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Versions: (draft-mirsky-mpls-tp-cv-adv) 00 01 02 03 04 05 06 RFC 7189

Network Working Group                                          G. Mirsky
Internet-Draft                                                  Ericsson
Intended status: Standards Track                      September 20, 2013
Expires: March 24, 2014


  VCCV MPLS-TP Connectivity Verification (CV) Capability Advertisement
                   draft-ietf-pwe3-mpls-tp-cv-adv-01

Abstract

   This document specifies how use of proactive Connectivity
   Verification, Continuity Check, and Remote Defect Indication for the
   MPLS Transport Profile [RFC6428] affects operation and management
   function election for PW VCCV [RFC5085], [RFC5885].

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
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   This Internet-Draft will expire on March 24, 2014.

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   Copyright (c) 2013 IETF Trust and the persons identified as the
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
     1.1.  Conventions used in this document . . . . . . . . . . . . . 3
       1.1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . 3
       1.1.2.  Requirements Language . . . . . . . . . . . . . . . . . 3
   2.  MPLS-TP CC-CV on Pseudowires  . . . . . . . . . . . . . . . . . 3
     2.1.  VCCV Extended CV Advertisement sub-TLV  . . . . . . . . . . 4
     2.2.  MPLS-TP CC-CV Types . . . . . . . . . . . . . . . . . . . . 4
     2.3.  MPLS-TP CC-CV Type Operation  . . . . . . . . . . . . . . . 5
     2.4.  CV Type Selection . . . . . . . . . . . . . . . . . . . . . 5
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
     3.1.  VCCV Extended CV Types  . . . . . . . . . . . . . . . . . . 6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 7
     6.1.  Normative References  . . . . . . . . . . . . . . . . . . . 7
     6.2.  Informative References  . . . . . . . . . . . . . . . . . . 7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 8
































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1.  Introduction

   Proactive Connectivity Verification (CV), Continuity Check (CC), and
   Remote Defect Indication (RDI) for the MPLS Transport Profile
   [RFC6428] are applicable to all constructs of the MPLS-TP, including
   pseudowires (PWs).  If Control Plane is used to operate and manage PW
   then procedure defined in [RFC5085] and [RFC5885] should be used to
   select proper type of Control Channel and corresponding type of
   Connectivity Verification.  This document specifies how signaling and
   selection process modified to ensure backward compatibility and allow
   use of proactive CV-CC-RDI over MPLS-TP PWs.

1.1.  Conventions used in this document

1.1.1.  Terminology

   BFD: Bidirectional Forwarding Detection

   CC: Continuity Check

   CV: Connectivity Verification

   PE: Provider Edge

   VCCV: Virtual Circuit Connectivity Verification

   VCCV CC: VCCV Control Channel

1.1.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119].


2.  MPLS-TP CC-CV on Pseudowires

   PW VCCV can support several CV Types.  Ability to support arbitrary
   combination of CV modes advertised in CV Types field of VCCV
   Interface Parameter sub-TLV [RFC4446], [RFC4447].  Currently six
   types of CV been defined for PW VCCV out of eight bit long field.
   This document introduces four new CV types and, to accommodate them,
   a new VCCV Extended CV parameter for PW Interface Parameters Sub-TLV
   is defined.






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2.1.  VCCV Extended CV Advertisement sub-TLV

   The format of VCCV Extended CV Advertisement is a TLV where:

    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 = 0x19 |    Length     |   CV Type    |   Reserved     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 1: VCCV Extended CV parameter format

   Length - the length of the sub-TLV, including type and the Length
   field itself.  Minimum length is 4.  It it isrecommended that
   extensions to the sub-TLV be done in 4 bytes increments with Reserved
   field being set to zero on transmit and ignored on receipt.

   Reserved field must be set to zeroes on transmit and ignored on
   receive.

   CV Type field is a bitmask that lists types of CV monitoring that a
   PE is capable to support.  VCCV Extended CV parameter sub-TLV must
   appear in combination with VCCV parameter sub-TLV.  If VCCV parameter
   sub-TLV is missing then VCCV Extended CV parameter sub-TLV should be
   ignored.

2.2.  MPLS-TP CC-CV Types

   The [RFC6428] defines coordinated and independent modes of monitoring
   point-to-point bi-directional connection that can be applied to
   monitoring PWs.  At the same time [RFC6310] defines how BFD-based OAM
   can map and be mapped to status of an Attachment Circuit.  Thus there
   could be four MPLS-TP CV types as combination of modes and
   functionality:

   +---------------+-------------------+-------------------------------+
   |     Modes     |  Fault Detection  |   Fault Detection and Status  |
   |               |        Only       |           Signalling          |
   +---------------+-------------------+-------------------------------+
   |  Independent  |        0x01       |              0x02             |
   |      Mode     |                   |                               |
   |  Coordinated  |        0x04       |              0x08             |
   |      Mode     |                   |                               |
   +---------------+-------------------+-------------------------------+

               Table 1: Bitmask Values for MPLS-TP CV Types





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2.3.  MPLS-TP CC-CV Type Operation

   Connectivity verification according to [RFC6428] is part of MPLS-TP
   CC/CV operation that can be used with VCCV Control Channel Type 1
   [RFC5085] .  If VCCV CC Type 1 selected, then PEs might select one of
   MPLS-TP CC-CV types as VCCV CV mechanism to be used for this PW.

2.4.  CV Type Selection

   CV selection rules that have been defined in Section 7 of [RFC5085]
   and updated Section 4 of [RFC5885] are augmented in this document.

   If VCCV Control Channel Type 1 is chosen according to Section 7
   [RFC5085] and common set of proactive CV types advertized by both PEs
   includes MPLS-TP CC-CV types and some BFD CV types, then MPLS-TP
   CC-CV takes precedence over any type of BFD CV.  If multiple MPLS-TP
   CV types advertised by both PEs, then following list sorted in
   descending priority order is used:

   1.  0x08 - coordinated mode for PW Fault Detection and AC/PW Fault
       Status Signaling

   2.  0x04 - coordinated mode for PW Fault Detection only

   3.  0x02 - independent mode for PW Fault Detection and AC/PW Fault
       Status Signaling

   4.  0x01 - independent mode for PW Fault Detection only


3.  IANA Considerations

   The PW Interface Parameters Sub-TLV registry defined in [RFC4446].

   IANA is requested to reserve a new PW Interface Parameters Sub-TLV
   type as follows:

   +-------------+--------+----------------------------+---------------+
   |  Parameter  | Length |         Description        | Reference     |
   |      ID     |        |                            |               |
   +-------------+--------+----------------------------+---------------+
   |     0x19    | 4      | VCCV Extended CV Parameter | This document |
   +-------------+--------+----------------------------+---------------+

               Table 2: New PW Interface Parameters Sub-TLV






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3.1.  VCCV Extended CV Types

   IANA is requested to set up a registry of ?VCCV Extended CV Types?.
   These are 8 bitfield values.  Extended CV Type values 0x01, 0x02,
   0x04 and 0x08 are specified in Section 2.2 of this document.  The
   remaining bitfield values (0x10 through 0x80) are to be assigned by
   IANA using the "IETF Consensus" policy defined in [RFC2434].  A VCCV
   Extended Control Verification Type description and a reference to an
   RFC approved by the IESG are required for any assignment from this
   registry.

   +--------------+----------------------------------------------------+
   |  Bit(Value)  | Description                                        |
   +--------------+----------------------------------------------------+
   | Bit 0 (0x01) | Independent mode for PW Fault Detection only       |
   | Bit 1 (0x02) | Independent mode for PW Fault Detection and AC/PW  |
   |              | Fault Status Signaling                             |
   | Bit 2 (0x04) | Coordinated mode for PW Fault Detection only       |
   | Bit 3 (0x08) | Coordinated mode for PW Fault Detection and AC/PW  |
   |              | Fault Status Signaling                             |
   | Bit 4 (0x10) | Reserved                                           |
   | Bit 5 (0x20) | Reserved                                           |
   | Bit 6 (0x40) | Reserved                                           |
   | Bit 7 (0x80) | Reserved                                           |
   +--------------+----------------------------------------------------+

            Table 3: MPLS Connectivity Verification (CV) Types


4.  Security Considerations

   Routers that implement the additional CV Type defined herein are
   subject to the same security considerations as defined in [RFC5085],
   [RFC5880], [RFC5881], and [RFC6428].  This specification does not
   raise any additional security issues beyond these.


5.  Acknowledgements

   The author gratefully acknowledges the thoughtful review, comments,
   and explanations provided by Dave Allan, and by Carlos Pignataro.


6.  References







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6.1.  Normative References

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

   [RFC4446]  Martini, L., "IANA Allocations for Pseudowire Edge to Edge
              Emulation (PWE3)", BCP 116, RFC 4446, April 2006.

   [RFC4447]  Martini, L., Rosen, E., El-Aawar, N., Smith, T., and G.
              Heron, "Pseudowire Setup and Maintenance Using the Label
              Distribution Protocol (LDP)", RFC 4447, April 2006.

   [RFC5085]  Nadeau, T. and C. Pignataro, "Pseudowire Virtual Circuit
              Connectivity Verification (VCCV): A Control Channel for
              Pseudowires", RFC 5085, December 2007.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, June 2010.

   [RFC5881]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881,
              June 2010.

   [RFC5882]  Katz, D. and D. Ward, "Generic Application of
              Bidirectional Forwarding Detection (BFD)", RFC 5882,
              June 2010.

   [RFC5885]  Nadeau, T. and C. Pignataro, "Bidirectional Forwarding
              Detection (BFD) for the Pseudowire Virtual Circuit
              Connectivity Verification (VCCV)", RFC 5885, June 2010.

   [RFC6310]  Aissaoui, M., Busschbach, P., Martini, L., Morrow, M.,
              Nadeau, T., and Y(J). Stein, "Pseudowire (PW) Operations,
              Administration, and Maintenance (OAM) Message Mapping",
              RFC 6310, July 2011.

   [RFC6428]  Allan, D., 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.

6.2.  Informative References

   [RFC2434]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 2434,
              October 1998.





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Author's Address

   Greg Mirsky
   Ericsson

   Email: gregory.mirsky@ericsson.com













































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