draft-ietf-pce-brpc-01.txt   draft-ietf-pce-brpc-02.txt 
Networking Working Group JP. Vasseur, Ed. Networking Working Group JP. Vasseur, Ed.
Internet-Draft Cisco Systems, Inc Internet-Draft Cisco Systems, Inc
Intended status: Informational R. Zhang Intended status: Informational R. Zhang
Expires: April 21, 2007 BT Infonet Expires: June 17, 2007 BT Infonet
N. Bitar N. Bitar
Verizon Verizon
JL. Le Roux JL. Le Roux
France Telecom France Telecom
October 18, 2006 December 14, 2006
A Backward Recursive PCE-based Computation (BRPC) procedure to compute A Backward Recursive PCE-based Computation (BRPC) procedure to compute
shortest inter-domain Traffic Engineering Label Switched Paths shortest inter-domain Traffic Engineering Label Switched Paths
draft-ietf-pce-brpc-01.txt draft-ietf-pce-brpc-02.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
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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.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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This Internet-Draft will expire on April 21, 2007. This Internet-Draft will expire on June 17, 2007.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The Internet Society (2006).
Abstract Abstract
The ability to compute constrained shortest Traffic Engineering (TE) The ability to compute constrained shortest Traffic Engineering (TE)
Label Switched Paths (LSPs) in Multiprotocol Label Switching (MPLS) Label Switched Paths (LSPs) in Multiprotocol Label Switching (MPLS)
and Generalized MPLS (GMPLS) networks across multiple domains (where and Generalized MPLS (GMPLS) networks across multiple domains (where
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4.1. Domain path selection . . . . . . . . . . . . . . . . . . 6 4.1. Domain path selection . . . . . . . . . . . . . . . . . . 6
4.2. Mode of Operation . . . . . . . . . . . . . . . . . . . . 6 4.2. Mode of Operation . . . . . . . . . . . . . . . . . . . . 6
5. PCEP Protocol Extensions . . . . . . . . . . . . . . . . . . . 8 5. PCEP Protocol Extensions . . . . . . . . . . . . . . . . . . . 8
6. Inter-AS TE Links . . . . . . . . . . . . . . . . . . . . . . 9 6. Inter-AS TE Links . . . . . . . . . . . . . . . . . . . . . . 9
7. Usage in conjunction with per-domain path computation . . . . 9 7. Usage in conjunction with per-domain path computation . . . . 9
8. BRPC procedure completion failure . . . . . . . . . . . . . . 9 8. BRPC procedure completion failure . . . . . . . . . . . . . . 9
9. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 10 9. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1. Diverse end-to-end path computation . . . . . . . . . . . 10 9.1. Diverse end-to-end path computation . . . . . . . . . . . 10
9.2. Path optimality . . . . . . . . . . . . . . . . . . . . . 10 9.2. Path optimality . . . . . . . . . . . . . . . . . . . . . 10
10. Reoptimization of an inter-domain TE LSP . . . . . . . . . . . 11 10. Reoptimization of an inter-domain TE LSP . . . . . . . . . . . 11
11. Metric normalization . . . . . . . . . . . . . . . . . . . . . 11 11. Path Computation failure . . . . . . . . . . . . . . . . . . . 11
12. Manageability Considerations . . . . . . . . . . . . . . . . . 11 12. Metric normalization . . . . . . . . . . . . . . . . . . . . . 11
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 13. Manageability Considerations . . . . . . . . . . . . . . . . . 12
14. Security Considerations . . . . . . . . . . . . . . . . . . . 12 14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
15. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 14.1. New flag of the RP object . . . . . . . . . . . . . . . . 12
16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 14.2. New flag of the NO-PATH-VECTOR TLV . . . . . . . . . . . . 12
16.1. Normative References . . . . . . . . . . . . . . . . . . . 12 15. Security Considerations . . . . . . . . . . . . . . . . . . . 12
16.2. Informative References . . . . . . . . . . . . . . . . . . 12 16. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
17. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
17.1. Normative References . . . . . . . . . . . . . . . . . . . 13
17.2. Informative References . . . . . . . . . . . . . . . . . . 13
Appendix A. Proposed Status and Discussion [To Be Removed Appendix A. Proposed Status and Discussion [To Be Removed
Upon Publication] . . . . . . . . . . . . . . . . . . 13 Upon Publication] . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
Intellectual Property and Copyright Statements . . . . . . . . . . 15 Intellectual Property and Copyright Statements . . . . . . . . . . 16
1. Terminology 1. Terminology
ABR: routers used to connect two IGP areas (areas in OSPF or levels ABR: routers used to connect two IGP areas (areas in OSPF or levels
in IS-IS). in IS-IS).
ASBR: routers used to connect together ASs of a different or the same ASBR: routers used to connect together ASs of a different or the same
Service Provider via one or more Inter-AS links. Service Provider via one or more Inter-AS links.
Boundary Node (BN): a boundary node is either an ABR in the context Boundary Node (BN): a boundary node is either an ABR in the context
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10. Reoptimization of an inter-domain TE LSP 10. Reoptimization of an inter-domain TE LSP
The ability to reoptimize an existing inter-domain TE LSP path has The ability to reoptimize an existing inter-domain TE LSP path has
been explicitly listed as a requirement in [RFC4105] and [RFC4216]. been explicitly listed as a requirement in [RFC4105] and [RFC4216].
In the case of a TE LSP reoptimization request, regular procedures In the case of a TE LSP reoptimization request, regular procedures
apply as defined in PCEP where the path in use (if available on the apply as defined in PCEP where the path in use (if available on the
head-end) is provided within the path computation request in order head-end) is provided within the path computation request in order
for the PCEs involved in the reoptimization request to avoid double for the PCEs involved in the reoptimization request to avoid double
bandwidth accounting. bandwidth accounting.
11. Metric normalization 11. Path Computation failure
If a PCE requires to relay a path computation request acccording to
the BRPC procedure defined in this document to a downstream PCE that
no such PCE is available, the PCE MUST send a negative path
computation reply to the requester using a PCReq message as specified
in [I-D.ietf-pce-pcep]that contains a NO-PATH object. In such case,
the NO-PATH object MUST carry a NO-PATH-VECTOR TLV (also defined in
[I-D.ietf-pce-pcep]) with the newly defined bit named "BRPC Path
Computation chain unvailable" set.
0x04: BRPC Path computation chain unavailable
12. Metric normalization
In the case of inter-area TE, the same IGP/TE metric scheme is In the case of inter-area TE, the same IGP/TE metric scheme is
usually adopted for all the IGP areas (e.g. based on the link-speed, usually adopted for all the IGP areas (e.g. based on the link-speed,
propagation delay or some other combination of link attributes). propagation delay or some other combination of link attributes).
Hence, the proposed set of mechanisms always computes the shortest Hence, the proposed set of mechanisms always computes the shortest
path across multiple areas obeying the required set of constraints path across multiple areas obeying the required set of constraints
with respect to a well-specified objective function. Conversely, in with respect to a well-specified objective function. Conversely, in
the case of Inter-AS TE, in order for this path computation to be the case of Inter-AS TE, in order for this path computation to be
meaningful, a metric normalization between ASs may be required. One meaningful, a metric normalization between ASs may be required. One
solution to avoid IGP metric modification would be for the SPs to solution to avoid IGP metric modification would be for the SPs to
agree on a TE metric normalization scheme and use the TE metric for agree on a TE metric normalization scheme and use the TE metric for
TE LSP path computation (in that case, this must be requested in the TE LSP path computation (in that case, this must be requested in the
PCEP Path computation request) thanks to the COST object. PCEP Path computation request) thanks to the COST object.
12. Manageability Considerations 13. Manageability Considerations
To be added in a further revision of this document. To be added in a further revision of this document.
13. IANA Considerations 14. IANA Considerations
14.1. New flag of the RP object
A new flag of the RP object (specified in [I-D.ietf-pce-pcep]) is A new flag of the RP object (specified in [I-D.ietf-pce-pcep]) is
defined in this document. defined in this document.
Name: VSPT (V) Name: VSPT (V)
Value: 0x20. Value: 0x20.
When set, this indicates that the PCC requests the computation of an When set, this indicates that the PCC requests the computation of an
inter-domain TE LSP using the BRPC procedure. inter-domain TE LSP using the BRPC procedure.
A new Error-Type is defined in this document (Error-Type and Error- A new Error-Type is defined in this document (Error-Type and Error-
value to be assigned by IANA). value to be assigned by IANA).
Error-type Meaning Error-type Meaning
10 BRPC procedure completion failure 10 BRPC procedure completion failure
Error-value Error-value
1: BRPC procedure not supported by one or PCEs 1: BRPC procedure not supported by one or PCEs
along the domain path along the domain path
14. Security Considerations 14.2. New flag of the NO-PATH-VECTOR TLV
A new flag of the NO-PATH-VECTOR TLV defined in [I-D.ietf-pce-pcep])
is specified in this document.
Defining RFC: draft-ietf-pce-pcep (to be replaced by RFC number when pusblished)
Name of bit: BRPC Path computation chain unavailable
Bit number (suggested value): 0x04
15. Security Considerations
The BRPC procedure does not introduce any additional security issues The BRPC procedure does not introduce any additional security issues
beyond the ones related to inter-PCE communication. beyond the ones related to inter-PCE communication.
15. Acknowledgements 16. Acknowledgements
The authors would like to thank Arthi Ayyangar and Dimitri The authors would like to thank Arthi Ayyangar, Dimitri Papadimitriou
Papadimitriou for their useful comments. A special thank to Adrian and Siva Sivabalan for their useful comments. A special thank to
Farrel for his useful comments and suggestions. Adrian Farrel for his useful comments and suggestions.
16. References 17. References
16.1. Normative References 17.1. Normative References
[I-D.ietf-pce-pcep] [I-D.ietf-pce-pcep]
Vasseur, J., "Path Computation Element (PCE) communication Roux, J. and J. Vasseur, "Path Computation Element (PCE)
Protocol (PCEP) - Version 1", draft-ietf-pce-pcep-02 (work communication Protocol (PCEP) - Version 1",
in progress), June 2006. draft-ietf-pce-pcep-04 (work in progress), December 2006.
[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.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006. Element (PCE)-Based Architecture", RFC 4655, August 2006.
16.2. Informative References 17.2. Informative References
[I-D.bradford-pce-path-key] [I-D.bradford-pce-path-key]
Bradford, R., "Preserving Topology Confidentiality in Bradford, R., "Preserving Topology Confidentiality in
Inter-Domain Path Computation and Signaling", Inter-Domain Path Computation using a key based
draft-bradford-pce-path-key-00 (work in progress), mechanism", draft-bradford-pce-path-key-01 (work in
June 2006. progress), October 2006.
[I-D.ietf-ccamp-inter-domain-framework] [I-D.ietf-ccamp-inter-domain-framework]
Farrel, A., "A Framework for Inter-Domain Multiprotocol Farrel, A., "A Framework for Inter-Domain Multiprotocol
Label Switching Traffic Engineering", Label Switching Traffic Engineering",
draft-ietf-ccamp-inter-domain-framework-06 (work in draft-ietf-ccamp-inter-domain-framework-06 (work in
progress), August 2006. progress), August 2006.
[I-D.ietf-ccamp-inter-domain-pd-path-comp] [I-D.ietf-ccamp-inter-domain-pd-path-comp]
Vasseur, J., "A Per-domain path computation method for Vasseur, J., "A Per-domain path computation method for
establishing Inter-domain Traffic Engineering (TE) Label establishing Inter-domain Traffic Engineering (TE) Label
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