cats                                                               C. Li
Internet-Draft                                                     Y. Yu
Intended status: Informational             Zhejiang Gongshang University
Expires: 25 June 2025                                           S. Zhang
                                                            China Mobile
                                                                   B. Ma
                                           Zhejiang Gongshang University
                                                        22 December 2024


   A Task Segmentation Framework for Computing-Aware Traffic Steering
              draft-li-cats-task-segmentation-framework-01

Abstract

   This document proposes an extension to the Computing-Aware Traffic
   Steering (CATS) framework by introducing a task segmentation module.
   This extension enables the CATS framework to handle divisible
   computing requests by breaking them down into smaller computational
   units, referred to as "Task".  The document focuses on two primary
   task segmentation modes: the distributed mode and the stepwise mode,
   providing detailed workflows for each.

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
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   This Internet-Draft will expire on 25 June 2025.

Copyright Notice

   Copyright (c) 2024 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.



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   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
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   2
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Task Segmentation Module (TSM)  . . . . . . . . . . . . . . .   4
     4.1.  Divisible and Indivisible Tasks . . . . . . . . . . . . .   4
     4.2.  Classification of Divisible Tasks . . . . . . . . . . . .   4
     4.3.  Task Segmentation Process . . . . . . . . . . . . . . . .   4
     4.4.  Application Scenarios for Task Segmentation . . . . . . .   5
   5.  The Role of Task Segmentation in the CATS Framework . . . . .   5
   6.  CATS Workflow under Multi-Task Segmentation . . . . . . . . .   6
     6.1.  Distributed Mode  . . . . . . . . . . . . . . . . . . . .   6
     6.2.  Stepwise Mode . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   With the growing demand for efficient and scalable network services,
   segmenting computational tasks for distributed processing has become
   increasingly important.  This document extends the existing CATS
   framework by introducing a "Task Segmentation Module" (TSM), which
   collaborates with the CATS Service Metric Agent (C-SMA) and the CATS
   Network Metric Agent (C-NMA) to optimize task allocation and
   execution.

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.






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3.  Terminology

   This document makes use of the terms defined in
   [I-D.ietf-cats-framework].  In addition, the following terms are
   defined below:

   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).  (From
      [I-D.ietf-cats-framework])

   CATS Network Metric Agent (C-NMA):  A functional entity that is
      responsible for collecting network capabilities and status, and
      for reporting them to a C-PS.  (From [I-D.ietf-cats-framework])

   CATS Path Selector (C-PS):  A functional entity that selects
      pathstowards service locations and instances and which
      accommodates therequirements of service requests.  Such a path
      selection engine takes into account the service and network status
      information.  (From [I-D.ietf-cats-framework])

   Task:  In this document, a Task refers to a logical computational
      unit within a service request that can be processed independently.
      Tasks may represent simple computational steps or form part of a
      complex computational process.  The granularity of a task is
      smaller than that of a "service" and represents specific
      operations executed within a service instance.  For detailed task
      classifications, see Sections Section 4.1 and Section 4.2.

   Computing Power Brain (CPB):  The Computing Power Brain (CPB) is
      responsible for coordinating the C-NMA and C-SMA to retrieve
      relevant data and determine the optimal task segmentation
      strategy.

   CATS Task Execution Agent (C-TEA):  The CATS Task Execution Agent
      (C-TEA) is responsible for receiving instructions from the CPB and
      carrying out the actual segmentation and distribution of tasks.
      During the task segmentation process, the C-TEA transforms logical
      tasks into actionable task units and interacts with the CATS Path
      Selector (C-PS) and the CATS Forwarder to ensure tasks are
      correctly delivered to the appropriate service sites.

   Task Segmentation Module (TSM):  The Task Segmentation Module (TSM),
      primarily composed of the CPB and C-TEA, is a functional component
      tasked with analyzing incoming requests and segmenting them into
      smaller task units based on their dependencies and independence.
      For further details, see Section 4.




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4.  Task Segmentation Module (TSM)

   To enhance the utilization of computing and network resources, this
   document extends the CATS framework by introducing the concept of
   task segmentation.  Task segmentation involves breaking down received
   service requests into smaller computational units to enable more
   efficient distribution and processing across network and computing
   resources.  Tasks can be categorized into two types based on their
   characteristics: divisible tasks and indivisible tasks.

4.1.  Divisible and Indivisible Tasks

   Divisible Tasks:  These refer to computational requests that can be
      further broken down into multiple subtasks.  Each subtask can
      either be processed Non-dependently or executed sequentially.
      Divisible tasks offer greater flexibility in allocation and
      processing, optimizing resource utilization.

   Indivisible Tasks:  These are computational requests that must be
      processed as a whole and cannot be broken into subtasks.  These
      tasks are typically handled by a single service site and often
      involve low-complexity operations that require consistent
      processing.

4.2.  Classification of Divisible Tasks

   Divisible tasks can be further divided into dependent tasks and Non-
   dependent tasks.

   Dependent Tasks:  These tasks exhibit a defined sequence of execution
      and dependencies among subtasks.  For example, the output of Task
      A serves as the input for Task B.  Task allocation and resource
      scheduling must consider these dependencies to ensure tasks are
      processed in a specific order, meeting computational logic and
      data flow requirements.

   Non-dependent Tasks:  These tasks can be divided into relatively
      autonomous atomic tasks, each of which can be completed Non-
      dependently without relying on the results of other tasks.  Non-
      dependent tasks are suitable for parallel processing,
      significantly improving computational efficiency.

4.3.  Task Segmentation Process

   This section describes the process of task segmentation, as
   determined and executed by the CPB.

   Task Reception:  The CPB receives computational requests from



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      clients.

   Task Analysis:  Based on the characteristics and requirements of the
      request, the CPB determines whether the task is divisible.

   Task Classification:  If the task is divisible, the CPB further
      analyzes whether it involves task dependencies.If the task is
      indivisible, the request is allocated as a whole to an appropriate
      service instance for processing, as described in
      [I-D.ietf-cats-framework].

   Task Allocation and Execution:  When task is divisible, dependent
      tasks are sequentially allocated and processed across service
      sites based on their dependencies.  Non-dependent tasks are
      divided into multiple subtasks and distributed to different
      service sites for parallel processing.  Specific segmentation
      details (e.g., segmentation ratio and the number of subtasks) are
      beyond the scope of this document.

4.4.  Application Scenarios for Task Segmentation

   Task segmentation significantly optimizes traffic steering and
   resource utilization within the CATS framework.

   Applications for Dependent Tasks:  These are suitable for scenarios
      requiring sequential execution, such as data stream computing or
      complex pipeline processing, e.g., multi-step encoding and
      compression in video processing.

   Applications for Non-dependent Tasks:  These are ideal for large-
      scale parallel computing, such as batch image processing or
      distributed data analysis tasks.  By classifying and segmenting
      tasks, the CATS framework can dynamically adjust and optimize
      resource scheduling strategies to meet the performance
      requirements and service quality needs of various application
      scenarios.

5.  The Role of Task Segmentation in the CATS Framework

   Tasks serve as the fundamental units for service request allocation
   and computing resource scheduling.  By segmenting requests into
   tasks, the CATS framework can optimize resource utilization and path
   selection in a more granular manner based on the current state of
   network and computing resources.  The introduction of tasks enables
   the CATS framework to achieve the following:

   Optimizing Resource Allocation:  Through task segmentation and




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      distribution, the network can dynamically select the most suitable
      paths and service instances, thereby enhancing the utilization of
      both computing and network resources.

   Improving Concurrent Processing Capability:  For divisible tasks,
      parallel processing can be leveraged to boost overall
      computational efficiency.

   Supporting Dependency Management:  In the stepwise task mode, inter-
      task dependencies can be maintained to ensure the correct order of
      computation.

6.  CATS Workflow under Multi-Task Segmentation

6.1.  Distributed Mode

   In the distributed mode, the task to be processed is intelligently
   segmented into Non-dependent subtasks and distributed across multiple
   service instances for parallel processing.  This mode is suitable for
   tasks without dependencies.

   As shown in Figure 1.The detailed workflow for distributed tasks is
   as follows:

   (1)  The client sends a service request, and the CPB receives the
        service request and determines that the task type is a Non-
        dependent task.

   (2)  The CPB evaluates the network and computing resource conditions
        using data from the C-SMA and C-NMA, then formulates an
        appropriate task allocation plan.  The C-TEA executes the
        specific segmentation operations.

   (3)  The CPB collaborates with the C-PS to determine the optimal path
        for each subtask.  The ingress CATS forwarder routes each
        subtask along its predetermined path to the corresponding egress
        CATS forwarder and service site.

   (4)  Each service site processes its assigned subtask in parallel,
        and the results are aggregated and returned to the client.











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                                +-----+
                              +------+|                         +-------+
                              |client|+------------------------>|  CPB  |
                              +---+--+                          +-------+
                                  |                             |   ^   ^
                                  |                             |   |   |
                              +---+---+                         |   |   |
                              | C-TEA |<------------------------+   |   |
                              +---+---+                             |   |
                                  |                                 |   |
                                  |                                 |   |
              +-------------------+---------------------+           |   |
              |                   |                     |           |   |
              |                   |                     |           |   |
    +---------+------+  +---------+------+  +-----------+----+      |   |
    |         |C-PS#1|  |         |C-PS#2|  |         |C-PS#3|      |   |
....|         +------|..|         +------|..|         +------|....  |   |
:   |CATS-Forwarder 1|  |CATS-Forwarder 2|  |CATS-Forwarder 3|   :  |   |
:   +----------------+  +----------------+  +----------------+   :  |   |
:                                                                :  |   |
:                                                                :  |   |
:                            Underlay            +-------+       :  |   |
:                         Infrastructure         | C-NMA |----------+   |
:                                                +-------+       :      |
:                                                                :      |
:                                                                :      |
:                                                                :      |
:   +----------------+  +----------------+  +----------------+   :      |
:   |CATS-Forwarder 4|  |CATS-Forwarder 5|  |CATS-Forwarder 6|   :  +-------+
....|                |..|                |..|                |....  | C-SMA |
    +------+---------+  +--------+-------+  +--------+-------+      +-------+
           |                     |                   |               ^  ^  ^
           |                     |                   |               |  |  |
           |                     |                   |               |  |  |
      +------------+         +------------+       +------------+     |  |  |
    +------------+ |       +------------+ |      +------------+ |    |  |  |
    |  Service   | |       |  Service   | |      |  Service   | |    |  |  |
    |  Contact   | |--+    |  Contact   | |--+   |  Contact   | |----+  |  |
    |  Instance  |-+  |    |  Instance  |-+  |   |  Instance  |-+       |  |
    +------------+    |    +------------+    |   +------------+         |  |
      Service Site 1  |     Service Site 2   |    Service Site 3        |  |
                      |                      +--------------------------+  |
                      +----------------------------------------------------+

     Figure 1: Distributed Framework (assumes segmentation into 3
                              subtasks)





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6.2.  Stepwise Mode

   The stepwise mode is applicable for tasks with interdependencies,
   where each subtask depends on the output of the previous subtask and
   must be routed sequentially between service sites.

   As shown in Figure 2.  The detailed workflow for stepwise tasks is as
   follows:

   (1)  The client sends a service request, and the CPB receives the
        service request and determines that the task type is a dependent
        task.

   (2)  The CPB evaluates the network and computing resource conditions
        using data from the C-SMA and C-NMA, then formulates an
        appropriate task allocation plan.  The C-TEA executes the
        specific segmentation operations.

   (3)  The CPB and C-PS determine the path for the first subtask using
        data from the C-SMA and C-NMA.  After the first subtask is
        processed at the initial service site, its output is routed to
        the next service site for further processing.  This process is
        repeated, with the C-PS selecting an appropriate path for each
        subtask, until all subtasks are completed.

   (4)  The final results are aggregated and returned to the client.

























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          +-----+
        +------+|                         +-------+<------------------------+
        |client|+------------------------>|  CPB  |                         |
        +---+--+                          +-------+<----------------------+ |
            |                             |                               | |
            |                             |                               | |
        +---+---+<------------------------+                               | |
        | C-TEA |                                                         | |
        +---+---+                                                         | |
            |          +-----------+            +---------+               | |
            |          |           |            |         |               | |
  +---------+------+   |   +-------+--------+   |   +-----+----------+    | |
  |         |C-PS#1|   |   |         |C-PS#2|   |   |         |C-PS#3|    | |
..|          +-----|.. | ..|         +------|.. | ..|         +------|..  | |
: |CATS-Forwarder 1| : | : |CATS-Forwarder 2| : | : |CATS-Forwarder 3| :  | |
: +----------------+ : | : +----------------+ : | : +----------------+ :  | |
:     Underlay       : | :     Underlay       : | :     Underlay       :  | |
:   Infrastructure   : | :   Infrastructure   : | :   Infrastructure   :  | |
:                    : | :                    : | :                    :  | |
:     +-------+      : | :     +-------+      : | :     +-------+      :  | |
:     | C-NMA |      : | :     | C-NMA |      : | :     | C-NMA |      :  | |
:     +---+---+      : | :     +---+---+      : | :     +---+---+      :  | |
:         |          : | :         |          : | :         |          :  | |
:         +----------:-|-:---------+----------:-|-:---------+----------:--|-+
: +----------------+ : | : +----------------+ : | : +----------------+ :  |
: |CATS-Forwarder 4| : | : |CATS-Forwarder 5| : | : |CATS-Forwarder 6| :  |
..|                |.. | ..|                |.. | ..|                |..  |
  +----------------+   |   +----------------+   |   +----------------+    |
         |             |          |             |         |               |
         |             |          |             |         |               |
   +------------+      |   +------------+       |  +------------+         |
 +------------+ |      | +------------+ |       | +------------+ |        |
 |  Service   | |------+ |  Service   | |-------+ |  Service   | |        |
 |  Contact   | |--+     |  Contact   | |--+      |  Contact   | |----+   |
 |  Instance  |-+  |     |  Instance  |-+  |      |  Instance  |-+    |   |
 +------------+    |     +------------+    |      +------------+      |   |
   Service Site 1  |       Service Site 2  |        Service Site 3    |   |
                   |                       |                          |   |
                   |                       |                          |   |
                   +----------->+-------+<-+                          |   |
                                | C-SMA |                             |   |
                                +---+---+<----------------------------+   |
                                    |                                     |
                                    +-------------------------------------+


 Figure 2: Stepwise Framework (assumes segmentation into 3 subtasks)




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7.  Security Considerations

   TBD

8.  IANA Considerations

   TBD

9.  References

9.1.  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>.

9.2.  Informative References

   [I-D.ietf-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-ietf-
              cats-framework-04, 17 October 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-cats-
              framework-04>.

Acknowledgements

   TBD

Authors' Addresses

   Chuanhuang Li
   Zhejiang Gongshang University
   Zhejiang
   China
   Email: chuanhuang_li@zjgsu.edu.cn


   Yingjie Yu
   Zhejiang Gongshang University
   Zhejiang
   China



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   Email: 1912190128@pop.zjgsu.edu.cn


   Shicong Zhang
   China Mobile
   China
   Email: zhangshicong@cmhi.chinamobile.com


   Bo Ma
   Zhejiang Gongshang University
   Zhejiang
   China
   Email: mabo@zjgsu.edu.cn





































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