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Traffic Steering using BGP Flowspec with SRv6 Policy
draft-jiang-idr-ts-flowspec-srv6-policy-07

Document Type Active Internet-Draft (individual)
Authors Jiang Wenying , Yisong Liu , Shuanglong Chen , Shunwan Zhuang
Last updated 2022-03-23
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draft-jiang-idr-ts-flowspec-srv6-policy-07
Network Working Group                                           W. Jiang
Internet-Draft                                                    Y. Liu
Intended status: Informational                              China Mobile
Expires: September 24, 2022                                      S. Chen
                                                               S. Zhuang
                                                                  Huawei
                                                          March 23, 2022

          Traffic Steering using BGP Flowspec with SRv6 Policy
               draft-jiang-idr-ts-flowspec-srv6-policy-07

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 aslo 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 September 24, 2022.

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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 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.  Operations  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Application Example . . . . . . . . . . . . . . . . . . . . .   4
   5.  Running Code  . . . . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  Interop-test Status . . . . . . . . . . . . . . . . . . .   7
     5.2.  Deployment Status . . . . . . . . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   8
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   8
     10.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

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 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 to the destination, instructing a device to forward

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   traffic through the path rather than the shortest 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, or BGP.

   [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.  Rules (Actions associated) are encoded
   in Extended Community attribute.  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.

2.  Definitions and Acronyms

   o  FlowSpec: Flow Specification

   o  SR: Segment Routing

   o  SRv6: IPv6 Segment Routing

   o  SID: Segment Identifier

   o  SRH: Segment Routing Header

   o  TE: Traffic Engineering

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 numerical value that associates the

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   SRv6 Policy, and it defines an application-level network Service
   Level Agreement (SLA) policy.

   Assume one or multiple SRv6 Policies are already setup 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
   and endpoint to map to a satisfying SRv6 policy, and steer 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 can be used to specify the
   endpoint of the SRv6 Policy.  When the packets reach to the TailEnd
   device, some specific function imformation 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.

   In this document, the usage of at most one Color Extended Community
   in combination at most one BGP Prefix SID Attribute is discussed.
   For the case that a flowspec route carries multiple Color Extend
   Communities and/or a BGP Prefix SID Attribute, a protocol extension
   to Flowspec is required, and is thus out of the scope of this
   document.

   However, the method proposed in this document still 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.

4.  Application Example

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

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      +------------+
      |  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 Flow into SRv6 Policy (Option 1)

   When the HeadEnd device (as a Flowspec client) receives such
   instructions, it will steer the 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 flows will be
   encapsulated with SRH using the SR List<S1, S2, S3, Service_id_x>.
   When the packets reach to the TailEnd device, they will be further
   procetssed 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 <S1, S2,
   Service_id_x>.

   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 send the FlowSpec route to the HeadEnd device (as
   a Flowspec client).

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      +------------+
      |  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 Flow into SRv6 Policy (Option 2)

   When the HeadEnd device (as a Flowspec client) receives such
   instructions, it will steer the 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 flows will be
   encapsulated with SRH using the SR List<S1, S2, S3>.  When the
   packets reach to the TailEnd device, they will be further procetssed
   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 lie
   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.

   .

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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, software
   implementations 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 software implementations 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 Unitecs | 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

   TBD

6.  IANA Considerations

   No IANA actions are required for this document.

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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
   Email: guyunan@huawei.com

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

   Jie Dong
   Huawei
   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, Kaliraj Vairavakkalai, Robin Li, Acee Lindem, Gunter
   Van De Velde, John Scudder, Rainbow Wu and Gang Yang.

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
              Services", draft-ietf-bess-srv6-services-15 (work in
              progress), March 2022.

   [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", draft-ietf-idr-flowspec-redirect-ip-02 (work
              in progress), February 2015.

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   [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", draft-ietf-idr-segment-routing-te-
              policy-16 (work in progress), March 2022.

   [I-D.ietf-idr-tunnel-encaps]
              Patel, K., Velde, G. V. D., Sangli, S. R., and J. Scudder,
              "The BGP Tunnel Encapsulation Attribute", draft-ietf-idr-
              tunnel-encaps-22 (work in progress), January 2021.

   [I-D.ietf-spring-segment-routing-policy]
              Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
              P. Mattes, "Segment Routing Policy Architecture", draft-
              ietf-spring-segment-routing-policy-22 (work in progress),
              March 2022.

   [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>.

   [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>.

10.2.  Informative References

   [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>.

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   [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
   Beijing
   China

   Email: jiangwenying@chinamobile.com

   Yisong Liu
   China Mobile
   Beijing
   China

   Email: liuyisong@chinamobile.com

   Shuanglong Chen
   Huawei
   Beijing
   China

   Email: chenshuanglong@huawei.com

   Shunwan Zhuang
   Huawei
   Beijing
   China

   Email: zhuangshunwan@huawei.com

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