Preserving Topology Confidentiality in Inter-Domain Path Computation Using a Path-Key-Based Mechanism
RFC 5520

Network Working Group                                   R. Bradford, Ed.
Request for Comments: 5520                                   JP. Vasseur
Category: Standards Track                            Cisco Systems, Inc.
                                                               A. Farrel
                                                      Old Dog Consulting
                                                              April 2009

                Preserving Topology Confidentiality in
     Inter-Domain Path Computation Using a Path-Key-Based Mechanism

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

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   document authors.  All rights reserved.

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Abstract

   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.

Bradford, et al.            Standards Track                     [Page 1]
RFC 5520          Preserving Topology Confidentiality         April 2009

   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.

Table of contents

   1. Introduction ....................................................3
      1.1. Terminology ................................................4
   2. Path-Key Solution ...............................................5
      2.1. Mode of Operation ..........................................5
      2.2. Example ....................................................6
   3. PCEP Protocol Extensions ........................................7
      3.1. Path-Keys in PCRep Messages ................................7
           3.1.1. PKS with 32-Bit PCE ID ..............................8
           3.1.2. PKS with 128-Bit PCE ID .............................9
      3.2. Unlocking Path-Keys .......................................10
           3.2.1. Path-Key Bit .......................................10
           3.2.2. PATH-KEY Object ....................................10
           3.2.3. Path Computation Request (PCReq) Message
                  with Path-Key ......................................11
   4. PCEP Mode of Operation for Path-Key Expansion ..................12
   5. Security Considerations ........................................12
   6. Manageability Considerations ...................................13
      6.1. Control of Function through Configuration and Policy ......13
      6.2. Information and Data Models ...............................14
      6.3. Liveness Detection and Monitoring .........................15
      6.4. Verifying Correct Operation ...............................15
      6.5. Requirements on Other Protocols and Functional
           Components ................................................15
      6.6. Impact on Network Operation ...............................16
   7. IANA Considerations ............................................16
      7.1. New Subobjects for the ERO Object .........................16
      7.2. New PCEP Object ...........................................17
      7.3. New RP Object Bit Flag ....................................17