Internet DRAFT - draft-xu-isis-service-sid-adv

draft-xu-isis-service-sid-adv







Network Working Group                                              X. Xu
Internet-Draft                                                    Huawei
Intended status: Standards Track                          April 22, 2014
Expires: October 24, 2014


            Signaling Services and Service SIDs Using IS-IS
                    draft-xu-isis-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 IS-IS.

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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 Sub-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  . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

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 IS-IS.

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 [RFC4971].

3.  Advertising Services and Service SIDs

   Service nodes within the network need to advertise each service they
   are offering by using a new sub-TLV of the IS-IS Router CAPABILITY
   TLV defined in [RFC4971].  These sub-TLVs are called as Service sub-
   TLVs.  The scope of the advertisement depends on the application but
   it is recommended that it SHOULD be domain-wide.  Furthermore, 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



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   Service sub-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 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     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                          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.filsfils-spring-segment-routing-mpls]
              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 with MPLS data plane", draft-filsfils-
              spring-segment-routing-mpls-01 (work in progress), April
              2014.

   [I-D.previdi-6man-segment-routing-header]
              Previdi, S., Filsfils, C., Field, B., and I. Leung, "IPv6
              Segment Routing Header (SRH)", draft-previdi-6man-segment-
              routing-header-00 (work in progress), March 2014.

   [I-D.quinn-sfc-arch]
              Quinn, P. and A. Beliveau, "Service Function Chaining
              (SFC) Architecture", draft-quinn-sfc-arch-04 (work in
              progress), January 2014.

   [I-D.quinn-sfc-nsh]
              Quinn, P., Guichard, J., Fernando, R., Surendra, S.,
              Smith, M., Yadav, N., Agarwal, P., Manur, R., Chauhan, A.,
              Elzur, U., McConnell, B., and C. Wright, "Network Service
              Header", draft-quinn-sfc-nsh-02 (work in progress),
              February 2014.

   [I-D.rijsman-sfc-metadata-considerations]
              Rijsman, B. and J. Moisand, "Metadata Considerations",
              draft-rijsman-sfc-metadata-considerations-00 (work in
              progress), February 2014.






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   [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.

   [RFC4971]  Vasseur, JP., Shen, N., and R. Aggarwal, "Intermediate
              System to Intermediate System (IS-IS) Extensions for
              Advertising Router Information", RFC 4971, July 2007.

7.2.  Informative References

   [I-D.filsfils-rtgwg-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-rtgwg-
              segment-routing-01 (work in progress), October 2013.

Author's Address

   Xiaohu Xu
   Huawei

   Email: xuxiaohu@huawei.com

























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