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PCE Working Group                                               D. Dhody
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                      September 18, 2017
Expires: March 22, 2018

 Conveying Vendor-Specific Information in the Path Computation Element
    (PCE) Communication Protocol (PCEP) extensions for stateful PCE.


   A Stateful Path Computation Element (PCE) maintains information on
   the current network state, including: computed Label Switched Path
   (LSPs), reserved resources within the network, and pending path
   computation requests.  This information may then be considered when
   computing new traffic engineered LSPs, and for associated and
   dependent LSPs, received from Path Computation Clients (PCCs).

   RFC 7470 defines a facility to carry vendor-specific information in

   This document extends this capability for stateful PCE.

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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on March 22, 2018.

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

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   (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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Procedures for the Vendor Information Object  . . . . . . . .   3
   3.  Procedures for the Vendor Information TLV . . . . . . . . . .   5
   4.  Vendor Information Object and TLV . . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   The Path Computation Element communication Protocol (PCEP) [RFC5440]
   provides mechanisms for Path Computation Elements (PCEs) to perform
   path computations in response to Path Computation Clients' (PCCs)

   A stateful PCE is capable of considering, for the purposes of path
   computation, not only the network state in terms of links and nodes
   (referred to as the Traffic Engineering Database or TED) but also the
   status of active services (previously computed paths, and currently
   reserved resources, stored in the Label Switched Paths Database
   (LSPDB).  [RFC8051] describes general considerations for a stateful
   PCE deployment and examines its applicability and benefits, as well
   as its challenges and limitations through a number of use cases.

   [I-D.ietf-pce-stateful-pce] describes a set of extensions to PCEP to
   provide stateful control.  A stateful PCE has access to not only the
   information carried by the network's Interior Gateway Protocol (IGP),
   but also the set of active paths and their reserved resources for its
   computations.  The additional state allows the PCE to compute
   constrained paths while considering individual LSPs and their
   interactions.  [I-D.ietf-pce-pce-initiated-lsp] describes the setup,
   maintenance and teardown of PCE-initiated LSPs under the stateful PCE
   model.  These extensions added new messages in PCEP.

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   [RFC7470] defined Vendor Information object that can be used to carry
   arbitrary, proprietary information such as vendor-specific
   constraints.  It also defined VENDOR-INFORMATION-TLV that can be used
   to carry arbitrary information within any existing or future PCEP
   object that supports TLVs.

   This document extend the usage of Vendor Information Object and
   can be carried inside any of the new objects added in PCEP for
   stateful PCE as per [RFC7470], this document extend the PCEP messages
   to also include the Vendor Information Object too.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Procedures for the Vendor Information Object

   A Path Computation LSP State Report message
   [I-D.ietf-pce-stateful-pce] (also referred to as PCRpt message) is a
   PCEP message sent by a PCC to a PCE to report the current state of an
   LSP.  A PCC that wants to convey proprietary or vendor-specific
   information or metrics to a PCE does so by including a Vendor
   Information object in the PCRpt message.  The contents and format of
   the object are described in Section 4 of [RFC7470].  The PCE
   determines how to interpret the information in the Vendor Information
   object by examining the Enterprise Number it contains.

   The Vendor Information object is OPTIONAL in a PCRpt message.
   Multiple instances of the object MAY be used on a single PCRpt
   message.  Different instances of the object can have different
   Enterprise Numbers.

   The format of the PCRpt message (with [I-D.ietf-pce-stateful-pce] as
   base) is updated as follows

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         <PCRpt Message> ::= <Common Header>

         <state-report-list> ::= <state-report>[<state-report-list>]

         <state-report> ::= [<SRP>]
         <vendor-info-list> ::= <VENDOR-INFORMATION>
         <path> is defined in [I-D.ietf-pce-stateful-pce].

   A Path Computation LSP Update Request message (also referred to as
   PCUpd message) is a PCEP message sent by a PCE to a PCC to update
   attributes of an LSP.  The Vendor Information object can be included
   in a PCUpd message to convey proprietary or vendor-specific

   The format of the PCUpd message (with [I-D.ietf-pce-stateful-pce] as
   base) is updated as follows

         <PCUpd Message> ::= <Common Header>

         <update-request-list> ::= <update-request>

         <update-request> ::= <SRP>
         <vendor-info-list> ::= <VENDOR-INFORMATION>
         <path> is defined in [I-D.ietf-pce-stateful-pce].

   A Path Computation LSP Initiate Message (also referred to as
   PCInitiate message) is a PCEP message sent by a PCE to a PCC to
   trigger LSP instantiation or deletion.  The Vendor Information object
   can be included in a PCInitiate message to convey proprietary or
   vendor-specific information.

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   The format of the PCInitiate message (with
   [I-D.ietf-pce-pce-initiated-lsp] as base) is updated as follows

        <PCInitiate Message> ::= <Common Header>

        <PCE-initiated-lsp-list> ::= <PCE-initiated-lsp-request>

        <PCE-initiated-lsp-request> ::=

        <PCE-initiated-lsp-instantiation> ::= <SRP>


        <vendor-info-list> ::= <VENDOR-INFORMATION>

      <PCE-initiated-lsp-deletion> and <attribute-list> is as per

   A legacy implementation that does not recognize the Vendor
   Information object will act according to the procedures set out in
   [I-D.ietf-pce-stateful-pce] and [I-D.ietf-pce-pce-initiated-lsp].  An
   implementation that supports the Vendor Information object, but
   receives one carrying an Enterprise Number that it does not support,
   SHOULD ignore the object as per [RFC7470].

3.  Procedures for the Vendor Information TLV

   The Vendor Information TLV can be used to carry vendor-specific
   information that applies to a specific PCEP object by including the
   TLV in the object.  This includes objects used in stateful PCE
   extension such as SRP and LSP object.  All the procedures as per
   section 3 of [RFC7470].

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4.  Vendor Information Object and TLV

   [RFC7470] specify the format of VENDOR-INFORMATION Object and VENDOR-

5.  IANA Considerations

   There are no IANA consideration.

6.  Security Considerations

   The protocol extensions defined in this document do not change the
   nature of PCEP.  Therefore, the security considerations set out in
   [RFC5440], [RFC7470], [I-D.ietf-pce-stateful-pce] and
   [I-D.ietf-pce-pce-initiated-lsp] apply unchanged.  Note that further
   security considerations for the use of PCEP over TCP are presented in

7.  Acknowledgments

   Thanks to Avantika, Mahendra Singh Negi, Udayasree Palle and Swapna K
   for their suggestions.

8.  References

8.1.  Normative References

              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-10 (work in
              progress), June 2017.

              Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
              Extensions for Stateful PCE", draft-ietf-pce-stateful-
              pce-21 (work in progress), June 2017.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC5440]  Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
              Element (PCE) Communication Protocol (PCEP)", RFC 5440,
              DOI 10.17487/RFC5440, March 2009,

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   [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,

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

8.2.  Informative References

   [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, DOI 10.17487/RFC6952, May 2013,

   [RFC8051]  Zhang, X., Ed. and I. Minei, Ed., "Applicability of a
              Stateful Path Computation Element (PCE)", RFC 8051,
              DOI 10.17487/RFC8051, January 2017,

Author's Address

   Dhruv Dhody
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066

   Email: dhruv.ietf@gmail.com

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