]> Huawei Technologies

China shihang9@huawei.com

Routing Area CATS This document analyses different methods for distributing the computing metric from the service instance to the ingress router.

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 , traffic steering that takes computing resource metrics into account would improve the quality of service. Such computing metrics are defined in . This document analysis different methods for distributing these metrics.

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 when, and only when, they appear in all capitals, as shown here. This document uses terms defined in . 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).
• 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.

Requirement of distributing computing metric The function components of the CATS is defined in (see , 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.

CATS Functional Components

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.

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.

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.

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.

Comparison 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

Security Considerations TBD

IANA Considerations This document has no IANA actions.

References Normative References In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. Informative References China Mobile Huawei Technologies Orange Telefonica Huawei Technologies Huawei Technologies China Mobile Many service providers have been exploring distributed computing techniques to achieve better service response time and optimized energy consumption. Such techniques rely upon the distribution of computing services and capabilities over many locations in the network, such as its edge, the metro region, virtualized central office, and other locations. In such a distributed computing environment, providing services by utilizing computing resources hosted in various computing facilities (e.g., edges) is being considered, e.g., for computationally intensive and delay sensitive services. Ideally, services should be computationally balanced using service-specific metrics instead of simply dispatching the service requests in a static way or optimizing solely connectivity metrics. For example, systematically directing end user-originated service requests to the geographically closest edge or some small computing units may lead to an unbalanced usage of computing resources, which may then degrade both the user experience and the overall service performance. We have named this kind of network with dynamic sharing of edge compute resources “Computing-Aware Networking” (CAN). This document provides the problem statement and the typical scenarios of CAN, which is to show the necessity of considering more factors when steering the traffic to the appropriate service instance based on the basic edge computing deployment to provide the service equivalency. China Mobile China Mobile Huawei Technologies ZTE This document describes the considerations and the potential architecture of the computing information that needs to be notified in the network in Computing-Aware Traffic Steering (CATS). Huawei Technologies China Mobile Orange Telefonica Juniper Networks, Inc. ZTE Verizon Inc. This document describes a framework for Computing-Aware Traffic Steering (CATS). Particularly, the document identifies a set of CATS components, describes their interactions, and exemplifies the workflow of the control and data planes.

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