Architecture

This section describes the architecture for the home routing roaming support feature.

Bufffering and Debuffering on the vUPF

The buffering and debuffering procedure on the vUPF for the UPF HR roaming, are as follows:

  1. Two dummy PDRs (UL or DL) is created initially at vUPF by vSMF with default value as QFI and the buffering as an FAR action.

  2. The packets coming from the N3 and N9 interfaces get buffered based on the FAR action before doing a packet classification and application of policy.

  3. If buffered packet count exceeds the configured limits then the subsequent packets are dropped.

  4. The buffered packets are sent for classification and policy application after the update FAR is received with action as forward and updated TEID in modify request from vSMF.

  5. The vSMF initiates the removal of default QER and URR while sending the update FAR with action forward and sends a new PDR with the required QER and URR.

  6. The packets are sent on the required interface that is based on the QFI defined in the new QER.

  7. If there is no matching PDR with TEID and QFI installed then the debuffered packets is dropped.

Charging — Predef and Dynamic Rules on the hUPF

The charging predef and dynamic rules on the hUPF, are as follows:

  1. The SMF associates FBC URRs + QBC URRs + Session URRs with dynamic PDRs.

  2. The SMF associates QBC URRs + Session URRs with predef PDRs.

  3. The UPF associates the URRs created by installed global PDRs to the received predef PDRs QBC URRs + Sess URRs.

  4. The QBC URRs have no Linked URRs.

  5. The QBC URRs include no FBC URRs or Session URRs usage reporting.

  6. The UPF links the Session URRs to FBC URRs as Linked URRs.

  7. The Session URRs include FBC URRs and QBC URRs usage reporting.

  8. The UPF relies on the SMF for the update or removal of each of the QBC and Sess URRs.

Charging — Static Rules on the hUPF

The charging static rules on the hUPF, are as follows:

  1. The SMF associates FBC URRs + QBC URRs + Session URRs with RB PDRs.

  2. The UPF associates the URRs created by installed global PDRs to the received RB PDRs QBC URRs + Sess URRs.

  3. The UPF does not link QBC URRs with any URRs.

  4. The UPF links the static FBC URRs with the Session URRs.

  5. The UPF links the Session URRs to the FBC URRs as linked URRs for usage reporting.

  6. The UPF relies on the SMF for the update or removal of each of the QBC and the SMF URRs.