AMF does not crash anymore when a new UE registration request arrives,
and there is no available space left in UE context pool. Now it just
rejects the request with an error.
Each UE context has 'current' and 'next' TMSI values. AMF first
allocates the 'next' value, before confirming it and releasing the
'previous'. This means that we potentially need pool size of 2x the
amount of maximum configured UE.
Without this change, AMF would crash in case that there are 'x'
configured maximum amount of UE, and there are already 'x' registered
UE.
[gmm] INFO: Registration request (../src/amf/gmm-sm.c:135)
[gmm] INFO: [suci-0-001-01-1234-0-1-1000000000] SUCI (../src/amf/gmm-handler.c:149)
[gmm] DEBUG: OLD TSC[UE:0,AMF:0] KSI[UE:7,AMF:0] (../src/amf/gmm-handler.c:179)
[gmm] DEBUG: NEW TSC[UE:0,AMF:0] KSI[UE:7,AMF:0] (../src/amf/gmm-handler.c:186)
[amf] FATAL: amf_m_tmsi_alloc: Assertion `m_tmsi' failed. (../src/amf/context.c:2160)
[core] FATAL: backtrace() returned 13 addresses (../lib/core/ogs-abort.c:37)
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.
Without this change, using metrics with core setup configurations
(configs/vonr.yaml for example) would not be possible. Having one
metrics section for whole config file causes every NF to start metrics
server on same port causing an abort.
== Known limitation ==
Placing npcf-smpolicycontrol and pcf-policyauthorization
in different NFs is not supported. Both npcf-smpolicycontrol
and pcf-policyauthorization should be placed in the same NF.
For null protection scheme the SUCI needs to be BCD encoded. Whereas for
protection scheme profiles A and B the SUCI needs to be converted from
hexadecimal to ASCII.
This still needs the support for protection schemes A and B in UDM to
work.
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.