Internet DRAFT - draft-mirsky-mpls-tp-cv-adv
draft-mirsky-mpls-tp-cv-adv
Network Working Group G. Mirsky
Internet-Draft Ericsson
Intended status: Standards Track January 10, 2013
Expires: July 14, 2013
VCCV MPLS-TP Connectivity Verification (CV) Capability Advertisement
draft-mirsky-mpls-tp-cv-adv-02
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
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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 . . . . . . . . . . . . . . . . . . 8
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] is 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 Types 1
[RFC5085] or Type 4 [I-D.ietf-pwe3-vccv-for-gal]. If VCCV CC Type 1
or Type 4 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 or Type 4 is chosen according to
Section 7 [RFC5085] or Section 4 [I-D.ietf-pwe3-vccv-for-gal] 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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Parameter ID Length Description Reference
0x19 4 VCCV Extended CV parameter This document
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
[I-D.ietf-pwe3-vccv-for-gal]
Martini, L. and T. Nadeau, "A Unified Control Channel for
Pseudowires", draft-ietf-pwe3-vccv-for-gal-00 (work in
progress), January 2012.
[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.
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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.
Author's Address
Greg Mirsky
Ericsson
Email: gregory.mirsky@ericsson.com
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