Assume the UE has Attached, the session has been created,
and is in the IDLE state with the UEContextRelease process.
This could result in the following call flow.
1. TAU request without Integrity Protected
2. Authentication request/response
3. Security-mode command/complete
MME can be performed simultaneously by the HSS(S6A) and UE(S1AP).
Update-Location-Request
Service request
Service reject
Delete Session Request
Delete Session Response
Update-Location-Answer
UEContextReleaseCommand for Service reject
TAU reject
UEContextReleaseCommand for TAU reject
UEContextReleaseComplete
UEContextReleaseComplete
MME crashes when UE sends a service request(S1AP) during ULR/ULA(S6A) with HSS,
which has been fixed.
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)
[ETSI TS 128 552 V16.9.0](https://www.etsi.org/deliver/etsi_ts/128500_128599/128552/16.09.00_60/ts_128552v160900p.pdf)
5.2.2 Registration procedure related measurements
SNSSAI labels are not provided.
- Number of registration requests received by the AMF is
exposed for each registration type.
```
fivegs_amffunction_rm_reginitreq 1
fivegs_amffunction_rm_regmobreq 0
fivegs_amffunction_rm_regperiodreq 0
fivegs_amffunction_rm_regemergreq 0
```
- Number of successful initial registrations at the AMF is
exposed for each registration type.
```
fivegs_amffunction_rm_reginitsucc 1
fivegs_amffunction_rm_regmobsucc 0
fivegs_amffunction_rm_regperiodsucc 0
fivegs_amffunction_rm_regemergsucc 0
```
- The existing counter of failed registrations at the AMF
is exposed separately for each registration type.
```
fivegs_amffunction_rm_reginitfail
fivegs_amffunction_rm_regmobfail
fivegs_amffunction_rm_regperiodfail
fivegs_amffunction_rm_regemergfail
```
5.2.5.2 Measurements for 5G paging
Number of 5G paging procedures initiated at the AMF:
```
fivegs_amffunction_mm_paging5greq 1
```
Number of successful 5G paging procedures initiated at the AMF:
```
fivegs_amffunction_mm_paging5gsucc 1
```
5.2.11 Authentication procedure related measurements
Number of authentication requests:
```
fivegs_amffunction_amf_authreq 2
```
Number of authentication rejections:
```
fivegs_amffunction_amf_authreject 1
```
Number of failed authentications due to parameter error:
```
fivegs_amffunction_amf_authfail{cause="21"} 1
```
5.2.8 UE Configuration Update procedure related measurements
Number of UE Configuration Update commands requested by the AMF:
```
fivegs_amffunction_mm_confupdate 2
```
Number of UE Configuration Update complete messages received by the AMF:
```
fivegs_amffunction_mm_confupdatesucc 1
```
Expose RM metrics with labels according to ETSI TS 128 552 V16.13.0 in
AMF by using hash.
The metrics are named respecting the rule:
<generation>_<measurement_object_class>_<measurement_family_name>_<metric_name_as_in_TS_128_552>
Since slice itself is not unique, the plmnid label is exposed in
addition to snssai.
RegInitFail is exposed as an alternative to RegInitReq and RegInitSucc
counters so cause label can be provided. It counts rejected registrations
and rejected authentications.
Rejected authentications are counted under label cause="0".
Exposed metrics example:
-standard gauge:
fivegs_amffunction_rm_registeredsubnbr{plmnid="00101",snssai="1000009"} 1
-nonstandard counter:
fivegs_amffunction_rm_reginitfail{cause="3"} 4
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.
TS24.501
8.2.11 DL NAS transport
8.2.11.4 5GMM cause
The AMF shall include this IE when the Payload container IE
contains an uplink payload which was not forwarded and
the Payload container type IE is not set to "Multiple payloads".
-0-
As such, this function 'nas_5gs_send_gsm_reject()' must be used
only when an N1 SM message has been forwarded to the SMF.
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.
Previously, AMF would sends PDUSessionResourceSetupRequest
when the following conditions were met:
- gNB didn't send UE Context Request IE of InitialUEMessage
- AMF should send SMF generated TRANSFER message(PDU_RES_SETUP_REQ)
to the gNB
However, in issues #771, the gNB did not accept
PDUSessionResourceSetupRequest. Perhaps the gNB engineer thought
that if gNB needs to send data traffic to the UE, AMF should send
an InitialContextSetupRequest regardless of UE Context Request IE.
This is because gNB requires the kgNB security context
for data connection.
So, in this case, Open5GS-AMF decided to send
an InitialContexSetupRequest regardless of
whether it received UE Context Request IE of InitialUEMessage.
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.
Sukchan Lee
Gaber Stare
mitmitmitm
Bostjan Meglic