Open5GS-Traces¶

!This is Work-In-Progress!

Setup of this example¶

• Ericsson RBS 6402 (eNodeB)
• Open5GS (4G network elements)
• OsmoHLR with OsmoDia2GSUP (HSS)
• OsmoMSC (SMS)

Idle¶

When all phones are Idle, one will see the following trace with Wireshark on the link between eNodeB (Ericsson RBS) and MME (Open5GS).

The eNodeB (IP 10.0.15.117) is connected to MME (IP 10.0.15.1) via SCTP. Also the eNodeB syncs its clock to NTP server (IP 10.0.15.1).
The network 10.0.15.0/24 is the RAN network in this example.

4G Attachment¶

A 4G phone is attached to the network, using SIM cards that is registered in the HSS. The APN name used is "internet".
Lets go into detail:

Attach request¶

The UE sends an "Attach request". It is the message type of the "NAS-PDU" information element of the "initiatingMessage". The "NAS-PDU" message type is highlighted blue in the picture above.
Also within the "NAS-PDU" is the "EPS mobile identity". In this case the UE has the mobile country code "999" and the mobile network code "10". The IMSI is not shown. Because the UE was attached before, a TMSI is used.

ESM information request¶

The MME sends an "ESM information request" to the UE, to request APN name. The "NAS-PDU" message type is highlighted blue in the picture above.

ESM information response¶

The UE send an "ESM information response." The UE uses the APN name "internet". The "NAS-PDU" message type is highlighted blue in the picture above.
This is the default configuration in the example setup. It can be configured in the configuration file for OsmoHLR. (osmo-hlr.cfg)

Attach accept¶

Attach complete¶

4G Detachment¶

The 4G phone is turned off or the airplane mode is turned on.

Lets go into detail:

h.3 Detach Reqeust

h.3 UE context release