the tunnel label mappings (T-labels) see Figure 5.

   o  the Leased Line label mappings (L-labels) see Figure 6.

   o  the reserved bandwidth, as well as other constraints and the path
      per Leased Line (L-labels)

4.3.  Annotations for Configuring Leased Lines

   The annotations given below are neither a programming guideline nor
   an indication how this architecture could be implemented.  It is
   rather an indication of how much data needs to be saved for each
   stratum and leased line, as well as where this data could be stored.





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   Considering the Hard Pipe stratum as it has been outline in Figure 2,
   there is actually some additional information related to the Hard
   Pipe Stratum that not is shown in the figure.

   Looking explicitly on the link between LSR J and K we find:


           +---+           +---+           +---+          +---+
        ---| H |-----------| J |-----------| K |----------| L |---
           +---+           +---+           +---+          +---+
                                  [4,0]G


                                 Figure 4

   The annotation [4,0]G means that 4G is allocated to the stratum on
   the link between J and K, and of these 0G has been allocated to a
   service.

   If we were to allocate two tunnels labels from the labels that has
   been configured to work within the Hard Pipe stratum the resource
   view would look like this:


           +---+           +---+           +---+          +---+
        ---| H |-----------| J |-----------| K |----------| L |---
           +---+           +---+           +---+          +---+
                               [4,0]G T1 ,T2


                                 Figure 5

   Note that allocating the tunnel labels does not reserve bandwidth for
   the tunnel from the Hard Pipe stratum.

   When the leased line labels (L-labels) are assigned, this will
   consume bandwidth.  So we need to keep track of the bandwidth per
   leased line and the total of bandwidth allocated from the Hard Pipe
   stratum.

   The annotation for the link between J and K could look like this:










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           +---+           +---+           +---+          +---+
        ---| H |-----------| J |-----------| K |----------| L |---
           +---+           +---+           +---+          +---+
                [4,1.5]G, T1, L1 [.5], L2 [.5], T2, L1 [.5]


                                 Figure 6

   The line [4,1.5]G, T1, L1 [.5], L2 [.5], T2, L1 [.5] would be
   interpreted as:

   The Hard Pipe Stratum link between nodes J and K has 4 G bandwidth
   allocated; of the total bandwidth 1.5 G is allocated for Leased
   Lines.

   Tunnel label T1, carries two Leased Lines, each of 0.5G and tunnel
   label T2 carries a third Leased Line of 0.5G.

   Note that it is not necessary to keep this information in the nodes,
   it is held within the NMS, it is also strictly not necessary to keep
   the bandwidth per leased line, but some operations are simplified
   (e.g. removing a leased line) if this is done.

5.  Setting Up Leased Lines

   Consider that the case where an operator want to set up a Leased Line
   of 0.4G from F to G in the Hard Pipe stratum in Figure 2.

   Since there are no other constraints than bandwidth and ingress and
   egress PEs, the shortest path will be chosen.  A tunnel will be
   configure from F to G over the following nodes.  F, H, J, K, L and G,
   and a Leased Line label (a) will be configured on F and G, and the
   available resources recalculated.

   A second leased line of 0.3G between the same PEs is easily configure
   by adding a new Leased Line label (b) at the ingress and egress PEs.

   After these operations a view of the Hard Pipe stratum resources
   (available bandwidth) would look like this:












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      The Hard Pipe Stratum:

           +---+    2G     +---+                          +---+
       +---| B |-----------| C |                          | E |---+
    1G |   +---+           +---+                          +---+   |  2G
       |                     |                              |     |
     +---+              2G   |                          1G  |   +---+
   --| F |                   |                              |   | G |--
     +---+                   |                              |   +---+
       |                     |                              |     |
   .3G |   +---+           +---+           +---+          +---+   | 1.3G
       +---| H |-----------| J |-----------| K |----------| L |---+
           +---+    1.3G   +---+    3.3G   +---+   3.3G   +---+



                                 Figure 7

   If the operator now wishes to establish a new leased line with the
   criteria that it should originate from F and terminate at G, have
   0.4G bandwidth and pass through node E, analysis of the Hard Pipe
   stratum (after establishing the first two listed lines) and the
   criteria for the new leased line would give the following;

   o  the existing tunnel cannot be used, since it does not pass through
      E; a new tunnel need to be established.

   o  the hop from F to H cannot be used since the available bandwidth
      is insufficient.

   o  since no existing meet the criteria requested, a new tunnel will
      be set up from F, to B, C, J, K, L, E (the criteria to pass
      through E) and to G.

   A new L-label (c) to be carried over T2 will be configured on F and
   G, and the available resources of the Hard Pipe stratum will be
   recalculated.

6.  Leased Line protection

   This leased line service uses the MPLS Transport Profile (MPLS-TP)
   line protection as it is defined in RFC 6378 [RFC6378], updated as
   specified in RFC 7271 [RFC7271] and RFC 7324 [RFC7324]

   The Connection Verification (CV) and Continuity Check (CC) are run
   over the tunnels between the Maintenance Entity Group End Points
   (MEP) at each end, i.e. the entire tunnel is protected end to end.




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   In general all of the MPLS-TP Operation, Administration and
   Maintenance (OAM), as defined in RFC 6371 [RFC6371] is applicable.

7.  Security Considerations

   The security considerations as defined in RFC 5920 "Security
   Framework for MPLS and GMPLS Networks" [RFC5920]  and RFC RFC 6941
   "MPLS Transport Profile (MPLS-TP) Security Framework" [RFC6941] apply
   to this document.

8.  IANA Considerations

   There are no requests for IANA actions in this document.

   Note to the RFC Editor, this section may be removed before
   publication.

9.  Acknowledgements

   The authors want to thank Andy Malis for detailed technical and
   language review and for valuable comments.

10.  Informative References

   [RFC3031]  Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
              Label Switching Architecture", RFC 3031, January 2001.

   [RFC3985]  Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to-
              Edge (PWE3) Architecture", RFC 3985, March 2005.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, February 2006.

   [RFC5036]  Andersson, L., Minei, I., and B. Thomas, "LDP
              Specification", RFC 5036, October 2007.

   [RFC5920]  Fang, L., "Security Framework for MPLS and GMPLS
              Networks", RFC 5920, July 2010.

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

   [RFC6371]  Busi, I. and D. Allan, "Operations, Administration, and
              Maintenance Framework for MPLS-Based Transport Networks",
              RFC 6371, September 2011.





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   [RFC6378]  Weingarten, Y., Bryant, S., Osborne, E., Sprecher, N., and
              A. Fulignoli, "MPLS Transport Profile (MPLS-TP) Linear
              Protection", RFC 6378, October 2011.

   [RFC6941]  Fang, L., Niven-Jenkins, B., Mansfield, S., and R.
              Graveman, "MPLS Transport Profile (MPLS-TP) Security
              Framework", RFC 6941, April 2013.

   [RFC7271]  Ryoo, J., Gray, E., van Helvoort, H., D'Alessandro, A.,
              Cheung, T., and E. Osborne, "MPLS Transport Profile (MPLS-
              TP) Linear Protection to Match the Operational
              Expectations of Synchronous Digital Hierarchy, Optical
              Transport Network, and Ethernet Transport Network
              Operators", RFC 7271, June 2014.

   [RFC7324]  Osborne, E., "Updates to MPLS Transport Profile Linear
              Protection", RFC 7324, July 2014.

Authors' Addresses

   JiangTao Hao
   Huawei Technologies Co., Ltd
   Q13 Huawei Campus
   No. 156 Beiqing Road
   Hai-dian District
   Beijing  100095
   China

   Email: haojiangtao@huawei.com


   Praveen Maheshwari
   Bharti Airtel Ltd.
   Plot No. 16, Udyog Bihar,
   Phase IV, Gurgaon - 122015
   Haryana
   India

   Email: Praveen.Maheshwari@in.airtel.com












T. Hao, et al.          Expires November 13, 2015              [Page 15]


Internet-Draft                Hard IP Pipes                     May 2015


   River Huang
   Huawei Technologies Co., Ltd
   Q13 Huawei Campus
   No. 156 Beiqing Road
   Hai-dian District
   Beijing  100095
   China

   Email: river.huang@huawei.com


   Loa Andersson
   Huawei Technologies Co., Ltd
   Stockholm
   Sweden

   Email: loa@mail01.huawei.com


   Mach Chen
   Huawei Technologies Co., Ltd
   Q13 Huawei Campus
   No. 156 Beiqing Road
   Hai-dian District
   Beijing  100095
   China

   Email: mach.chen@huawei.com























T. Hao, et al.          Expires November 13, 2015              [Page 16]


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