Network Working Group                                             L. Jin
Internet-Draft                                                   R. Chen
Intended status: Standards Track                                     ZTE
Expires: April 12, 2013                                       S. Boutros
                                                           Cisco Systems
                                                                 S. Kini
                                                                Ericsson
                                                         October 9, 2012


   Static pseudowire configuration checking using Generic Associated
                 Channel (G-ACh) Advertisement Protocol
                draft-jc-pwe3-static-config-check-01.txt

Abstract

   This document defines a method to verify the configuration parameters
   of static pseudowires (PW).  Since a static PW can be independently
   provisioned at each end of the PW there is a potential for a
   configuration parameter mismatch and this can result in the PW not
   being operational.  This document introduces a configuration checking
   protocol to simplify the provisioning and ease trouble shooting.

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/.

   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 12, 2013.

Copyright Notice

   Copyright (c) 2012 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



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   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 . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  GAP Extensions . . . . . . . . . . . . . . . . . . . . . . . .  4
     3.1.  Static PW Application Message  . . . . . . . . . . . . . .  4
     3.2.  PE Procedure for SS-PW . . . . . . . . . . . . . . . . . .  7
       3.2.1.  Sending PW application Element TLV . . . . . . . . . .  7
       3.2.2.  Receiving PW application Element TLV . . . . . . . . .  7
       3.2.3.  PW Configuration Verification Process  . . . . . . . .  8
       3.2.4.  Remote Label Advertisement . . . . . . . . . . . . . .  8
     3.3.  PE Procedure for MS-PW . . . . . . . . . . . . . . . . . .  8
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  9
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     7.1.  Normative references . . . . . . . . . . . . . . . . . . .  9
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 10
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
























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1.  Introduction

   The manual configuration of static PW in MPLS and MPLS-TP network
   requires configuring different PW parameters at the two terminating
   PEs (Provider Edge).  The PW parameters include PW-id, PW-Type,
   Control word setting, interface and VCCV parameters settings.

   The PW provisioned parameters MUST be aligned, so as to make the PW
   operational.  For dynamically signaled PW, the PW parameters are
   negotiated using the signaling protocol, and only when the PW
   parameters match at the terminating PE end points, the P2P (Point-to-
   Point) PW is made operational and can be used to forward data
   traffic.

   In the absence of a signaling protocol, this draft defines a method
   to do static PW configuration verification, so as to ease the
   troubleshooting of end to end static PW provisioning in both MPLS and
   MPLS-TP networks.  The mechanism to exchange the PW configuration
   parameters uses the Generic Associated Channel (G-ACh) Advertisement
   Protocol (GAP) defined in [I-D.ietf-mpls-gach-adv].  In this draft,
   the GAP functionality assumes that the PW's underlying PSN Tunnel
   with GAP enabled is operational.

   In the following sections we will describe the extension to the GAP
   mechanism to do the PW configuration verification at the two
   terminating PEs for P2P PW.  The P2MP (Point-to-Multipoint) PW
   configuration verification is for further study.


2.  Terminology

   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].

   This document uses some terms and acronyms as follows:

      MPLS: Multi Protocol Label Switching.

      OAM: MPLS Operations, Administration and Maintenance.

      PE: Provide Edge Node.

      T-PE: PW Terminating Provider Edge.

      S-PE: PW Switching Provider Edge.





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      PW: PseudoWire.

      TLV: Type, Length, and Value.

      SS-PW: Single-segment PseudoWire

      MS-PW: Multi-segment PseudoWire


3.  GAP Extensions

3.1.  Static PW Application Message


     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Static PW          |              Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Lifetime           |              Reserve            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    +                    Static PW FEC Element TLV                  +
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 1

   A new GAP application "Static PW" is defined in this draft.  The
   Static PW Application ID is to be assigned by IANA, and suggested
   value is 0x0002.

   Length: as per [I-D.ietf-mpls-gach-adv].

   Lifetime: as per [I-D.ietf-mpls-gach-adv], and the default value is
   suggested to be 120 seconds.

   Static PW FEC Element TLV for "Static PW" GAP application:













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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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |      Type     |    Reserved   |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                       Source Global ID                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Source Node ID                         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                         Source AC-ID                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    Destination Global ID                      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                     Destination Node ID                       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      Destination AC-ID                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          PW Type            |C|            Reserved           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      TX Sequence Number                       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      RX Sequence Number                       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0|0|  Label Sub-TLV(0x0200)  |              Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                          Incoming Label                       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0|0|  Label Sub-TLV(0x0200)  |              Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                          Outgoing Label                       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    +             Optional Interface Parameters Sub-TLV             +
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                                 Figure 2

   The Static PW FEC Element TLV type is to be assigned by IANA.  The
   Length field specifies the length in octets of the Static PW FEC
   Element and all Optional Interface Parameters Sub-TLVs.

   The Static PW FEC element TLV value MUST include the following:

   o  The Global ID and Node ID fields MUST be set as per [RFC6370].





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   o  The AC-ID fields MUST be set as per [RFC5003].

   o  PW-Type and control word bit (C) MUST be set as per [RFC4447].

   o  TX Sequence Number: The transmitted message sequence number for
      the associated Static PW FEC Element TLV.

   o  RX Sequence Number: The last received sequence number for the
      associated Static PW FEC Element TLV.

   o  Two Generic Label TLVs as defined in [RFC5036] to encode static PW
      incoming and outgoing labels in the order shown above.

   o  Optional Interface parameters Sub-TLV as defined in [RFC4447].

   The GAP Suppress message defined in [I-D.ietf-mpls-gach-adv] only
   applies all TLVs for a given application.  We define a new TLV,
   static PW suppress TLV, to suppress static PW FEC element
   transmission.  Multiple static PW FEC element TLVs could be included
   in this TLV.  The format would be as follows:


     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |PW Suppress TLV|    Reserved   |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    +                      Static PW FEC Element                    +
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    ~               Multiple Static PW FEC Element TLVs             ~
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 3

   The type of static PW suppress TLV is to be assigned by IANA.

   The static PW suppress TLV could be sent by a receiving PE to request
   a transmitting PE to stop sending GAP messages for the static PW FEC
   Element TLVs in the static PW suppress TLV.

   The static PW application MUST follow all procedures defined in
   [I-D.ietf-mpls-gach-adv].







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3.2.  PE Procedure for SS-PW

   The mechanism defined in this draft provides a verification tool for
   the P2P PW configuration information between two PEs.  Upon the
   provisioning or re-provisioning of a PW at an endpoint PE, GAP
   messages carrying the static PW application TLV will be sent over the
   PW's corresponding PSN tunnel which the endpoints PEs of the P2P PW
   selects by local policy.

3.2.1.  Sending PW application Element TLV

   When a PW is configured at one endpoint PE, and the PW corresponding
   PSN Tunnel is operational and UP, the PE MUST send its local PW
   configuration information using the GAP over the PSN tunnel.

   The transmitting PE MUST set the TX sequence number to a non-zero
   value in Static PW FEC Element TLV, and MUST increment the TX
   sequence number each time any local PW parameters change.

   If the transmitting PE has previously received a GAP message with the
   static PW FEC Element, the transmitting PE MUST verify local PW
   parameters with the remote PE parameters as specified in section
   4.2.3.  The RX sequence number MUST be set to the previously received
   TX sequence number, otherwise set to zero.

3.2.2.  Receiving PW application Element TLV

   The receiving PE MUST update the remote PW parameters associated with
   a static PW FEC Element TLV, when the received TX sequence number in
   the GAP message is different from the last one received.

   If the receiving PE has been provisioned locally with the PW
   parameters and has previously sent GAP message for the PW parameters,
   it MUST check if the RX sequence number in the received GAP message
   is equal to the TX sequence number it previously sent.

   If the RX sequence number is equal, the receiving PE MUST send GAP
   message with static PW suppress TLV as a response to remote PE, and
   then verify local static PW parameters with the remote static PW FEC
   parameters as specified in section 3.2.3.

   Otherwise, if the RX sequence number is not equal, the receiving PE
   MUST continue sending GAP message with static PW FEC element TLV,
   with the RX sequence number set to the last received TX sequence
   number from the remote PE.

   If there is no local PW configuration associated with the static PW
   FEC Element TLV, the receiving PE MUST retain the remote static PW



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   FEC Element information.

   Whenever PE receives the GAP message with static PW suppress TLV, it
   MUST stop sending GAP messages with the specified static PW FEC
   element TLVs included in the static suppress TLV.

   The GAP message of static PW application SHOULD be sent at least
   three times within lifetime.

   The mechanism described above applies as well for MS-PW.

3.2.3.  PW Configuration Verification Process

   Using source/destination Global-IDs, and source/destination node-ID
   and AC-IDs, to identify a locally provisioned static PW, once found,
   perform the following parameter verification checks:

   1.  Check the control word bit (C), and MUST do logical operation
       "AND".  Only when both ends have the use of control word enabled,
       the result would be with control word presented on this PW.

   2.  Check PW type mismatch as defined in [RFC4447].

   3.  Check and negotiate interface parameters as defined in [RFC4447].

   4.  Check incoming and outgoing static PW labels.  The local incoming
       label should be equal to remote outgoing label, and the local
       outgoing label should be equal to remote incoming label,
       otherwise checking failed.

3.2.4.  Remote Label Advertisement

   The mechanism described in this draft MAY also be used to communicate
   local static PW labels to allow for single side provisioning of
   labels.  As such, only incoming label will be included in the GAP
   message and this label will be used by the remote PE as the output
   label for the PW.

3.3.  PE Procedure for MS-PW

   The mechanism described above for verifying the SS-PW configuration
   applies for MS-PW.  As described in section 3.2, an S-PE MUST verify
   the incoming and outgoing static PW labels, however no other PW
   configuration parameters checking are needed at S-PE, since only the
   labels will be configured at S-PE.

   An S-PE MUST pass through static PW application TLVs carried in GAP
   messages, from one PW segment's corresponding PSN tunnel to the other



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   PW segment's corresponding PSN tunnel.


4.  Security Considerations

   The mechanisms defined in this draft do not introduce any new threats
   more than what's described in [I-D.ietf-mpls-gach-adv].


5.  IANA Considerations

   IANA is requested to allocate a new "Static PW" Application ID in the
   "G-Ach Advertisement Protocol Applications" registry.

   Application ID Description                  Reference
   -------------- ---------------------------- ------------
   (TBD)          Static PW Application        (this draft)

   This document requests that IANA create a new registry, "GAP Static
   PW Application: TLV objects", with fields and initial value as
   follows:

   Type Name               Type ID Reference
   ----------------------- ------- ------------
   Static PW FEC Element      0    (this draft)
   Static PW suppress TLV     1    (this draft)

   The range of the Type ID field is 0 - 255.

   The allocation policy for this registry is IETF Review.


6.  Acknowledgements

   The authors would like to thank Stewart Bryant, Dan Frost for their
   review and contributions.


7.  References

7.1.  Normative references

   [I-D.ietf-mpls-gach-adv]
              Frost, D., Bryant, S., and M. Bocci, "MPLS Generic
              Associated Channel (G-ACh) Advertisement Protocol",
              draft-ietf-mpls-gach-adv-02 (work in progress), May 2012.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.


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7.2.  Informative References

   [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.

   [RFC5003]  Metz, C., Martini, L., Balus, F., and J. Sugimoto,
              "Attachment Individual Identifier (AII) Types for
              Aggregation", RFC 5003, September 2007.

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

   [RFC6370]  Bocci, M., Swallow, G., and E. Gray, "MPLS Transport
              Profile (MPLS-TP) Identifiers", RFC 6370, September 2011.


Authors' Addresses

   Lizhong Jin
   ZTE Corporation
   889, Bibo Road
   Shanghai, 201203, China

   Email: lizhong.jin@zte.com.cn


   Ran Chen
   ZTE Corporation
   No.19 East Huayuan Road
   Beijing, 100191, China

   Email: chen.ran@zte.com.cn


   Sami Boutros
   Cisco Systems, Inc.
   3750 Cisco Way
   San Jose, California 95134
   USA

   Email: sboutros@cisco.com









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   Sriganesh Kini
   Ericsson
   Ericsson
   San Jose, CA 95134

   Email: sriganesh.kini@ericsson.com













































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