Page 324 - 5G Basics - Core Network Aspects

1 Core network aspects

– Send default accesses for FSC to the network (in MUE-initiated FSC mode);

– Receive decisions from the network on whether FSC applies to a connection, on the FSC mode and
on the default access;
– Provide handover indication and FSC indication if an access is added for a multi-connection;

– Exchange routing rules with the network;
– Route IP flow(s) by using routing access information;
– Notify to the network that a connection becomes "usable" or "Not usable" (in network-initiated FSC
mode).
7.3.2 FSC-enhanced AC-FE requirements

To support FSC, the following capabilities of the FSC-enhanced AC-FE are required:
– Negotiate the capability to support FSC and the FSC mode if the MUE is connected to the network.
This negotiation includes receiving the MUE request for FSC, as well as receiving the corresponding
support indications from other entities in the network;
– Receive MUE request on a default connection for FSC (in MUE-initiated FSC mode);

– Route IP flow(s) by using the routing access information;
– Exchange routing rules between network and MUE over control plane (protocols);
– Receive UE notification that a connection has become "usable" or "Not usable" (in network-initiated
FSC mode).
7.3.3 FSC-enhanced MPC-FE requirements

To support FSC, the following capabilities of the FSC-enhanced MPC-FE are required:
– The MPC-FE controls whether FSC may apply to a multi-connection;
– The MPC-FE may request to be notified by the AC-FE when a connection is added or removed for
the multi-connection;
– The MPC-FE may request to be notified by the AC-FE when a connection becomes not "Usable" or
"Usable" again;
– The MPC-FE can send policy control rules including access type routing information per policy
control rule to the AC-FE;
– The MPC-FE may subscribe to notifications from AC-FE about the routing rules received from the
MUE. If the routing rules received from the MUE comply with the user subscription, the MPC-FE
installs or modifies policy control rules based on these notifications, only in MUE-initiated FSC mode;
– The MPC-FE determines the desired access type routing information for a policy control rule and
accordingly installs or modifies policy control rules to the AC-FE. The MPC-FE request may be
rejected by the MUE due to local access conditions. In such cases, the MPC-FE is notified that the
policy control rule cannot be fulfilled, only for network-initiated FSC mode.

7.4 Procedures

7.4.1 MUE initiated FSC
Multi-connection FSC operates in the MUE-initiated mode in the following manner. When a MUE is
connected simultaneously to multiple access networks, the MUE can use multiple connections to send and
receive IP flows. Because of the changes in the access network, sometimes the MUE needs to move one IP
flow from one access to another. In that case, the MUE moves one or more IP flow(s) by providing a routing
rule to the network, thus updating the routing rules. MUE initiated FSC is shown in Figure 7-2.

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