Internet-Draft Analysis of metric distribution August 2023
Shi & Yang Expires 11 February 2024 [Page]
Workgroup:
Computing-Aware Traffic Steering
Internet-Draft:
draft-shi-cats-analysis-of-metric-distribution-01
Published:
Intended Status:
Informational
Expires:
Authors:
H. Shi
Huawei Technologies
T. Yang
China Broadcast Mobile Network Company

Design analysis of methods for distributing the computing metric

Abstract

This document analyses different methods for distributing the computing metrics from service instances to the ingress router.

Discussion Venues

This note is to be removed before publishing as an RFC.

Discussion of this document takes place on the Computing-Aware Traffic Steering Working Group mailing list (cats@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/cats/.

Source for this draft and an issue tracker can be found at https://github.com/VMatrix1900/draft-cats-method-analysis.

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 11 February 2024.

Table of Contents

1. Introduction

Many modern computing services are deployed in a distributed way. Multiple service instances deployed in multiple sites provide equivalent function to the end user. As described in [I-D.yao-cats-ps-usecases], traffic steering that takes computing resource metrics into account would improve the quality of service. Such computing metrics are defined in [I-D.du-cats-computing-modeling-description]. This document analysis different methods for distributing these metrics.

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.

3. Requirement of distributing computing metric

The CATS functional components are defined in [I-D.ldbc-cats-framework](see Figure 1, the figure is replicated here for better understanding). C-SMA is responsible for collecting the computing metrics of the service instance and distributing the metrics to the C-PSes. A C-PS then selects a path based on the computing metrics and network metrics.

      +-----+              +------+            +------+
    +------+|            +------+ |          +------+ |
    |client|+            |client|-+          |client|-+
    +------+             +------+            +------+
        |                    |                   |
        |   +-------------+  |            +-------------+
        +---|    C-TC     |---+     +------|    C-TC     |
            |-------------|         |      |-------------|
            |     | C-PS  |     +------+   |CATS-Router 4|
    ........|     +-------|.....| C-PS |...|             |...
    :       |CATS-Router 2|     |      |   |             |  .
    :       +-------------+     +------+   +-------------+  :
    :                                                       :
    :                                            +-------+  :
    :                         Underlay           | C-NMA |  :
    :                      Infrastructure        +-------+  :
    :                                                       :
    :                                                       :
    :   +-------------+                 +-------------+     :
    :   |CATS-Router 1|  +-------+      |CATS-Router 3|     :
    :...|             |..| C-SMA |.... .|             |.....:
        +-------------+  +-------+      +-------------+
                |         |             |    C-SMA    |
                |         |             +-------------+
                |         |                     |
                |         |                     |
              +------------+               +------------+
            +------------+ |             +------------+ |
            |  service   | |             |  service   | |
            |  instance  |-+             |  instance  |-+
            +------------+               +------------+

              edge site 1                   edge site 2
Figure 1: CATS Functional Components

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

The computing metrics can be collected internally with a hosting infrastructure by a centralized monitor of the hosting infrastructure. Various tools such as Prometheus for this purpose. The monitor can pass the metrics to a network controller, which behaves as a C-PS. Then, the network controller calculates the optimal path and distribute the paths to CATS ingress routers. When a service request arrives at the CATS ingress router, it just steers the request to the path. The network controller distributed the metric update to the C-PS using south-bound protocol.

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

Similar to option 1, the network controller does not calculate the path. It just passes the computing metrics received from the cloud monitor to the C-PS embedded in a CATS ingress router. The C-PS at each CATS ingress router will proceed with path computation locally.

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

The C-SMA can be deployed in a distributed way. For example, C-SMA running at each site collects the computing metrics of the service instances running in a site. Then, it reports the metrics to a network controller, which behaved as a C-PS. The network controller calculates the best path for a service and distribute the path to a CATS ingress router.

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

Similar to option 3, each C-SMA collects the computing metrics of each site. Then it needs to distribute the metric to C-PS at each ingress router. It can do so directly or through a network controller.

8. Comparaison

Table 1: Comparison between different option
  Option 1 Option 2 Option 3 Option 4
Protocol None Southbound Southbound Southbound or Eastbound
CATS router requirement Low High Low High
Network controller requirement High Low High Low

9. Security Considerations

TBD

10. IANA Considerations

This document has no IANA actions.

11. References

11.1. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/rfc/rfc2119>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/rfc/rfc8174>.

11.2. Informative References

[I-D.du-cats-computing-modeling-description]
Du, Z., Fu, Y., Li, C., Huang, D., and Z. Fu, "Computing Information Description in Computing-Aware Traffic Steering", Work in Progress, Internet-Draft, draft-du-cats-computing-modeling-description-01, , <https://datatracker.ietf.org/doc/html/draft-du-cats-computing-modeling-description-01>.
[I-D.ldbc-cats-framework]
Li, C., Du, Z., Boucadair, M., Contreras, L. M., Drake, J., Huang, D., and G. S. Mishra, "A Framework for Computing-Aware Traffic Steering (CATS)", Work in Progress, Internet-Draft, draft-ldbc-cats-framework-03, , <https://datatracker.ietf.org/doc/html/draft-ldbc-cats-framework-03>.
[I-D.yao-cats-ps-usecases]
Yao, K., Trossen, D., Boucadair, M., Contreras, L. M., Shi, H., Li, Y., and S. Zhang, "Computing-Aware Traffic Steering (CATS) Problem Statement, Use Cases, and Requirements", Work in Progress, Internet-Draft, draft-yao-cats-ps-usecases-03, , <https://datatracker.ietf.org/doc/html/draft-yao-cats-ps-usecases-03>.

Acknowledgments

The author would like to thank Xia Chen, Guofeng Qian, Haibo Wang for their help.

Authors' Addresses

Hang Shi
Huawei Technologies
China
Tianle Yang
China Broadcast Mobile Network Company
China