Path Computation Element (pce) ------------------------------ Charter Last Modified: 2007-05-09 Current Status: Active Working Group Chair(s): JP Vasseur Adrian Farrel Routing Area Director(s): Ross Callon David Ward Routing Area Advisor: Ross Callon Mailing Lists: General Discussion:pce@ietf.org To Subscribe: pce-request@ietf.org In Body: subscribe pce Archive: http://www.ietf.org/mail-archive/web/pce/ Description of Working Group: The PCE Working Group is chartered to specify a Path Computation Element (PCE) based architecture for the computation of paths for MPLS and GMPLS Traffic Engineering LSPs. In this architecture path computation does not occur on the head-end (ingress) LSR, but on some other path computation entity that may physically not be located on the head-end LSR. The PCE WG will work on application of this model within a single domain or within a small group of domains (where a domain is a layer, IGP area or Autonomous System with limited visibility from the head-end LSR). At this time, applying this model to large groups of domains such as the Internet is not thought to be possible, and the PCE WG will not spend energy on that topic. The WG will specify a protocol for communication between LSRs (termed Path Computation Clients - PCCs) and PCEs, and between cooperating PCEs. This protocol will be capable of representing requests for path computation including a full set of constraints, will be able to return multiple paths, and will include security mechanisms such as authentication and confidentiality. The WG will determine requirements for extensions to existing routing and signaling protocols in support of PCE discovery and signaling of inter-domain paths. Candidate protocols for extensions are RSVP-TE, OSPF-TE, ISIS-TE and BGP. Any necessary extensions will be produced in collaboration with the Working Groups responsible for the protocols. The Working Group will also work on the definition of metrics to evaluate path quality, scalability, responsiveness and robustness of path computation models. Work Items: - Functional specification of MPLS and GMPLS Traffic Engineered LSP path computation models involving Path Computation Element(s). This includes the case of computing the paths of intra and inter-domain TE LSPs. Such path computation includes the generation of primary, protection and recovery paths, as well as computations for (local/global) reoptimization and load balancing. The WG will address the inter-area (single IGP domain) scenario first. WG progress will be evaluated before inter-AS related work is started. - Specification of the PCE-based architecture. - Specification of requirements and protocol extensions related to the policy, and security aspects of PCE-based path computation involving PCEs of multiple administrative entities. - In cooperation with protocol specific Working Group (OSPF, ISIS, IDR, MPLS, CCAMP), development of routing (OSPF, ISIS, BGP) and LSP signaling (RSVP-TE) extensions required to support PCE-based path computation models. - Specification of techniques in support of PCE discovery within and across domains. Where such techniques result in the extensions of existing protocols (e.g., OSPF, ISIS or BGP), this work will be done in conjunction with the appropriate WGs. - Specification of a new communication protocol for use between a PCC and a PCE, and between PCEs. A single protocol will be selected from among candidates that include the existing protocols defined in other WGs. - Definition of objective metrics to evaluate various criteria such as the measurement of path quality, response time, robustness and scalability of path computation models. Review of the document "Requirements for path computation element in GMPLS inter-domain networks" produced by the CCAMP WG. Goals and Milestones: Done Submit first draft of PCE architecture document Done Submit first draft of PCE discovery requirements and protocol extensions documents Done Submit first draft of the PCE communication protocol requirements May 2005 Submit first draft of the definition of objective metrics Done Submit first draft of the PCE communication protocol specification Done Submit PCE architecture specification to the IESG to be considered as Informational RFC Nov 2005 Submit first draft of applicability statement (describing the processes and procedures for the use of the PCE architecture, protocols and protocol extensions for inter-area MPLS and GMPLS Traffic Engineering) Done Submit first draft of the MIB module for the PCE protocol Done Submit PCE communication protocol requirements to the IESG to be considered as an Informational RFC Done Submit PCE discovery protocol extensions specifications to the IESG to be considered as a Proposed Standard Dec 2005 Submit PCE communication protocol specification to the IESG to be considered as a Proposed Standard Feb 2006 Submit the applicability and metrics documents to the considered as Informational RFCIESG to be Feb 2006 Evaluate WG progress, recharter or close Internet-Drafts: Posted Revised I-D Title ------ ------- -------------------------------------------- Nov 2005 Jul 2007 Path Computation Element (PCE) communication Protocol (PCEP) Nov 2005 Jul 2007 PCC-PCE Communication and PCE Discovery Requirements for Inter-Layer Traffic Engineering Apr 2006 Jul 2007 Framework for PCE-Based Inter-Layer MPLS and GMPLS Traffic Engineering Aug 2006 Jul 2007 Policy-Enabled Path Computation Framework Aug 2006 Jul 2007 Inter-AS Requirements for the Path Computation Element Communication Protocol (PCECP) Aug 2006 Sep 2007 A Backward Recursive PCE-based Computation (BRPC) procedure to compute shortest inter-domain Traffic Engineering Label Switched Paths Sep 2006 Sep 2007 OSPF protocol extensions for Path Computation Element (PCE) Discovery Sep 2006 Sep 2007 IS-IS protocol extensions for Path Computation Element (PCE) Discovery Jan 2007 Aug 2007 Inclusion of Manageability Sections in PCE Working Group Drafts Apr 2007 Sep 2007 Extensions to the Path Computation Element Communication Protocol (PCEP) for Route Exclusions May 2007 Sep 2007 Preserving Topology Confidentiality in Inter-Domain Path Computation Using a Key-Based Mechanism Jun 2007 Jun 2007 Path Computation Element Communication Protocol (PCECP) Requirements and Protocol Extensions In Support of Global Concurrent Optimization Sep 2007 Sep 2007 Encoding of Objective Functions in Path Computation Element (PCE) communication and discovery protocols Request For Comments: RFC Stat Published Title ------- -- ----------- ------------------------------------ RFC4655 I Aug 2006 A Path Computation Element (PCE) Based Architecture RFC4657 I Sep 2006 Path Computation Element (PCE) Communication Protocol Generic Requirements RFC4674 I Oct 2006 Requirements for Path Computation Element (PCE) Discovery RFC4927 I Jun 2007 PCE Communication Protocol (PCECP) Specific Requirements for Inter-Area Multi Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering