Page 1380 - 5G Basics - Core Network Aspects

3 Signalling aspects

Figure 2 – Service management message types

Detailed descriptions of the message pairs are as follows:
1) Create service: used for setting up a service instance for a dedicated user flow. The functionalities
of the service instance are specified by the parameters enclosed in the message. The response
message for the create service shows the handling results, either success or failure. If it is successful,
a service instance ID will be enclosed. The service instance ID can be used to fast index the service
instance.
2) Delete service: used for deleting the service instance created by the create service message. The
service instance can only be deleted when there is no flow steering into this service instance. The
response message for the delete service message shows the handling result.
3) Chain service: used for steering the flow traffic across the service instances or the service nodes.
Each service node can run multiple service instances with each one having its own service instance
ID.
4) Unchain service: used for stopping the steering of flow traffic to the specified service.
5) Update service: used for updating the configurations of a specified service.
No transport protocol for the signalling messages is specified here. No message content format is specified
here either.

The signalling messages may be XML-based messages over (or carried by) TCP, UDP, SCTP, TLS, etc. All of the
messages are in the message header and message body format.

The message header and message body format are described in Figure 3 as follows:

Figure 3 – Message composition

The message header field specifies the message types. The message body field contains the message
contents.

The message header field should contain the following information:
1) Message type: uniquely specifies the type of the message;
2) Message length: specifies the length of the message body, which comes right after the message
header;

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