



CATS                                                         X. Gao, Ed.
Internet-Draft                                                X. Yi, Ed.
Intended status: Standards Track                            China Unicom
Expires: 4 January 2026                                            H. Fu
                                                         ZTE Corporation
                                                             3 July 2025


  Operations, Administration and Maintenance (OAM) data collection for
      service decision-making in Computing-Aware Traffic Steering
                 draft-gao-cats-oam-data-collection-02

Abstract

   This document describes the collection of OAM data for services
   decision-making in Computing-Aware Traffic Steering.In the following
   section, the main functional components and processes of OAM data
   collection will be elaborated in detail.

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   This Internet-Draft will expire on 4 January 2026.

Copyright Notice

   Copyright (c) 2025 IETF Trust and the persons identified as the
   document authors.  All rights reserved.











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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  Requirements and Motivation . . . . . . . . . . . . . . . . .   4
   4.  Framework and Components  . . . . . . . . . . . . . . . . . .   4
   5.  OAM data collection under different architectures . . . . . .   6
     5.1.  Option 1: Centralized C-SMA + Centralized C-PS  . . . . .   6
     5.2.  Option 2: Centralized C-SMA + Distributed C-PS  . . . . .   7
     5.3.  Option 3: Distributed C-SMA + Centralized C-PS  . . . . .   7
     5.4.  Option 4: Distributed C-SMA + Distributed C-PS  . . . . .   8
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   [I-D.fu-cats-oam-fw-02] establishes an end-to-end OAM for Computing-
   Aware Traffic Steering（CATS），and the collection of indicators of
   computing resources and network status is an important component of
   Operations, Administration and Maintenance (OAM) for Computing-Aware
   Traffic Steering (CATS) . The collection of OAM data in Computing-
   Aware Traffic Steering (CATS) includes two stages.  In the first
   stage, before the business is launched, Service Instance has not been
   selected and the path has not been planned.  Based on measurement
   technology, end-to-end CATS OAM data is collected to support service
   decision-making; In the second stage, after the business is launched,
   real-time monitoring of network performance data and computing
   resource status is required to verify whether the calculation and
   selection results meet business requirements, and to achieve
   adjustments to service instances and network paths.  This article
   focuses on stage one and elaborates on the process of collecting
   network OAM and computing power OAM data as input for C-PS decision-
   making before business activation, in order to achieve the selection
   of service instances and paths planning.




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2.  Conventions and Definitions

   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.

   This document uses terms defined in [I-D.ldbc-cats-framework].  We
   list them below for clarification.

   *  Computing-Aware Traffic Steering (CATS): A traffic engineering
      approach RFC9522] that takes into account the dynamic nature of
      computing resources (e.g., compute and storage) and network state
      to optimize service-specific traffic forwarding towards a given
      service contact instance.  Various relevant metrics may be used to
      enable such computing-aware traffic steering policies.

   *  CATS-Forwarder: A network entity that makes forwarding decisions
      based on CATS information to steer traffic specific to a service
      request towards a corresponding yet selected service contact
      instance.  The selection of a service contact instance relies upon
      a multi-metric path computation

   *  Ingress CATS-Forwarder: An entity that steers service
      specifictraffic along a CATS-computed path that leads to an Egress
      CATS-Forwarder that connects to the most suitable service site
      that host the service contact instance selected to satisfy the
      initial service request

   *  Egress CATS-Forwarder: An entity that is located at the end of a
      CATS-computed path and which connects to a CATS-serviced site

   *  CATS Path Selector (C-PS): A functional entity that computes and
      selects paths towards service locations and instances and which
      accommodates the requirements of service requests.  Such a path
      computation engine takes into account the service and network
      status information

   *  CATS Service Metric Agent (C-SMA): A functional entity that is
      responsible for collecting service capabilities and status, and
      for reporting them to a CATS Path Selector (C-PS)









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3.  Requirements and Motivation

   Before the business is launched, the goal of collecting CATS OAM data
   in this stage is for C-PS to make decision to achieve the selection
   of service instances and paths planning.  The collection of network
   OAM includes hop by hop and end-to-end data, with different
   collection requirements in different scenarios.  For example, Ingress
   CATS Forwarder collects network hop by hop OAM and computing power
   OAM based on anycast forwarding method, and finally calculates end-
   to-end OAM based on the collected data to determine the optimal
   service instance and implement path planning; In additon, collect
   end-to-end CATS OAM data directly and evaluate the optimal path and
   calculation instance based on the results.  The network OAM data
   includes status information such as network latency and packet loss.
   It consists of three parts: internal carrier network, the inter
   domain link between the carrier network and the cloud network, and
   Internal cloud network.Computing power OAM data refers to the status
   of computing service instances, etc.

4.  Framework and Components

   [I-D.ldbc-cats-framework-06]defines the CATS framework and
   components.




























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          +-----+              +------+           +------+
        +------+|            +------+ |         +------+ |
        |client|+            |client|-+         |client|-+
        +---+--+             +---+--+           +---+--+
            |                    |                  |
            | +----------------+ |            +-----+----------+
            +-+    C-TC#1      +-+      +-----+    C-TC#2      |
              |----------------|        |     |----------------|
              |     |C-PS#1    |    +------+  |CATS-Forwarder 4|
        ......|     +----------|....|C-PS#2|..|                |...
        :     |CATS-Forwarder 2|    |      |  |                |  .
        :     +----------------+    +------+  +----------------+  :
        :                                                         :
        :                                            +-------+    :
        :                         Underlay           | C-NMA |    :
        :                      Infrastructure        +-------+    :
        :                                                         :
        :                                                         :
        : +----------------+                +----------------+    :
        : |CATS-Forwarder 1|  +-------+     |CATS-Forwarder 3|    :
        :.|                |..|C-SMA#1|.... |                |....:
          +---------+------+  +-------+     +----------------+
                    |         |             |   C-SMA#2      |
                    |         |             +-------+--------+
                    |         |                     |
                    |         |                     |
                 +------------+               +------------+
                +------------+ |             +------------+ |
                |  Service   | |             |  Service   | |
                |  Contact   | |             |  Contact   | |
                |  Instance  |-+             |  Instance  |-+
                +------------+               +------------+
                 service site 1              service site 2

                    Figure 1: CATS-Functional-Components
















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   The CATS Service Metric Agent (C-SMA) is a functional component that
   gathers information about service sites and server resources, as well
   as the status of the different service instances.  C-SMA can be
   deployed as a standalone component or hosted by the Egress CATS-
   Forwarder.  CATS Path Selectors (C-PSes) use OAM information to
   select the Egress CATS-Forwarders where to forward traffic for a
   given service request.  C-PSes also determine the best paths to
   forward traffic, according to various criteria that include network
   state and traffic congestion conditions.  A C-PS can be integrated
   into CATS-Forwarders or may be deployed as a standalone component .
   The method of deploying as independent components is called
   independent deployment, and the method of deploying integrated in
   CATS transceivers is called distributed deployment.

5.  OAM data collection under different architectures

   Based on the distributed and centralized deployment architecture of
   C-PS and C-SMA, network OAM and computing OAM can be independently or
   jointly collected.

5.1.  Option 1: Centralized C-SMA + Centralized C-PS

   *  Independent collection of network OAM:

   End to end performance data collection: It supports both pre arranged
   paths (such as SRv6 Policy) and non arranged paths.Ingress CATS-
   Forwarder initiates active measurements, collects performance data
   from the Ingress CATS-Forwarder to the service instance, Ultimately,
   The Ingress CATS-Forwarder reports network OAM data to C-PS, For
   example, BGP-LS protocol and telemetry can be used.

   Performance data collection for hop by hop links: Performance data is
   collected between each link based on active measurements (such as
   Twamp), including links within the host network, between the host
   network and cloud network domains, and within the cloud network.  The
   collected performance data is ultimately reported to C-PS.

   *  Independent collection of computing power OAM:

   C-SMA collects computing power OAM data and transmits it to C-PS
   through API interfaces and other methods.

   *  Collaborative collection of network OAM and computing power OAM:

   The request and response mechanisms of network protocols can be used
   to jointly collect network OAM and computing power OAM.  Data
   collection is initiated at Ingress CATS-Forwarder, and network
   devices collect network status information (such as packet loss and



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   delay).  The network status information collection instruction header
   and statistical data can be placed in the extension header of IPv6.
   The receiver (service instance) adds computing OAM information and
   network OAM information collected along the way in the ACK in the
   response.For example, through the extension of the stamp protocol,
   while measuring network OAM information, computing power OAM
   information can be collected together.  Finally, the Ingress CATS-
   Forwarder reports the CATS OAM data to C-PS,BGP-LS protocol and
   telemetry can be used.

5.2.  Option 2: Centralized C-SMA + Distributed C-PS

   *  Independent collection of network OAM:

   End to end performance data collection: It supports both pre arranged
   paths (such as SRv6 Policy) and non arranged paths.Ingress CATS-
   Forwarder initiates active measurements, collects performance data
   from the Ingress CATS-Forwarder to the service instance.

   Performance data collection for hop by hop links: Performance data is
   collected between each link based on active measurements (such as
   Twamp), including links within the host network, between the host
   network and cloud network domains, and within the cloud network.
   Finally, The collected performance data will be notified to Ingress
   CATS-Forwarder.

   *  Independent collection of computing power OAM:

   The method is the same as option 1.  C-SMA collects computing power
   OAM data and transmits it to C-PS through API interfaces and other
   methods.

   *  Collaborative collection of network OAM and computing power OAM:

   Similar to option 1,The difference is that the ACK carrying network
   OAM and computing OAM information can be finally notified to the C-PS
   integrated and deployed in Ingress CATS-Forwarder.

5.3.  Option 3: Distributed C-SMA + Centralized C-PS

   *  Independent collection of network OAM:

   The method is the same as option 1.

   *  Independent collection of computing power OAM:

   C-SMA collects computing power OAM data and transmits it to C-PS
   through API interfaces and other means.



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   *  Collaborative collection of network OAM and computing power OAM:

   Similar to option 1,The difference is that the receiver of the
   request and response mechanism is the Egress CATS- Forwarder, as
   C-SMA is hosted by the Egress CATS- Forwarder.(In this case, network
   status indicators such as latency, packet loss, and bandwidth are
   measured between the Egress CATS- Forwarder and service instance, and
   these measurement results are usually fed back to the Egress CATS-
   Forwarder).

5.4.  Option 4: Distributed C-SMA + Distributed C-PS

   *  Independent collection of network OAM:

   The method is the same as option 2.

   *  Independent collection of computing power OAM:

   The method is the same as option 3.

   *  Collaborative collection of network OAM and computing power OAM:

   Similar to option 3,The difference is that the ACK carrying OAM data
   is ultimately notified to the C-PS integrated and deployed in Ingress
   CATS-Forwarder.

6.  Security Considerations

   TBD

7.  IANA Considerations

   TBD

8.  References

8.1.  Normative References

   [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>.

8.2.  Informative References



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   [I-D.ldbc-cats-framework]
              Li, C., Du, Z., Boucadair, M., Contreras, L. M., and J.
              Drake, "A Framework for Computing-Aware Traffic Steering
              (CATS)", Work in Progress, Internet-Draft, draft-ldbc-
              cats-framework-06, 8 February 2024,
              <https://datatracker.ietf.org/doc/html/draft-ldbc-cats-
              framework-06>.

   [I-D.fu-cats-oam-fw]
              付华楷, Liu, B., Li, Z., Huang, D., Huang, C., Ma, L., and W.
              Duan, "Operations, Administration and Maintenance (OAM)
              for Computing-Aware Traffic Steering", Work in Progress,
              Internet-Draft, draft-fu-cats-oam-fw-02, 25 February 2025,
              <https://datatracker.ietf.org/doc/html/draft-fu-cats-oam-
              fw-02>.

Authors' Addresses

   Xing Gao (editor)
   China Unicom
   Beijing
   China
   Email: gaox60@chinaunicom.cn


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


   Huakai Fu
   ZTE Corporation
   Wuhan
   China
   Email: fu.huakai@zte.com.cn














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