An Architecture for Use of PCE and the PCE Communication Protocol (PCEP) in a Network with Central Control
RFC 8283

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Internet Engineering Task Force (IETF)                    A. Farrel, Ed.
Request for Comments: 8283                              Juniper Networks
Category: Informational                                     Q. Zhao, Ed.
ISSN: 2070-1721                                                    R. Li
                                                     Huawei Technologies
                                                                 C. Zhou
                                                           Cisco Systems
                                                           December 2017

An Architecture for Use of PCE and the PCE Communication Protocol (PCEP)
                   in a Network with Central Control

Abstract

   The Path Computation Element (PCE) is a core component of Software-
   Defined Networking (SDN) systems.  It can compute optimal paths for
   traffic across a network and can also update the paths to reflect
   changes in the network or traffic demands.

   PCE was developed to derive paths for MPLS Label Switched Paths
   (LSPs), which are supplied to the head end of the LSP using the Path
   Computation Element Communication Protocol (PCEP).

   SDN has a broader applicability than signaled MPLS traffic-engineered
   (TE) networks, and the PCE may be used to determine paths in a range
   of use cases including static LSPs, segment routing, Service Function
   Chaining (SFC), and most forms of a routed or switched network.  It
   is, therefore, reasonable to consider PCEP as a control protocol for
   use in these environments to allow the PCE to be fully enabled as a
   central controller.

   This document briefly introduces the architecture for PCE as a
   central controller, examines the motivations and applicability for
   PCEP as a control protocol in this environment, and introduces the
   implications for the protocol.  A PCE-based central controller can
   simplify the processing of a distributed control plane by blending it
   with elements of SDN and without necessarily completely replacing it.

   This document does not describe use cases in detail and does not
   define protocol extensions: that work is left for other documents.

Farrel, et al.                Informational                     [Page 1]
RFC 8283                   PCE-CC Architecture             December 2017

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8283.

Copyright Notice

   Copyright (c) 2017 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
   (https://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 Simplified BSD License.

Farrel, et al.                Informational                     [Page 2]
RFC 8283                   PCE-CC Architecture             December 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Architecture  . . . . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  Resilience and Scaling  . . . . . . . . . . . . . . . . .   8
       2.1.1.  Partitioned Network . . . . . . . . . . . . . . . . .   9
       2.1.2.  Multiple Parallel Controllers . . . . . . . . . . . .  10
       2.1.3.  Hierarchical Controllers  . . . . . . . . . . . . . .  12
   3.  Applicability . . . . . . . . . . . . . . . . . . . . . . . .  13
     3.1.  Technology-Oriented Applicability . . . . . . . . . . . .  14
       3.1.1.  Applicability to Control-Plane Operated Networks  . .  14
       3.1.2.  Static LSPs in MPLS . . . . . . . . . . . . . . . . .  14
       3.1.3.  MPLS Multicast  . . . . . . . . . . . . . . . . . . .  15
       3.1.4.  Transport SDN . . . . . . . . . . . . . . . . . . . .  15
       3.1.5.  Segment Routing . . . . . . . . . . . . . . . . . . .  15
       3.1.6.  Service Function Chaining . . . . . . . . . . . . . .  16
     3.2.  High-Level Applicability  . . . . . . . . . . . . . . . .  16