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Versions: 00 draft-xu-ospf-service-function-adv

Network Working Group                                              X. Xu
Internet-Draft                                                    Huawei
Intended status: Standards Track                          April 25, 2014
Expires: October 27, 2014


             Signaling Services and Service SIDs Using OSPF
                    draft-xu-ospf-service-sid-adv-00

Abstract

   The Segment Routing mechanism can be leveraged to realize the service
   path layer functionality of the Service Function Chaining (i.e,
   steering traffic through the service function path).  This document
   describes how to advertise services and the corresponding service
   segment IDs using OSPF.

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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   This Internet-Draft will expire on October 27, 2014.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Advertising Services and Service SIDs . . . . . . . . . . . .   2
     3.1.  Service TLVs  . . . . . . . . . . . . . . . . . . . . . .   3
     3.2.  Service SID Sub-TLVs  . . . . . . . . . . . . . . . . . .   3
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   [I-D.xu-spring-sfc-use-case] describes a particular use case for
   SPRING where the Segment Routing (SR) mechanism is leveraged to
   realize the service path layer functionality of the SFC (i.e,
   steering traffic through the service function path).  To allow the
   service classifier to encode the segment list represeting a
   particular service path, the classifier needs to know on which
   service node(s) a given service is located and what segment ID (SID)
   is used to indicate that service on a given service node.  This
   document describes how to advertise services and the corresponding
   service SIDs using OSPF including both OSPFv2 [RFC2328] and OSPFv3
   [RFC2740].

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 RFC 2119 [RFC2119].

2.  Terminology

   This memo makes use of the terms defined in [RFC4970].

3.  Advertising Services and Service SIDs

   Service nodes within the network need to advertise each service they
   are offering by using a TLV within the body of the OSPF Router
   Information (RI) Opaque LSA [RFC4970].  These TLVs are called as
   Service TLVs.  These Service TLVs are applicable to both OSPFv2 and
   OSPFv3.  The scope of the advertisement depends on the application
   but it is recommended that it SHOULD be domain-wide.  Furthermore,



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   they may need to allocate at least one corresponding SID for each
   service and meanwhile advertise it by using a sub-TLV of the
   corresponding Service TLV for that service, called Service SID sub-
   TLV.  In the MPLS-SR case, service nodes within the network would
   allocate a locally significant MPLS label to each service they are
   offering.  In the IPv6-SR case, service nodes within the network
   would allocate a locally unique link-local IPv6 address to each
   service they are offering.  For a given service, the service node
   offering that service could advertise the service ID in MPLS label
   format or the one in IPv6 address format, or both.

3.1.  Service TLVs

      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             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                          Sub-TLVs                             ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type: each service is allocated with a unique type code.

      Length: variable

      Value: contains zero or more sub-TLVs.  Besides the Service SID
      sub-TLVs, other sub-TLVs (to be defined in future) which are used
      to describe some characters of a service could also be contained
      in this field.

3.2.  Service SID Sub-TLVs

      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             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                         Service SID                           ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type: TBD1 for the service SID in MPLS label format and TBD2 for
      the service SID in IPv6 address format.

      Length: variable (3 or 16).

      Value: if the Length is set to 3, the 20 rightmost bits represent
      a MPLS label.  If the length is set to 16, the value represents an
      IPv6 address.



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4.  Acknowledgements

   TBD.

5.  IANA Considerations

   TBD.

6.  Security Considerations

   This document does not introduce any new security risk.

7.  References

7.1.  Normative References

   [I-D.xu-spring-sfc-use-case]
              Xu, X., "Service Function Chaining Use Case", draft-xu-
              spring-sfc-use-case-00 (work in progress), April 2014.

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

   [RFC4970]  Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R., and S.
              Shaffer, "Extensions to OSPF for Advertising Optional
              Router Capabilities", RFC 4970, July 2007.

7.2.  Informative References

   [I-D.filsfils-spring-segment-routing]
              Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
              Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,
              Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe,
              "Segment Routing Architecture", draft-filsfils-spring-
              segment-routing-00 (work in progress), April 2014.

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.

   [RFC2740]  Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6", RFC
              2740, December 1999.

Author's Address

   Xiaohu Xu
   Huawei

   Email: xuxiaohu@huawei.com




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