Unanswered Questions in the Path Computation Element Architecture
RFC 7399

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Internet Engineering Task Force (IETF)                         A. Farrel
Request for Comments: 7399                              Juniper Networks
Category: Informational                                          D. King
ISSN: 2070-1721                                       Old Dog Consulting
                                                            October 2014

   Unanswered Questions in the Path Computation Element Architecture

Abstract

   The Path Computation Element (PCE) architecture is set out in RFC
   4655.  The architecture is extended for multi-layer networking with
   the introduction of the Virtual Network Topology Manager (VNTM) in
   RFC 5623 and generalized to Hierarchical PCE (H-PCE) in RFC 6805.

   These three architectural views of PCE deliberately leave some key
   questions unanswered, especially with respect to the interactions
   between architectural components.  This document draws out those
   questions and discusses them in an architectural context with
   reference to other architectural components, existing protocols, and
   recent IETF efforts.

   This document does not update the architecture documents and does not
   define how protocols or components must be used.  It does, however,
   suggest how the architectural components might be combined to provide
   advanced PCE function.

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 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7399.

Farrel & King                 Informational                     [Page 1]
RFC 7399              Questions in PCE Architecture         October 2014

Copyright Notice

   Copyright (c) 2014 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 Simplified BSD License.

Farrel & King                 Informational                     [Page 2]
RFC 7399              Questions in PCE Architecture         October 2014

Table of Contents

   1. Introduction ....................................................3
      1.1. Terminology ................................................4
   2. What Is Topology Information? ...................................4
   3. How Is Topology Information Gathered? ...........................5
   4. How Do I Find My PCE? ...........................................6
   5. How Do I Select between PCEs? ...................................7
   6. How Do Redundant PCEs Synchronize TEDs? .........................8
   7. Where Is the Destination? .......................................9
   8. Who Runs or Owns a Parent PCE? .................................10
   9. How Do I Find My Parent PCE? ...................................11
   10. How Do I Find My Child PCEs? ..................................11
   11. How Is the Parent PCE Domain Topology Built? ..................12
   12. Does H-PCE Solve the Internet? ................................12
   13. What are Sticky Resources? ....................................13
   14. What Is a Stateful PCE for? ...................................14
   15. How Is the LSP-DB Built? ......................................14
   16. How Do Redundant Stateful PCEs Synchronize State? .............15
   17. What Is an Active PCE? What Is a Passive PCE? .................16
   18. What is LSP Delegation? .......................................17
   19. Is an Active PCE with LSP Delegation Just a Fancy NMS? ........18
   20. Comparison of Stateless and Stateful PCE ......................18
   21. How Does a PCE Work with a Virtual Network Topology? ..........19
   22. How Does PCE Communicate with VNTM ............................21
   23. How Does Service Scheduling and Calendering Work? .............21
   24. Where Does Policy Fit In? .....................................22
   25. Does PCE Play a Role in SDN? ..................................23
   26. Security Considerations .......................................23