Control Plane-Initiated N4 Association Support

This chapter covers the following topics:

Feature Summary and Revision History

Summary Data

Table 1. Summary Data
Applicable Product(s) or Functional Area 5G-UPF
Applicable Platform(s)

VPC-SI

Feature Default Setting Disabled – Configuration Required
Related Changes in this Release Not Applicable
Related Documentation Not Applicable

Revision History

Table 2. Revision History
Revision Details Release
First Introduced. 2020.02.0

Feature Description

SMF initiated N4 Association Setup Procedure

The N4 association set up procedure sets up an N4 association between the Session Management Function (SMF) and User Plane Function (UPF). It enables the SMF to use the UPF resources to establish the N4 sessions. The SMF and UPF exchange the supported functionalities on each side during this procedure.

How it Works

The N4 association setup is initiated by the SMF. The setting of N4 association setup procedure is controlled through sx-association initiated-by-cp CLI command in the Control Plane Group Configuration mode. By default, the configuration is set to support the UPF-initiated N4 association setup procedure.

Call Flows

Session Management Function Initiated N4 Association Setup Procedure

The following call flow depicts the SMF-initiated N4 Association Setup procedure.

Step Description
1 The SMF initiates the N4 Association Setup procedure to request the setup of an N4 association towards a UPF prior to establishing a first N4 session on this UPF.
2 After receiving an N4 Association Setup Request, the UPF sends an N4 Association Setup Response.

Configuring the CP-Initiated N4 Association Setup Feature

This section describes how to configure the CP-Initiated N4 Association Setup feature.

Configuring this feature involves using the "sx-association initiated-by-cp" CLI command in the Control Plane Group Configuration mode. The default configuration is UPF-initiated N4 association setup procedure.

Use the following configuration to configure the N4 association setup feature.


configure 
   context 
      control-plane-group group_name 
         peer-node-id ipv4-address ip_address interface n4 
         sx-association { initiated-by-cp | initiated-by-up } 
         end 

NOTES:

  • initiated-by-cp: This keyword is used to initiate the Sx association request through control plane.

  • initiated-by-up: This keyword is used to initiate the Sx association request through user plane.

  • By default, the UPF-initiated N4 association setup procedure is configured.

  • To revert to the default setting, use the no sx-association command.

CP-Initiated N4 Association Setup Feature OAM Support

This section describes operations, administration, and maintenance information for this feature.

Show Command Support

Use the following show command to verify the CP-initiated N4 Association Setup feature configuration.
show control-plane-group all 
The following is a sample output of the show command.
show control-plane-group all
Control Plane Group
---------------------------------
Name           : default
Sx-Association : initiated-by-up
Name           : default
Sx-Association : initiated-by-up
Node-Id        : 1.1.2.2
Interface      : N4