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[AMF] Added Additional-GUTI to ClearText (#3315)

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UE attached to 4G cell, terminates 4G connection,
then attempts 5G cell attach with TAC update - fails connection

Setup a UE on a 4G cell. Also have a 5G cell available to the UE.

Next, disable the 4G cell. The 4G connection terminates normally.

The UE scans the network and finds the 5G cell.

At this time the UE sends a registration to the 5G cell.
Open5gs sent back a reject with reason "Semantically incorrect message".
Then the UE did not try to attach again and lost the call forever.

Compare this scenario with a different core that we tested this scenario on.
With a different core (other than open5gs) the core sent back a reject
also but with a reason "UE can't be derived by network".
Then the UE tried attach again and the 5G call was successful.
Although this was successful for the other core it could be suggested
that not rejecting at all is good behavior.

There is a workaround which is that the Samsung UE could be put into
airplane mode and taken out of airplane mode and at that point
the UE is able to attach to the 5G cell. But this is a lot of manual effort
on the user of the UE which could be avoided with a simple open5gs change.

Note: Issue only happens when registration request + tracking area update
occurs on 5G cell attach following LTE cell being disabled.
If only registration occurs without a tracking area update
(such as the first time system is up) then it is ok with no rejection.

To solve this issue, added Additional-GUTI to the ClearText Group.
This commit is contained in:
Sukchan Lee
2024-07-12 13:19:02 +09:00
parent 6f73a74690
commit 1b82ff08b6
1 changed files with 2 additions and 1 deletions
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3
src/amf/gmm-handler.c
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@@ -107,7 +107,8 @@ ogs_nas_5gmm_cause_t gmm_handle_registration_request(amf_ue_t *amf_ue,
(OGS_NAS_5GS_REGISTRATION_REQUEST_UE_SECURITY_CAPABILITY_PRESENT| \
OGS_NAS_5GS_REGISTRATION_REQUEST_UE_STATUS_PRESENT| \
OGS_NAS_5GS_REGISTRATION_REQUEST_EPS_NAS_MESSAGE_CONTAINER_PRESENT| \
OGS_NAS_5GS_REGISTRATION_REQUEST_NAS_MESSAGE_CONTAINER_PRESENT)
OGS_NAS_5GS_REGISTRATION_REQUEST_NAS_MESSAGE_CONTAINER_PRESENT| \
OGS_NAS_5GS_REGISTRATION_REQUEST_ADDITIONAL_GUTI_PRESENT)
if (ngap_code == NGAP_ProcedureCode_id_InitialUEMessage &&
registration_request->presencemask &