Internet DRAFT - draft-dong-pwe3-mpls-tp-li-lb
draft-dong-pwe3-mpls-tp-li-lb
Network Working Group J. Dong
Internet-Draft M. Chen
Intended status: Standards Track Huawei Technologies
Expires: October 23, 2014 G. Mirsky
Ericsson
April 21, 2014
LDP Extensions for Lock Instruct and Loopback of Pseudowire in MPLS
Transport Profile
draft-dong-pwe3-mpls-tp-li-lb-06
Abstract
This document specifies extensions to the Label Distribution Protocol
(LDP) to support the provisioning of lock instruct (LI) and loopback
(LB) mechanisms for MPLS Transport Profile (MPLS-TP) pseudowires
(PWs).
Requirements Language
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 RFC 2119 [RFC2119].
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
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This Internet-Draft will expire on October 23, 2014.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
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(http://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. LDP Extensions . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Extensions to MPLS-TP PW OAM Administration TLV . . . . . 3
2.2. Extensions to PW Status TLV . . . . . . . . . . . . . . . 3
3. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Lock Instruct . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Loopback . . . . . . . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Normative References . . . . . . . . . . . . . . . . . . 6
6.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The requirements for Lock Instruct (LI) and Loopback (LB) are
specified in [RFC5860], and the framework of LI and LB is specified
in [RFC6371]. [RFC6435] defines management plane based LI and LB
mechanisms, and LI OAM message is defined for additional lock
coordination between the Maintenance Entity Group End Points (MEPs).
Management plane based LI and LB are suitable for scenarios where
dynamic control plane is not available.
When a dynamic control plane is used for establishing MPLS-TP
pseudowires (PWs), it's natural to use and extend the control plane
protocol for the provisioning of LI and LB functions. Unlike other
OAM mechanisms, LI and LB would modify the forwarding plane of PW,
thus without the involvement of control plane this may result in
inconsistency between control plane and data plane. Besides, control
plane based mechanism does not need to rely on the TTL expiration to
make the OAM requests reach particular Maintenance Entity Group
Intermediate Point (MIP) or MEP.
There are some existing control plane based OAM provisioning
mechanisms for MPLS-TP PWs. For example,
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[I-D.ietf-pwe3-mpls-tp-oam-config] specifies the LDP extensions for
the configuration of proactive OAM functions for MPLS-TP PWs when
control plane is used.
This document defines mechanisms similar to
[I-D.ietf-pwe3-mpls-tp-oam-config] for the provisioning of LI and LB
functions for MPLS-TP PWs when MPLS-TP control plane is used. The
mechanisms defined in this document are complementary to [RFC6435].
2. LDP Extensions
2.1. Extensions to MPLS-TP PW OAM Administration TLV
Two new flags (Lock bit and Loopback bit) are defined in MPLS-TP PW
OAM Administration TLV [I-D.ietf-pwe3-mpls-tp-oam-config].
The format of the extended MPLS-TP PW OAM Administration TLV is as
below:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0| Type (TBD) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|I|A|K|B| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Lock (K): When this bit is set, it indicates that the T-PE needs to
enable "Lock" function for this PW.
Loopback (B): When this bit is set, it indicates that the target node
of this message SHOULD enable loopback function for this PW.
2.2. Extensions to PW Status TLV
Two new Status bits are defined in PW Status TLV:
Bit Mask Description
====================================================================
TBD1 Pseudowire in Lock Mode [this document]
TBD2 Pseudowire in Loopback Mode [this document]
3. Operations
The control plane based LI and LB functions are applicable to both
Single-Segment Pseudowire (SS-PW) [RFC3985] [RFC4447] and Multi-
Segment Pseudowire (MS-PW) [RFC5659] [RFC6073].
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3.1. Lock Instruct
When a PE/T-PE intends to put a PW into lock mode, it MUST send a
Mapping message with the Lock (K) bit in the MPLS-TP PW OAM
Administration TLV set.
For SS-PW, when the Mapping message arrives at the remote PE, the
receiving PE SHOULD try to take the PW out of service. If the
receiving PE locks the PW successfully, it SHOULD send a Notification
message with PW status "Pseudowire in Lock Mode". Otherwise, it
SHOULD send a Notification message with the LDP Status code set to
"PW Lock Failure".
For MS-PW, when the Mapping message arrives at a downstream S-PE, the
receiving S-PE SHOULD forward this Mapping message with the K bit
unchanged towards the remote T-PE. When the Mapping message arrives
at the remote T-PE, the receiving T-PE node SHOULD try to take the PW
out of service. If the receiving T-PE locks the PW successfully, it
SHOULD send a Notification message with PW status "Pseudowire in Lock
Mode" to the upstream S-PE. Otherwise, it SHOULD send a Notification
message with the LDP Status code set to "PW Lock Failure". On
receipt of the Notification message, the S-PEs would know whether the
MS-PW is in lock mode or not, and the S-PEs SHOULD forward the
Notification message back to the Source T-PE.
When the PE/T-PE intends to take the PW out of the lock mode, it MUST
send a Mapping message with the Lock (K) bit in the MPLS-TP PW OAM
Administration TLV cleared. The receiving PE/T-PE SHOULD try to
unlock the PW. If the PW is unlocked successfully, the receiving PE/
T-PE SHOULD send a Notification message with PW status bit
"Pseudowire in Lock Mode" cleared. Otherwise, it SHOULD send a
Notification message with the LDP Status code set to "PW Unlock
Failure".
3.2. Loopback
When a PE/T-PE intends to put the remote PE/T-PE of a PW into
loopback mode, it MUST send a Mapping message with both the Lock (K)
bit and Loopback (B) bit in the MPLS-TP PW OAM Administration TLV
set. When a T-PE intends to put a particular S-PE of the MS-PW into
loopback mode, it MUST send a Mapping message with both the Lock (K)
bit and Loopback (B) bit set, and an Explicit Route Hop TLV(ER-Hop
TLV) [I-D.ietf-pwe3-mspw-er] identifying the Target S-PE node MUST be
carried in the Mapping message. The L flag in the ER-Hop TLV SHOULD
be cleared. To ensure that the ER-Hop TLV identifies a single node
as the Target S-PE, the PreLen field in the IPv4 prefix ER-Hop TLV
SHOULD be set to 32, the PreLen field in the IPv6 prefix ER-Hop TLV
SHOULD be set to 128, and the PreLen field in the L2 PW Address ER-
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Hop TLV SHOULD be set to 96. Information of the S-PE node may be
collected using the SP-PE TLVs [RFC6073].
When the Mapping message arrives at the remote PE/T-PE, the receiving
PE SHOULD try to put the PW in loopback mode. If the receiver node
puts the PW into loopback mode successfully, it SHOULD send a
Notification message with PW status "Pseudowire in Loopback Mode".
Otherwise, it SHOULD send a Notification message with the LDP Status
code set to "PW Enter Loopback Failure".
When a Mapping message with an ER-Hop TLV arrives an S-PE, the S-PE
SHOULD check the ER-Hop TLV to see if it is the target S-PE of the
message. If not, the S-PE SHOULD forward the message with the K and
B bit unchanged to the next hop S-PE. When the Mapping message
arrives at the target S-PE, the S-PE SHOULD parse the MPLS-TP PW OAM
Administration TLV and try to put the PW into loopback mode. If the
S-PE puts the PW into loopback mode successfully, it SHOULD send a
Notification message with PW status set to "Pseudowire in Loopback
Mode". An SP-PE TLV [RFC6073] identifying the S-PE in loopback mode
SHOULD also be carried in the Notification message. If the S-PE
fails to put the PW into loopback mode, it SHOULD send a Notification
message with the LDP Status code set to "PW Enter Loopback Failure".
An SP-PE TLV identifying this S-PE SHOULD also be carried in the
Notification message.
When the PE/T-PE intends to take the remote PE/T-PE out of the
loopback mode, it MUST send a Mapping message with the Lock (K) bit
set and Loopback (B) bit cleared. When the T-PE intends to take a
particular S-PE out of loopback mode, the message MUST also carry an
ER-Hop TLV to identify the target S-PE. If the PW is taken out of
loopback mode successfully on the receiving PE/T-PE/S-PE, it SHOULD
send a Notification message with PW status bit "Pseudowire in
Loopback Mode" cleared. Otherwise, it SHOULD send a Notification
message with the LDP Status code set to "PW Exit Loopback Failure".
For the S-PE case, An SP-PE TLV identifying this S-PE node SHOULD
also be carried in the Notification message.
4. IANA Considerations
Two bits "Lock" (K) and "Loopback" (B) as defined in section 2.1 need
to be allocated in the MPLS-TP PW OAM Administration TLV.
Two new PW Status bits as defined in section 2.2 need to be allocated
by IANA in the "Pseudowire Status Codes" registry.
Four new LDP status codes need to be assigned by IANA in the LDP
"Status Code Name Space" registry:
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Range/Value E Description
TBA 0 PW Lock Failure
TBA 0 PW Unlock Failure
TBA 0 PW Enter Loopback Failure
TBA 0 PW Exit Loopback Failure
5. Security Considerations
This document introduces no new security considerations over
[RFC5036], [RFC4447] and [RFC6073].
6. References
6.1. Normative References
[I-D.ietf-pwe3-mpls-tp-oam-config]
Zhang, F., Bo, W., and E. Bellagamba, "Label Distribution
Protocol Extensions for Proactive Operations,
Administration and Maintenance Configuration of Dynamic
MPLS Transport Profile PseudoWire", draft-ietf-pwe3-mpls-
tp-oam-config-00 (work in progress), January 2012.
[I-D.ietf-pwe3-mspw-er]
Dutta, P., Bocci, M., and L. Martini, "Explicit Path
Routing for Dynamic Multi-Segment Pseudowires", draft-
ietf-pwe3-mspw-er-03 (work in progress), March 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3985] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to-
Edge (PWE3) Architecture", RFC 3985, March 2005.
[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.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007.
[RFC5659] Bocci, M. and S. Bryant, "An Architecture for Multi-
Segment Pseudowire Emulation Edge-to-Edge", RFC 5659,
October 2009.
[RFC5860] Vigoureux, M., Ward, D., and M. Betts, "Requirements for
Operations, Administration, and Maintenance (OAM) in MPLS
Transport Networks", RFC 5860, May 2010.
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[RFC6073] Martini, L., Metz, C., Nadeau, T., Bocci, M., and M.
Aissaoui, "Segmented Pseudowire", RFC 6073, January 2011.
[RFC6371] Busi, I. and D. Allan, "Operations, Administration, and
Maintenance Framework for MPLS-Based Transport Networks",
RFC 6371, September 2011.
6.2. Informative References
[RFC6435] Boutros, S., Sivabalan, S., Aggarwal, R., Vigoureux, M.,
and X. Dai, "MPLS Transport Profile Lock Instruct and
Loopback Functions", RFC 6435, November 2011.
Authors' Addresses
Jie Dong
Huawei Technologies
Huawei Campus, No.156 Beiqing Rd.
Beijing 100095
China
Email: jie.dong@huawei.com
Mach(Guoyi) Chen
Huawei Technologies
Huawei Campus, No.156 Beiqing Rd.
Beijing 100095
China
Email: mach.chen@huawei.com
Greg Mirsky
Ericsson
Email: gregory.mirsky@ericsson.com
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