Traffic Steering using BGP FlowSpec with SRv6 Policy
draft-ietf-idr-ts-flowspec-srv6-policy-00

Network Working Group                                           W. Jiang
Internet-Draft                                                    Y. Liu
Intended status: Informational                              China Mobile
Expires: 1 April 2023                                          S. Zhuang
                                                     Huawei Technologies
                                                               G. Mishra
                                             Verizon Communications Inc.
                                                                 S. Chen
                                                     Huawei Technologies
                                                       28 September 2022

          Traffic Steering using BGP FlowSpec with SRv6 Policy
               draft-ietf-idr-ts-flowspec-srv6-policy-00

Abstract

   BGP Flow Specification (FlowSpec) [RFC8955] [RFC8956] has been
   proposed to distribute BGP FlowSpec NLRI to FlowSpec clients to
   mitigate (distributed) denial-of-service attacks, and to provide
   traffic filtering in the context of a BGP/MPLS VPN service.
   Recently, traffic steering applications in the context of SRv6 using
   FlowSpec also attract attention.  This document introduces the usage
   of BGP FlowSpec to steer packets into an SRv6 Policy.

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 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 1 April 2023.

Jiang, et al.             Expires 1 April 2023                  [Page 1]
Internet-Draft          FlowSpec with SRv6 Policy         September 2022

Copyright Notice

   Copyright (c) 2022 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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definitions and Acronyms  . . . . . . . . . . . . . . . . . .   3
   3.  Operations  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Application Examples  . . . . . . . . . . . . . . . . . . . .   5
   5.  Running Code  . . . . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  Interop-test Status . . . . . . . . . . . . . . . . . . .   7
     5.2.  Deployment Status . . . . . . . . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   8
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   8
     10.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   Segment Routing IPv6 (SRv6) is a protocol designed to forward IPv6
   data packets on a network using the source routing model.  SRv6
   enables the ingress network device to add a segment routing header
   (SRH) [RFC8754] to an IPv6 packet and push an explicit IPv6 address
   stack into the SRH.  After receiving the packet, each transit node
   updates the IPv6 destination IP address in the packet and segment
   list to implement hop-by-hop forwarding.

   SRv6 Policy [I-D.ietf-spring-segment-routing-policy] is a tunneling
   technology developed based on SRv6.  An SRv6 Policy is a set of
   candidate paths consisting of one or more segment lists, that is,
   segment ID (SID) lists.  Each SID list identifies an end-to-end path
   from the source node to the destination node, instructing a network
   device to forward traffic through the path rather than the shortest

Jiang, et al.             Expires 1 April 2023                  [Page 2]
Internet-Draft          FlowSpec with SRv6 Policy         September 2022

   path computed using an IGP.  The header of a packet steered into an
   SRv6 Policy is augmented with an ordered list of segments associated
   with that SRv6 Policy, so that other devices on the network can
   execute the instructions encapsulated into the list.

   The headend of an SRv6 Policy may learn multiple candidate paths for
   an SRv6 Policy.  Candidate paths may be learned via a number of
   different mechanisms, e.g., CLI, NetConf,
   PCEP[I-D.ietf-pce-segment-routing-policy-cp], or
   BGP[I-D.ietf-idr-segment-routing-te-policy].

   [RFC8955] [RFC8956] defines the flow specification (FlowSpec) that
   allows to convey flow specifications and traffic Action/Rules
   associated (rate- limiting, redirect, remark ...).  BGP Flow
   specifications are encoded within the MP_REACH_NLRI and
   MP_UNREACH_NLRI attributes[RFC4760].  Rules (Actions associated) are
   encoded in Extended Community attribute[RFC4360].  The BGP Flow
   Specification function allows BGP Flow Specification routes that
   carry traffic policies to be transmitted to BGP Flow Specification
   peers to steer traffic.

   This document proposes BGP flow specification usage that are used to
   steer data flow into an SRv6 Policy as well as to indicate Tailend
   function.  This work is helpful for promoting the deployment of SRv6
   networks.

2.  Definitions and Acronyms

   *  FlowSpec: Flow Specification

   *  SR: Segment Routing

   *  SRv6: IPv6 Segment Routing

   *  SID: Segment Identifier

   *  SRH: Segment Routing Header

   *  TE: Traffic Engineering

   *  USD: Ultimate Segment Decapsulation

Jiang, et al.             Expires 1 April 2023                  [Page 3]
Internet-Draft          FlowSpec with SRv6 Policy         September 2022

3.  Operations

   An SRv6 policy [I-D.ietf-spring-segment-routing-policy] is identified
   through the tuple <headend, color, endpoint>.  In the context of a
   specific headend, one may identify an SRv6 policy by the <color,
   endpoint> tuple.  The headend is the node where the SRv6 policy is
   instantiated/implemented.  The headend is specified as an IPv4 or
   IPv6 address and is expected to be unique in the domain.  The
   endpoint indicates the destination of the SRv6 policy.  The endpoint
   is specified as an IPv6 address and is expected to be unique in the
   domain.  The color is a 32-bit unsigned numerical value that
   associates with the SRv6 policy, and it defines an application-level
   network Service Level Agreement (SLA) policy or intent.

   Assume one or multiple SRv6 policies are already setup/instantiated
   in the SRv6 HeadEnd device.  In order to steer traffic into a
   specific SRv6 Policy at the Headend, one can use the SRv6 Color
   Extended community [RFC9012] and endpoint to map to a satisfying SRv6
   policy, and steer the traffic into this specific policy.

   [I-D.ietf-idr-flowspec-redirect-ip] defines the redirect to IPv4 and
   IPv6 Next-hop action.  The IPv6 next-hop address in the Flow-spec
   Redirect to IPv6 Extended Community[RFC5701] can be used to specify
   the endpoint of the SRv6 Policy.  When the packets reach to the
   TailEnd device, some specific function information identifiers can be
   used decide how to further process the flows.  Several endpoint
   functions are already defined, e.g., End.DT6: Endpoint with
   decapsulation and IPv6 table lookup, and End.DX6: Endpoint with
   decapsulation and IPv6 cross-connect.  The BGP Prefix-SID defined in
   [RFC8669] is utilized to enable SRv6 VPN services
   [I-D.ietf-bess-srv6-services].  SRv6 Services TLVs within the BGP
   Prefix-SID Attribute can be used to indicate the endpoint functions.

   This document proposes to carry the Color Extended Community and BGP
   Prefix-SID Attribute in the context of a Flowspec NLRI [RFC8955]
   [RFC8956] to an SRv6 Headend to steer traffic into one SRv6 policy,
   as well as to indicate specific Tailend functions.

   For the case that a flowspec route carries multiple Color Extend
   Communities, the Color Extended community with the highest numerical
   value will be given higher preference per the description in
   Section 8.4.1 of [I-D.ietf-spring-segment-routing-policy].

   The method proposed in this document supports load balancing to the
   tailend device.  To achieve that, the headend device CAN set up
   multiple paths in one SRv6 policy, and use a Flowspec route to
   indicate the specific SRv6 policy.

Jiang, et al.             Expires 1 April 2023                  [Page 4]
Internet-Draft          FlowSpec with SRv6 Policy         September 2022

4.  Application Examples

   In following scenario, BGP FlowSpec Controller signals the filter
   rules, the redirect to IPv6 Nexthop action, the policy color and the
   function information (SRv6 SID: Service_id_x) to the HeadEnd device.

      +------------+
      |  BGP FS    |
      | Controller |
      +------------+
         | FlowSpec route to HeadEnd:
         |   NLRI: Filter Rules
         |   Redirect to IPv6 Nexthop: TailEnd's Address
         |   Policy Color: C1
         |   PrefixSID: Service_id_x
         |          .-----.
         |         (       )
         V     .--(         )--.
   +-------+  (                 )  +-------+
   |       |_( SRv6 Core Network )_|       |
   |HeadEnd| ( ================> ) |TailEnd|
   +-------+  (SR List<S1,S2,S3>)  +-------+
               '--(         )--'   Service SID: Service_id_x
                   (       )       (e.g.: End.DT4 or End.DT6 or others)
                    '-----'

         Figure 1: Steering the Traffic Flow into SRv6 Policy (Option 1)

   When the HeadEnd device (as a FlowSpec client) receives such
   instructions from BGP FS Controller, it will steer the traffic flows
   matching the criteria in the FlowSpec route into the SRv6 Policy
   matching the tuple (Endpoint: TailEnd's Address, Color: C1).  And the
   packets of such traffic flows will be encapsulated with SRH(Segment
   Routing Header) using the SR List <S1, S2, S3, Service_id_x>.  When
   the packets reach to the TailEnd device, they will be further
   processed per the function denoted by the Service_id_x.

   When the HeadEnd device determines (with the help of SRv6 SID
   Structure) that the Service SID belongs to the same SRv6 Locator as
   the last SRv6 SID of the TailEnd device in the SRv6 Policy segment
   list, it MAY exclude that last SRv6 SID when steering the service
   flow.  For example, the effective segment list of the SRv6 Policy
   associated with SID list <S1, S2, S3> would be replaced as <S1, S2,
   Service_id_x>.

Jiang, et al.             Expires 1 April 2023                  [Page 5]
Internet-Draft          FlowSpec with SRv6 Policy         September 2022

   If the last SRv6 SID (For example, S3 we use here) of the TailEnd
   device in the SRv6 Policy segment list is USD-flavored, an SRv6
   Service SID (e.g., End.DT4 or End.DT6) is not required when BGP
   FlowSpec Controller sends the FlowSpec route to the HeadEnd device
   (as a FlowSpec client).

      +------------+
      |  BGP FS    |
      | Controller |
      +------------+
         | FlowSpec route to HeadEnd:
         |   NLRI: Filter Rules
         |   Redirect to IPv6 Nexthop: TailEnd's Address
         |   Policy Color: C2
         |          .-----.
         |         (       )
         V     .--(         )--.
   +-------+  (                 )  +-------+
   |       |_( SRv6 Core Network )_|       |
   |HeadEnd| ( ================> ) |TailEnd|
   +-------+  (SR List<S1,S2,S3>)  +-------+
               '--(         )--'
                   (       )
                    '-----'
   Note: S3 MUST be a USD-flavored SRv6 SID of the TailEnd

         Figure 2: Steering the Traffic Flow into SRv6 Policy (Option 2)

   When the HeadEnd device (as a FlowSpec client) receives such
   instructions from BGP FS Controller, it will steer the traffic flows
   matching the criteria in the Flowspec route into the SRv6 Policy
   matching the tuple (Endpoint: TailEnd's Address, Color: C2).  And the
   packets of such traffic flows will be encapsulated with SRH(Segment
   Routing Header) using the SR List <S1, S2, S3>.  When the packets
   reach to the TailEnd device, they will be further processed per the
   function denoted by the USD-flavored SRv6 SID S3.

   At this point, the work discusses the matching of global routing
   table prefixes.

   For the cases of intra-AS and inter-AS traffic steering using this
   method, the usages of Flowspec Color Extended Community with BGP
   prefix SID are the same for both scenarios.  The difference lies
   between the local SRv6 policy configurations.  For the inter-domain
   case, the operator can configure an inter-domain SRv6 policy/path at
   the Headend device.  For the intra-domain case, the operator can
   configure an intra-domain SRv6 policy/path at the Headend device.

Jiang, et al.             Expires 1 April 2023                  [Page 6]
Internet-Draft          FlowSpec with SRv6 Policy         September 2022

5.  Running Code

5.1.  Interop-test Status

   The Traffic Steering using BGP FlowSpec with SRv6 Policy mechanism
   has been implemented on the following hardware devices, Network
   Operating System software and SDN controllers.  They had also
   successfully participated in the series of joint interoperability
   testing events hosted by China Mobile from July 2021 to October 2021.
   The following hardware devices and Network Operating System software
   had successfully passed the interoperability testing (in alphabetical
   order).

   Routers:
   +---------+---------------+-------------------------------+
   | Vendors | Device Model  | Version                       |
   +---------+---------------+-------------------------------+
   | Huawei  | NE40-X8A      | NE40E V800R021C00SPC091T      |
   +---------+---------------+-------------------------------+
   | New H3C | CR16010H-FA   | Version 7.1.075, ESS 8305     |
   +---------+---------------+-------------------------------+
   | Ruijie  | RG-N8010-R    | N8000-R_RGOS 12.8(1)B08T1     |
   +---------+---------------+-------------------------------+
   | ZTE     | M6000-8S Plus | V5.00.10(5.60.5)              |
   +---------+---------------+-------------------------------+

   Controllers:
   +----------------+---------------+-------------------------+
   | Vendors        | Device Model  | Version                 |
   +----------------+---------------+-------------------------+
   | China Unitechs | I-T-E SC      | V1.3.6P3                |
   +----------------+---------------+-------------------------+
   | Huawei         | NCE-IP        | V100R021C00             |
   +----------------+---------------+-------------------------+
   | Ruijie         | RG-ONC-AIO-H  | RG-ION-WAN-CLOUD_2.00T1 |
   +----------------+---------------+-------------------------+
   | ZTE            | ZENIC ONE     | R22V16.21.20            |
   +----------------+---------------+-------------------------+

5.2.  Deployment Status

   Currently, this feature has beed deployed on the IP backbone network
   of China Mobile.

Jiang, et al.             Expires 1 April 2023                  [Page 7]
Internet-Draft          FlowSpec with SRv6 Policy         September 2022

6.  IANA Considerations

   No IANA actions are required for this document.

7.  Security Considerations

   This document does not change the security properties of SRv6 and
   BGP.

8.  Contributors

   The following people made significant contributions to this document:

   Yunan Gu
   Huawei Technologies
   Email: guyunan@huawei.com

   Haibo Wang
   Huawei Technologies
   Email: rainsword.wang@huawei.com

   Jie Dong
   Huawei Technologies
   Email: jie.dong@huawei.com

   Xue Yang
   China Mobile
   Email: yangxuewl@chinamobile.com

9.  Acknowledgements

   The authors would like to acknowledge the review and inputs from
   Jeffrey Haas, Susan Hares, Weiqiang Cheng, Kaliraj Vairavakkalai,
   Robin Li, Acee Lindem, Gunter Van De Velde, John Scudder, Rainbow Wu,
   Linda Dunbar, Gang Yan, Feng Yang, Wim Henderickx, Robert Raszuk,
   Ketan Talaulikar, Changwang Lin, Aijun Wang, Hao Li, Huaimo Chen,
   Sheng Fang, Yuanxiang Qiu, Ran Chen, Cheng Li, Zheng Zhang, Xuewei
   Wang, Yanrong Liang, Xuhui Cai, Haojie Wang, Lili Wang and Nan Geng.

10.  References

10.1.  Normative References

   [I-D.ietf-bess-srv6-services]
              Dawra, G., Talaulikar, K., Raszuk, R., Decraene, B.,
              Zhuang, S., and J. Rabadan, "SRv6 BGP based Overlay

Jiang, et al.             Expires 1 April 2023                  [Page 8]
Internet-Draft          FlowSpec with SRv6 Policy         September 2022

              Services", Work in Progress, Internet-Draft, draft-ietf-
              bess-srv6-services-15, 22 March 2022,
              <https://www.ietf.org/archive/id/draft-ietf-bess-srv6-
              services-15.txt>.

   [I-D.ietf-idr-flowspec-redirect-ip]
              Uttaro, J., Haas, J., Texier, M., Karch, A., Ray, S.,
              Simpson, A., and W. Henderickx, "BGP Flow-Spec Redirect to
              IP Action", Work in Progress, Internet-Draft, draft-ietf-
              idr-flowspec-redirect-ip-02, 5 February 2015,
              <https://www.ietf.org/archive/id/draft-ietf-idr-flowspec-
              redirect-ip-02.txt>.

   [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://www.ietf.org/archive/id/draft-ietf-idr-segment-
              routing-te-policy-20.txt>.

   [I-D.ietf-pce-segment-routing-policy-cp]
              Koldychev, M., Sivabalan, S., Barth, C., Peng, S., and H.
              Bidgoli, "PCEP extension to support Segment Routing Policy
              Candidate Paths", Work in Progress, Internet-Draft, draft-
              ietf-pce-segment-routing-policy-cp-07, 21 April 2022,
              <https://www.ietf.org/archive/id/draft-ietf-pce-segment-
              routing-policy-cp-07.txt>.

   [I-D.ietf-spring-segment-routing-policy]
              Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
              P. Mattes, "Segment Routing Policy Architecture", Work in
              Progress, Internet-Draft, draft-ietf-spring-segment-
              routing-policy-22, 22 March 2022,
              <https://www.ietf.org/archive/id/draft-ietf-spring-
              segment-routing-policy-22.txt>.

   [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>.

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <https://www.rfc-editor.org/info/rfc4271>.

Jiang, et al.             Expires 1 April 2023                  [Page 9]
Internet-Draft          FlowSpec with SRv6 Policy         September 2022

   [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>.

   [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
              "Multiprotocol Extensions for BGP-4", RFC 4760,
              DOI 10.17487/RFC4760, January 2007,
              <https://www.rfc-editor.org/info/rfc4760>.

   [RFC5701]  Rekhter, Y., "IPv6 Address Specific BGP Extended Community
              Attribute", RFC 5701, DOI 10.17487/RFC5701, November 2009,
              <https://www.rfc-editor.org/info/rfc5701>.

   [RFC8669]  Previdi, S., Filsfils, C., Lindem, A., Ed., Sreekantiah,
              A., and H. Gredler, "Segment Routing Prefix Segment
              Identifier Extensions for BGP", RFC 8669,
              DOI 10.17487/RFC8669, December 2019,
              <https://www.rfc-editor.org/info/rfc8669>.

   [RFC8955]  Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
              Bacher, "Dissemination of Flow Specification Rules",
              RFC 8955, DOI 10.17487/RFC8955, December 2020,
              <https://www.rfc-editor.org/info/rfc8955>.

   [RFC8956]  Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed.,
              "Dissemination of Flow Specification Rules for IPv6",
              RFC 8956, DOI 10.17487/RFC8956, December 2020,
              <https://www.rfc-editor.org/info/rfc8956>.

   [RFC9012]  Patel, K., Van de Velde, G., Sangli, S., and J. Scudder,
              "The BGP Tunnel Encapsulation Attribute", RFC 9012,
              DOI 10.17487/RFC9012, April 2021,
              <https://www.rfc-editor.org/info/rfc9012>.

10.2.  Informative References

   [I-D.ietf-idr-flowspec-path-redirect]
              Velde, G. V. D., Patel, K., and Z. Li, "Flowspec
              Indirection-id Redirect", Work in Progress, Internet-
              Draft, draft-ietf-idr-flowspec-path-redirect-11, 26 May
              2020, <https://www.ietf.org/archive/id/draft-ietf-idr-
              flowspec-path-redirect-11.txt>.

   [RFC4456]  Bates, T., Chen, E., and R. Chandra, "BGP Route
              Reflection: An Alternative to Full Mesh Internal BGP
              (IBGP)", RFC 4456, DOI 10.17487/RFC4456, April 2006,
              <https://www.rfc-editor.org/info/rfc4456>.

Jiang, et al.             Expires 1 April 2023                 [Page 10]
Internet-Draft          FlowSpec with SRv6 Policy         September 2022

   [RFC8754]  Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
              Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
              (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
              <https://www.rfc-editor.org/info/rfc8754>.

Authors' Addresses

   Wenying Jiang
   China Mobile
   No.32 XuanWuMen West Street
   Beijing
   100053
   China
   Email: jiangwenying@chinamobile.com

   Yisong Liu
   China Mobile
   No.32 XuanWuMen West Street
   Beijing
   100053
   China
   Email: liuyisong@chinamobile.com

   Shunwan Zhuang
   Huawei Technologies
   Huawei Bld., No.156 Beiqing Rd.
   Beijing
   100095
   China
   Email: zhuangshunwan@huawei.com

   Gyan Mishra
   Verizon Communications Inc.
   13101 Columbia Pike
   Silver Spring, MD 20904,
   United States of America
   Email: gyan.s.mishra@verizon.com

   Shuanglong Chen
   Huawei Technologies
   Huawei Bld., No.156 Beiqing Rd.
   Beijing
   100095
   China

Jiang, et al.             Expires 1 April 2023                 [Page 11]
Internet-Draft          FlowSpec with SRv6 Policy         September 2022

   Email: chenshuanglong@huawei.com

Jiang, et al.             Expires 1 April 2023                 [Page 12]