"Path Computation Element (PCE) Communication Protocol (PCEP)", Arthi Ayyangar, Eiji Oki, Alia Atlas, Andrew Dolganow, Yuichi Ikejiri, Kenji Kumaki, JP Vasseur, Jean-Louis Le Roux, 25-Mar-08. ( bytes)

This document specifies the Path Computation Element Communication Protocol (PCEP) for communications between a Path Computation Client (PCC) and a Path Computation Element (PCE), or between two PCEs. Such interactions include path computation requests and path computation replies as well as notifications of specific states related to the use of a PCE in the context of Multiprotocol Label Switching (MPLS) and Generalized (GMPLS) Traffic Engineering. PCEP is designed to be flexible and extensible so as to easily allow for the addition of further messages and objects, should further requirements be expressed in the future.

"PCC-PCE Communication and PCE Discovery Requirements for Inter-Layer Traffic Engineering", Eiji Oki, 9-Apr-08. ( bytes)

The Path Computation Element (PCE) provides functions of path computation in support of traffic engineering in Multi-Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks. MPLS and GMPLS networks may be constructed from layered client/server networks. It is advantageous for overall network efficiency to provide end-to-end traffic engineering across multiple network layers. PCE is a candidate solution for such requirements. Generic requirements for a communication protocol between Path Computation Clients (PCCs) and PCEs are presented in "PCE Communication Protocol Generic Requirements". Generic requirements for PCE discovery protocol are presented in "Requirements for Path Computation Element (PCE) Discovery". This document complements the generic requirements and presents detailed sets of PCC-PCE communication protocol requirements and PCE discovery protocol requirements for inter-layer traffic engineering.

"Framework for PCE-Based Inter-Layer MPLS and GMPLS Traffic Engineering", Eiji Oki, 21-Jan-08. ( bytes)

A network may comprise multiple layers. It is important to globally optimize network resource utilization, taking into account all layers, rather than optimizing resource utilization at each layer independently. This allows better network efficiency to be achieved through a process that we call inter-layer traffic engineering. The Path Computation Element (PCE) can be a powerful tool to achieve inter-layer traffic engineering. This document describes a framework for applying the PCE-based architecture to inter-layer Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) traffic engineering. It provides suggestions for the deployment of PCE in support of multi-layer networks. This document also describes network models where PCE performs inter-layer traffic engineering, and the relationship between PCE and a functional component called the Virtual Network Topology Manager (VNTM).

"Policy-Enabled Path Computation Framework", Igor Bryskin, Dimitri Papadimitriou, Lou Berger, Gerald Ash, 1-Nov-07. ( bytes)

The Path Computation Element (PCE) Architecture introduces the concept of policy in the context of path computation. This document provides additional details on policy within the PCE Architecture and also provides context for the support of PCE Policy. This document introduces the use of the Policy Core Information Model (PCIM) as a framework for supporting path computation policy. This document also provides representative scenarios for the support of PCE Policy.Contents

"Inter-AS Requirements for the Path Computation Element Communication Protocol (PCEP)", Nabil Bitar, Kenji Kumaki, Raymond Zhang, 7-May-08. ( bytes)

Multiprotocol Label Switching Traffic Engineered (MPLS TE) Label Switched Paths (LSPs) may be established wholly within an Autonomous System (AS) or may cross AS boundaries. The Path Computation Element (PCE) is a component that is capable of computing constrained paths for (G)MPLS TE LSPs. The PCE Communication Protocol(PCEP) is defined to allow communication between Path Computation Clients (PCCs) and PCEs, and between PCEs. The PCEP is used to request constrained paths and to supply computed paths in response. Generic requirements for the PCEP are set out in "Path Computation Element (PCE) Communication Protocol Generic Requirements", RFC 4657. This document extends those requirements to cover the use of PCEP in support of inter-AS MPLS TE.Conventions Used in This Document

"A Backward Recursive PCE-based Computation (BRPC) Procedure To Compute Shortest Constrained Inter-domain Traffic Engineering Label Switched Paths", JP Vasseur, Raymond Zhang, Nabil Bitar, Jean-Louis Roux, 14-Apr-08. ( bytes)

The ability to compute shortest constrained Traffic Engineering Label Switched Paths (TE LSPs) in Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks across multiple domains (where a domain is a collection of network elements within a common sphere of address management or path computational responsibility such as an IGP area or an Autonomous Systems) has been identified as a key requirement. This document specifies a procedure relying on the use of multiple Path Computation Elements (PCEs) to compute such inter- domain shortest constrained paths across a predetermined sequence of domains, using a backward recursive path computation technique. This technique preserves confidentiality across domains, which is sometimes required when domains are managed by different Service Providers.

"Definitions of Managed Objects for Path Computation Element Discovery", Emile Stephan, 14-Feb-08. ( bytes)

This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it describes objects used for managing Path Computation Elements Discovery.

"Inclusion of Manageability Sections in PCE Working Group Drafts", Adrian Farrel, 19-Feb-08. ( bytes)

It has often been the case that manageability considerations have been retrofitted to protocols after they have been specified, standardized, implemented, or deployed. This is sub-optimal. Similarly, new protocols or protocol extensions are frequently designed without due consideration of manageability requirements. This document specifies the recommendation for all new Internet-Drafts in the PCE Working Group to include a "Manageability Considerations" section, and gives guidance on what that section should contain.

"Extensions to the Path Computation Element Communication Protocol (PCEP) for Route Exclusions", Eiji Oki, Adrian Farrel, 25-Mar-08. ( bytes)

The Path Computation Element (PCE) provides functions of path computation in support of traffic engineering in Multi-Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks. When a Path Computation Client (PCC) requests a PCE for a route, it may be useful for the PCC to specify, as constraints to the path computation, abstract nodes, resources, and Shared Risk Link Groups (SRLGs) that are to be explicitly excluded from the computed route. Such constraints are termed route exclusions. The PCE Communication Protocol (PCEP) is designed as a communication protocol between PCCs and PCEs. This document presents PCEP extensions for route exclusions.

"Preserving Topology Confidentiality in Inter-Domain Path Computation Using a Key-Based Mechanism", Richard Bradford, JP Vasseur, 12-May-08. ( bytes)

Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering (TE) Label Switched Paths (LSPs) may be computed by Path Computation Elements (PCEs). Where the TE LSP crosses multiple domains, such as Autonomous Systems (ASes), the path may be computed by multiple PCEs that cooperate, with each responsible for computing a segment of the path. However, in some cases (e.g., when ASes are administered by separate Service Providers), it would break confidentiality rules for a PCE to supply a path segment to a PCE in another domain, thus disclosing AS-internal topology information. This issue may be circumvented by returning a loose hop and by invoking a new path computation from the domain boundary Label Switching Router (LSR) during TE LSP setup as the signaling message enters the second domain, but this technique has several issues including the problem of maintaining path diversity. This document defines a mechanism to hide the contents of a segment of a path, called the Confidential Path Segment (CPS). The CPS may be replaced by a path-key that can be conveyed in the PCE Communication Protocol (PCEP) and signaled within in a Resource Reservation Protocol TE (RSVP-TE) explicit route object.

"Path Computation Element Communication Protocol (PCECP) Requirements and Protocol Extensions In Support of Global Concurrent Optimization", Young Lee, Jean-Louis Le Roux, Daniel King, Eiji Oki, 21-Feb-08. ( bytes)

The Path Computation Element (PCE) is a network component, application, or node that is capable of performing path computations at the request of Path Computation Clients (PCCs). The PCE is applied in Multiprotocol Label Switching Traffic Engineering (MPLS-TE) networks and in Generalized MPLS (GMPLS) networks to determine the routes of Label Switched Paths (LSPs) through the network. The Path Computation Element Communication Protocol (PCEP) is specified for communications between PCCs and PCEs, and between cooperating PCEs. When computing or re-optimizing the routes of a set of LSPs through a network it may be advantageous to perform bulk path computations in order to avoid blocking problems and to achieve more optimal network- wide solutions. Such bulk optimization is termed Global Concurrent Optimization (GCO). A Global Concurrent Optimization is able to simultaneously consider the entire topology of the network and the complete set of existing LSPs, and their respective constraints, and look to optimize or re-optimize the entire network to satisfy all constraints for all LSPs. The Global Concurrent Optimization (GCO) application is primarily an NMS based solution. This document provides application-specific requirements and the PCEP extensions in support of a global concurrent optimization (GCO) application.

"Encoding of Objective Functions in Path Computation Element communication Protocol (PCEP)", Jean-Louis Le Roux, 27-Feb-08. ( bytes)

The computation of one or a series of Traffic Engineering Label Switched Paths (TE LSPs) in MultiProtocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks, is subject to a set of one or more specific optimization criteria(s), referred to as an objective function (e.g. minimum cost path, widest path, etc.). A Path Computation Element (PCE) may support one or multiple objective functions, and it is desired for a Path Computation Client (PCC) to automatically discover the set of objective functions supported by a PCE. Furthermore, it may be useful for a PCC to specify in a path computation request the required objective function to be used by the PCE to compute a TE LSP or a set of TE LSPs. Thus the aim of this document is to define extensions to the PCE communication Protocol (PCEP) in order to allow a PCC to discover the set of objective functions supported by a PCE as well as to allow a PCC to indicate in a path computation request the required objective function and a PCE to indicate in a path computation reply the objective function that was used for path computation.

"A set of monitoring tools for Path Computation Element based Architecture", JP Vasseur, Jean-Louis Le Roux, Yuichi Ikejiri, 6-Feb-08. ( bytes)

A Path Computation Element (PCE) based architecture has been specified for the computation of Traffic Engineering (TE) Label Switched Paths (LSPs) in Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks in the context of single or multiple domains (where a domain is referred to as a collection of network elements within a common sphere of address management or path computational responsibility such as IGP areas and Autonomous Systems). In PCE-based environments it is thus critical to monitor the state of the path computation chain for troubleshooting and performance monitoring purposes: liveness of each element (PCE) involved in the PCE chain, detection of potential resource contention states, statistics in term of path computation times are examples of such metrics of interest. This document specifies procedures and extensions to the Path Computation Element Protocol (PCEP) in order to gather such information.

"Extensions to the Path Computation Element communication Protocol (PCEP) for Inter-Layer MPLS and GMPLS Traffic Engineering", Eiji Oki, Jean-Louis Le Roux, Adrian Farrel, 18-Feb-08. ( bytes)

The Path Computation Element (PCE) provides path computation functions in support of traffic engineering in Multi-Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks. MPLS and GMPLS networks may be constructed from layered service networks. It is advantageous for overall network efficiency to provide end-to-end traffic engineering across multiple network layers through a process called inter-layer traffic engineering. PCE is a candidate solution for such requirements. The PCE communication Protocol (PCEP) is designed as a communication protocol between Path Computation Clients (PCCs) and PCEs. This document presents PCEP extensions for inter-layer traffic engineering. Oki, Le Roux, and Farrel [page 1] PCEP Extensions for Inter-Layer TE February 2008

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