PCE Working Group U. Palle
Internet-Draft D. Dhody
Intended status: Standards Track Huawei Technologies
Expires: August 18, 2014 Y. Tanaka
Y. Kamite
NTT Communications
February 14, 2014
PCEP Extensions for PCE-initiated Point-to-Multipoint LSP Setup in a
Stateful PCE Model
draft-palle-pce-stateful-pce-initiated-p2mp-lsp-01
Abstract
The Path Computation Element (PCE) has been identified as an
appropriate technology for the determination of the paths of point-
to-multipoint (P2MP) TE LSPs. The extensions described in
[I-D.ietf-pce-stateful-pce] provide stateful control of Multiprotocol
Label Switching (MPLS) Traffic Engineering Label Switched Paths (TE
LSP) via PCE communication Protocol (PCEP), for a model where the
Path Computation Client (PCC) delegates control over one or more
locally configured LSPs to the PCE. Further
[I-D.ietf-pce-pce-initiated-lsp] describes the creation and deletion
of PCE-initiated LSPs under the stateful PCE model. This document
provides extensions required for PCEP so as to enable the usage of a
stateful PCE initiation capability in supporting point-to-multipoint
(P2MP) TE LSP instantiation.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 18, 2014.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Architectural Overview . . . . . . . . . . . . . . . . . . . 4
3.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Operation Overview . . . . . . . . . . . . . . . . . . . 4
4. Support of PCE Initiated P2MP TE LSPs . . . . . . . . . . . . 5
5. PCE-initiated P2MP TE LSP Operations . . . . . . . . . . . . 5
5.1. The PCInitiate message . . . . . . . . . . . . . . . . . 5
5.2. P2MP TE LSP Instantiation . . . . . . . . . . . . . . . . 6
5.3. P2MP TE LSP Deletion . . . . . . . . . . . . . . . . . . 7
5.4. Adding and Pruning Leaves for the P2MP TE LSP . . . . . . 7
5.5. P2MP TE LSP Delegation and Cleanup . . . . . . . . . . . 7
6. PCIntiate Message Fragmentation . . . . . . . . . . . . . . . 7
6.1. PCIntiate Fragmentation Procedure . . . . . . . . . . . . 8
7. Non-Support of P2MP TE LSP Instantiation for Stateful PCE . . 8
8. Security Considerations . . . . . . . . . . . . . . . . . . . 8
9. Manageability Considerations . . . . . . . . . . . . . . . . 8
9.1. Control of Function and Policy . . . . . . . . . . . . . 8
9.2. Information and Data Models . . . . . . . . . . . . . . . 8
9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 8
9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 9
9.5. Requirements On Other Protocols . . . . . . . . . . . . . 9
9.6. Impact On Network Operations . . . . . . . . . . . . . . 9
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
12.1. Normative References . . . . . . . . . . . . . . . . . . 9
12.2. Informative References . . . . . . . . . . . . . . . . . 10
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1. Introduction
As per [RFC4655], the Path Computation Element (PCE) is an entity
that is capable of computing a network path or route based on a
network graph, and applying computational constraints. A Path
Computation Client (PCC) may make requests to a PCE for paths to be
computed.
[RFC4857]describes how to set up point-to-multipoint (P2MP) Traffic
Engineering Label Switched Paths (TE LSPs) for use in Multiprotocol
Label Switching (MPLS) and Generalized MPLS (GMPLS) networks. The
PCE has been identified as a suitable application for the computation
of paths for P2MP TE LSPs ( [RFC5671]).
The PCEP is designed as a communication protocol between PCCs and
PCEs for point-to-point (P2P) path computations and is defined in
[RFC5440]. The extensions of PCEP to request path computation for
P2MP TE LSPs are described in [RFC6006].
Stateful PCEs are shown to be helpful in many application scenarios,
in both MPLS and GMPLS networks, as illustrated in
[I-D.ietf-pce-stateful-pce-app]. These scenarios apply equally to
P2P and P2MP TE LSPs. [I-D.ietf-pce-stateful-pce]provides the
fundamental extensions needed for stateful PCE to support general
functionality for P2P TE LSP. Further
[I-D.palle-pce-stateful-pce-p2mp]focuses on the extensions that are
necessary in order for the deployment of stateful PCEs to support
P2MP TE LSPs. It includes mechanisms to effect P2MP LSP state
synchronization between PCCs and PCEs, delegation of control of P2MP
LSPs to PCEs, and PCE control of timing and sequence of P2MP path
computations within and across PCEP sessions and focuses on a model
where P2MP LSPs are configured on the PCC and control over them is
delegated to the PCE.
[I-D.ietf-pce-pce-initiated-lsp]provides the fundamental extensions
needed for stateful PCE-initiated P2P TE LSP instantiation.
This document describes the setup, maintenance and teardown of PCE-
initiated P2MP LSPs under the stateful PCE model, without the need
for local configuration on the PCC, thus allowing for a dynamic
network that is centrally controlled and deployed.
1.1. 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 [RFC2119].
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2. Terminology
Terminology used in this document is same as terminology used in
[I-D.ietf-pce-stateful-pce], [I-D.ietf-pce-pce-initiated-lsp]and
[RFC6006].
3. Architectural Overview
3.1. Motivation
[I-D.palle-pce-stateful-pce-p2mp] provides stateful control over P2MP
TE LSPs that are locally configured on the PCC. This model relies on
the Ingress taking an active role in delegating locally configured
P2MP TE LSPs to the PCE, and is well suited in environments where the
P2MP TE LSP placement is fairly static. However, in environments
where the P2MP TE LSP placement needs to change in response to
application demands, it is useful to support dynamic creation and
tear down of P2MP TE LSPs. The ability for a PCE to trigger the
creation of P2MP TE LSPs on demand can be seamlessly integrated into
a controller-based network architecture, where intelligence in the
controller can determine when and where to set up paths.
Section 3 of [I-D.ietf-pce-pce-initiated-lsp]further describes the
motivation behind the PCE-Initiation capability, which are equally
applicable for P2MP TE LSPs.
3.2. Operation Overview
A PCC or PCE indicates its ability to support PCE provisioned dynamic
LSPs and P2MP operations during the PCEP Initialization Phase via
mechanism described in Section 4.
As per section 5.1 of [I-D.ietf-pce-pce-initiated-lsp], the PCE sends
a Path Computation LSP Initiate Request (PCInitiate) message to the
PCC to instantiate or delete a P2P TE LSP. This document extends the
PCInitiate message to support P2MP TE LSP Instantiation (see details
in Section 5.1).
P2MP TE LSP instantiation and deletion operations are same as P2P LSP
Instantiation as described in section 5.3 and 5.4 of
[I-D.ietf-pce-pce-initiated-lsp]. This document focuses on
extensions needed for further handling of P2MP TE LSP Instantiation
(see details in Section 5.2).
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4. Support of PCE Initiated P2MP TE LSPs
As per Section 3.1 of [RFC6006], PCE advertises P2MP capability via
IGP discovery or a P2MP capable TLV in open message. To support
instantiation of PCE-initiated P2MP TE LSPs, this document extends
the advertisement of P2MP capable TLV in open message by all PCEP
speakers. As per Section 4 of [I-D.ietf-pce-pce-initiated-lsp], PCC
or PCE advertises capability for instantiation of PCE-initiated LSPs
via Stateful PCE Capability TLV (LSP-INSTANTIATION-CAPABILITY bit) in
open message. These mechanism when used together indicates the
instantiation capability for P2MP TE LSPs by the PCEP speaker.
5. PCE-initiated P2MP TE LSP Operations
5.1. The PCInitiate message
As defined in section 5.1 of [I-D.ietf-pce-pce-initiated-lsp], PCE
sends a PCInitiate message to a PCC to instantiate a P2P TE LSP, this
document extends the format of PCInitiate message for the creation of
P2MP TE LSPs but the creation and deletion operations of P2MP TE LSP
are same to the P2P TE LSP.
The format of PCInitiate message is as follows:
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<PCInitiate Message> ::= <Common Header>
<PCE-initiated-lsp-list>
Where:
<PCE-initiated-lsp-list> ::= <PCE-initiated-lsp-request>
[<PCE-initiated-lsp-list>]
<PCE-initiated-lsp-request> ::=
(<PCE-initiated-lsp-instantiation>|<PCE-initiated-lsp-deletion>)
<PCE-initiated-lsp-instantiation> ::= <SRP>
<LSP>
<end-point-path-pair-list>
[<attribute-list>]
<PCE-initiated-lsp-deletion> ::= <SRP>
<LSP>
Where:
<end-point-path-pair-list>::=
[<END-POINTS>]
<path>
[<end-point-path-pair-list>]
<path> ::= (<ERO>|<SERO>)
[<path>]
<attribute-list> is defined in [RFC5440] and extended
by PCEP extensions.
The PCInitiate message with an LSP object with N bit (P2MP) set is
used to convey operation on a P2MP TE LSP. The SRP object is used to
correlate between initiation requests sent by the PCE and the error
reports and state reports sent by the PCC as described in
[I-D.ietf-pce-stateful-pce].
5.2. P2MP TE LSP Instantiation
The Instantiation operation of P2MP TE LSP is same as defined in
section 5.3 of [I-D.ietf-pce-pce-initiated-lsp] including handling of
PLSP-ID, SYMBOLIC-PATH-NAME etc. Rules of processing and error codes
remains unchanged. Further, as defined in section 6.1 of
[I-D.palle-pce-stateful-pce-p2mp], N bit MUST be set in LSP object in
PCInitiate message by PCE to specify the instantiation is for P2MP TE
LSP and the PCC or PCE MUST follow the mechanism defined in
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[I-D.palle-pce-stateful-pce-p2mp] for delegation and updation of P2MP
TE LSPs.
Though N bit is set in the LSP object, P2MP-LSP-IDENTIFIER TLV
defined in section 6.2 of [I-D.palle-pce-stateful-pce-p2mp] MUST NOT
be included in the LSP object in PCIntiitate message as it SHOULD be
generated by PCC and carried in PCRpt message.
5.3. P2MP TE LSP Deletion
The deletion operation of P2MP TE LSP is same as defined in section
5.4 of [I-D.ietf-pce-pce-initiated-lsp] by sending an LSP Initiate
Message with an LSP object carrying the PLSP-ID of the LSP to be
removed and an SRP object with the R flag set (LSP-REMOVE as per
section 5.2 of [I-D.ietf-pce-pce-initiated-lsp]). Rules of
processing and error codes remains unchanged.
5.4. Adding and Pruning Leaves for the P2MP TE LSP
Adding of new leaves and Pruning of old Leaves for the PCE initiated
P2MP TE LSP MUST be carried in PCUpd message and SHOULD refer
[I-D.palle-pce-stateful-pce-p2mp] for P2MP TE LSP extensions. As
defined in [RFC6006], leaf type = 1 for adding of new leaves, leaf
type = 2 for pruning of old leaves of P2MP END-POINTS Object are used
in PCUpd message.
5.5. P2MP TE LSP Delegation and Cleanup
P2MP TE LSP delegation and cleanup operations are same as defined in
section 6 of [I-D.ietf-pce-pce-initiated-lsp]. Rules of processing
and error codes remains unchanged.
6. PCIntiate Message Fragmentation
The total PCEP message length, including the common header, is 16
bytes. In certain scenarios the P2MP LSP Initiate may not fit into a
single PCEP message (initial PCInitiate message). The F-bit is used
in the LSP object to signal that the initial PCInitiate was too large
to fit into a single message and will be fragmented into multiple
messages.
Fragmentation procedure described below for PCInitiate message is
similar to [RFC6006] which describes request and response message
fragmentation.
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6.1. PCIntiate Fragmentation Procedure
Once the PCE initiates to set up the P2MP TE LSP, a PCInitiate
message is sent to the PCC. If the PCInitiate is too large to fit
into a single PCInitiate message, the PCE will split the PCInitiate
over multiple messages. Each PCInitiate message sent by the PCE,
except the last one, will have the F-bit set in the LSP object to
signify that the PCInitiate has been fragmented into multiple
messages. In order to identify that a series of PCInitiate messages
represents a single Initiate, each message will use the same PLSP-ID
(in this case 0) and SRP-ID-number.
[Editor Note: P2MP message fragmentation errors associated with a
P2MP path initiation will be defined in future version].
7. Non-Support of P2MP TE LSP Instantiation for Stateful PCE
The PCEP protocol extensions described in this document for PCC or
PCE with instantiation capability for P2MP TE LSPs MUST NOT be used
if PCC or PCE has not advertised its stateful capability with
Instantiation and P2MP capability as per Section 4. If this is not
the case and Stateful operations on P2MP TE LSPs are attempted, then
a PCErr with error-type 19 (Invalid Operation) and error-value TBD
needs to be generated.
[Editor Note: more information on exact error value is needed]
8. Security Considerations
TBD
9. Manageability Considerations
9.1. Control of Function and Policy
TBD.
9.2. Information and Data Models
TBD.
9.3. Liveness Detection and Monitoring
TBD.
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9.4. Verify Correct Operations
TBD.
9.5. Requirements On Other Protocols
TBD.
9.6. Impact On Network Operations
TBD.
10. IANA Considerations
TBD
11. Acknowledgments
TBD
12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element
(PCE) Communication Protocol (PCEP)", RFC 5440, March
2009.
[I-D.ietf-pce-stateful-pce]
Crabbe, E., Medved, J., Minei, I., and R. Varga, "PCEP
Extensions for Stateful PCE", draft-ietf-pce-stateful-
pce-07 (work in progress), October 2013.
[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-00 (work in
progress), December 2013.
[I-D.palle-pce-stateful-pce-p2mp]
Palle, U. and D. Dhody, "Path Computation Element (PCE)
Protocol Extensions for Stateful PCE usage for Point-to-
Multipoint Traffic Engineering Label Switched Paths",
draft-palle-pce-stateful-pce-p2mp-01 (work in progress),
January 2014.
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12.2. Informative References
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
[RFC4857] Fogelstroem, E., Jonsson, A., and C. Perkins, "Mobile IPv4
Regional Registration", RFC 4857, June 2007.
[RFC5671] Yasukawa, S. and A. Farrel, "Applicability of the Path
Computation Element (PCE) to Point-to-Multipoint (P2MP)
MPLS and GMPLS Traffic Engineering (TE)", RFC 5671,
October 2009.
[RFC6006] Zhao, Q., King, D., Verhaeghe, F., Takeda, T., Ali, Z.,
and J. Meuric, "Extensions to the Path Computation Element
Communication Protocol (PCEP) for Point-to-Multipoint
Traffic Engineering Label Switched Paths", RFC 6006,
September 2010.
[I-D.ietf-pce-stateful-pce-app]
Zhang, X. and I. Minei, "Applicability of Stateful Path
Computation Element (PCE)", draft-ietf-pce-stateful-pce-
app-01 (work in progress), September 2013.
Authors' Addresses
Udayasree Palle
Huawei Technologies
Leela Palace
Bangalore, Karnataka 560008
INDIA
EMail: udayasree.palle@huawei.com
Dhruv Dhody
Huawei Technologies
Leela Palace
Bangalore, Karnataka 560008
INDIA
EMail: dhruv.ietf@gmail.com
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Yosuke Tanaka
NTT Communications Corporation
Granpark Tower
3-4-1 Shibaura, Minato-ku
Tokyo 108-8118
Japan
EMail: yosuke.tanaka@ntt.com
Yuji Kamite
NTT Communications Corporation
Granpark Tower
3-4-1 Shibaura, Minato-ku
Tokyo 108-8118
Japan
EMail: y.kamite@ntt.com
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