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Hi free5gc,
It seems that there is no CreatedPDR IE when sending SessionEstablishmentResponse back to the SMF. The spec 29244 says that if the SMF request to allocate a local F-TEID then the UPF shall allocate a local F-TEID and send back to SMF in a CreatedPDR IE.
Many SMF will ask the UPF to allocate TEID.
Am i correct about this behavior? why is there no CreatedPDR in SessionEstablishmentResponse in go-upf?

Hi,

I would like to know why go-upf implementation ?
Is it run only in user space without interaction of the kernel ?

Thanks.

In my environment, the UPF is expected to use separate network interfaces for N3 and N9 interfaces.
The example UPF config allows two methods to write the configuration:

If there are multiple connection, set addr to 0.0.0.0 or list all the addresses

In the first method, I can write as:

gtpu:
  forwarder: 'gtp5g'
  ifList:
    - addr: '0.0.0.0'
      type: 'N3'

In the second method, I can write as:

gtpu:
  forwarder: 'gtp5g'
  ifList:
    - addr: '172.25.194.6'
      type: 'N3'
    - addr: '172.25.196.6'
      type: 'N9'

As tested, only the first method works.
This is caused by forwarder.NewDriver only listens on the first configured IP address, and ignores other addresses in ifList:

Suggested solution is updating the example config, asking user to take the first method only.

./free5gc/src/upf/lib/utlt/src/utlt_test.c: In function 'TestTerminate':
./free5gc/src/upf/lib/utlt/src/utlt_test.c:23:67: error: pointer 'it' used after 'free' [-Werror=use-after-free]
   23 |     for (TestNode *it = ListFirst(&testSelf.node); it != NULL; it = ListNext(it)) {
./free5gc/src/upf/lib/utlt/src/utlt_test.c:25:9: note: call to 'free' here
   25 |         free(it);
      |         ^~~~~~~~

I'm on kernel 5.4 and have successfully compiled the gtp5g-0.7.0 kernel module.

This error seems related to free5gc/free5gc#365 (unsolved)