Update to Include Route Object (IRO) specification in Path Computation Element communication Protocol (PCEP)
draft-ietf-pce-iro-update-00

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PCE Working Group                                               D. Dhody
Internet-Draft                                       Huawei Technologies
Updates: 5440 (if approved)                                March 6, 2015
Intended status: Standards Track
Expires: September 7, 2015

 Update to Include Route Object (IRO) specification in Path Computation
                 Element communication Protocol (PCEP)
                      draft-ietf-pce-iro-update-00

Abstract

   During discussions of a document to provide a standard representation
   and encoding of Domain-Sequence within the Path Computation Element
   (PCE) communication Protocol (PCEP) for communications between a Path
   Computation Client (PCC) and a PCE, or between two PCEs.  It was
   determined that there was a need for clarification with respect to
   the ordered nature of the Include Route Object (IRO).

   An informal survey was conducted to determine the state of current
   and planned implementation with respect to IRO ordering and handling
   of Loose bit (L bit).

   This document updates the IRO specification based on the survey
   conclusion and recommendation.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 7, 2015.

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Copyright Notice

   Copyright (c) 2015 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
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Update in IRO specification . . . . . . . . . . . . . . . . .   3
   3.  Other Considerations  . . . . . . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Appendix A.  Details of IRO survey  . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   The Path Computation Element Communication Protocol (PCEP) provides
   mechanisms for Path Computation Elements (PCEs) to perform path
   computations in response to Path Computation Clients (PCCs) requests.

   [RFC5440] defines the Include Route Object (IRO) to specify that the
   computed path must traverse a set of specified network elements.  The
   specification did not mention if IRO is an ordered or un-ordered list
   of sub-objects.  It mentioned that the Loose bit (L bit) has no
   meaning within an IRO.

   [RFC5441] suggested the use of IRO to indicate the sequence of
   domains to be traversed during inter-domain path computation.

   During discussion of [I-D.ietf-pce-pcep-domain-sequence] it was
   proposed to have a new IRO type with ordered nature, as well as
   handling of Loose bit (L bit).

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   In order to discover the current state of affairs amongst
   implementations a survey of the existing and planned implementations
   was conducted.  This survey [I-D.dhody-pce-iro-survey] was informal
   and conducted via email.  Responses were collected and anonymized by
   the PCE working group chair.

   This document updates the IRO specifications in [RFC5440] as per the
   conclusion and action points presented in [I-D.dhody-pce-iro-survey].

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.  Update in IRO specification

   [RFC5440] describes IRO as an optional object used to specify that
   the computed path MUST traverse a set of specified network elements.
   It further state that the Loose bit (L bit) of such sub-object has no
   meaning within an IRO.  It did not mention if IRO is an ordered or
   un-ordered list of sub-objects.

   A survey of the existing and planned implementations was conducted in
   order to discover the current state of affairs amongst
   implementations.  [I-D.dhody-pce-iro-survey] describe the
   questionnaire, results and presents some conclusions and proposed
   action items.  More details in Appendix A.

   The survey suggest that most implementations construct or interpret
   IRO in an ordered fashion and consider it to be an ordered list.
   More than half of implementation under survey consider the IRO sub-
   objects as strict hops, others consider loose or support both.  The
   results shown in this survey seems to suggest that most
   implementations would be fine with updating [RFC5440] to specify IRO
   as an ordered list as well as to enable support for Loose bit (L bit)
   such that both strict and loose hops could be supported in the IRO.

   This document thus updates [RFC5440] regarding the IRO specification
   making IRO as an ordered list as well as support for Loose bit (L
   bit).

   The content of an IRO object is an ordered list of subobjects
   representing a series of abstract nodes.  An abstract node may just
   be a simple abstract node comprising one node or a group of nodes for
   example an AS (comprising of multiple hops within the AS) (refer
   [RFC3209] for details).  Further each subobject has an attribute
   called 'L bit', which is set if the subobject represents a loose hop.

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   If the bit is not set, the subobject represents a strict hop.  The
   interpretation of Loose bit (L bit) is as per section 4.3.3.1 of
   [RFC3209].

3.  Other Considerations

   Based on the survey, it should be noted that most implementation
   already support the update in the IRO specification as per this
   document.  The other implementation are expected to make an update to
   the IRO procedures.

4.  Security Considerations

   This update in IRO specification does not introduce any new security
   considerations, apart from those mentioned in [RFC5440].
   Clarification in the supported IRO ordering or Loose bit handling
   will not have any negative security impact.

   It is worth noting that PCEP operates over TCP.  An analysis of the
   security issues for routing protocols that use TCP (including PCEP)
   is provided in [RFC6952], while [I-D.ietf-pce-pceps] discusses an
   experimental approach to provide secure transport for PCEP.

5.  IANA Considerations

   This informational document makes no requests to IANA for action.

6.  Acknowledgments

   A special thanks to PCE chairs for guidance regarding this work.

   Thanks to Francesco Fondelli for his suggestions in clarifying the L
   bit usage.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5440]  Vasseur, JP. and JL. Le Roux, "Path Computation Element
              (PCE) Communication Protocol (PCEP)", RFC 5440, March
              2009.

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7.2.  Informative References

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, December 2001.

   [RFC5441]  Vasseur, JP., Zhang, R., Bitar, N., and JL. Le Roux, "A
              Backward-Recursive PCE-Based Computation (BRPC) Procedure
              to Compute Shortest Constrained Inter-Domain Traffic
              Engineering Label Switched Paths", RFC 5441, April 2009.

   [RFC6952]  Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
              BGP, LDP, PCEP, and MSDP Issues According to the Keying
              and Authentication for Routing Protocols (KARP) Design
              Guide", RFC 6952, May 2013.

   [I-D.ietf-pce-pcep-domain-sequence]
              Dhody, D., Palle, U., and R. Casellas, "Standard
              Representation of Domain-Sequence", draft-ietf-pce-pcep-
              domain-sequence-07 (work in progress), December 2014.

   [I-D.ietf-pce-pceps]
              Lopez, D., Dios, O., Wu, W., and D. Dhody, "Secure
              Transport for PCEP", draft-ietf-pce-pceps-03 (work in
              progress), March 2015.

   [I-D.dhody-pce-iro-survey]
              Dhody, D., "Informal Survey into Include Route Object
              (IRO) Implementations in Path Computation Element
              communication Protocol (PCEP)", draft-dhody-pce-iro-
              survey-02 (work in progress), December 2014.

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Appendix A.  Details of IRO survey

   During discussions of this document to provide a standard
   representation and encoding of Domain-Sequence within PCEP.  It was
   determined that there was a need for clarification with respect to
   the ordered nature of the IRO.

   Since there was a proposal to have a new IRO type with ordering, as
   well as handling of Loose bit, in an earlier version of this document
   (refer - draft-ietf-pce-pcep-domain-sequence-05), it was deemed
   necessary to conduct a survey of the existing and planned
   implementations.  An informal survey was conducted via email.
   Responses were collected and anonymized by the PCE working group
   chairs.

   [I-D.dhody-pce-iro-survey] summarizes the survey questions and
   captures the results.  It further list some conclusions and action
   points.

   This document was considered as one possible venue to handle the
   proposed action points.

Author's Address

   Dhruv Dhody
   Huawei Technologies
   Leela Palace
   Bangalore, Karnataka  560008
   India

   EMail: dhruv.ietf@gmail.com

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