* [SBI] Handle and store AMF info
* [SBI] Add "target GUAMI" discovery option
* [SBI] Handle UeContextTransfer request and response messages
* [AMF] Handle NF discovery from AMF to AMF
* [AMF] Add UE Context Transfer Request/Response from AMF to AMF
* [SCP] Handle UeContextTransfer
* Follow-up on #3052
* [AMF] force authentication after 'Ue context transfer' for now
* [AMF] force authentication after 'Ue context transfer' for now
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Co-authored-by: Sukchan Lee <acetcom@gmail.com>
While they were continuing their fuzzy testing and developing PacketRusher, an unusual issue with the AMF was observed. The problem arises when a single Ethernet frame containing three bundled SCTP chunks is sent. This behavior is reproduced with PacketRusher when attempting to concurrently register two UEs with the same MSIN.
The expected behavior is that the PDU Session Establishment Accept is sent inside a DownlinkNASTransport to RAN UE NGAP ID 1. However, it is actually sent inside an InitialContextSetupRequest to RAN UE NGAP ID 2. The MAC of this NAS message is invalid for the Security Context of RAN UE NGAP ID 2 (probably valid for RAN UE NGAP ID 1)
Based on the standard document below, when the UE is in the IDLE state,
we checked the implicit timer and tried to send a message to the UE,
but it doesn't work properly.
So, first of all, I deleted the related code.
- TS 24.301 Ch 5.3.7
If ISR is not activated, the network behaviour upon expiry of
the mobile reachable timer is network dependent, but typically
the network stops sending paging messages to the UE on the
first expiry, and may take other appropriate actions
- TS 24.501 Ch 5.3.7
The network behaviour upon expiry of the mobile reachable timer is network dependent,
but typically the network stops sending paging messages to the UE on the first expiry,
and may take other appropriate actions.
TS23.007 17.4.1
19A PFCP based restart procedures
After a PFCP entity has restarted, it shall immediately update all local Recovery Time Stamps and shall clear all remote
Recovery Time Stamps. When peer PFCP entities information is available, i.e. when the PFCP Association is still alive,
the restarted PFCP entity shall send its updated Recovery Time Stamps in a Heartbeat Request message to the peer
PFCP entities before initiating any PFCP session signalling.
When UDM issues a SDM Data Change Notification with request to modify
RAT restrictions, AMF would crash when it tried to send a SDM
subscription delete as part of Network Initiated Deregistration.
Function amf_ue_sbi_discover_and_send() changed from returning boolean,
to returning integer (one of OGS_OK/OGS_ERROR/...).
[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.
Add additional check when receiving Deregistration Notification from
UDM. UE should already be in registered state before accepting the
request and deregistering the UE.
Also add additional check that PCF association policy exists before
sending a delete request to PCF.
UDM may send a Deregistration Notification to AMF, to deregister
specific UE from the network - Network-Initiated Deregistration.
Deregistration procedure includes sending Deregistration Request to UE,
starting a timer T3522, releasing PDU sessions from SMF, releasing PCF
policies from PCF, and waiting for Deregistration Accept from UE.
Not yet implemented is:
- to prevent deregistration of UE in case it has any emergency sessions,
- page UE when UE is in IDLE mode.
All process will be forcely exited if it failed to encode the S1AP/NGAP/GTP/PFCP message. It is to make sure there was no problem with the encoding of open5gs.
Matej Gradišar
Sukchan Lee
mitmitmitm
Bostjan Meglic
Flander Bojan
Bostjan Meglic