PCE Working Group H. Ananthakrishnan
Internet-Draft Juniper Networks
Intended status: Standards Track S. Sivabalan
Expires: January 1, 2015 Cisco
C. Barth
R. Torvi
Juniper Networks
I. Minei
E. Crabbe
Google, Inc
June 30, 2014
PCEP Extensions for MPSL-TE LSP Path Protection with stateful PCE
draft-ananthakrishnan-pce-stateful-path-protection-00.txt
Abstract
A stateful Path Computation Element (PCE) is capable of computing as
well as controlling via Path Computation Element Protocol (PCEP)
Multiprotocol Label Switching Traffic Engineering Label Switched
Paths (MPLS LSP). Furthermore, it is also possible for a stateful
PCE to create, maintain, and delete LSPs. This document describes
PCEP extension to associate two or more LSPs to provide end-to-end
path protection.
Status of This Memo
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Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . . 4
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. State Synchronization . . . . . . . . . . . . . . . . . . 5
4.2. Error Handling . . . . . . . . . . . . . . . . . . . . . 5
5. IANA considerations . . . . . . . . . . . . . . . . . . . . . 6
5.1. Association Type . . . . . . . . . . . . . . . . . . . . 6
5.2. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Information References . . . . . . . . . . . . . . . . . 7
1. Introduction
[RFC5440] describes PCEP for communication between a Path Computation
Client (PCC) and a PCE or between one a pair of PCEs. A PCE computes
paths for MPLS-TE LSPs based on various constraints and optimization
criteria.
Stateful pce [I-D.ietf-pce-stateful-pce] specifies a set of
extensions to PCEP to enable stateful control of paths such as MPLS
TE LSPs between and across PCEP sessions in compliance with
[RFC4657]. It includes mechanisms to effect LSP state
synchronization between PCCs and PCEs, delegation of control of LSPs
to PCEs, and PCE control of timing and sequence of path computations
within and across PCEP sessions and focuses on a model where LSPs are
configured on the PCC and control over them is delegated to the PCE.
Furthermore, a mechanism to dynamically instantiate LSPs on a PCC
based on the requests from a stateful PCE or a controller using
stateful PCE is specified in [I-D.ietf-pce-pce-initiated-lsp].
Path protection refers to a paradigm in which the working LSP is
protected by one or more protection LSP(s). When the working LSP
fails, protection LSP(s) is/are activated. When the working LSPs are
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computed and controlled by the PCE, there is benefit in a mode of
operation where protection LSPs are as well.
This document specifies a stateful PCEP extension to associate two or
more LSPs for the purpose of setting up path protection. The
proposed extension covers the following scenarios:
1. A protection LSP is initiated on a PCC by a stateful PCE which
retains the control of the LSP. The PCE is responsible for
computing the path of the LSP and updating the PCC with the
information about the path.
2. A PCC initiates a protection LSP and retains the control of the
LSP. The PCC computes the path and updates the PCE with the
information about the path as long as it controls the LSP.
3. A PCC initiates a protection LSP and delegates the control of the
LSP to a stateful PCE. The PCE may compute the path for the LSP
and update the PCC with the information about the path as long as
it controls the LSP.
Note that protection LSP can be established (e.g., using RSVP-TE
signaling) prior to the failure (in which case the LSP is said to me
in standby mode) or post failure of the corresponding working LSP
according to the operator choice/policy.
2. Terminology
The following terminologies are used in this document:
AGID: Association Group ID.
ERO: Explicit Route Object.
LSP: Label Switched Path.
PCC: Path Computation Client.
PCE: Path Computation Element
PCEP: Path Computation Element Protocol.
PPAG: Path Protection Association Group.
TLV: Type, Length, and Value.
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3. PCEP Extensions
LSPs are not associated by listing the other LSPs with which they
interact, but rather by making them belong to an association group
referred to as "Path Protection Association Group" (PPAG) in this
document. All LSPs join a PPAG individually. PPAG is based on the
generic Association object used to associate two or more LSPs
specified in [I-D.minei-pce-association-group]. A member of a PPAG
can take the role of working or protection LSP. This document
defines a new association type called "Path Protection Association
Type" of value TBD. A PPAG can have one working LSP and one or more
protection LSPs. The source and destination of all LSPs within a
PPAG MUST be the same.
The format of the Association object used for PPAG is shown in
Figure 1:
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 | Generic flags |R| Type-specific flags |S|P|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Association group id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Optional TLVs //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The Association Object format
Type - TBD for the Path Protection Associaiton Type
The description of the flags are as follows:
The 'P' Flag indicates whether the LSP associated with the PPAG is
working or protection LSP. If this flag is set, the LSP is
protection LSP.
The 'S' Flag if P flag is set, S flag indicates whether the
protection LSP associated with the PPAG is in standby mode (e.g.,
signaled via RSVP-TE prior to failure). The S flag is ignored if
P flag is set to 0.
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4. Operation
A PCE can create/update working and protection LSPs independently.
However, it can add a protection LSP to a PPAG only after adding a
working LSP to that group. As specified in
[I-D.minei-pce-association-group], Association Group ID (AGID) is
allocated by PCC. In order to reserve an AGID, PCE sends an
association object with AGID of 0 either in PCInitiate message or
PCUpd message for a working LSP, with both the P and S flags set to
0. Upon receiving an association object with AGID of 0, PCC MUST
allocate a new AGID and send it the PCE via PCRpt message. Once the
PCE receives the AGID, it can either create one or more protection
LSP(s) and add it/them to the PPAG or simply add already existing
LSP(s) to the PPAG.
A PCE can remove a protection LSP from a PPAG as specified in
[I-D.minei-pce-association-group].
A PCC can associate a set of LSPs under its control for path
protection purpose. Similarly, the PCC can remove one or more LSPs
under its control from the corresponding PPAG. In both cases, the
PCC must report the change in association to PCE(s) via PCRpt
message.
The forwarding behavior after failure of the protected LSP, in
particular how and whether traffic will be load balanced among
protection pahts will be detailed in a future version of this
document.
4.1. State Synchronization
During state synchronization, a PCC MUST report all the existing path
protection association groups as well as any path protection flags to
PCE(s). Following the state synchronization, the PCE MUST remove all
stale path protection associations.
4.2. Error Handling
All LSPs (working or protection) within a PPAG MUST have the same
source and destination. If a PCE attempts to add an LSP to a PPAG
and the source and/or destination of the LSP is/are different from
the LSP(s) in the PPAG, the PCC MUST send PCErr with Error-Type= TBD
(Path Protection Association Error) and Error-Value = 1 (End points
mismatch).
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5. IANA considerations
5.1. Association Type
This document defines a new association type for path protection as
follows:
+-----------------------+--------------------------+----------------+
| Association Type | Association Name | Reference |
| Value | | |
+-----------------------+--------------------------+----------------+
| 1 | Path Protection | This |
| | Association | document |
+-----------------------+--------------------------+----------------+
5.2. PCEP Errors
This document defines new Error-Type and Error-Value related to path
protection association as follows:
+-------------+------------------------------------+
| Error-Type | Meaning |
+-------------+------------------------------------+
| 25 | Path Protection Association error: |
| | Error-value=1: End-Points mismatch |
+-------------+------------------------------------+
6. Security Considerations
The same security considerations apply in head end as described in
[I-D.ietf-pce-pce-initiated-lsp]
7. References
7.1. Normative References
[I-D.ietf-pce-pce-initiated-lsp]
Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
Extensions for PCE-initiated LSP Setup in a Stateful PCE
Model", draft-ietf-pce-pce-initiated-lsp-01 (work in
progress), June 2014.
[I-D.ietf-pce-stateful-pce]
Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
Extensions for Stateful PCE", draft-ietf-pce-stateful-
pce-09 (work in progress), June 2014.
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[I-D.minei-pce-association-group]
Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H.,
Zhang, X., and Y. Tanaka, "PCEP Extensions for
establishing relationships between sets of LSPs", draft-
minei-pce-association-group-00 (work in progress), June
2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element
(PCE) Communication Protocol (PCEP)", RFC 5440, March
2009.
7.2. Information References
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
[RFC4657] Ash, J. and J. Le Roux, "Path Computation Element (PCE)
Communication Protocol Generic Requirements", RFC 4657,
September 2006.
[RFC5394] Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash,
"Policy-Enabled Path Computation Framework", RFC 5394,
December 2008.
[RFC5557] Lee, Y., Le Roux, JL., King, D., and E. Oki, "Path
Computation Element Communication Protocol (PCEP)
Requirements and Protocol Extensions in Support of Global
Concurrent Optimization", RFC 5557, July 2009.
Authors' Addresses
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Hariharan Ananthakrishnan
Juniper Networks
1194 N Mathilda Ave,
Sunnyvale, CA, 94086
USA
EMail: hanantha@juniper.net
Siva Sivabalan
Cisco
2000 Innovation Drive
Kananta, Ontaria K2K 3E8
Cananda
EMail: msiva@cisco.com
Colby Barth
Juniper Networks
1194 N Mathilda Ave,
Sunnyvale, CA, 94086
USA
EMail: cbarth@juniper.net
Raveendra Torvi
Juniper Networks
1194 N Mathilda Ave,
Sunnyvale, CA, 94086
USA
EMail: rtorvi@juniper.net
Ina Minei
Google, Inc
1600 Amphitheatre Parkway
Mountain View, CA, 94043
USA
EMail: inaminei@google.com
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Edward Crabbe
Google, Inc
1600 Amphitheatre Parkway
Mountain View, CA, 94043
USA
EMail: edc@google.com
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