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Carrying SID Algorithm information in PCE-based Networks.
draft-tokar-pce-sid-algo-00

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Document Type
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
Authors Zoey Rose , Siva Sivabalan , Mahendra Singh Negi
Last updated 2019-07-03
Replaced by draft-ietf-pce-sid-algo, draft-ietf-pce-sid-algo, draft-ietf-pce-sid-algo, draft-ietf-pce-sid-algo
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draft-tokar-pce-sid-algo-00
PCE Working Group                                               A. Tokar
Internet-Draft                                              S. Sivabalan
Intended status: Standards Track                     Cisco Systems, Inc.
Expires: January 1, 2020                                         M. Negi
                                                     Huawei Technologies
                                                           June 30, 2019

       Carrying SID Algorithm information in PCE-based Networks.
                      draft-tokar-pce-sid-algo-00

Abstract

   The Algorithm associated with a prefix Segment-ID (SID) defines the
   path computation Algorithm used by Interior Gateway Protocols (IGPs).
   This information is available to controllers such as the Path
   Computation Element (PCE) via topology learning.  This document
   proposes an approach for informing headend routers regarding the
   Algorithm associated with each prefix SID used in PCE-computed paths.

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 https://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."

   This Internet-Draft will expire on January 1, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (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
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  SR ERO NAI Extensions . . . . . . . . . . . . . . . . . . . .   3
   4.  Operation . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
     6.1.  PCEP SR-ERO NAI Types . . . . . . . . . . . . . . . . . .   4
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   A PCE can compute SR-TE paths using prefix SIDs with different
   Algorithms depending on the use-case, constraints, etc.  While this
   information is available on the PCE, there is no method of conveying
   this information to the headend router.

   Similarly, the headend can also compute SR-TE paths using different
   Algorithms, and this information also needs to be conveyed to the PCE
   for collection or troubleshooting purposes.  In addition, in the case
   of multiple (redundant) PCEs, when the headend receives a path from
   the primary PCE, it needs to be able to report the complete path
   information - including the Algorithm - to the backup PCE so that in
   HA scenarios, the backup PCE can verify the prefix SIDs
   appropriately.

   Refer to [I-D.ietf-ospf-segment-routing-extensions] and
   [I-D.ietf-isis-segment-routing-extensions] for details about the
   prefix SID Algorithm.

   This document introduces two new NAI types for the SR-ERO subobject,
   which is defined in [I-D.ietf-pce-segment-routing].

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2.  Terminology

   The following terminologies are used in this document:

   ERO:  Explicit Route Object

   IGP:  Interior Gateway Protocol

   NAI:  Node or Adjacency Identifier.

   PCE:  Path Computation Element

   PCEP:  Path Computation Element Protocol.

   SID:  Segment Identifier.

   SR:  Segment Routing.

   SR-TE:  Segment Routing Traffic Engineering.

3.  SR ERO NAI Extensions

   The SR-ERO subobject encoding is extended with additional NAI types.

   The following new NAI types (NT) are defined:

   o  NT=TBD1: The NAI is an IPv4 node ID with Algorithm.

   o  NT=TBD1: The NAI is an IPv6 node ID with Algorithm.

   This document defines the following NAIs:

   'IPv4 Node ID with Algorithm'  is specified as an IPv4 address and
      Algorithm identifier.  In this case, the NT value is TBD1 and the
      NAI field length is 8 octets.

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                      Node IPv4 address                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                  Reserved                     |  Algorithm    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 1: NAI for IPv4 Node SID with Algorithm

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   'IPv6 Node ID with Algorithm'  is specified as an IPv6 address and
      Algorithm identifier.  In this case, the NT value is TBD2 and the
      NAI field length is 20 octets.

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //               Node IPv6 address (16 octets)                 //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                  Reserved                     |  Algorithm    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 2: NAI for IPv6 Node SID with Algorithm

4.  Operation

   IPv4 prefix SIDs used by SR-TE paths with an associated Algorithm
   SHOULD be encoded with 'IPv4 Node ID with Algorithm' NAI.

   IPv6 prefix SIDs used by SR-TE paths with an associated Algorithm
   SHOULD be encoded with 'IPv6 Node ID with Algorithm' NAI.

5.  Security Considerations

   No additional security measure is required.

6.  IANA Considerations

6.1.  PCEP SR-ERO NAI Types

   IANA is requested to allocate new SR-ERO NAI types for the new NAI
   types specified in this document.

                Value    Description           Reference

                 TBD1    IPv4 Node ID with     This document
                         Algorithm
                 TBD2    IPv6 Node ID with     This document
                         Algorithm

7.  Normative References

   [I-D.ietf-isis-segment-routing-extensions]
              Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A.,
              Gredler, H., and B. Decraene, "IS-IS Extensions for
              Segment Routing", draft-ietf-isis-segment-routing-
              extensions-25 (work in progress), May 2019.

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   [I-D.ietf-ospf-segment-routing-extensions]
              Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
              Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
              Extensions for Segment Routing", draft-ietf-ospf-segment-
              routing-extensions-27 (work in progress), December 2018.

   [I-D.ietf-pce-segment-routing]
              Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
              and J. Hardwick, "PCEP Extensions for Segment Routing",
              draft-ietf-pce-segment-routing-16 (work in progress),
              March 2019.

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

Authors' Addresses

   Alex Tokar
   Cisco Systems, Inc.
   Eurovea Central 3.
   Pribinova 10
   Bratislava  811 09
   Slovakia

   Email: atokar@cisco.com

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

   Email: msiva@cisco.com

   Mahendra Singh Negi
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066
   India

   Email: mahendrasingh@huawei.com

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