draft-ietf-pce-comm-protocol-gen-reqs-04.txt   draft-ietf-pce-comm-protocol-gen-reqs-05.txt 
IETF Internet Draft PCE Working Group Jerry Ash (AT&T) IETF Internet Draft PCE Working Group Jerry Ash (AT&T)
Proposed Status: Informational Editor Proposed Status: Informational Editor
Expires: August 2006 J.L. Le Roux (France Telecom) Expires: December 2006 J.L. Le Roux (France Telecom)
Editor Editor
February 2006 May 2006
draft-ietf-pce-comm-protocol-gen-reqs-04.txt draft-ietf-pce-comm-protocol-gen-reqs-05.txt
PCE Communication Protocol Generic Requirements PCE Communication Protocol Generic Requirements
Status of this Memo Status of this Memo
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have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
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This Internet-Draft will expire on August 1, 2006. This Internet-Draft will expire on December 18, 2006.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The Internet Society (2006).
Abstract Abstract
The PCE model is described in the "PCE Architecture" document and The PCE model is described in the "PCE Architecture" document and
facilitates path computation requests from Path Computation Clients facilitates path computation requests from Path Computation Clients
(PCCs) to Path Computation Elements (PCEs). This document specifies (PCCs) to Path Computation Elements (PCEs). This document specifies
generic requirements for a communication protocol between PCCs and generic requirements for a communication protocol between PCCs and
PCEs, and also between PCEs where cooperation between PCEs is PCEs, and also between PCEs where cooperation between PCEs is
desirable. Subsequent documents will specify application-specific desirable. Subsequent documents will specify application-specific
requirements for the PCE communication protocol. requirements for the PCE communication protocol.
Table of Contents Table of Contents
1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . . . 3 2. Conventions used in this document . . . . . . . . . . . . . . . . 3
3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Overview of PCE Communication Protocol (PCECP) . . . . . . . . . 3 5. Overview of PCE Communication Protocol (PCECP) . . . . . . . . . 4
6. PCE Communication Protocol Generic Requirements . . . . . . . . . 4 6. PCE Communication Protocol Generic Requirements . . . . . . . . . 5
6.1 Basic Protocol Requirements . . . . . . . . . . . . . . . . . 5 6.1 Basic Protocol Requirements . . . . . . . . . . . . . . . . . 5
6.1.1 Commonality of PCC-PCE and PCE-PCE Communication . . . 5 6.1.1 Commonality of PCC-PCE and PCE-PCE Communication . . . 5
6.1.2 Client-Server Communication . . . . . . . . . . . . . . 5 6.1.2 Client-Server Communication . . . . . . . . . . . . . . 5
6.1.3 Transport . . . . . . . . . . . . . . . . . . . . . . . 5 6.1.3 Transport . . . . . . . . . . . . . . . . . . . . . . . 5
6.1.4 Path Computation Requests . . . . . . . . . . . . . . . 6 6.1.4 Path Computation Requests . . . . . . . . . . . . . . . 6
6.1.5 Path Computation Responses . . . . . . . . . . . . . . 7 6.1.5 Path Computation Responses . . . . . . . . . . . . . . 7
6.1.6 Cancellation of Pending Requests . . . . . . . . . . . 8 6.1.6 Cancellation of Pending Requests . . . . . . . . . . . 8
6.1.7 Multiple Requests and Responses . . . . . . . . . . . . 8 6.1.7 Multiple Requests and Responses . . . . . . . . . . . . 8
6.1.8 Reliable Message Exchange . . . . . . . . . . . . . . . 8 6.1.8 Reliable Message Exchange . . . . . . . . . . . . . . . 8
6.1.9 Secure Message Exchange . . . . . . . . . . . . . . . . 9 6.1.9 Secure Message Exchange . . . . . . . . . . . . . . . . 9
6.1.10 Request Prioritization . . . . . . . . . . . . . . . . 9 6.1.10 Request Prioritization . . . . . . . . . . . . . . . . 10
6.1.11 Unsolicited Notifications . . . . . . . . . . . . . . 10 6.1.11 Unsolicited Notifications . . . . . . . . . . . . . . 10
6.1.12 Asynchronous Communication . . . . . . . . . . . . . . 10 6.1.12 Asynchronous Communication . . . . . . . . . . . . . . 10
6.1.13 Communication Overhead Minimization . . . . . . . . . 10 6.1.13 Communication Overhead Minimization . . . . . . . . . 10
6.1.14 Extensibility . . . . . . . . . . . . . . . . . . . . 10 6.1.14 Extensibility . . . . . . . . . . . . . . . . . . . . 10
6.1.15 Scalability . . . . . . . . . . . . . . . . . . . . . 11 6.1.15 Scalability . . . . . . . . . . . . . . . . . . . . . 11
6.1.16 Constraints . . . . . . . . . . . . . . . . . . . . . 11 6.1.16 Constraints . . . . . . . . . . . . . . . . . . . . . 12
6.1.17 Objective Functions Supported . . . . . . . . . . . . 12 6.1.17 Objective Functions Supported . . . . . . . . . . . . 12
6.2 Deployment Support Requirements . . . . . . . . . . . . . . . 13 6.2 Deployment Support Requirements . . . . . . . . . . . . . . . 13
6.2.1 Support for Different Service Provider Environments . . 13 6.2.1 Support for Different Service Provider Environments . . 13
6.2.2 Policy Support . . . . . . . . . . . . . . . . . . . . 13 6.2.2 Policy Support . . . . . . . . . . . . . . . . . . . . 13
6.3 Aliveness Detection & Recovery Requirements . . . . . . . . . 13 6.3 Aliveness Detection & Recovery Requirements . . . . . . . . . 13
6.3.1 Aliveness Detection . . . . . . . . . . . . . . . . . . 13 6.3.1 Aliveness Detection . . . . . . . . . . . . . . . . . . 13
6.3.2 Protocol Recovery . . . . . . . . . . . . . . . . . . . 14 6.3.2 Protocol Recovery . . . . . . . . . . . . . . . . . . . 14
6.3.3 LSP Rerouting & Reoptimization . . . . . . . . . . . . 14 6.3.3 LSP Rerouting & Reoptimization . . . . . . . . . . . . 14
6.4 Requirements Summary . . . . . . . . . . . . . . . . . . . . 14 6.4 Requirements Summary . . . . . . . . . . . . . . . . . . . . 14
7. Security Considerations . . . . . . . . . . . . . . . . . . . . . 17 7. Security Considerations . . . . . . . . . . . . . . . . . . . . . 17
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It MUST be possible for a PCC to specify, in the request message, the It MUST be possible for a PCC to specify, in the request message, the
maximum acceptable response message sizes and the maximum number of maximum acceptable response message sizes and the maximum number of
computed paths per response message it can support. computed paths per response message it can support.
It MUST be possible to limit the message size by configuration on It MUST be possible to limit the message size by configuration on
PCCs and PCEs. PCCs and PCEs.
6.1.8 Reliable Message Exchange 6.1.8 Reliable Message Exchange
The PCECP MUST include reliability. This may form part of the The PCECP MUST support reliable transmission of PCECP packets. This
protocol itself or may be achieved by the selection of a suitable may form part of the protocol itself or may be achieved by the
transport protocol (see Section 6.1.3). selection of a suitable transport protocol (see Section 6.1.3).
In particular, it MUST allow for the detection and recovery of lost In particular, it MUST allow for the detection and recovery of lost
messages to occur quickly and not impede the operation of the PCECP. messages to occur quickly and not impede the operation of the PCECP.
In some cases (e.g. after link failure), a large number of PCCs may In some cases (e.g. after link failure), a large number of PCCs may
simultaneously send requests to a PCE, leading to a potential simultaneously send requests to a PCE, leading to a potential
saturation of the PCEs. The PCECP MUST support indication of saturation of the PCEs. The PCECP MUST support indication of
congestion state and rate limitation state. This should enable, for congestion state and rate limitation state. This should enable, for
example, a PCE to limit the rate of incoming request messages if the example, a PCE to limit the rate of incoming request messages if the
request rate is too high. request rate is too high.
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failure after the PCECP communication is recovered failure after the PCECP communication is recovered
If it is necessary to add functions to PCECP to overcome shortcomings If it is necessary to add functions to PCECP to overcome shortcomings
in the chosen transport mechanisms, these functions SHOULD be based in the chosen transport mechanisms, these functions SHOULD be based
on and re-use where possible techniques developed in other protocols on and re-use where possible techniques developed in other protocols
to overcome the same shortcomings. Functionality MUST NOT be added to overcome the same shortcomings. Functionality MUST NOT be added
to the PCECP where the chosen transport protocol already provides it. to the PCECP where the chosen transport protocol already provides it.
6.1.9 Secure Message Exchange 6.1.9 Secure Message Exchange
The PCC-PCE communication protocol MUST include provisions to insure The PCC-PCE communication protocol MUST include provisions to ensure
the security of the exchanges between the entities. In particular, the security of the exchanges between the entities. In particular,
it MUST support mechanisms to prevent spoofing (e.g., it MUST support mechanisms to prevent spoofing (e.g.,
authentication), snooping (e.g., encryption) and DOS attacks (e.g., authentication), snooping (e.g., encryption) and DOS attacks (e.g.,
rate limiting, no promiscuous listening). rate limiting, no promiscuous listening).
The PCC-PCE communication protocol MUST include provisions to ensure
the security of the exchanges between the entities. In particular,
it MUST support mechanisms to prevent spoofing (e.g.,
authentication), snooping (e.g., encryption) and DOS attacks (e.g.,
packet filtering, rate limiting, no promiscuous listening). Where
the PCE-PCC communication takes place entirely within one limited
domain, the use of a private address space which is not available to
customer systems MAY be used to help protect the information
exchange, but other mechanisms MUST also be available.
This function may be provided by the transport protocol or directly This function may be provided by the transport protocol or directly
by the PCECP. by the PCECP.
See Section 7 for further discussion of security considerations. See Section 7 for further discussion of security considerations.
6.1.10 Request Prioritization 6.1.10 Request Prioritization
The PCECP MUST allow a PCC to specify the priority of a computation The PCECP MUST allow a PCC to specify the priority of a computation
request. request.
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optimization methods and parameters, etc., without requiring optimization methods and parameters, etc., without requiring
major modifications in the protocol. major modifications in the protocol.
The PCECP MUST be easily extensible to support various PCE based The PCECP MUST be easily extensible to support various PCE based
applications that have been currently identified including: applications that have been currently identified including:
- intra-area path computation [PCECP-INTER-AREA] - intra-area path computation [PCECP-INTER-AREA]
- inter-area path computation - inter-area path computation
- inter-AS intra provider and inter-AS inter-provider path - inter-AS intra provider and inter-AS inter-provider path
computation computation
- inter-layer path computation [PCECP-MULTI-LAYER] - inter-layer path computation [PCECP-INTER-LAYER]
The PCECP MUST support the requirements specified in the The PCECP MUST support the requirements specified in the
application-specific requirements documents. The PCECP MUST also application-specific requirements documents. The PCECP MUST also
allow extensions as more PCE applications will be introduced in the allow extensions as more PCE applications will be introduced in the
future. future.
The PCECP SHOULD also be extensible to support future applications The PCECP SHOULD also be extensible to support future applications
not currently in the scope of the PCE working group, such as, for not currently in the scope of the PCE working group, such as, for
instance, point-to-multipoint path computations, multi-hop pseudowire instance, point-to-multipoint path computations, multi-hop pseudowire
path computation, etc. path computation, etc.
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limitation state, and MAY allow the operator to control such a limitation state, and MAY allow the operator to control such a
function. function.
9. IANA Considerations 9. IANA Considerations
This document makes no requests for IANA action. This document makes no requests for IANA action.
10. Acknowledgements 10. Acknowledgements
The authors would like to extend their warmest thanks to (in The authors would like to extend their warmest thanks to (in
alphabetical order) Lou Berger, Adrian Farrel, Thomas Morin, Dimitri alphabetical order) Lou Berger, Ross Callon, Adrian Farrel, Thomas
Papadimitriou, and JP Vasseur for their review and suggestions. Morin, Dimitri Papadimitriou, and JP Vasseur for their review and
suggestions.
11. Normative References 11. Normative References
[PCE-ARCH] Farrel, A., Vasseur, JP, Ash, J., "Path Computation [PCE-ARCH] Farrel, A., Vasseur, JP, Ash, J., "Path Computation
Element (PCE) Architecture", work in progress. Element (PCE) Architecture", work in progress.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
12. Informational References 12. Informational References
[METRIC] Le Faucheur, F., et. al., "Use of Interior Gateway Protocol [METRIC] Le Faucheur, F., et. al., "Use of Interior Gateway Protocol
(IGP) Metric as a second MPLS Traffic Engineering (TE) Metric", BCP (IGP) Metric as a second MPLS Traffic Engineering (TE) Metric", BCP
87, RFC 3785, May 2004. 87, RFC 3785, May 2004.
[PCE-DISC-REQ] Le Roux, JL, et. al., "Requirements for Path [PCE-DISC-REQ] Le Roux, JL, et. al., "Requirements for Path
Computation Element (PCE) Discovery," work in progress. Computation Element (PCE) Discovery," work in progress.
[RFC3209] Awduche, D., et. al., "RSVP-TE: Extensions to RSVP for LSP [PCECP-INTER-AREA] Le Roux, JL, et. al., "PCE Communication Protocol
Tunnels," RFC 3209, December 2001.
[PCE-INTER-AREA] Le Roux, JL, et. al., "PCE Communication Protocol
(PCECP) specific requirements for Inter-Area (G)MPLS Traffic (PCECP) specific requirements for Inter-Area (G)MPLS Traffic
Engineering," work in progress. Engineering," work in progress.
[PCE-INTER-LAYER] Oki, E., et. al., "PCC-PCE Communication [PCECP-INTER-LAYER] Oki, E., et. al., "PCC-PCE Communication
Requirements for Inter-Layer Traffic Engineering," work in progress. Requirements for Inter-Layer Traffic Engineering," work in progress.
13. Authors' & Contributors' Addresses 13. Authors' & Contributors' Addresses
Jerry Ash (Editor) Jerry Ash (Editor)
AT&T AT&T
Room MT D5-2A01 Room MT D5-2A01
200 Laurel Avenue 200 Laurel Avenue
Middletown, NJ 07748, USA Middletown, NJ 07748, USA
Phone: (732)-420-4578 Phone: (732)-420-4578
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