SMFd uses first PFCP udp socket disregarding multiple IP homing

[n0p]

Open5GS Release, Revision, or Tag

commit 87b4e45

Steps to reproduce

Configure smf to use more than a pfcp server ip, connect an upf to the second address and the smf fails with:

05/10 15:37:52.803: [pfcp] ERROR: ogs_sendto(21, 0x56433981e798, 30, 0, 10.152.56.140:8805) failed (22:Invalid argument) (../lib/pfcp/path.c:120)) 05/10 15:37:29.290: [pfcp] ERROR: ogs_pfcp_xact_commit: ExpectationOGS_OK == ogs_pfcp_sendto(xact->node, pkbuf)' failed. (../lib/pfcp/xact.c:559)
`

21 is the fd for the udp socket on the other subnet (10.90.0.0) and the upf on the first ip connects correctly

Logs

05/10 15:32:10.166: [pfcp] ERROR: ogs_sendto(21, 0x7fe6a8071908, 16, 0, 10.152.56.140:8805) failed (22:Invalid argument) (../lib/pfcp/path.c:120)
05/10 15:32:10.166: [pfcp] ERROR: ogs_pfcp_xact_commit: Expectation `OGS_OK == ogs_pfcp_sendto(xact->node, pkbuf)' failed. (../lib/pfcp/xact.c:559)
05/10 15:32:12.382: [pfcp] WARNING: [2] LOCAL  No Reponse. Give up! for step 1 type 5 peer [10.152.56.140]:8805 (../lib/pfcp/xact.c:601)
05/10 15:32:12.666: [pfcp] ERROR: ogs_sendto(21, 0x7fe6a8071908, 16, 0, 10.152.56.140:8805) failed (22:Invalid argument) (../lib/pfcp/path.c:120)
05/10 15:32:12.666: [pfcp] ERROR: response_timeout: Expectation `OGS_OK == ogs_pfcp_sendto(xact->node, pkbuf)' failed. (../lib/pfcp/xact.c:599)
05/10 15:32:12.668: [pfcp] WARNING: [165] REMOTE Request Duplicated. Retransmit! for step 2 type 5 peer [10.152.56.140]:8805 (../lib/pfcp/xact.c:384)
05/10 15:32:12.668: [pfcp] ERROR: ogs_sendto(21, 0x7fe6a800d7c8, 35, 0, 10.152.56.140:8805) failed (22:Invalid argument) (../lib/pfcp/path.c:120)
05/10 15:32:12.668: [pfcp] ERROR: ogs_pfcp_xact_update_rx: Expectation `OGS_OK == ogs_pfcp_sendto(xact->node, pkbuf)' failed. (../lib/pfcp/xact.c:393)
05/10 15:32:15.167: [pfcp] ERROR: ogs_sendto(21, 0x7fe6a8071908, 16, 0, 10.152.56.140:8805) failed (22:Invalid argument) (../lib/pfcp/path.c:120)
05/10 15:32:15.167: [pfcp] ERROR: response_timeout: Expectation `OGS_OK == ogs_pfcp_sendto(xact->node, pkbuf)' failed. (../lib/pfcp/xact.c:599)
05/10 15:32:15.171: [pfcp] WARNING: [165] REMOTE Request Duplicated. Retransmit! for step 2 type 5 peer [10.152.56.140]:8805 (../lib/pfcp/xact.c:384)

Expected behaviour

smf should handle ip multi homing correctly

Observed Behaviour

fails on the second ip as it only uses the first udp socket fd

eNodeB/gNodeB

No response

UE Models and versions

No response

[acetcom]

@n0p

This is likely an DISCUSSION with the way it is set up or how it is used, rather than an ISSUE with open5gs.

Therefore, I've moved it to DISCUSSION first.

If you suspect a bug in open5gs, please share your config file, pcap, log file, etc. If there are any issues with Open5GS, I'll create an issue again.

Thanks a lot!
Sukchan

[n0p]

It was setup as:

pfcp:
server:
- address: ip A
- address: ip B
client:
upf:
- address: upf subnet A
- address: upf subnet B

The upfs are configured to be selected with different DNN

UPF B tries to connect to the smf, but the smf fails with
[pfcp] ERROR: ogs_sendto(21, 0x7fe6a8071908, 16, 0, upf B :8805) failed (22:Invalid argument) (../lib/pfcp/path.c:120)

When debugging, the filedescriptor 21 corresponds to the udp socket in the subnet A

[acetcom]

@n0p

SMF is not designed to be set up that way.

Is there any mention in the standards documentation or elsewhere that SMF can support this kind of functionality?

[n0p]

Haven't seen it, nor the contrary
I set up two server addresses and I had two open ports, so I assumed it would work :)