1. HandoverRequired
2. HandoverRequest
3. HandoverFailure
4. UEContextReleaseCommand
5. HandoverPreparationFailure
If UEContextReleaseComplete is not received,
the Source-UE will have the Target-UE.
6. HandoverRequired
There may be cases where the Source UE has a Target UE
from a previous HandoverRequired process. In this case,
it is recommended to force the deletion of the Target UE information
when receiving a new HandoverRequired.
7. HandoverRequest
8. HandoverFailure
9. UEContextReleaseCommand
10. UEContextReleaseComplete
11. HandoverPreparationFailure
... Crashed ...
There is an issue with SESSION RELEASE not working properly
depending on the PDU session release complete order
in the PDUSessionResourceReleaseResponse.
If the AMF receives PDUSessionResourceReleaseResponse
followed by PDU session release complete, it works correctly.
However, if it receives PDU session release complete
followed by PDUSessionResourceReleaseResponse, it does not work correctly
and sends an Error Indication to the UE/gNB.
To fix this issue, we added pdu_session_release_complete_received and
pdu_session_resource_release_response_received to the content
so that CLEAR_SM_CONTEXT_REF() is executed when both are received.
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)
* [AMF/MME] UEContextReleaseCommand in Integrity (#2786)
Modified not to send UEContextReleaseCommand in Integrity Unprotected
NAS message such like Registration or Service request.
* [AMF/MME] UEContextReleaseCommand after Interity Protected (#2786)
Modified not to send UEContextReleaseCommand in Integrity Unprotected
NAS message such like Registration or Service request.
amf_ue->mac_failed flag to be cleared during security mode procedure but it was not.
At this point, the only way to cleare the amf_ue->mac_failed flag is by UE Context Release.
But I'd like to connect UEs as fast as possible without UE Context Release.
- have a more consistent naming among the NF's
- always have the same prefix (amf_/smf_/pcf_) depending on the NF
- function name is always the same, how the function calculates the load
is NF specific and internal to the function itself (but not the function
name).
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.
[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.
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.
The current load percentage of the NF Service Consumer is provided
in the payload body of the PATCH request when periodically
contacting the NRF (heart-beat).
AMF: ratio between currently connected ran_ue and maximum number of them
SMF: ratio between current PDU sessions and maximum available
PCF: ratio between current AM+SM policy associations and maximum available
or ratio between currently connected UEs and maximum number of them
(the load which is higher)
AUSF, UDM: ratio between currently connected UE and maximum number of them
BSF: ratio between current sessions and maximum available
NSSF: ratio between currently used NSIs and maximum number of them
NRF currently doesn't determine that the NF Profile has changed.
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
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.
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.
During PDU Session Establishment,
if gNB sends PDUSessionResourceReleaseResponse,
AMF was crashed.
In this case, AMF/SMF remove Session Context and sends ErrorIndication.
Confirmation for non-cleartext IE should only be applied
to the initial NAS message. Registration requests and Service requests
with UplinkNASTransport do not have to.
1. DownlinkNASTransport
If AMF has not sent it previously, UE-AMBR is included in Registration
accept.
2. InitialContextSetupRequest
If PDUSessionResourceSetup is available, UE-AMBR is included
3. PDUSessionResourceSetupRequest
If AMF has not sent it previously, UE-AMBR is included
4. HandoverRequest
If PDUSessionResourceSetup is available, UE-AMBR is included
The AMF shall assign a new 5G-GUTI for a particular UE:
a) during a successful initial registration procedure;
b) during a successful registration procedure
for mobility registration update; and
c) after a successful service request procedure invoked as a response
to a paging request from the network and before the release
of the N1 NAS signalling connection as specified in subclause 5.4.4.1.
The AMF should assign a new 5G-GUTI for a particular UE
during a successful registration procedure
for periodic registration update. The AMF may assign a new 5G-GUTI
at any time for a particular UE by performing
the generic UE configuration update procedure.
If both Delete-Session-Request/Response and
UEContextReleaseCommand/UEContextReleaseComplete are failed at the same time,
UE cannot attach to the EPC infinitely.
So, I've add the protection code
if timer expires when MME does not receive Delete-Session-Response.
Sukchan Lee
Bostjan Meglic
Gaber Stare
mitmitmitm
Carlos Giraldo