UPF Traffic Duplication

Hi there!

I was wondering if the free5GC UPF supports traffic duplication and how I would configure it. My goal is sending user traffic to two destination addresses instead of only one. This could be a use-case for the branching point feature, where traffic is duplicated by an i-UPF and sent to two PSA UPFs for redundancy reasons.

The PFCP session rules in the SMF code have a single FAR. I noted that there is a “Dupl” field in the pfcpType.ApplyAction struct, but I see only a single ForwardingParameters option for a FAR. So adding a second forwarding configuration to a single PDR does not work.

To add a second PDR, I would need to create an entire Tunnel and add the PDR with the second FAR. However, the tunnel would have a different TEID and thus traffic from the gNB would have a different header.

What would be an acceptable procedure to add a second FAR to one Tunnel and duplicate traffic?


PS: The specification describes such a use-case in TS 123.501, Figure But what I want to do is both encapsulate GTP-U traffic and send out the N6 link to the data network at the same time.

A workaround for me would be duplicating traffic outside the UPF, so using mechanisms on the host machine itself. I was just wondering if such a scenario seems achievable.

Hi there. Unfortunately, even modifying the code for containing multiple FARs. The gtp5g doesn’t support multiple FARs so it is not achievable so far.

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Best regards,