RFC 7189

Virtual Circuit Connectivity Verification (VCCV) Capability Advertisement for MPLS Transport Profile (MPLS-TP)

📅 published March 2014, from ietf

RFC 7189 Title Block 🎀

okay bestie, this is RFC 7189 💖 The title is Virtual Circuit Connectivity Verification (VCCV) Capability Advertisement for MPLS Transport Profile (MPLS-TP). It's from the IETF, written by G. Mirsky at Ericsson, and it's a Standards Track doc dated March 2014. The ISSN is 2070-1721. The header doesn't list anything it obsoletes or updates, so there's no drama there 🌸

The whole vibe is making proactive Connectivity Verification (CV), Continuity Check (CC), and Remote Defect Indication (RDI) work over MPLS-TP pseudowires without breaking older stuff. ✨

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions Used in This Document . . . . . . . . . . . .   2
       1.1.1.  Terminology . . . . . . . . . . . . . . . . . . . . .   2
       1.1.2.  Requirements Language . . . . . . . . . . . . . . . .   3
   2.  MPLS-TP CC-CV on Pseudowires  . . . . . . . . . . . . . . . .   3
     2.1.  VCCV Extended CV Advertisement Sub-TLV  . . . . . . . . .   3
     2.2.  MPLS-TP CC-CV Types . . . . . . . . . . . . . . . . . . .   3
     2.3.  MPLS-TP CC-CV Type Operation  . . . . . . . . . . . . . .   4
     2.4.  CV Type Selection . . . . . . . . . . . . . . . . . . . .   4
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  VCCV Extended CV Types  . . . . . . . . . . . . . . . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   7

Status of This Memo 📜

This is an Internet Standards Track document, which means it's officially part of the Internet Standards family 👑

It's a product of the IETF, and it represents the consensus of the IETF community. It went through public review and got approved for publication by the Internet Engineering Steering Group (IESG). More info on Internet Standards is in Section 2 of RFC 5741 🦋

You can check the current status, any errata, and how to send feedback at http://www.rfc-editor.org/info/rfc7189 💅

Copyright Notice ©️

This doc is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) as they stand on the publication date. Please actually read them, because they describe your rights and restrictions for this document 🙈 Code Components pulled out of this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions, and they come without warranty as described in the Simplified BSD License 💜

1. Introduction ✨

okay so the big picture: proactive Connectivity Verification (CV), Continuity Check (CC), and Remote Defect Indication (RDI) for the MPLS Transport Profile [RFC6428] apply to all the MPLS-TP constructs, and that includes pseudowires (PWs) 💖 If the control plane is used to operate and manage PWs, then the procedures in [RFC5085] and [RFC5885] should be used to pick the right type of Control Channel and the matching type of Connectivity Verification 🔥

This document is the glow-up for that process. It specifies how the signaling and selection processes get modified so they stay backward compatible and let proactive CV-CC-RDI work over MPLS-TP PWs. It's giving compatibility, no cap 🫶

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

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]. so those words have their formal meaning here, periodt 💅

2. MPLS-TP CC-CV on Pseudowires 🦋

PW VCCV can support several CV Types, and it can support any combination of CV modes advertised in the CV Types field of the VCCV Interface Parameter sub-TLV [RFC4446] [RFC4447]. Right now, six types of CV are defined for PW VCCV. This document introduces four new CV types, and to fit them in, a new VCCV Extended CV parameter for the PW Interface Parameters Sub-TLV is defined ✨

2.1. VCCV Extended CV Advertisement Sub-TLV 💜

The VCCV Extended CV Advertisement is a TLV, and it's laid out like this 👑

    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, counting the 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. 🙈 That's a hard rule, bestie.

The CV Type field is a bitmask that lists the types of CV monitoring 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 for monitoring a point-to-point bidirectional connection, and those modes can be applied to monitoring PWs 🧚 At the same time, [RFC6310] defines how BFD-based Operations, Administration, and Maintenance (OAM) can map to the status of an Attachment Circuit. So there could be four MPLS-TP CV types, one 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 Types

2.3. MPLS-TP CC-CV Type Operation 🫧

According to [RFC6428], connectivity verification is part of the MPLS-TP CC/CV operation, and it 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 for this PW. it's optional, not a vibe check 💅

2.4. CV Type Selection 🎯

The CV selection rules defined in Section 7 of [RFC5085] and updated in Section 4 of [RFC5885] get augmented by this document ✨

If VCCV Control Channel Type 1 is chosen according to Section 7 of [RFC5085], and a common set of proactive CV types advertised by both PEs includes both 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:

0x08 - Coordinated mode for PW Fault Detection and AC/PW Fault Status Signaling
0x04 - Coordinated mode for PW Fault Detection only
0x02 - Independent mode for PW Fault Detection and AC/PW Fault Status Signaling
0x01 - Independent mode for PW Fault Detection only

the top of the list wins, so 0x08 is the main character here 🍓

3. IANA Considerations 🗂️

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

IANA has reserved a new PW Interface Parameters Sub-TLV type, and it looks like this:

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

            Table 2: New PW Interface Parameters Sub-TLV

3.1. 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 in Section 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) Types

4. Security Considerations 🔐

Routers that implement the additional CV Type defined here are subject to the same security considerations as defined in [RFC5085], [RFC5880], [RFC5881], and [RFC6428] 😭 This specification doesn't raise any additional security issues beyond those. so you're covered, but go check those other docs too, they're the real security tea ☕

5. Acknowledgements 🫶

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

6. References 📚

The reference entries pick up in part 2, starting with 6.1. Normative References and then 6.2. Informative References 🌟

6.1. Normative References 💖

okay bestie, these are the must-reads. the spec leans on every one of them, so they're the ones to have open in another tab 📚

[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.
[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 🌸

okay, this one's the extra-credit reading, not a must-read 🤓

[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.com

and that's a wrap on RFC 7189 🎀 you made it, bestie!! 🫶

📦 where this page comes from

ietf: rfc7189 2014-03
💖 girlified by claude-haiku-5-5 on 2026-10-18: a language model's rewrite of the original, under its terms