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Dual-Homing Coordination for MPLS Transport Profile (MPLS-TP) Pseudowires Protection
draft-ietf-pals-mpls-tp-dual-homing-coordination-01

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This is an older version of an Internet-Draft that was ultimately published as RFC 8185.
Authors Weiqiang Cheng , Lei Wang , Han Li , Kai Liu , Shahram Davari , Jie Dong , Alessandro D'Alessandro
Last updated 2015-10-19
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draft-ietf-pals-mpls-tp-dual-homing-coordination-01
Network Working Group                                           W. Cheng
Internet-Draft                                                   L. Wang
Intended status: Standards Track                                   H. Li
Expires: April 21, 2016                                     China Mobile
                                                                  K. Liu
                                                     Huawei Technologies
                                                               S. Davari
                                                    Broadcom Corporation
                                                                 J. Dong
                                                     Huawei Technologies
                                                         A. D'Alessandro
                                                          Telecom Italia
                                                        October 19, 2015

     Dual-Homing Coordination for MPLS Transport Profile (MPLS-TP)
                         Pseudowires Protection
          draft-ietf-pals-mpls-tp-dual-homing-coordination-01

Abstract

   In some scenarios, the MPLS Transport Profile (MPLS-TP) Pseudowires
   (PWs) are provisioned through either static configuration or
   management plane, where a dynamic control plane is not available.  A
   fast protection mechanism for MPLS-TP PWs is needed to protect
   against the failure of Attachment Circuit (AC), the failure of
   Provider Edge (PE) and also the failure in the Packet Switched
   Network (PSN).  The framework and scenarios for dual-homing
   pseudowire (PW) local protection are described in [draft-ietf-pals-
   mpls-tp-dual-homing-protection].  This document proposes a dual-
   homing coordination mechanism for MPLS-TP PWs, which is used for
   state exchange and coordination between the dual-homing PEs for dual-
   homing PW local protection.

Requirements Language

   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 RFC 2119 [RFC2119].

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

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   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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 April 21, 2016.

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
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Overview of the Proposed Solution . . . . . . . . . . . . . .   3
   3.  Protocol Extensions for MPLS-TP PW Dual-Homing Protection . .   4
     3.1.  Information Exchange Between Dual-Homing PEs  . . . . . .   4
     3.2.  Protection Procedures . . . . . . . . . . . . . . . . . .   7
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   [RFC6372], [RFC6378] and [I-D.ietf-pals-ms-pw-protection] describe
   the framework and mechanism of MPLS-TP Linear protection, which can
   provide protection for the MPLS LSP and PW between the edge nodes.
   These mechanisms does not protect the failure of the Attachment
   Circuit (AC) or the edge nodes.  [RFC6718] and [RFC6870] specifies
   the PW redundancy framework and mechanism for protecting the AC or
   edge node failure by adding one or more edge nodes, but it requires

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   PW switchover in case of a AC failure, also PW redundancy relies on
   PSN protection mechanisms to protect the failure of PW.

   In some scenarios such as mobile backhauling, the MPLS PWs are
   provisioned with dual-homing topology, in which at least the CE node
   on one side is dual-homed to two PEs.  If a failure occurs in the
   primary AC, operators usually prefer to perform switchover only in
   the dual-homing PE side and keep the working pseudowire unchanged if
   possible.  This is to avoid massive PW switchover in the mobile
   backhaul network due to the AC failure in the core site, and also
   could achieve efficient and balanced link bandwidth utilization.
   Similarly, it is preferable to keep using the working AC when one
   working PW fails in PSN network.  A fast dual-homing PW protection
   mechanism is needed to protect the failure in AC, the PE node and the
   PSN network to meet the above requirements.

   [I-D.ietf-pals-mpls-tp-dual-homing-protection] describes a framework
   and several scenarios for dual-homing pseudowire (PW) local
   protection.  This document proposes a dual-homing coordination
   mechanism for static MPLS-TP PWs, which is used for information
   exchange and coordination between the dual-homing PEs for the dual-
   homing PW local protection.  The proposed mechanism has been deployed
   in several mobile backhaul networks which use static MPLS-TP PWs for
   the backhauling of mobile traffic from the RF sites to the core site.

2.  Overview of the Proposed Solution

   Linear protection mechanisms for MPLS-TP network are defined in
   [RFC6378], [RFC7271] and [RFC7324].  When such mechanisms are applied
   to PW linear protection [I-D.ietf-pals-ms-pw-protection], both the
   working PW and the protection PW are terminated on the same PE nodes.
   In order to provide dual-homing protection for MPLS-TP PWs, some
   additional mechanisms are needed.

   In MPLS-TP PW dual-homing protection, the linear protection mechanism
   on the single-homing PE (e.g.  PE3 in figure 1) is not changed, while
   on the dual-homing side, the working PW and protection PW are
   terminated on two dual-homing PEs (e.g.  PE1 and PE2 in figure 1)
   respectively to protect the failure occurs in the dual-homing PEs and
   the connected ACs.  As specified in
   [I-D.ietf-pals-mpls-tp-dual-homing-protection], a dedicated Dual-Node
   Interconnection (DNI) PW is provisioned between the two dual-homing
   PE nodes, which is used to bridge the traffic between the dual-homing
   PEs when failure happens in the working PW or the primary AC.  In
   order to make the linear protection mechanism work in the dual-homing
   PEs scenario, some coordination between the dual-homing PE nodes is
   needed, so that the dual-homing PEs can set the connection between
   AC, the service PW and the DNI-PW properly in a coordinated fashion.

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               +----------------+
               /                |                +--------+
          AC1 /|   PE1          |  Working PW    |        |
             / |                X----------------X        |
            /  |                |  Service PW1   |        |
       +---/+  +--------X-------+                |        |   +----+
       |    |           | DNI PW                 |  PE3   |   |    |
       | CE1|           |                        |        |---| CE2|
       +---\+  +--------X-------+                |        |   +----+
            \  |                | Protection PW  |        |
             \ |                X----------------X        |
          AC2 \|                | Service PW2    |        |
               \   PE2          |                +--------+
               +----------------+

              Figure 1. Dual-homing Protection with DNI-PW

3.  Protocol Extensions for MPLS-TP PW Dual-Homing Protection

   In dual-homing MPLS-TP PW local protection, the forwarding state of
   the dual-homing PEs are determined by the forwarding state machine as
   defined in [I-D.ietf-pals-mpls-tp-dual-homing-protection].  In order
   to achieve the MPLS-TP PW dual-homing protection, coordination
   between the dual-homing PE nodes is needed to exchange the PW status
   and protection coordination requests.

3.1.  Information Exchange Between Dual-Homing PEs

   The coordination information will be sent over the G-ACh as described
   in [RFC5586].  A new G-ACh channel type is defined for the
   coordination between the dual-homing PEs of MPLS-TP PWs.  This
   channel type can be used for the exchange of different kinds of
   information between the dual-homing PEs.  This document uses this
   channel type for the PW status exchange and switchover coordination
   between the dual-homing PEs.  Other potential usage of this channel
   type are for further study and are out of the scope of this document.

   The MPLS-TP Dual-Homing Coordination (DHC) message is sent on the DNI
   PW between the dual-homing PEs.  The format of MPLS-TP DHC message is
   shown below:

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   0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |0 0 0 1|Version|     Flags     |         DHC Code Point        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Dual-Homing PEs Group ID                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         TLV  Length           |           Reserved            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                              TLVs                             ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          Figure 2. MPLS-TP Dual-Homing Coordination Message

   The Dual-Homing Group ID is a 4-octet unsigned integer to identify
   the dual-homing PEs in the same dual-homing group.

   In this document, two TLVs are defined in MPLS-TP Dual-Homing
   Coordination message for dual-homing MPLS-TP PW protection:

   Type        Description               Length
    1           PW State                 20 Bytes
    2        Dual-Node Switching         16 Bytes

   The PW Status TLV is used by a dual-homing PE to report its service
   PW state to the other dual-homing PE in the same dual-homing group.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Type=1 (PW Status)        |          Length               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |              Destination Dual-homing PE Node_ID               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                Source Dual-homing PE Node_ID                  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         DNI PW-ID                             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         Flags                               |P|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                      Service PW State                     |D|F|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                       Figure 3. PW State TLV

   - The Destination Dual-homing PE Node_ID is the 32-bit Identifier of
   the receiver PE.

   - The Source Dual-homing PE Node_ID is the 32-bit identifier of the
   sending PE.

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   - The DNI PW-ID field contains the 32-bit PW-ID of the DNI PW.

   - The Flag field contains 32 bit flags.

   o  The P (Protection) bit indicates whether the Source Dual-homing PE
      is the working PE (P=0) or the protection PE (P=1).

   o  Other bits are reserved for future use.

   - The Service PW State field indicates the state of the Service PW
   between the sending PE and the remote PE.  Currently two bits are
   defined in the Service PW Request field:

   o  F bit: If set, it indicates Signal Fail (SF) is generated on the
      service PW.  It can be either a local request or a remote request
      received from the remote PE.

   o  D bit: If set, it indicates Signal Degrade (SD) generated on the
      service PW.  It can be either a local request or a remote request
      received from the remote PE.

   o  Other bits are reserved and MUST be set to 0 on transmission and
      SHOULD be ignored upon receipt.

   The Dual-Node Switching TLV is used by the protection dual-homing PE
   to send protection state coordination to the working dual-homing PE.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Type=2 (Dual-Node Switching) |          Length               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |              Destination Dual-homing PE Node_ID               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                Source Dual-homing PE Node_ID                  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         DNI PW-ID                             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                          Flags                            |S|P|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                      Figure 4. Dual-node Switching TLV

   - The Destination Dual-homing PE Node_ID is the 32-bit Identifier of
   the receiver PE.

   - The Source Dual-homing PE Node_ID is the 32-bit identifier of the
   sending PE.

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   - The DNI PW-ID field contains the 32-bit PW-ID of the DNI PW.

   - The Flag field contains 32 bit flags.

   o  The P (Protection) bit indicates whether the Source Dual-homing PE
      is the working PE (P=0) or the protection PE (P=1).  With the
      mechanism described in this document, only the protection PE can
      send DHC message with the Dual-node Switching TLV therefore it is
      always set to 1 when sent.

   o  The S (PW Switching) bit indicates which service PW is used for
      forwarding traffic.  It is set to 0 when traffic will be
      transported on the working PW, and is set to 1 if traffic will be
      transported on the protection PW.  The value of the S bit is
      determined by the protection coordination mechanism between the
      dual-homing protection PE and the remote PE.

   The MPLS-TP DHC message is exchanged periodically between the dual-
   homing PEs.  Whenever a change of service PW state is detected by a
   dual-homing PE, it MUST be reflected in the PW State TLV and sent to
   the other dual-homing PE using a DHC message immediately.  The Dual-
   Node Switching TLV is carried in the DHC message when a switchover
   request is issued by the protection PE according to the linear
   protection mechanism.

3.2.  Protection Procedures

   The dual-homing MPLS-TP PW protection mechanism can be deployed with
   the existing AC redundancy mechanisms, e.g.  Multi-Chassis Link
   Aggregation Group (MC-LAG).  On the PSN network side, PSN tunnel
   protection mechanism is not required, as the dual-homing PW
   protection can also protect the failure occurs in the PSN network.

   This section takes one-side dual-homing scenario as example to
   describe the dual-homing PW protection procedures, the procedures for
   two-side dual-homing scenario would be similar.

   On dual-homing PE side, the role of working and protection PE are set
   by NMS or local configuration.  The service PW connecting to the
   working PE is the working PW, and the service PW connecting to the
   protection PE is called protection PW.

   On single-homing PE side, it just treats the working PW and
   protection PW as if they terminate on the same remote PE node, thus
   normal MPLS-TP protection coordination mechanisms still apply on the
   single-homing PE.

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   The forwarding behavior of the dual-homing PEs is determined by the
   components shown in the figure below:

             +----------------------------------+           +-----+
             |        PE1 (Working PE)          |           |     |
             +----------------------------------+           |     |
             |                 |                |    PW1    |     |
             +    Forwarder    +     Service    X<--------->X     |
            /|                 |       PW       |  Working  |     |
           / +--------+--------+                |    PW     |     |
     AC1  /  |     DNI PW      |                |           |     |
         /   +--------X--------+----------------+           |     |
 +-----+/             ^                                     |     |
 | CE1 |              |  DNI PW                             | PE3 | +---+
 +-----+              |                                     |     --|CE3|
        \             V                                     |     | +---+
     AC2 \   +--------X--------+----------------+           |     |
          \  |     DNI PW      |                |           |     |
           \ +--------+--------+                |           |     |
            \|                 |     Service    |    PW2    |     |
             +    Forwarder    +       PW       X<--------->X     |
             |                 |                | Protection|     |
             +----------------------------------+     PW    |     |
             |        PE2 (Protection PE)       |           |     |
             +----------------------------------+           +-----+
            Figure 5. Components of one-side dual-homing PW protection

   In figure 5, for a dual-homing PE, service PW is the PW used to carry
   service between the dual-homing PE and the remote PE.  The state of
   service PW is determined by some mechanisms between the dual-homing
   PE and the remote PE (e.g. by OAM).

   DNI PW is provisioned between the two dual-homing PE nodes.  It is
   used to bridge traffic when failure occurs in the PSN network or in
   the ACs.  The state of DNI PW is determined by some mechanisms
   between the dual-homing PEs (e.g. by OAM).  Since DNI PW is used to
   carry both the coordination messages and service traffic, it is
   RECOMMENDED to provision multiple links between the dual-homing PEs
   and use some protection mechanism for the DNI PW.

   AC is the link which connects the dual-homing PEs to the dual-homed
   CE.  The status of AC is determined by some AC redundancy mechanisms
   (e.g. by MC-LAG).

   In order to perform dual-homing PW local protection, the service PW
   state and Dual-node switching coordination requests are exchanged
   between the dual-homing PEs using the DHC message defined above.

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   Whenever a change of service PW state is detected by a dual-homing
   PE, it MUST be reflected in the PW State TLV and sent to the other
   dual-homing PE using a DHC message immediately.  In case there is a
   switchover request received on the protection PW from the remote PE,
   the protection PE MUST set the switchover request in the Dual-Node
   Switching TLV and send it to the working PE using the DHC message.
   After the exchange of service PW state and switching request, both
   dual-homing PEs could determine the Active/Standby forwarding status
   of the working and protection service PWs.  The status of DNI PW and
   the ACs are determined by other mechanisms out of the scope of this
   document.  The forwarding behavior of the dual-homing PE nodes is
   determined by the forwarding state machine as shown in the following
   table:

          +-----------+---------+--------+---------------------+
          |Service PW |   AC    | DNI PW | Forwarding Behavior |
          +-----------+---------+--------+---------------------+
          |  Active   | Active  |   Up   |Service PW <-> AC    |
          +-----------+---------+--------+---------------------+
          |  Active   | Standby |   Up   |Service PW <-> DNI PW|
          +-----------+---------+--------+---------------------+
          |  Standby  | Active  |   Up   |    DNI PW <-> AC    |
          +-----------+---------+--------+---------------------+
          |  Standby  | Standby |   Up   |  Drop all packets   |
          +-----------+---------+--------+---------------------+
             Table 1. Dual-homing PE Forwarding State Machine

   Take the topology in figure 5 as example, in normal state, the
   working PW (PW1) is in active state, the protection PW (PW2) is in
   standby state, the DNI PW is up, and AC1 is in active state according
   to AC side redundancy mechanism.  According to Table 1, traffic will
   be forwarded through the working PW (PW1) and the primary AC (AC1).
   No traffic will go through the protection PE (PE2) or the DNI PW, as
   both the protection PW (PW2) and the AC connecting to PE2 are in
   standby status.

   If some failure occurs in AC1, the state of AC2 changes to active
   according to the AC redundancy mechanism, while there is no change in
   the state of the working and protection PWs.  According to the
   forwarding state machine in Table 1, PE1 starts to forward traffic
   between the working PW and the DNI PW, and PE2 starts to forward
   traffic between AC2 and the DNI PW.  It should be noted that in this
   case only AC switchover takes place, in PSN network traffic is still
   forwarded using the working PW.

   If some failure in the PSN network causes PW1 to go down, the failure
   can be detected by the working PE (PE1) or the remote PE (PE3) using
   some mechanisms (e.g. by OAM).  If PE1 detects the failure of PW1, it

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   MUST inform PE2 the state of working PW using the PW State TLV in DHC
   message and change the forwarding status of PW1 to standby.  On
   receipt of the DHC message, PE2 SHOULD change the forwarding status
   of PW2 to active.  Then according to the forwarding state machine in
   Table 1, PE1 SHOULD set up the connection between the DNI PW and AC1,
   and PE2 SHOULD set up the connection between PW2 and the DNI PW.
   According to linear protection mechanism, PE2 also sends an
   appropriate protection coordination message on the protection PW
   (PW2) to PE3 for the remote side switchover from PW1 to PW2.  If PE3
   detects the failure of PW1, according to linear protection mechanism,
   it sends a protection coordination message on the protection PW (PW2)
   to inform PE2 to switchover to the protection PW.  Upon receipt of
   the message, PE2 SHOULD change the forwarding status of PW2 to active
   and set up the connection according to Table 1.  PE2 SHOULD send a
   DHC message to PE1 with the S bit in the Dual-Node Switching TLV set
   to coordinate the switchover on PE1 and PE2.  This can be useful for
   unidirectional failure which was not detected by PE1.

   If some failure causes the working PE (PE1) to go down, the failure
   can be detected by both the protection PE(PE2) and the remote PE(PE3)
   using some mechanisms (e.g.  OAM).  PE2 changes the forwarding status
   of PW2 to active, and PE3 sends a protection coordination message on
   the protection path to inform PE2 to switchover to the protection PW.
   According to AC redundancy mechanism, the status of AC1 changes to
   standby, and the state of AC2 changes to active.  According to the
   forwarding state machine in Table 1, PE2 starts to forward traffic
   between the protection PW and AC2.

4.  IANA Considerations

   IANA needs to assign one new channel type for "MPLS-TP Dual-Homing
   Coordination message" from the "Pseudowire Associated Channel Types"
   registry.

   This document creates a new registry called "MPLS-TP DHC TLVs"
   registry.  Two new TLVs are defined in this document:

   Type        Description               Length
    1          PW Status                 20 Bytes
    2        Dual-Node Switching         16 Bytes

5.  Security Considerations

   Procedures and protocol extensions defined in this document do not
   affect the security model of MPLS-TP linear protection as defined in
   [RFC6378].  Please refer to [RFC5920] for MPLS security issues and
   generic methods for securing traffic privacy and integrity.

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6.  References

6.1.  Normative References

   [I-D.ietf-pals-mpls-tp-dual-homing-protection]
              Cheng, W., Wang, L., Li, H., Liu, K., Davari, S., Dong,
              J., and A. D'Alessandro, "Dual-Homing Protection for MPLS
              and MPLS-TP Pseudowires", draft-ietf-pals-mpls-tp-dual-
              homing-protection-00 (work in progress), April 2015.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC5586]  Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed.,
              "MPLS Generic Associated Channel", RFC 5586,
              DOI 10.17487/RFC5586, June 2009,
              <http://www.rfc-editor.org/info/rfc5586>.

   [RFC6378]  Weingarten, Y., Ed., Bryant, S., Osborne, E., Sprecher,
              N., and A. Fulignoli, Ed., "MPLS Transport Profile (MPLS-
              TP) Linear Protection", RFC 6378, DOI 10.17487/RFC6378,
              October 2011, <http://www.rfc-editor.org/info/rfc6378>.

   [RFC7271]  Ryoo, J., Ed., Gray, E., Ed., 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, DOI 10.17487/RFC7271, June 2014,
              <http://www.rfc-editor.org/info/rfc7271>.

   [RFC7324]  Osborne, E., "Updates to MPLS Transport Profile Linear
              Protection", RFC 7324, DOI 10.17487/RFC7324, July 2014,
              <http://www.rfc-editor.org/info/rfc7324>.

6.2.  Informative References

   [I-D.ietf-pals-ms-pw-protection]
              Malis, A., Andersson, L., Helvoort, H., Shin, J., Wang,
              L., and A. D'Alessandro, "S-PE Protection for MPLS and
              MPLS-TP Static Multi-Segment Pseudowires", draft-ietf-
              pals-ms-pw-protection-03 (work in progress), October 2015.

   [RFC5920]  Fang, L., Ed., "Security Framework for MPLS and GMPLS
              Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
              <http://www.rfc-editor.org/info/rfc5920>.

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Internet-Draft  Dual-Homing Coordination for MPLS-TP PWs    October 2015

   [RFC6372]  Sprecher, N., Ed. and A. Farrel, Ed., "MPLS Transport
              Profile (MPLS-TP) Survivability Framework", RFC 6372,
              DOI 10.17487/RFC6372, September 2011,
              <http://www.rfc-editor.org/info/rfc6372>.

   [RFC6718]  Muley, P., Aissaoui, M., and M. Bocci, "Pseudowire
              Redundancy", RFC 6718, DOI 10.17487/RFC6718, August 2012,
              <http://www.rfc-editor.org/info/rfc6718>.

   [RFC6870]  Muley, P., Ed. and M. Aissaoui, Ed., "Pseudowire
              Preferential Forwarding Status Bit", RFC 6870,
              DOI 10.17487/RFC6870, February 2013,
              <http://www.rfc-editor.org/info/rfc6870>.

Authors' Addresses

   Weiqiang Cheng
   China Mobile
   No.32 Xuanwumen West Street
   Beijing  100053
   China

   Email: chengweiqiang@chinamobile.com

   Lei Wang
   China Mobile
   No.32 Xuanwumen West Street
   Beijing  100053
   China

   Email: Wangleiyj@chinamobile.com

   Han Li
   China Mobile
   No.32 Xuanwumen West Street
   Beijing  100053
   China

   Email: Lihan@chinamobile.com

Cheng, et al.            Expires April 21, 2016                [Page 12]
Internet-Draft  Dual-Homing Coordination for MPLS-TP PWs    October 2015

   Kai Liu
   Huawei Technologies
   Huawei Base, Bantian, Longgang District
   Shenzhen  518129
   China

   Email: alex.liukai@huawei.com

   Shahram Davari
   Broadcom Corporation
   3151 Zanker Road
   San Jose  95134-1933
   United States

   Email: davari@broadcom.com

   Jie Dong
   Huawei Technologies
   Huawei Campus, No. 156 Beiqing Rd.
   Beijing  100095
   China

   Email: jie.dong@huawei.com

   Alessandro D'Alessandro
   Telecom Italia
   via Reiss Romoli, 274
   Torino  10148
   Italy

   Email: alessandro.dalessandro@telecomitalia.it

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