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Versions: 00 draft-dhody-pce-association-policy

PCE Working Group                                           S. Sivabalan
Internet-Draft                                               C. Filsfils
Intended status: Standards Track                     Cisco Systems, Inc.
Expires: April 8, 2016                                       J. Tantsura
                                                                Ericsson
                                                             J. Hardwick
                                                     Metaswitch Networks
                                                         October 6, 2015


 Conveying policies associated with traffic engineering paths over PCEP
                                session
              draft-sivabalan-pce-policy-identifier-00.txt

Abstract

   This document describes a simple extension to the Path Computation
   Element (PCE) Communication Protocol (PCEP) using which a PCEP
   speaker can enforce one or more policies on the other PCEP speaker.
   A policy is represented by a numeric value which can be interpreted
   only by the receiving PCEP speaker.  Using the proposed extension, a
   path computation client (PCC) can signal one or more policies that
   must be taken into consideration by a PCE during path computation.
   Similarly, when initiating or updating a path, a stateful PCE can
   signal one or more policies (e.g., traffic steering rules) that a PCC
   is expected to apply to the path.

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].

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."




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   This Internet-Draft will expire on April 8, 2016.

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
   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Motivation  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Policy Identifier TLV . . . . . . . . . . . . . . . . . . . .   4
   5.  Operation . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   [RFC5440] describes the Path Computation Element Protocol (PCEP) for
   communication between a Path Computation Client (PCC) and a PCE or
   between a pair of PCEs.  [I-D.ietf-pce-stateful-pce] specifies
   extension to PCEP that allows a PCC to delegate its LSPs to a PCE.
   The PCE can then update the state of LSPs delegated to it.
   [I-D.ietf-pce-pce-initiated-lsp] specifies a mechanism allowing a PCE
   to dynamically instantiate, maintain, and tear down Label Switched
   Paths (LSPs) without the need for configuring those LSPs on the PCC.
   Currently, the LSPs can either be signaled via RSVP-TE or can be
   segment routed as specified in [I-D.ietf-pce-segment-routing].

   As described in the next section, a PCEP speaker may want to
   influence its PCEP counterpart with respect to path selection and
   other policies.  This document describes a PCEP extension to signal
   policy identifier represented by numeric value using OPTIONAL PCEP




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   TLV.  The specification is applicable to both stateful and stateless
   PCEP sessions.

2.  Motivation

   Paths computed using PCEP are subject to various policies on both PCE
   as well as PCC.  For example, in a centralized traffic engineering
   scenario, network operators may instantiate LSPs and specifies
   policies for traffic steering, path monitoring, etc., for those LSPs
   via stateful PCE.  Similarly, a PCC can request a path that is
   diverse from any other path originating from other PCC(s) from a
   stateful PCE.  With a current state of PCEP, introducing such policy
   requires new PCEP extension.  A generic mechanism that allows a PCEP
   speaker to specify the path policies without the need to know the
   details of such policies simplifies network operations, avoids
   frequent software upgrades, as well provides an ability to introduce
   new policy faster.


                                                         Policy-ID Y
          Initiate & Monitor LSP                       {Disjoint paths}
                   |                                          |
                   |                          PCReq           |
                   V                       {policy-ID Y}      V
                +-----+                   ----------------> +-----+
     _ _ _ _ _ _| PCE |                  |                  | PCE |
    |           +-----+                  |      ----------> +-----+
    | PCEInitiate                        |     |    PCReq
    |{policy-ID X}                       |     | {policy-ID Y}
    |                                    |     |
    |              .-----.               |     |         .-----.
    |             (       )              |  +----+      (       )
    |         .--(         )--.          |  |PCC1|--.--(         )--.
    V        (                 )         |  +----+ (                 )
  +---+     (                   )        |        (                   )
  |PCC|----(    MPLS network     )    +----+     (    MPLS network     )
  +---+     (                   )     |PCC2|------(                   )
Policy ID X  (                 )      +----+       (                 )
{Monitor LSP} '--(         )--'                     '--(         )--'
                  (       )                             (       )
                   '-----'                               '-----'

  Case 1: Policy initiated by PCE        Case 2: Policy initiated by PCC
          and enforced by PCC                    and enforced by PCE


    Figure 1: Sample use-cases for carrying policies over PCEP session




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3.  Terminology

   The following terminologies are used in this document:

   LSP:  Label Switched Path.

   PCC:  Path Computation Client.

   PCE:  Path Computation Element

   PCEP:  Path Computation Element Protocol.

   TLV:  Type, Length, and Value.

4.  Policy Identifier TLV

   The new optional TLV is called "POLICY-ID-TLV" whose format is shown
   in the diagram below is defined to indicate the policies applied to a
   path.  This TLV is associated with the RP or SRP objects specified
   in[RFC5440] and [I-D.ietf-pce-stateful-pce] respectively.  The type
   of this TLV is to be allocated by IANA.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Type (TBD)           |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Flags    |M|             Policy ID                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                   VENDOR-INFORMATION-TLV (optional)           ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 2: Format of POLICY-ID-TLV

   The TLV is formatted according to the rules specified in [RFC5440].
   The body of the POLICY-ID-TLV contains one 1-Octet flags and 3-Octet
   policy identifier.  By default, a policy is OPTIONAL.  If the M-flag
   is set, the policy is considered MANDATORY.  This TLV can optionally
   carry vendor-specific information via VENDOR-INFORMATION-TLV whose
   format and processing rules are specified in [RFC7470].  The presence
   of VENDOR-INFORMATION-TLV is detected based on the TLV length, and
   the content and processing rule of vendor-specific information is
   outside the scope of this specification.








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5.  Operation

   A single message MAY contain more than one POLICY-ID-TLVs.  In case,
   a a speaker receives a message containing multiple POLICY-ID-TLVs
   with the same policy ID, it MUST ignore all except for the first one
   itencounters in the message.  If a PCEP speaker does not recognize
   the TLV, it MUST ignore the TLV in accordance with ([RFC5440]).  If a
   PCEP speaker recognizes the TLV but does not support a mandatory
   policy included in the message, it MUST ignore the whole message and
   send PCErr with Error-Type = 2 (Capability not supported) as well
   include the POLICY-ID-TLV corresponding to the unsupported policies.

   When requesting a path from a PCE using a PCReq message ([RFC5440]),
   a PCC MAY include the POLICY-ID-TLV in the RP object.  The PCE MUST
   take into account all the policies included in the PCReq otherwise it
   MUST ignore the whole message and send PCErr message as mentioned
   above.

   In the case of stateful PCE, POLICY-ID-TLV MAY be included in PCReq,
   PCRpt, PCUpd, and PCInitiate messages as well.  When including
   POLICY-ID-TLV in PCRpt message, the SRP object MUST be present even
   in cases when the SRP-ID-number is the reserved value of 0x00000000.

6.  Security Considerations

   No additional security measure is required.

7.  IANA Considerations

   IANA is requested to allocate a new code point in the PCEP TLV Type
   Indicators registry, as follows:

                Value    Description           Reference

                 TBD     POLICY-ID-TLV         This document

8.  Acknowledgements

9.  Normative References

   [I-D.ietf-pce-pce-initiated-lsp]
              Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
              Extensions for PCE-initiated LSP Setup in a Stateful PCE
              Model", draft-ietf-pce-pce-initiated-lsp-04 (work in
              progress), April 2015.






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   [I-D.ietf-pce-segment-routing]
              Sivabalan, S., Medved, J., Filsfils, C., Crabbe, E.,
              Lopez, V., Tantsura, J., Henderickx, W., and J. Hardwick,
              "PCEP Extensions for Segment Routing", draft-ietf-pce-
              segment-routing-06 (work in progress), August 2015.

   [I-D.ietf-pce-stateful-pce]
              Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
              Extensions for Stateful PCE", draft-ietf-pce-stateful-
              pce-11 (work in progress), April 2015.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC4206]  Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP)
              Hierarchy with Generalized Multi-Protocol Label Switching
              (GMPLS) Traffic Engineering (TE)", RFC 4206,
              DOI 10.17487/RFC4206, October 2005,
              <http://www.rfc-editor.org/info/rfc4206>.

   [RFC5440]  Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
              Element (PCE) Communication Protocol (PCEP)", RFC 5440,
              DOI 10.17487/RFC5440, March 2009,
              <http://www.rfc-editor.org/info/rfc5440>.

   [RFC5462]  Andersson, L. and R. Asati, "Multiprotocol Label Switching
              (MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic
              Class" Field", RFC 5462, DOI 10.17487/RFC5462, February
              2009, <http://www.rfc-editor.org/info/rfc5462>.

   [RFC7470]  Zhang, F. and A. Farrel, "Conveying Vendor-Specific
              Constraints in the Path Computation Element Communication
              Protocol", RFC 7470, DOI 10.17487/RFC7470, March 2015,
              <http://www.rfc-editor.org/info/rfc7470>.

Authors' Addresses

   Siva Sivabalan
   Cisco Systems, Inc.
   2000 Innovation Drive
   Kanata, Ontario  K2K 3E8
   Canada

   Email: msiva@cisco.com





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   Clarence Filsfils
   Cisco Systems, Inc.
   Pegasus Parc
   De kleetlaan 6a, DIEGEM  BRABANT 1831
   BELGIUM

   Email: cfilsfil@cisco.com


   Jeff Tantsura
   Ericsson
   300 Holger Way
   San Jose, CA  95134
   USA

   Email: jeff.tantsura@ericsson.com


   Jonathan Hardwick
   Metaswitch Networks
   100 Church Street
   Enfield, Middlesex
   UK

   Email: Jonathan.Hardwick@metaswitch.com


























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