N4 Session Establishment and Modification Procedure for IPv4v6 Call Flow
The following call flow provides a high-level description of the N4 session establishment and modification procedure for IPv4v6.
The IPv4v6 session establishment and modification procedure are similar to the IPv6 session establishment and modification procedure, except for the following procedures:
Step | Description |
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1 | In the session establishment request, a PDR IE is created to include both IPv4 and IPv6 UE addresses. The SDF filter also includes the IPv4 and IPv6 filters for selecting the PDRs. |
2 | When the IPv6 address is assigned to the UE, an extra procedure – Router Solicitation and Router Advertisement – is required. The UE sends the Router Solicitation message to the network to receive the link layer address, once the session is established. The UPF forwards this message to the SMF and the SMF sends the Router Advertisement Message with the required parameters for configuring the IPv6 address of the UE. |
3 | The RS/RA between UPF and SMF is GTP-u encapsulated. In addition, the SMF sends an extra pair of PDRs during session establishment and modification procedure, in which the GTP-u tunnel IDs are exchanged for GTP-u tunneling. |
4 |
The additional pair of PDRs that are sent from the SMF are as follows:
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5 | The UE sends the IPv6 traffic to PDN once the RS/RA procedure is complete. |
6 | No additional procedures are required for the IPv4 traffic for this PFCP session. |