Applicability of the Path Computation Element (PCE) to Point-to-Multipoint (P2MP) MPLS and GMPLS Traffic Engineering (TE)
RFC 5671
Network Working Group S. Yasukawa
Request for Comments: 5671 NTT
Category: Informational A. Farrel, Ed.
Old Dog Consulting
October 2009
Applicability of the Path Computation Element (PCE) to
Point-to-Multipoint (P2MP) MPLS and GMPLS Traffic Engineering (TE)
Abstract
The Path Computation Element (PCE) provides path computation
functions in support of traffic engineering in Multiprotocol Label
Switching (MPLS) and Generalized MPLS (GMPLS) networks.
Extensions to the MPLS and GMPLS signaling and routing protocols have
been made in support of point-to-multipoint (P2MP) Traffic Engineered
(TE) Label Switched Paths (LSPs).
This document examines the applicability of PCE to path computation
for P2MP TE LSPs in MPLS and GMPLS networks. It describes the
motivation for using a PCE to compute these paths and examines which
of the PCE architectural models are appropriate.
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) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the BSD License.
Yasukawa & Farrel Informational [Page 1]
RFC 5671 PCE for P2MP MPLS and GMPLS TE October 2009
Table of Contents
1. Introduction ....................................................2
2. Architectural Considerations ....................................4
2.1. Offline Computation ........................................4
2.2. Online Computation .........................................4
2.2.1. LSR Loading .........................................5
2.2.2. PCE Overload ........................................6
2.2.3. PCE Capabilities ....................................6
3. Fragmenting the P2MP Tree .......................................7
4. Central Replication Points ......................................8
5. Reoptimization and Modification .................................9
6. Repair .........................................................10
7. Disjoint Paths .................................................11
8. Manageability Considerations ...................................11
8.1. Control of Function and Policy ............................11
8.2. Information and Data Models ...............................11
8.3. Liveness Detection and Monitoring .........................12
8.4. Verifying Correct Operation ...............................12
8.5. Requirements on Other Protocols and Functional
Components ................................................12
8.6. Impact on Network Operation ...............................13
9. Security Considerations ........................................13
10. Acknowledgments ...............................................13
11. References ....................................................13
11.1. Normative References .....................................13
11.2. Informative References ...................................13
1. Introduction
The Path Computation Element (PCE) defined in [RFC4655] is an entity
that is capable of computing a network path or route based on a
network graph and of applying computational constraints. The
intention is that the PCE is used to compute the path of Traffic
Engineered Label Switched Paths (TE LSPs) within Multiprotocol Label
Switching (MPLS) and Generalized MPLS (GMPLS) networks.
[RFC4655] defines various deployment models that place PCEs
differently within the network. The PCEs may be collocated with the
Label Switching Routers (LSRs), may be part of the management system
that requests the LSPs to be established, or may be positioned as one
or more computation servers within the network.
Requirements for point-to-multipoint (P2MP) MPLS TE LSPs are
documented in [RFC4461], and signaling protocol extensions for
setting up P2MP MPLS TE LSPs are defined in [RFC4875]. In this
Yasukawa & Farrel Informational [Page 2]
Show full document text