[AMF] Implicit Network-initiated Deregistration
Two timers are introduced (both with duration of T3512 + 4 min):
-MOBILE_REACHABLE
-IMPLICIT_DEREGISTRATION
MOBILE_REACHABLE is set when NAS connection for the UE is released.
IMPLICIT_DEREGISTRATION is set when MOBILE_REACHABLE expires.
On MOBILE_REACHABLE expiry Paging is ignored.
On IMPLICIT_DEREGISTRATION expiry:
-UE's RM_State is set to DEREGISTERED
-UE is Nudm_SDM_Unsubscribed
-UE is Nudm_UECM_Deregistered
-PDU sessions are released
-AM policies are deleted
Existing flag amf_ue->network_initiated_de_reg is used.
AMF subscribes to UDM for each registered UE.
At the moment, UDM does not send callback to AMF when any of the UE's
properties in the database changes.
At the moment, AMF does properly parse the ModificationNotification, but
does not do anything useful.
If parameter.ignore_requsted_nssai is true,
AMF will ignore the UE Requested NSSAI and create an allowed-NSSAI
based on the Default S-NSSAI in the Subscription DB.
AMF checks whether it can serve all the S-NSSAI(s) from
the Requested NSSAI present in the Subscribed S-NSSAIs
(potentially using configuration for mapping S-NSSAI values
between HPLMN and Serving PLMN), or all the S-NSSAI(s) marked
as default in the Subscribed S-NSSAIs in the case that
no Requested NSSAI was provided or none of the S-NSSAIs
in the Requested NSSAI are permitted,
i.e. do not match any of the Subscribed S-NSSAIs or not available
at the current UE's Tracking Area (see clause 5.15.3).
o Tester
1. UE registered to 5GS and can connect to internet.
2. Turn off the UE and turn on the UE immediately
3. UE send PDU session request message
without sending registration complete
o Analysis Result
1. UE sends registration request with unknown GUTI
2. AMF send registration accept without GUTI
3. UE skips the registration complete
So, we need the handler UL NAS Transport in this state.
Bostjan Meglic
Sukchan Lee
mitmitmitm