CATS                                                             H. Yao
Internet Draft                                             China Mobile
Intended status: Informational                                  X. Wang
Expires: April 23, 2024                                 Ruijie Networks
                                                                  Z. Li
                                                           China Mobile
                                                            D.H. Daniel
                                                        ZTE Corporation
                                                                 C. Lin
                                                   New H3C Technologies
                                                       October 23, 2023

         Computing and Network Information Awareness (CNIA) system
                           architecture for CATS


   This document describes a Computing and Network Information
   Awareness (CNIA)system architecture for Computing-Aware Traffic
   Steering (CATS). Based on the CATS framework, this document further
   describes a proposal detailed awareness architecture about the
   network information and computing information. It includes a new
   component and the corresponding interfaces and workflows in the CATS
   control plane.

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   This Internet-Draft will expire on April 23, 2024.

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Table of Contents

   1. Introduction...................................................3
   2. Architecture Components and Interfaces.........................3
   3. Architecture Workflow..........................................5
      3.1. Awareness Information Classification......................5
      3.2. Workflow..................................................6
         3.2.1. A centralized model..................................6
         3.2.2. A hybrid model.......................................8
         3.2.3. A distributed model..................................9
   4. IANA Considerations...........................................10
   5. Security Considerations.......................................10
   6. References....................................................10
      6.1. Normative References.....................................10
      6.2. Informative References...................................10
   Authors' Addresses...............................................12

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1. Introduction

   Computing-Aware Traffic Steering (CATS)[I-D.ldbc-cats-framework]aims
   to solve the problem of how the network edge can steer traffic
   between clients of a service and sites offering the service. To
   enable the computing- and network-aware traffic steering decisions,
   awareness of computing information and network information is the

   Currently there are some work being done on the classification and
   awareness of computing and network information. As described in[I-
   D.du-cats-computing-modeling-description], there could be two models
   of computing information: one is some detailed computing parameters,
   and another is a comprehensive computing level parameter.

   Further, the former includes some static information such as service
   ability, and some dynamic information such as service status.  This
   modeling document could be a solid foundation of CATS.  For the
   awareness solution of computing and network information, the current
   recommended methods are generally BGP[I-D.ietf-idr-5g-edge-service-
   metadata], BGP-LS[], and BGP-FS[I-
   D.yi-idr-bgp-fs-edge-service-metadata].  CATS Service Metric
   Agent(C-SMA) and CATS Path Selector (C-PS) components defined in [I-
   D.ldbc-cats-framework] could be deployed in different locations.

   Overall, the current awareness technology is some sporadic
   solutions. This document hopes to comprehensively sort out the
   computing and network awareness method and defines a comprehensive
   awareness architecture to support the different types of computing
   and network information, to facilitate the deployment of CATS.  This
   awareness architecture acts as the control plane of CATS.

2. Architecture Components and Interfaces

To consider various kinds of computing and network information, a
control center component is additionally introduced on the basis of
CATS framework. That is, CATS framework includes a control center and
CAT routers. A control center performs computing management and control
functions, including computing information  awareness function, service
scheduling function, etc., A control center collects computing and
network information, and schedules service based on computing and
network information.  CATS Router collects omputing and network
information, and schedules service based on computing and network
information, then forwarding data packets based on service scheduling.
 As a comprehensive awareness architecture CNIA supports both
distributed,centralized,hybrid awareness models.

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For some coarse-grained and relatively static information with low
update frequency, it is recommended to be aware in a distributed way.
The distributed way has better robustness and high scalability.
For some fine-grained dynamic information with a high update frequency,
it is recommended to aware it in a centralized way. Frequent
information updates will greatly increase the burden on network devices
and are not conducive to information convergence. The centralized way
is more suitable for the management of fine- grained dynamic
information.  This comprehensive-aware model is consistent with the
design philosophy of segment routing architecture[RFC8402]. The
services that require planning for dynamic resources, such as
TE(Traffic Engineering), are implemented by a centralized controller.
The BE(best-effort) service is still preserved on the devices and
implemented in a distributed manner, which could take advantage of
distributed robustness and reduce the burden of interfacing between the
controller and devices, facilitating deployment.
      CATS-control center                 |
    +----------------------------------+  |         +----------+
    |         Management Plane         |  |   API   |cloud     |
    +----------------------------------+  |<=========>|management|
    |           Control Plane          |  |           |platform  |
    +----------------------------------+  |           +---+------+
                    /\ CATS-SBI           |               |
                    ||                    |               |
     CATS-Forwarder \/                    |               |
    +----------------------------------+  |           +--------+
    |           Data Plane             |  |    API    | +--------+
    +----------------------------------+  |<=========>| |service |
                                          |           +-|instance|
                                          |             +--------+
                       Figure 1: CNIA System Arhicteture

To realize the scheduling of fine-grained computing information, the
control center introduces several components and interface:
   CATS Computing information Base(C-CIB):  Maintain fine-grained
      computing information, such as service connections,CPU
      performance,which may be obtained from the CATS-Forwarders or from
      the cloud management platform.

   CATS Network Metric information Base(C-NIB):  Maintain fine-grained
      network information, such as remaining bandwidth,delay, which
      could be obtained from the routers.

   CATS Path Calculation Unit(C-PCE):  Calculate optimal computing
      resource and network path based on C-CIB and C-NIB, and generate
      path policy and deliver to the CATS-Forwarders.

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   CATS-SBI interface:  An extended interface based on the traditional
      controller southbound interface between the CATS-Forwarders and
      the CATS-control center, could be used to report network and
      computing information from CATS routers to the CATS-control
      center, and also could be used to send path and service policy
      information or compute information to CATS-Forwarders.

   C-SMA API: An extended interface based on the traditional controller
      southbound interface between the CATS-Forwarders and the cloud
      management or between CATS-Forwarders and service-instance, used
      to report network and computing information to the CATS-control
      center or to CATS-Forwarders.

   Given the comprehensive architecture described above, this document
   proposes a comprehensive awareness system of the deployment
   location, real-time resource and service status, load information
   and requirements of computing resources and services.  On the one
   hand, the network aggregates the computing and network metrics
   reported by multiple nodes to build a globally unified computing and
   network status view.  On the other hand, the network completes the
   unified analysis of service, computing and network requirements,
   realizes the comprehensive perception and provides guarantee for
   computing-aware scheduling based on service requirement.

3. Architecture Workflow

3.1. Awareness Information Classification

   Currently the detailed network and computing parameters used by CATS
   have not yet reached a consensus in the industry, in order to avoid
   introducing too much signaling overhead into the whole network
   advertisement, this document proposes to classify the content of the
   computing advertisement according to the characteristics of the
   content and frequency of information announcement, and adopt
   different information awareness methods and information announcement
   protocols.  As shown in Table 1, the computing and network
   information could be classified into capability information and
   status information.  Capability information contains the deployment
   location and identifier information, and so on.  Status information
   tends to be some real-time status parameters of the network and
   computing, such as remaining bandwidth,delay,service connections,CPU
   performance.  This type of information is mainly used for some
   services that are sensitive to network and computing status, such as
   AR/VR services.

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   | Awareness   |   Network information   |  Computing information  |
   | information |                         |                         |
   | Capability  | Device location; Device |   Service ID; Service-  |
   | parameters  |      type; Topology     |  domain name; Computing |
   |             |       information       |   energy consumption;   |
   |             |                         |   Computing cost; Peak  |
   |             |                         |    value of available   |
   |             |                         |        computing        |
   | Status      |      Service policy     |   Number of available   |
   | parameters  |   information; Traffic  |   service connections;  |
   |             |       information       |   Available resources;  |
   |             | (bandwidth,delay,packet |       CPU/GPU/NPU       |
   |             | loss rate,delay jitter) |   performance; Storage  |
   |             |                         | capacity; Service delay |

                  Table 1: Awareness information content examples

   Table 1 provides some detailed parameters examples about the two
   kinds of awareness information.

3.2. Workflow

3.2.1. A centralized model

   In centralized mode, the collection of computing information and the
   selection of paths are implemented by the controller, which is then
   sent to the CATS-Forwarder via the CATS-SBI interface.

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         CATS-control center
        +----------------------------------+           +----------+
        | Management                       | API     |cloud     |
        | Plane   +------+----------+      |<=========>|management|
        |         |      |          |      |           |platform  |
        |         |   +--v---+   +--v---+  |           +---+------+
        |         |   |C-CIB |   |C-NIB |  |               |
        |         |   +---^--+   +--^---+  |               |
        |         |       |         |      |               |
        +---------|-------|---------|------+               |
        | Control |   +---v--+   +--v---+  |               |
        | Plane   |   |C-SMA |   |C-NMA |  |               |
        |         |   +------+   +------+  |               |
        |         |                        |               |
        |         |   +-------+            |               |
        |         +-->| C-PCE |            |               |
        |             +-------+            |               |
        +----------------------------------+               |
                        /\ CATS-SBI                        |
                        ||                                 |
         CATS-Forwarder \/                                 |
        +----------------------------------+               |
        | Data      +------+               |            +--------+
        | Plane     |C-TC  |               | ...........| +--------+
        |           +------+               | ...........| |service |
        +----------------------------------+            +-|instance|
                          Figure 2: centralized model

    For some services that are sensitive to computing and network
   status, especially latency, such as AV/VR services, the network
   needs to be able to perceive detailed computing information and
   network information to meet the strict requirements of the service.
   This kind of computing information could be aware by the CATS-
   control center by restful interface from cloud management platform.
   The network information could be aware by the BGP-LS or telemetry
   interface to get the status parameters such as remaining bandwidth
   and the delay.  Further, CATS-control center performs service
   scheduling according to the computing information and network
   information, then generates routing policy and sends to CATS ingress
   router . When CATS ingress router receives the service demand from
   the client, it selects the optimal service instance and network
   policy, and maintains the instance affinity subsequently.

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3.2.2. A hybrid model

   In hybrid mode, both the controller and the CATS-Forwarder with
   routing capabilities can perform the collection of computing
   information and the selection of paths. The CATS-Forwarder with
   routing capabilities can perform more precise path selection
   operations based on instructions from the controller. CATS-
   Forwarders without routing capabilities, on the other hand, directly
   forward data based on the results provided by the controller.

                  CATS-control center
                 +----------------------------------+              +----------+
                 | Management                       |      API    |cloud     |
                 | Plane   +------+----------+      |<============>|management|
                 |         |      |          |      |              |platform  |
                 |         |   +--v---+   +--v---+  |              +---+------+
                 |         |   |C-CIB |   |C-NIB |  |                  |
                 |         |   +---^--+   +--^---+  |                  |
                 |         |       |         |      |                  |
                 +---------|-------|---------|------+                  |
                 | Control |   +---v--+   +--v---+  |                  |
                 | Plane   |   |C-SMA |   |C-NMA |  |                  |
                 |         |   +------+   +------+  |                  |
                 |         |                        |                  |
                 |         |   +-------+            |                  |
                 |         +-->| C-PCE |            |                  |
                 |             +-------+            |                  |
                 +----------------------------------+                  |
                    /\ CATS-SBI               /\ CATS-SBI              |
                    ||                        ||                       |
    CATS-Forwarder1 \/        CATS-Forwarder2 \/                       |
    +-------------------+     +--------------------------------+       |
    | Data     +------+ |     | Data  +-----+-------+          |       +--------+
    | Plane    |C-TC  | |     | Plane   |C-TC |C-PS   |        |...... | +--------+
    |          +------+ |     |         +-----+---+---+        |...... | |service |
    +-------------------+     |                   |            |       +-|instance|
                              |            +------+---+        |         +--------+
                              |            |          |        |
                              |         +--+---+    +-+----+   |
                              |         |C-SMA |    |C-NMA |   |
                              |         +------+    +------+   |
                           Figure 4: hybrid model

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   For some high-value customers, hybrid awareness can be deployed to
   accurately match customer requirements.  After the CATS-control
   center obtains computing and network information through SBI or
   restful interfaces, the details of this information are directly
   transmitted to the CATS ingress routers.  The device performs
   accurate resource matching and continuous experience detection after
   receiving service traffic.

3.2.3. A distributed model

   In distributed mode, these operations are performed by the CATS-
   Forwarder itself, while the controller is responsible for monitoring
   the information.

         CATS-control center
        | Management  +------+   +------+  |
        | Plane       |C-CIB |   |C-NIB |  |
        |             +------+   +------+  |            +----------+
        |                                  |            |cloud     |
        +----------------------------------+            |management|
        | Control                          |            |platform  |
        | Plane                            |            +---+------+
        +----------------------------------+                |
                            /\ CATS-SBI                     |
                            ||                              |
            CATS-Forwarder  \/                              |
        +--------------------------------+                 |
        | Data    +-----+-------+        |   API    +--------+
       | Plane   |C-TC |C-PS   |        |<========= | +--------+
        |         +-----+---+---+        |           | |service |
       |                   |            |           +-|instance|
        |            +------+---+        |             +--------+
        |            |          |        |
        |         +--+---+    +-+----+   |
        |         |C-SMA |    |C-NMA |   |
        |         +------+    +------+   |
                         Figure 3: distributed model

   For distributed mode, the ingress CATS router responsibles for
   collecting computing and network information and scheduling service.
   When the ingress CATS router receives the service demand from the
   client it makes decision of the service instance to access
   independently according to the service instances status and network
   status and maintains instance affinity.  The detailed workflow can
   be seen in[I-D.ldbc-cats-framework].

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4. IANA Considerations


5. Security Considerations


6. References

6.1. Normative References

   [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
             Decraene, B., Litkowski, S., and R. Shakir, "Segment
             Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
             July 2018, <>.

6.2. Informative References

   [I-D.ietf-idr-5g-edge-service-metadata] Dunbar, L., Majumdar, K.,
             Wang, H., Mishra, G. S., and Z. Du, "BGP Extension for 5G
             Edge Service Metadata", Work in Progress, Internet-Draft,
             draft-ietf-idr-5g-edge-service- metadata-04, 6 July 2023,

   [] Li, C., Shi, H., He, T., Pang,
             R., and G. Qian, "Distribution of Service Metadata in BGP-
             LS", Work in Progress, Internet-Draft, draft-ls-idr-bgp-
             ls-service-metadata-01, 24 February 2023,

   [I-D.yi-idr-bgp-fs-edge-service-metadata] yixinxin, He, T., Shi, H.,
             Ding, X., and H. Wang, "Distribution of Service Metadata
             in BGP FlowSpec", Work in Progress, Internet-Draft, draft-
             yi-idr-bgp-fs-edge-service-metadata-00, 23 February 2023,

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   [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-02, 22 June 2023,

   [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, 4 July 2023,

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Authors' Addresses

   Huijuan Yao
   China Mobile
   No.32 XuanWuMen West Street

   Xuewei Wang
   Ruijie Networks

   Zhiqiang Li
   China Mobile
   No.32 XuanWuMen West Street

   Daniel Huang
   ZTE Corporation
   Phone: +86 13770311052

   Changwang Lin
   New H3C Technologies

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