Distribution of Service Metadata in BGP FlowSpec
draft-yi-idr-bgp-fs-edge-service-metadata-00

IDR                                                           X. Yi, Ed.
Internet-Draft                                                T. He, Ed.
Intended status: Standards Track                            China Unicom
Expires: 28 August 2023                                      H. Shi, Ed.
                                                                 X. Ding
                                                                 H. Wang
                                                     Huawei Technologies
                                                        24 February 2023

            Distribution of Service Metadata in BGP FlowSpec
              draft-yi-idr-bgp-fs-edge-service-metadata-00

Abstract

   In edge computing, a service may be deployed on multiple instances
   within one or more sites, called edge service.  The edge service is
   associated with an ANYCAST IP address, and the route of it along with
   service metadata can be collected by a central controller.  The
   controller may process the metadata and distribute the result to
   ingress routers using BGP FlowSpec.  The service metadata can be used
   by ingress routers to make path selections not only based on the
   routing cost but also the running environment of the edge services.
   This document describes a mechanism to distribute the information of
   the service routes and related service metadata using BGP FlowSpec.

Status of This Memo

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   This Internet-Draft will expire on 28 August 2023.

Copyright Notice

   Copyright (c) 2023 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  BGP FlowSpec Extension for Service Metadata . . . . . . . . .   3
     2.1.  Metadata Path Attribute TLV . . . . . . . . . . . . . . .   4
     2.2.  Aggregated Metric Path Attribute TLV  . . . . . . . . . .   4
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   5.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   Many modern services deploy their service instances in multiple sites
   to get better response time and resource utilization.  These sites
   are often geographically distributed to serve the user demand.  For
   some services such as VR/AR and intelligent transportation, the QoE
   will depend on both the network metrics and the compute metrics.  For
   example, if the nearest site is overloaded due to the demand
   fluctuation, then steer the user traffic to another light-loaded
   sites may improve the QoE.  To steer the traffic to the best site,
   the computing metadata of the site needs to be collected.

   [I-D.ietf-idr-5g-edge-service-metadata] describes the BGP extension
   of distributing service route with network and computing-related
   metrics.  The router connected to the site will received the service
   routes and service metadata sent from devices inside the edge site,
   and then generates the corresponding routes and distributes them to
   ingress routers.  However, the route with service metadata on the
   router connected to the site can be also collected by a central
   controller using BGP LS.  Then the central controller may process the
   metadata and distributes the result to the ingress router using BGP
   FlowSpec.

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   This document defines an extension of BGP FlowSpec to carry the
   service metadata along with the service route which is received from
   the controller.  Using the service metadata and the service route,
   the ingress router can calculate the best site for the traffic,
   giving each user the best QoE.

1.1.  Terminology

1.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  BGP FlowSpec Extension for Service Metadata

   The goal of the BGP FlowSpec extension is to distribute the
   information of the service route and metadata.  A service is
   identified by an prefix and this information is carried using the
   existing Destination Prefix Component specified in [RFC8955] and
   [RFC8956].  [I-D.ietf-idr-ts-flowspec-srv6-policy] defines that the
   Color Extended Community and BGP Prefix-SID attribute is carried in
   the context of the FlowSpec NLRI.

   In addition to that, this document proposes to carry the service
   metadata attribute(See Figure 1).  The ingress router can compare the
   compute metric of different sites and steer the traffic into the best
   one using the SR policy.  The metadata can be original values defined
   in [I-D.ietf-idr-5g-edge-service-metadata] or an aggregated one
   calculated using original values.

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      +------------+
      |  BGP FS    |
      | Controller |
      +------------+
         | FlowSpec route to Ingress:
         |   NLRI: Destination Prefix
         |   Redirect to IPv6 Nexthop: Egress's Address
         |   Policy Color: C1
         |   PrefixSID: End.X1
         |   Service Metadata: Compute metric
         |          .-----.
         |         (       )
         V     .--(         )--.
   +-------+  (                 )  +------+          +---------+
   |       |_( SRv6 Core Network )_|      | (End.X1) |         |
   |Ingress| ( ================> ) |Egress|----------|   Site  |
   +-------+  (SR List<S1,S2,S3>)  +------+          +---------+
               '--(         )--'
                   (       )
                    '-----'

     Figure 1: Example of using BGP FlowSpec to distribute the service
                             route and metadata

2.1.  Metadata Path Attribute TLV

   The Metadata Path Attribute TLV is the same as defined in
   [I-D.ietf-idr-5g-edge-service-metadata], including the following
   three sub-TLVs:

   1.  Site Preference Index sub-TLV indicates the preference to choose
       the site.

   2.  Capacity Index sub-TLV indicates the capability of a site.  One
       Edge Site can be in full capacity, reduced capacity, or
       completely out of service.

   3.  Load Measurement sub-TLV indicates the load level of the site.

2.2.  Aggregated Metric Path Attribute TLV

   The Aggregated Metric Path Attribute is a newly defined TLV(See
   Figure 2).  It contains a single aggregated value which is calculated
   by the controller using the original metrics such as site preference,
   capacity and load measurement.

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      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Aggregated Metadata Type   |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |            Aggregated Metric Value (4 octets)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure 2: Aggregated Metric Path Attribute TLV format

   *  Type: identify the Aggregated Metadata Attribute, to be assigned
      by IANA.

   *  Length: the total number of the octets of the value field.

   *  Value: value of Aggregated Computing metric.

3.  Security Considerations

   TBD

4.  IANA Considerations

   This document requires IANA to assign the following code points from
   the registry called "BGP Path Attributes":

            +=======+==========================+=============+
            | Value | Description              | Reference   |
            +=======+==========================+=============+
            | TBD1  | Aggregated Metadata Type | Section 2.2 |
            +-------+--------------------------+-------------+

                                 Table 1

5.  Normative References

   [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>.

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   [I-D.ietf-idr-5g-edge-service-metadata]
              Dunbar, L., Majumdar, K., Wang, H., and G. S. Mishra, "BGP
              Extension for 5G Edge Service Metadata", Work in Progress,
              Internet-Draft, draft-ietf-idr-5g-edge-service-metadata-
              00, 2 December 2022, <https://www.ietf.org/archive/id/
              draft-ietf-idr-5g-edge-service-metadata-00.txt>.

   [I-D.ietf-idr-ts-flowspec-srv6-policy]
              Wenying, J., Liu, Y., Zhuang, S., Mishra, G. S., and S.
              Chen, "Traffic Steering using BGP FlowSpec with SRv6
              Policy", Work in Progress, Internet-Draft, draft-ietf-idr-
              ts-flowspec-srv6-policy-01, 9 October 2022,
              <https://www.ietf.org/archive/id/draft-ietf-idr-ts-
              flowspec-srv6-policy-01.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>.

   [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>.

Authors' Addresses

   Xinxin Yi (editor)
   China Unicom
   Beijing
   China
   Email: yixx3@chinaunicom.cn

   Tao He (editor)
   China Unicom
   Beijing
   China
   Email: het21@chinaunicom.cn

   Hang Shi (editor)
   Huawei Technologies
   Beijing
   China
   Email: shihang9@huawei.com

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   Xiangfeng Ding
   Huawei Technologies
   Beijing
   China
   Email: dingxiangfeng@huawei.com

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

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