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Versions: (draft-xu-isis-service-sid-adv) 00 01 02 03 04 05

ISIS Working Group                                                 X. Xu
Internet-Draft                                                     N. Wu
Intended status: Standards Track                                  Huawei
Expires: November 11, 2017                                       H. Shah
                                                                   Ciena
                                                            L. Contreras
                                                          Telefonica I+D
                                                            May 10, 2017


               Advertising Service Functions Using IS-IS
                 draft-xu-isis-service-function-adv-05

Abstract

   The MPLS source routing mechanism developed by Source Packet Routing
   in Networking (SPRING) WG can be leveraged to realize a unified
   source routing instruction which works across both IPv4 and IPv6
   underlays in addition to the MPLS underlay.  The unified source
   routing instruction can be used to realize a transport-independent
   service function chaining by encoding the service function path
   information or service function chain information as an MPLS label
   stack.  This document describes how to advertise service functions
   and their corresponding attributes (e.g., service function label)
   using IS-IS.

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 RFC 2119 [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."

   This Internet-Draft will expire on November 11, 2017.



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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
   (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.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Solution Description  . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Service Function Sub-TLV  . . . . . . . . . . . . . . . .   3
     3.2.  SF Label Sub-TLV  . . . . . . . . . . . . . . . . . . . .   4
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   [I-D.xu-mpls-service-chaining] describes how to leverage the unified
   source routing instruction
   [I-D.xu-mpls-unified-source-routing-instruction] to realize a
   transport-independent service function chaining by encoding the
   Service Function Path (SFP) or Service Function Chain (SFC)
   information as an MPLS label stack.  To allow a service classifier to
   attach the MPLS label stack which represents a particular SFP or SFC
   to the selected traffic, the service classifier needs to know on
   which Service Function Forwarder (SFF) a given Service Function (SF)
   is located and what service function label is used to indicate that
   SF.  This document describes how to advertise SFs and their
   corresponding attributes (e.g., service function label) using IS-IS.







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2.  Terminology

   This memo makes use of the terms defined in
   [I-D.xu-mpls-service-chaining] and [RFC4971].

3.  Solution Description

   SFFs within the SFC domain need to advertise each SF they are
   offering by using a new sub-TLV of the IS-IS Router CAPABILITY TLV
   [RFC4971].  This new sub-TLV is called as Service Function sub-TLV.
   The Service Function sub-TLV could appear multiple times wihin a
   given IS-IS Router CAPABILITY TLV when more than one SF needs to be
   advertised.  The scope of the advertisement depends on the
   application but it is recommended that it SHOULD be domain-wide.  To
   support the approach of encoding SFP information in the form of an
   MPLS label stack as described in [I-D.xu-mpls-service-chaining], SFFs
   SHOULD allocate a locally significant MPLS label to each SF they are
   offering.  Therefore, SFFs need to advertise the corresponding
   service function label to each SF they are offering by using a sub-
   TLV of the above Service Function sub-TLV, called SF Label sub-TLV.

3.1.  Service Function Sub-TLV

        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=TBD1   |    Length     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                  Service Function Identifier                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       ~                          Sub-TLVs                             ~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type: TBD1.

      Length: variable.

      Service Function Identifier: A unique identifier that represents
      an SF within an SFC-enabled domain.

      Sub-TLVs: contains zero or more sub-TLVs corresponding to the
      particular attributes of a given SF.  The SF Label sub-TLV as
      defined in Section 3.2 is one such sub-TLV.  Other sub-TLVs are to
      be defined in the future.







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3.2.  SF Label Sub-TLV

         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=TBD2   |    Length     |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |  Resv |                  SF Label             |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type: TBD2.

      Length: 3.

      Value: The rightmost 20 bits represent an MPLS label which is the
      SF Label of the corresponding SF.

4.  Acknowledgements

   TBD.

5.  IANA Considerations

   This document includes a request to IANA for allocating type codes
   for the Service Function sub-TLV and the SF Label sub-TLV.

6.  Security Considerations

   This document does not introduce any new security risk.

7.  References

7.1.  Normative References

   [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>.

   [RFC4971]  Vasseur, JP., Ed., Shen, N., Ed., and R. Aggarwal, Ed.,
              "Intermediate System to Intermediate System (IS-IS)
              Extensions for Advertising Router Information", RFC 4971,
              DOI 10.17487/RFC4971, July 2007,
              <http://www.rfc-editor.org/info/rfc4971>.







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7.2.  Informative References

   [I-D.ietf-sfc-architecture]
              Halpern, J. and C. Pignataro, "Service Function Chaining
              (SFC) Architecture", draft-ietf-sfc-architecture-11 (work
              in progress), July 2015.

   [I-D.xu-mpls-service-chaining]
              Xu, X., Bryant, S., Assarpour, H., Shah, H., Contreras,
              L., and d. daniel.bernier@bell.ca, "Service Chaining using
              MPLS Source Routing", draft-xu-mpls-service-chaining-00
              (work in progress), October 2016.

   [I-D.xu-mpls-unified-source-routing-instruction]
              Xu, X., Bryant, S., Raszuk, R., Chunduri, U., Contreras,
              L., Jalil, L., and H. Assarpour, "Unified Source Routing
              Instruction using MPLS Label Stack", draft-xu-mpls-
              unified-source-routing-instruction-00 (work in progress),
              March 2017.

Authors' Addresses

   Xiaohu Xu
   Huawei

   Email: xuxiaohu@huawei.com


   Nan Wu
   Huawei

   Email: eric.wu@huawei.com


   Himanshu Shah
   Ciena

   Email: hshah@ciena.com













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Internet-Draft                                                  May 2017


   Luis M. Contreras
   Telefonica I+D
   Ronda de la Comunicacion, s/n
   Sur-3 building, 3rd floor
   Madrid,  28050
   Spain

   Email: luismiguel.contrerasmurillo@telefonica.com
   URI:   http://people.tid.es/LuisM.Contreras/










































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