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Versions: 00 01

Network Working Group                                              Z. Li
Internet-Draft                                                     L. Li
Intended status: Standards Track                                  Huawei
Expires: May 7, 2020                                             H. Chen
                                                               Futurewei
                                                                C. Loibl
                                               Next Layer Communications
                                                                  Y. Zhu
                                                           China Telecom
                                                                  L. Liu
                                                                 Fujitsu
                                                                  X. Liu
                                                          Volta Networks
                                                        November 4, 2019


                    BGP Flow Specification for SRv6
                     draft-li-idr-flowspec-srv6-01

Abstract

   This draft proposes extensions to BGP to distribute traffic Flow
   Specifications for SRv6 for filtering SRv6 packets that match a
   sequence of conditions.

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 May 7, 2020.




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Copyright Notice

   Copyright (c) 2019 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
   (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.  Definitions and Acronyms  . . . . . . . . . . . . . . . . . .   3
   3.  The Flow Specification Encoding for SRv6  . . . . . . . . . .   4
     3.1.  Type TBD1 - Whole SID . . . . . . . . . . . . . . . . . .   4
     3.2.  Type TBD2 - Some bits of SID  . . . . . . . . . . . . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   5.  IANA  . . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   7
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   BGP Flow Specification (BGP-FS) [RFC5575] defines a new BGP NLRI to
   distribute a flow specification, which is an n-tuple comprising a
   sequence of matching criteria that can be applied to IP traffic.  It
   defines a minimum set of filtering actions as BGP extended community
   values [RFC4360] that modify the traffic packet and forwards/drops
   the packet.  [I-D.ietf-idr-rfc5575bis] gives more details about them.
   The NLRI (AFI=1, SAFI=133) is for IPv4 unicast flow specification and
   NLRI (AFI=1, SAFI=134) is for BGP/MPLS VPNv4 flow specification.
   [I-D.ietf-idr-flow-spec-v6] redefines the [RFC5575] SAFIs to make
   them AFI specific and applicable to both IPv4 and IPv6 applications.
   [I-D.ietf-idr-flowspec-l2vpn] extends the flow-spec rules for layer 2
   Ethernet packets.

   Segment Routing (SR) for unicast traffic has been proposed to cope
   with the usecases in traffic engineering, fast re-reroute, service
   chain, etc.  SR architecture can be implemented over an IPv6 data



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   plane using a new type of Segment Routing Header (SRH)
   [I-D.ietf-6man-segment-routing-header].  SRv6 Network Programming
   [I-D.filsfils-spring-srv6-network-programming] defines the SRv6
   network programming concept and its most basic functions.  SRv6 SID
   may have the form of LOC:FUNCT:ARGS::.

   LOC: Each operator is free to use the locator length it chooses.
   Most often the LOC part of the SID is routable and leads to the node
   which instantiates that SID.

   FUNCT: The FUNCT part of the SID is an opaque identification of a
   local function bound to the SID. (e.g.  End: Endpoint, End.X, End.T,
   End.DX2 etc.).

   ARGS: A function may require additional arguments that would be
   placed immediately after the FUNCT.

   This document specifies a couple of new BGP-FS component types to
   support Segment Routing over IPv6 data plane (SRv6) filtering.  The
   match field is destination address of IPv6 header, but it's a SID
   copy from SRH rather than a traditional IPv6 address (refer to the
   figure below).

            +-----------------------------+
 IPv6 Header|     SA      |     DA        |<--Match field of this document
            +--------------------^--------+
                                 |
            +--------------------|--------+
            |             +-------------+ |     +-------------------+
            |             | Segment[0]  +-------> Loc | Func | Args |
            |             +-------------+ |     +-------------------+
            |             | Segment[1]  | |
            |             +-------------+ |
            |             |    ...      | |
   SR Header|             +-------------+ |
            |             | Segment[n]  | |
            |             +-------------+ |
            |             +-------------+ |
            |             ~  Option TLV ~ |
            |             +-------------+ |
            +-----------------------------+

2.  Definitions and Acronyms

   o  FS: Flow Specification

   o  SR: Segment Routing




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   o  SRv6: IPv6 Segment Routing, SRv6 is a method of forwarding IPv6
      packets on the network based on the concept of source routing.

   o  SID: Segment Identifier

   o  BSID: Binding SID

3.  The Flow Specification Encoding for SRv6

   The Flow Specification NLRI-type consists of several optional
   components, each of which begins with a type field (1 octet) followed
   by a variable length parameter.  [RFC5575] defines 12 component types
   for IPv4.  IPv6 NLRI component types are described in
   [I-D.ietf-idr-flow-spec-v6].  This document defines two new component
   types for SRv6.

3.1.  Type TBD1 - Whole SID

   Encoding: <type (1 octet), length(1 octet), [op, value]+>

   Contains a list of {operator, value} pairs that are used to match the
   SID/binding SID or a range of whole SID.

   The operator byte is encoded as:

                          0   1   2   3   4   5   6   7
                        +---+---+---+---+---+---+---+---+
                        | e | a |lt |gt |eq |  reserve  |
                        +---+---+---+---+---+---+---+---+

   Where:

   e - end-of-list bit.  Set in the last {op, value} pair in the
   sequence.

   a - AND bit.  If unset, the previous term is logically ORed with the
   current one.  If set, the operation is a logical AND.  It should be
   unset in the first operator byte of a sequence.  The AND operator has
   higher priority than OR for the purposes of evaluating logical
   expressions.

   lt - less than comparison between data and value.

   gt - greater than comparison between data and value.

   eq - equality between data and value.





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   The bits lt, gt, and eq can be combined to match the SID or a range
   of SID (e.g. less than SID1 and greater than SID2).

   The value field is encoded as:

    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
   +---------------------------------------------------------------+
   ~                         SID(128bits)                          ~
   +---------------------------------------------------------------+

   The format of SID is described in
   [I-D.ietf-6man-segment-routing-header] and
   [I-D.filsfils-spring-srv6-network-programming]

3.2.  Type TBD2 - Some bits of SID

   For some scenarios route policy with the whole 128 bits SID matching
   is too long and not necessary.
   [I-D.filsfils-spring-srv6-network-programming] defines the format of
   SID is LOC:FUNCT:ARGS::. In some scenarios, traffic packets can just
   match Locator, Function ID, Argument or some combinations of these
   different fields rather than whole 128 bits SID.  The new component
   type TBD2 defined below is for matching some bits of SID.

   Encoding: <type (1 octet), length(1 octet), [op, value]+>

   Contains a list of {operator, value} pairs that are used to match
   some bits of SID.

   The operator byte is encoded as:

                           0   1   2   3   4   5   6   7
                        +---+---+---+---+---+---+---+---+
                        | e | a |      type     |reserve|
                        +---+---+---+---+---+---+---+---+

   Where:

   e - end-of-list bit.  Set in the last {op, value} pair in the list.

   a - AND bit.  If unset, the previous term is logically ORed with the
   current one.  If set, the operation is a logical AND.  It should be
   unset in the first operator byte of a sequence.  The AND operator has
   higher priority than OR for the purposes of evaluating logical
   expressions.

   type:



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   0000 : SID's LOC bits

   0001 : SID's FUNCT bits

   0010 : SID's LOC:FUNCT bits

   0011 : SID's FUNCT:ARGS bits

   The value field is encoded below as the lengths in bits of LOC, FUNCT
   and ARGS followed by the SID rounding up to bytes:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  LOC Length   | FUNCT Length  | ARGS Length |    SID          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                        SID(continue)                          ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   LOC Length : 1-octet field indicating the length in bits of LOC in
   SID.

   FUNCT Length : 1-octet field indicating the length in bits of FUNCT
   in SID.

   ARGS Length : 1-octet field indicating the length in bits of ARGS in
   SID.

   SID : the SID containing LOC, FUNCT and ARGS, and rounding up to
   bytes.

4.  Security Considerations

   No new security issues are introduced to the BGP protocol by this
   specification.

5.  IANA

   Under "Flow Spec Component Types" registry, IANA is requested to
   assign the following values:









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      +-----------+-------------------+----------------+
      | Value     | Name              | Reference      |
      +-----------+-------------------+----------------+
      | TBD1 (15) | Whole SID         | This Document  |
      +-----------+-------------------+----------------+
      | TBD2 (16) | Some bits of SID  | This Document  |
      +-----------+-------------------+----------------+

6.  Acknowledgments

   The authors would like to thank Shunwan Zhuang and Rainsword Wang for
   their valuable suggestions and comments on this draft.

7.  References

7.1.  Normative References

   [I-D.ietf-idr-flow-spec-v6]
              McPherson, D., Raszuk, R., Pithawala, B.,
              akarch@cisco.com, a., and S. Hares, "Dissemination of Flow
              Specification Rules for IPv6", draft-ietf-idr-flow-spec-
              v6-09 (work in progress), November 2017.

   [I-D.ietf-idr-rfc5575bis]
              Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
              Bacher, "Dissemination of Flow Specification Rules",
              draft-ietf-idr-rfc5575bis-17 (work in progress), June
              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>.

   [RFC4360]  Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
              Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
              February 2006, <https://www.rfc-editor.org/info/rfc4360>.

   [RFC5575]  Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
              and D. McPherson, "Dissemination of Flow Specification
              Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009,
              <https://www.rfc-editor.org/info/rfc5575>.

7.2.  Informative References







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   [I-D.filsfils-spring-srv6-network-programming]
              Filsfils, C., Camarillo, P., Leddy, J.,
              daniel.voyer@bell.ca, d., Matsushima, S., and Z. Li, "SRv6
              Network Programming", draft-filsfils-spring-srv6-network-
              programming-07 (work in progress), February 2019.

   [I-D.ietf-6man-segment-routing-header]
              Filsfils, C., Dukes, D., Previdi, S., Leddy, J.,
              Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
              (SRH)", draft-ietf-6man-segment-routing-header-26 (work in
              progress), October 2019.

   [I-D.ietf-idr-flowspec-l2vpn]
              Weiguo, H., Eastlake, D., Uttaro, J., Litkowski, S., and
              S. Zhuang, "BGP Dissemination of L2VPN Flow Specification
              Rules", draft-ietf-idr-flowspec-l2vpn-11 (work in
              progress), July 2019.

Authors' Addresses

   Zhenbin Li
   Huawei
   156 Beiqing Road
   Beijing, 100095
   P.R. China

   Email: lizhenbin@huawei.com


   Lei Li
   Huawei
   156 Beiqing Road
   Beijing  100095
   P.R. China

   Email: lily.lilei@huawei.com


   Huaimo Chen
   Futurewei
   Boston, MA
   USA

   Email: Huaimo.chen@futurewei.com







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   Christoph Loibl
   Next Layer Communications
   Mariahilfer Guertel 37/7
   Vienna  1150
   AT

   Email: cl@tix.at


   Yongqing
   China Telecom
   109, West Zhongshan Road, Tianhe District
   Guangzhou  510000
   China

   Email: zhuyq.gd@chinatelecom.cn


   Lei Liu
   Fujitsu
   USA

   Email: liulei.kddi@gmail.com


   Xufeng Liu
   Volta Networks
   McLean, VA
   USA

   Email: xufeng.liu.ietf@gmail.com




















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