PDU Session success,but N3 interface is not ok (test "echo request but no response")

PDUSessionSuccess.pcap (27.1 KB) 0113UPDlog.docx (21.6 KB)
With many helps from the forum ,We have the right procedure with commercial RAN, but we test from the RAN, N3 seems link failure. We test GTPU request (echo request) but with no response. Is there any experience to share ? Thanks !

ping is ok from each other

@chengjiaming1987 Hi,
I think you say that N3 seems link failure means UPF N3 Uplink didn’t receive packets from UE.
Please check following :

  1. Use sysctl -a | grep forward check if net.ipv4.ip_forward is set to 1
    To solve this problem: sysctl -w net.ipv4.ip_forward=1

  2. Check whether the rules or policy in iptables -nvL FORWARD block the UE packet.
    To solve this problem: iptables -I FORWARD 1 -j ACCEPT

  3. Check whether the PCFP rules are true or not ?
    Use the tool in updk/src/third_party/libgtp5gnl/tools/
    Enter ./gtp5g-tunnel list pdr to check pdr rules
    Enter ./gtp5g-tunnel list far to check far rules

Hi,
PCAP does not show UEContextSetupRequest from CU to DU.