Roamer Calls with N3 and N9 Separation

Following call flow process change happens during Roamer calls:

  • For roamers, vSMF sends source interface type as N9 while creating downlink (DL) PDRs for N9 traffic and as “N3 3GPP Access” while creating Uplink (UL) PDRs for N3 traffic in N4 messages.

  • The hSMF sends source interface type as N9 while creating UL PDRs for N9 traffic and as S5-U while creating UL PDRs (secondary PDR) for 4G traffic.

  • The UPF allocates two different tunnels for the NR and 4G default bearer/flow.

Note
To achieve further optimization, SMF can send N9 as source interface type while creating both 4G and 5G UL PDRs if required, without any changes on the UPF.