OsmoGGSN sends Direct Tunnel packets to the wrong IP address
When GTP-U Direct Tunnel is used, GGSN shall send all data packets to the RNC.
But sometimes when data packets are queued right after the Echo Request message from the SGSN, data packets are sent to the SGSN instead of RNC, causing SGSN to crash.
Attached is a pcap of the bug.
Packet no. 1-6 are correctly sent to the RNC at 10.27.30.100
But after packet no. 18 Echo response subsequent GTP-U packets are wrongly sent to the SGSN at 10.27.30.99 and SGSN reports Error indication.
Updated by manatails over 1 year ago
I found that st_pmm_idle_on_enter() from osmo-sgsn is resetting the GTP-U address.
Is it necessary when the RNC is in Direct Tunnel mode? I am not sure what the correct behavior is. Disabling st_pmm_idle_on_enter seems to fix the problem for me.