[ETSI TS 128 552 V16.9.0](https://www.etsi.org/deliver/etsi_ts/128500_128599/128552/16.09.00_60/ts_128552v160900p.pdf):
Registration type label is not provided.
A nonstandard PLMNID label is added to achieve uniqueness.
- 5.3.1.3 Number of PDU sessions requested to be created by the SMF
PLMNID and SNSSAI are defined during PDU session creation processing.
Some requests can be rejected during processing before label values are known.
Those requests are not counted under particular labels.
To count also such requests, the basic metric with empty labels is exposed too.
```
fivegs_smffunction_sm_pdusessioncreationreq{plmnid="",snssai=""} 1
fivegs_smffunction_sm_pdusessioncreationreq{plmnid="00101",snssai="1000009"} 1
```
- 5.3.1.4 Number of PDU sessions successfully created by the SMF
```
fivegs_smffunction_sm_pdusessioncreationsucc{plmnid="00101",snssai="1000009"} 1
```
- 5.3.1.5 Number of PDU sessions failed to be created by the SMF
```
fivegs_smffunction_sm_pdusessioncreationfail{cause="400"} 1
```
Example for one successful and one failed (during creation processing) PDU session creation:
```
fivegs_smffunction_sm_pdusessioncreationreq{plmnid="",snssai=""} 2
fivegs_smffunction_sm_pdusessioncreationreq{plmnid="00101",snssai="1000009"} 1
fivegs_smffunction_sm_pdusessioncreationsucc{plmnid="00101",snssai="1000009"} 1
fivegs_smffunction_sm_pdusessioncreationfail{cause="400"} 1
```
Other NF instances are obtained through NRF
or created directly through configuration files.
Other NFs created by the config file should not be passed
through NRF discovery or anything like that.
Since self-created NF Instances do not have an ID,
they are implemented to exclude them from NRF Discovery.
== 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.
In case there are multiple AMF registered to NRF, SMF would pick only
the first AMF from the list.
In the case of sending PDU Session Establishment Accept from SMF to
AMF, this would mean a high chance of failure since the AMF might
be different than the original requester, and would not know about a
particular UE.
Modify SMF to use ServingNfId field from original request
SmContextCreateData from AMF to determine to which AMF should it send
PDU Session Establishment Accept message.
- Set the number of UEs in units of AMF/MME instead of gNB/eNB.
- See default value as shown below
Number of UEs per AMF/MME : 4,096
Number of gNB/eNB per AMF/MME : 32