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Internet Engineering Task Force (IETF)                         G. MirskyRequest for Comments: 7189                                      EricssonCategory: Standards Track                                     March 2014ISSN: 2070-1721Virtual Circuit Connectivity Verification (VCCV)Capability Advertisement for MPLS Transport Profile (MPLS-TP)Abstract   This document specifies how signaling and selection processes for   Pseudowire (PW) Virtual Circuit Connectivity Verification (VCCV) are   modified to ensure backward compatibility and allow use of proactive   Connectivity Verification (CV), Continuity Check (CC), and Remote   Defect Indication (RDI) over MPLS Transport Profile (MPLS-TP) PWs.   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.Status of This Memo   This is an Internet Standards Track document.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Further information on   Internet Standards is available inSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc7189.Copyright Notice   Copyright (c) 2014 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 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.Mirsky                       Standards Track                    [Page 1]

RFC 7189                    VCCV for MPLS-TP                  March 2014Table of Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .21.1.  Conventions Used in This Document . . . . . . . . . . . .21.1.1.  Terminology . . . . . . . . . . . . . . . . . . . . .21.1.2.  Requirements Language . . . . . . . . . . . . . . . .32.  MPLS-TP CC-CV on Pseudowires  . . . . . . . . . . . . . . . .32.1.  VCCV Extended CV Advertisement Sub-TLV  . . . . . . . . .32.2.  MPLS-TP CC-CV Types . . . . . . . . . . . . . . . . . . .32.3.  MPLS-TP CC-CV Type Operation  . . . . . . . . . . . . . .42.4.  CV Type Selection . . . . . . . . . . . . . . . . . . . .43.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .53.1.  VCCV Extended CV Types  . . . . . . . . . . . . . . . . .54.  Security Considerations . . . . . . . . . . . . . . . . . . .65.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .66.  References  . . . . . . . . . . . . . . . . . . . . . . . . .66.1.  Normative References  . . . . . . . . . . . . . . . . . .66.2.  Informative References  . . . . . . . . . . . . . . . . .71.  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 the control plane is used to operate and   manage PWs then the procedures defined in [RFC5085] and [RFC5885]   should be used to select the proper type of Control Channel and the   corresponding type of Connectivity Verification.  This document   specifies how signaling and selection processes are modified to   ensure backward compatibility and allow use of proactive CV-CC-RDI   over MPLS-TP PWs.1.1.  Conventions Used in This Document1.1.1.  Terminology   BFD: Bidirectional Forwarding Detection   CC: Continuity Check   CV: Connectivity Verification   PE: Provider Edge   VCCV: Virtual Circuit Connectivity VerificationMirsky                       Standards Track                    [Page 2]

RFC 7189                    VCCV for MPLS-TP                  March 20141.1.2.  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, and it can support an arbitrary   combination of CV modes advertised in the CV Types field of the VCCV   Interface Parameter sub-TLV [RFC4446] [RFC4447].  Currently, six   types of CV have been defined for PW VCCV.  This document introduces   four new CV types and, to accommodate them, a new VCCV Extended CV   parameter for the PW Interface Parameters Sub-TLV is defined.2.1.  VCCV Extended CV Advertisement Sub-TLV   The format of the VCCV Extended CV Advertisement is a TLV where the   format is 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    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    | Type = 0x19 |    Length     |   CV Type    |   Reserved     |    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                Figure 1: VCCV Extended CV Parameter Format   The Length field is the length of the sub-TLV, including type and the   Length field itself.  The minimum length is 4.  It is recommended   that extensions to the sub-TLV be done in 4-byte increments.   The Reserved field MUST be set to zeroes on transmit and ignored on   receive.   The CV Type field is a bitmask that lists types of CV monitoring that   a PE is capable of supporting.  The VCCV Extended CV parameter sub-   TLV MUST appear in combination with the VCCV parameter sub-TLV.  If   the VCCV parameter sub-TLV is missing, then the VCCV Extended CV   parameter sub-TLV SHOULD be ignored.2.2.  MPLS-TP CC-CV Types   [RFC6428] defines coordinated and independent modes of monitoring   point-to-point bidirectional connection that can be applied to   monitoring PWs.  At the same time, [RFC6310] defines how BFD-basedMirsky                       Standards Track                    [Page 3]

RFC 7189                    VCCV for MPLS-TP                  March 2014   Operations, Administration, and Maintenance (OAM) can map to the   status of an Attachment Circuit.  Thus, there could be four MPLS-TP   CV types for each combination of mode and functionality:   +----------------+-------------------+------------------------------+   |     Modes      |  Fault Detection  |  Fault Detection and Status  |   |                |        Only       |          Signaling           |   +----------------+-------------------+------------------------------+   |  Independent   |        0x01       |             0x02             |   |      Mode      |                   |                              |   |  Coordinated   |        0x04       |             0x08             |   |      Mode      |                   |                              |   +----------------+-------------------+------------------------------+               Table 1: Bitmask Values for MPLS-TP CV Types2.3.  MPLS-TP CC-CV Type Operation   According to [RFC6428], connectivity verification is part of MPLS-TP   CC/CV operation that can be used with VCCV Control Channel Type 1   [RFC5085].  If VCCV Control Channel Type 1 is selected, then PEs MAY   select one of the MPLS-TP CC-CV types as the VCCV CV mechanism to be   used for this PW.2.4.  CV Type Selection   CV selection rules that have been defined inSection 7 of [RFC5085]   and updated inSection 4 of [RFC5885] are augmented in this document.   If VCCV Control Channel Type 1 is chosen according toSection 7 of   [RFC5085] and a common set of proactive CV types that are advertised   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 are advertised by both PEs, then the following list   (ordered by descending priority) 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 onlyMirsky                       Standards Track                    [Page 4]

RFC 7189                    VCCV for MPLS-TP                  March 20143.  IANA Considerations   The PW Interface Parameters Sub-TLV registry is defined in [RFC4446].   IANA has reserved a new PW Interface Parameters Sub-TLV type as   follows:   +-----------+----------+----------------------------+---------------+   | Parameter | Length   |        Description         | Reference     |   |     ID    |          |                            |               |   +-----------+----------+----------------------------+---------------+   |    0x19   | variable | VCCV Extended CV Parameter | This document |   +-----------+----------+----------------------------+---------------+               Table 2: New PW Interface Parameters Sub-TLV3.1.  VCCV Extended CV Types   IANA has set up a registry of VCCV Extended CV Types.  These are   8-bit values.  Extended CV Type values 0x01, 0x02, 0x04, and 0x08 are   specified inSection 2.2 of this document.  The remaining values   (0x10 through 0x80) are to be assigned by IANA using the "IETF   Review" policy defined in [RFC5226].  A VCCV Extended Connectivity   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) | Unassigned                                         |   | Bit 5 (0x20) | Unassigned                                         |   | Bit 6 (0x40) | Unassigned                                         |   | Bit 7 (0x80) | Unassigned                                         |   +--------------+----------------------------------------------------+        Table 3: VCCV Extended Connectivity Verification (CV) TypesMirsky                       Standards Track                    [Page 5]

RFC 7189                    VCCV for MPLS-TP                  March 20144.  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 those.5.  Acknowledgements   The author gratefully acknowledges the thoughtful review, comments,   and explanations provided by Dave Allan and Carlos Pignataro.6.  References6.1.  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.   [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.Mirsky                       Standards Track                    [Page 6]

RFC 7189                    VCCV for MPLS-TP                  March 2014   [RFC6428]  Allan, D., Swallow Ed. , G., and J. Drake Ed. , "Proactive              Connectivity Verification, Continuity Check, and Remote              Defect Indication for the MPLS Transport Profile",RFC6428, November 2011.6.2.  Informative References   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an              IANA Considerations Section in RFCs",BCP 26,RFC 5226,              May 2008.Author's Address   Greg Mirsky   Ericsson   EMail: gregory.mirsky@ericsson.comMirsky                       Standards Track                    [Page 7]