QoS Feature Support in Free5GC

[Gowrish]

I am using latest version of Free5GC. I am trying to check the QoS flow feature by enabling specific QoS, based on Packet filter. In the Free5GC GUI, I have filled in the default 5QI with AMBR UL/DL values and have also filled in the flow rules with IP filter, 5QI (GBR/Non-GBR), GBR UL/DL, MBR UL/DL, etc. But even after updating the flow rules with IP filter and required GBR UL/DL, it is not getting considered in the traffic.
We observed that the traffic is only getting altered when there is any change in the AMBR which is associated with the default 5QI. The IP filter, GBR UL/DL values given under the flow rules are not getting considered during the traffic flow.

What is the expected behavior in such cases when flow rules are defined with GBR QoS, GBR UL/DL in the GUI.

I have attached the snapshot of flow rules defined in GUI.

[williamlin0518]

In the gtp5g, QoS is disabled by default. The qos_enable variable in src/pfcp/pdr.c` is set to 0 initially.

And why AMBR changes because separately from the QoS enforcement mechanism

GBR and specific flow rules with IP filters require QoS to be enabled and in trTCM.c use GBR/MBR rates you’ve configured.

if (get_qos_enable() && tp != NULL) {
    color = policePacket(tp, volume_mbqe);
}
if (color == Red) {
    volume = 0;
    // Packets eventually get dropped
}

In current implementation, GBR stored in the QER structure but aren’t directly used for traffic enforcement. Only MBR shape traffic by creating token bucket-based policers that mark packets colors based on conformance to the configured rate.

[Gowrish]

Hi Team,

Thank you for the update. I have tried the same in Version 3.4.4 and I observed that the IP filter with required flow rules got applied in the traffic. I have filled in same IP filter with required Bit rate for the flow rules and it got reflected in the traffic. Below snapshot is from the flow rules which I have used. Kindly help me to understand this traffic flow behavior for latest version.

Also, I have triggered the PDU modification with updated QoS through PCF and I have observed that the updated QoS Bit rates are getting passed to the UPF in PFCP modification request. Can you please let me know whether this will be applied to Data plane traffic as well.