Internet DRAFT - draft-shi-cats-analysis-of-metric-distribution
draft-shi-cats-analysis-of-metric-distribution
CATS H. Shi
Internet-Draft Huawei Technologies
Intended status: Informational 13 March 2023
Expires: 14 September 2023
Design analysis of methods for distributing the computing metric
draft-shi-cats-analysis-of-metric-distribution-00
Abstract
This document analyses different methods for distributing the
computing metric from the service instance to the ingress router.
Status of This Memo
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This Internet-Draft will expire on 14 September 2023.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 2
3. Requirement of distributing computing metric . . . . . . . . 3
4. Option 1: Centralized C-SMA + Centralized C-PS . . . . . . . 4
5. Option 2: Centralized C-SMA + Distributed C-PS . . . . . . . 4
6. Option 3: Distributed C-SMA + Centralized C-PS . . . . . . . 4
7. Option 4: Distributed C-SMA + Distributed C-PS . . . . . . . 4
8. Comparison . . . . . . . . . . . . . . . . . . . . . . . . . 4
9. Security Considerations . . . . . . . . . . . . . . . . . . . 5
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
11.1. Normative References . . . . . . . . . . . . . . . . . . 5
11.2. Informative References . . . . . . . . . . . . . . . . . 5
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
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.
* Computing-Aware Traffic Steering (CATS): An architecture that
takes into account the dynamic nature of computing resources and
network state to steer service traffic to a service instance.
This dynamicity is expressed by means of relevant metrics.
* CATS Service Metric Agent (C-SMA):Responsible for collecting
service capabilities and status, and reporting them to a CATS Path
Selector (C-PS).
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* CATS Path Selector (C-PS): An entity that determines the path
toward the appropriate service location and service instances to
meet a service demand given the service status and network status
information.
3. Requirement of distributing computing metric
The function components of the CATS is 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 metric of the service instance and distributing the metrics
to the C-PS. C-PS then select the path based on the computing metric
and network metric.
+-----+ +------+ +------+
+------+| +------+ | +------+ |
|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
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Figure 1: CATS Functional Components
4. Option 1: Centralized C-SMA + Centralized C-PS
The computing metric can be collected internally by a centralized
cloud monitor of the cloud platform. Various tools such as
Prometheus for this purpose. The cloud monitor can pass the metric
to the network controller. Then the network controller calculate the
optimal path and distribute the path to the CATS ingress router. The
ingress router just need to steer the flow 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 metric received from the cloud
monitor to the C-PS in the CATS ingress router. The C-PS at each
CATS ingress router will calculate the best path independently.
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 metric of the service
instance running in the site. Then it reports the metric to the
network controller. The network controller calculates the best path
and distribute the path to the CATS ingress router.
7. Option 4: Distributed C-SMA + Distributed C-PS
Similar to option 3, each C-SMA collect the computing metric 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. Comparison
+=============+========+============+============+==============+
| | Option | Option 2 | Option 3 | Option 4 |
| | 1 | | | |
+=============+========+============+============+==============+
| Protocol | None | Southbound | Southbound | Southbound |
| | | | | or Eastbound |
+-------------+--------+------------+------------+--------------+
| CATS router | Low | High | Low | High |
| requirement | | | | |
+-------------+--------+------------+------------+--------------+
| Network | High | Low | High | Low |
| controller | | | | |
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| requirement | | | | |
+-------------+--------+------------+------------+--------------+
Table 1: Comparison between different option
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, March 1997,
<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,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
11.2. Informative References
[I-D.du-cats-computing-modeling-description]
Du, Z., Fu, Y., Li, C., and D. Huang, "Computing
Information Description in Computing-Aware Traffic
Steering", Work in Progress, Internet-Draft, draft-du-
cats-computing-modeling-description-00, 5 March 2023,
<https://datatracker.ietf.org/doc/html/draft-du-cats-
computing-modeling-description-00>.
[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-01, 10
March 2023, <https://datatracker.ietf.org/doc/html/draft-
ldbc-cats-framework-01>.
[I-D.yao-cats-ps-usecases]
Yao, K., Eardley, P., Trossen, D., Boucadair, M.,
Contreras, L. M., Li, C., Li, Y., and P. Liu, "Computing-
Aware Traffic Steering (CATS) Problem Statement and Use
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Cases", Work in Progress, Internet-Draft, draft-yao-cats-
ps-usecases-00, 3 March 2023,
<https://datatracker.ietf.org/doc/html/draft-yao-cats-ps-
usecases-00>.
Acknowledgments
The author would like to thank Xia Chen, Guofeng Qian, Haibo Wang for
their help.
Author's Address
Hang Shi
Huawei Technologies
China
Email: shihang9@huawei.com
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