Internet DRAFT - draft-liu-idr-bgp-network-slicing

draft-liu-idr-bgp-network-slicing







IDR Working Group                                                 Y. Liu
Internet-Draft                                                   S. Peng
Intended status: Standards Track                                     ZTE
Expires: 2 October 2023                                    31 March 2023


     BGP Extensions to Support Packet Network Slicing in SR Policy
                  draft-liu-idr-bgp-network-slicing-02

Abstract

   This document defines extensions to BGP in order to advertise Network
   Resource Partition (NRP) in SR policy.

Status of This Memo

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   This Internet-Draft will expire on 2 October 2023.

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   provided without warranty as described in the Revised BSD License.







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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  SR policy with NRP  . . . . . . . . . . . . . . . . . . . . .   3
   3.  Operations  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   [I-D.ietf-teas-ietf-network-slices] specified the definition of the
   IETF Network Slice and the general principles of network slicing in
   the IETF context.  It introduced the concept of Network Resource
   Partition (NRP), which is is a subset of the forwarding resources and
   associated policies on each of a connected set of links in the
   underlay network.

   [I-D.ietf-teas-ns-ip-mpls] introduces the terminology NRP Identifier
   (NRP-ID) which is globally unique within an NRP domain and that can
   be used in the control or management plane to identify the resources
   associated with the NRP.

   [RFC9256] details the concepts of SR Policy and steering into an SR
   Policy.[I-D.ietf-idr-segment-routing-te-policy] specifies the way to
   use BGP to distribute one or more of the candidate paths of an SR
   Policy to the headend of that policy.

   This document defines extensions to BGP in order to advertise NRP-ID
   in SR policy.

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 [RFC2119] [RFC8174]
   when, and only when, they appear in all capitals, as shown here.










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2.  SR policy with NRP

   To distinguish forwarding behavior of different network slices, each
   segment lists in SR policy need to be computed within the scope of
   NRP identified by NRP-ID.  As NRP has global significance, all
   segments of the same segment list can share a single NRP.  This
   document defines a new NRP sub-TLV in Segment List Sub-TLV to
   indicate which slice this segment list belongs to,

       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      |     Flags     |   RESERVED    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              NRP-ID                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 1: NRP sub-TLV in Segment List Sub-TLV

   where,

   *  Type: TBD1

   *  Length: 6

   *  Flags: 1 octet of flags.  None are defined at this stage.  Flags
      SHOULD be set to zero on transmission and MUST be ignored on
      receipt

   *  RESERVED: 1 octet of reserved bits.  SHOULD be set to zero on
      transmission and MUST be ignored on receipt.

   *  NRP-ID: 4-octet identifier of Network Resource Partition of the
      segment list.

   The new SR Policy encoding structure with Path Segmentg sub-TLV is
   expressed as below:














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          SR Policy SAFI NLRI: <Distinguisher, Policy-Color, Endpoint>
          Attributes:
             Tunnel Encaps Attribute (23)
                Tunnel Type: SR Policy
                    Binding SID
                    Preference
                    Priority
                    Policy Name
                    Explicit NULL Label Policy (ENLP)
                    Segment List
                        Weight
                        NRP-ID
                        Segment
                        Segment
                        Segment
                        ...
                        Segment
                        Segment
                        Segment
                        ...
                    ...

3.  Operations

   The operations about advertisement and reception of SR policy can
   refer to [I-D.ietf-idr-segment-routing-te-policy].  Typically, a
   controller can compute SR path taking acount of NRP criteria, so that
   the SR path can be limited in the scope of NRP identified by NRP-ID.
   The controller can obtain the NRP virtual topology information
   through necessary tools such BGP-LS, netconf, etc, and maintain the
   database for the traffic engineering path computation.  The proposal
   in this document supports that multiple segment list each with
   different NRP-ID, to meet the requirements that service flow is
   carried by multiple network slices.  However, it also support that
   all segment list or all candidate path of the SR policy belongs to
   the same slice.

   The NRP information contained in Segment List Sub-TLV can help the
   headend to translate the segment to NRP related SID, if the Segment
   Sub-TLV has not provided optional SID information.  Even if Segment
   Sub-TLV has provided valid SID information, it is also beneficial for
   the headend to know which slice this path belongs to, according to
   the NRP information contained in Segment List Sub-TLV.

4.  IANA Considerations

   TBD




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5.  Security Considerations

   Procedures and protocol extensions defined in this document do not
   affect the security considerations discussed in
   [I-D.ietf-idr-segment-routing-te-policy].

6.  References

6.1.  Normative References

   [I-D.ietf-idr-segment-routing-te-policy]
              Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P.,
              Jain, D., and S. Lin, "Advertising Segment Routing
              Policies in BGP", Work in Progress, Internet-Draft, draft-
              ietf-idr-segment-routing-te-policy-20, 27 July 2022,
              <https://datatracker.ietf.org/doc/html/draft-ietf-idr-
              segment-routing-te-policy-20>.

   [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>.

   [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>.

6.2.  Informative References

   [I-D.bestbar-spring-scalable-ns]
              Saad, T., Beeram, V. P., Chen, R., Peng, S., Wen, B., and
              D. Ceccarelli, "Scalable Network Slicing over SR
              Networks", Work in Progress, Internet-Draft, draft-
              bestbar-spring-scalable-ns-02, 16 September 2021,
              <https://datatracker.ietf.org/doc/html/draft-bestbar-
              spring-scalable-ns-02>.

   [I-D.ietf-teas-ietf-network-slices]
              Farrel, A., Drake, J., Rokui, R., Homma, S., Makhijani,
              K., Contreras, L. M., and J. Tantsura, "A Framework for
              IETF Network Slices", Work in Progress, Internet-Draft,
              draft-ietf-teas-ietf-network-slices-19, 21 January 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-teas-
              ietf-network-slices-19>.

   [I-D.ietf-teas-ns-ip-mpls]
              Saad, T., Beeram, V. P., Dong, J., Wen, B., Ceccarelli,
              D., Halpern, J. M., Peng, S., Chen, R., Liu, X.,



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              Contreras, L. M., Rokui, R., and L. Jalil, "Realizing
              Network Slices in IP/MPLS Networks", Work in Progress,
              Internet-Draft, draft-ietf-teas-ns-ip-mpls-02, 13 March
              2023, <https://datatracker.ietf.org/doc/html/draft-ietf-
              teas-ns-ip-mpls-02>.

   [RFC9256]  Filsfils, C., Talaulikar, K., Ed., Voyer, D., Bogdanov,
              A., and P. Mattes, "Segment Routing Policy Architecture",
              RFC 9256, DOI 10.17487/RFC9256, July 2022,
              <https://www.rfc-editor.org/info/rfc9256>.

Authors' Addresses

   Yao Liu
   ZTE
   Nanjing
   China
   Email: liu.yao71@zte.com.cn


   Shaofu Peng
   ZTE
   Nanjing
   China
   Email: peng.shaofu@zte.com.cn


























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