Path Computation Element Communication Protocol (PCECP) Specific Requirements for Inter-Area MPLS and GMPLS Traffic Engineering
RFC 4927
Document | Type | RFC - Informational (June 2007; No errata) | |
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Author | Jean-Louis Le Roux | ||
Last updated | 2015-10-14 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4927 (Informational) | |
Action Holders |
(None)
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Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Ross Callon | ||
Send notices to | (None) |
Network Working Group J.-L. Le Roux, Ed. Request for Comments: 4927 France Telecom Category: Informational June 2007 Path Computation Element Communication Protocol (PCECP) Specific Requirements for Inter-Area MPLS and GMPLS Traffic Engineering Status of This Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract For scalability purposes, a network may comprise multiple Interior Gateway Protocol (IGP) areas. An inter-area Traffic Engineered Label Switched Path (TE-LSP) is an LSP that transits through at least two IGP areas. In a multi-area network, topology visibility remains local to a given area, and a head-end Label Switching Router (LSR) cannot compute an inter-area shortest constrained path. One key application of the Path Computation Element (PCE)-based architecture is the computation of inter-area TE-LSP paths. The PCE Communication Protocol (PCECP) is used to communicate computation requests from Path Computation Clients (PCCs) to PCEs, and to return computed paths in responses. This document lists a detailed set of PCECP-specific requirements for support of inter-area TE-LSP path computation. It complements the generic requirements for a PCE Communication Protocol. Le Roux Informational [Page 1] RFC 4927 PCECP Requirements for MPLS and GMPLS June 2007 Table of Contents 1. Introduction ....................................................2 2. Terminology .....................................................3 2.1. Conventions Used in This Document ..........................4 3. Motivations for PCE-Based Inter-Area Path Computation ...........4 4. Detailed Inter-Area Specific Requirements on PCECP ..............5 4.1. Control and Recording of Area Crossing .....................5 4.2. Area Recording .............................................6 4.3. Strict Explicit Path and Loose Path ........................6 4.4. PCE List Enforcement and Recording in Multiple-PCE Computation ................................................6 4.5. Inclusion of Area IDs in Request ...........................7 4.6. Area Inclusion/Exclusion ...................................7 4.7. Inter-Area Diverse Path Computation ........................7 4.8. Inter-Area Policies ........................................8 4.9. Loop Avoidance .............................................8 5. Manageability Considerations ....................................9 6. Security Considerations .........................................9 7. Acknowledgments .................................................9 8. References ......................................................9 8.1. Normative References .......................................9 8.2. Informative References ....................................10 9. Contributors ...................................................10 1. Introduction [RFC4105] lists a set of motivations and requirements for setting up TE-LSPs across IGP area boundaries. These LSPs are called inter-area TE-LSPs. These requirements include the computation of inter-area shortest constrained paths with a key guideline being to respect the IGP hierarchy concept, and particularly the containment of topology information. The main challenge with inter-area MPLS-TE lies in path computation. Indeed, the head-end LSR cannot compute an explicit path across areas, as its topology visibility is limited to its own area. Inter-area path computation is one of the key applications of the PCE-based architecture [RFC4655]. The computation of optimal inter- area paths may be achieved using the services of one or more PCEs. Such PCE-based inter-area path computation could rely for instance on a single multi-area PCE that has the TE database of all the areas in the IGP domain and can directly compute an end-to-end constrained shortest path. Alternatively, this could rely on the cooperation between PCEs whereby each PCE covers one or more IGP areas and the full set of PCEs covers all areas. Le Roux Informational [Page 2] RFC 4927 PCECP Requirements for MPLS and GMPLS June 2007 The generic requirements for a PCE Communication Protocol (PCECP), which allows a PCC to send path computation requests to a PCE and the PCE to send path computation responses to a PCC, are set forth in [RFC4657]. The use of a PCE-based approach for inter-area path computation implies specific requirements on a PCE CommunicationShow full document text