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jolly, 01/30/2024 11:58 AM


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).

Wireshark eNB Idle

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

The phone is turned on and ready to attach to 4G network.

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

The MME sends an "Attach accept" to the UE. The "NAS-PDU" message type is highlighted blue in the picture above.

Also within the “NAS-PDU” is an “ESM message container” with an “EPS session management message” to activate the default EPS bearer context. (Highlighted light blue in the picture above.)

The subsequent “InitialContextSetupResponse” and “UECapabilityInfoIndication” messages are not depicted. The latter message contains capabilities of the UE.

Attach complete

Finally the UE sends an "Attach complete". The "NAS-PDU" message type is highlighted blue in the picture above.
Also within the “NAS-PDU” is an “ESM message container” with an “Activate default EPS bearer context accept”. (Highlighted light blue in the picture above.)

Packet transfer

The "GPRS Tunneling Protocol" (GTP) is used to tunnel packet traffic of the user plane. between eNodeB and SGW.

As depicted above, the GTP packet transmitted from the eNodeB (IP 10.0.15.117) to the SGW (IP 10.0.15.3).

The carried packet is transmitted from the UE (IP 10.0.6.2) to the destination in the Internet (IP 104.26.15.42)

4G Detachment

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

Lets go into detail:

h.3 Detach Request

Similar to the "Attach request", described above, the UE sends an "Detach 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". This is also similar to the "Attach request".

The subsequent “UEContextReleaseCommand” message (sent from EMM) and “UEContextREleaseComplete” messages (sent from UE) are not depicted.

Files (23)
wireshark_enb_idle.png View wireshark_enb_idle.png 62.2 KB Wireshark eNB Idle jolly, 01/29/2024 01:19 PM
wireshark_enb_attach_attach_request.png View wireshark_enb_attach_attach_request.png 153 KB jolly, 01/29/2024 02:07 PM
wireshark_enb_attach_ESM_infomation_request.png View wireshark_enb_attach_ESM_infomation_request.png 91.6 KB jolly, 01/29/2024 02:08 PM
wireshark_enb_attach_ESM_infomation_response.png View wireshark_enb_attach_ESM_infomation_response.png 86.6 KB jolly, 01/29/2024 02:08 PM
wireshark_enb_attach_attach_accept.png View wireshark_enb_attach_attach_accept.png 186 KB jolly, 01/29/2024 02:08 PM
wireshark_enb_attach_attach_complete.png View wireshark_enb_attach_attach_complete.png 98.8 KB jolly, 01/29/2024 02:08 PM
wireshark_enb_detach_detach_request.png View wireshark_enb_detach_detach_request.png 115 KB jolly, 01/29/2024 02:08 PM
wireshark_enb_gtp_2.png View wireshark_enb_gtp_2.png 32.8 KB jolly, 01/30/2024 11:20 AM
wireshark_enb_gtp_1.png View wireshark_enb_gtp_1.png 102 KB jolly, 01/30/2024 11:20 AM
wireshark_enb_attach.png View wireshark_enb_attach.png 92.8 KB jolly, 01/31/2024 09:15 AM
wireshark_enb_detach.png View wireshark_enb_detach.png 21.6 KB jolly, 01/31/2024 09:19 AM
wireshark_enb_attach_authentication_response.png View wireshark_enb_attach_authentication_response.png 80.6 KB jolly, 01/31/2024 10:12 AM
wireshark_enb_attach_authentication_request.png View wireshark_enb_attach_authentication_request.png 93.5 KB jolly, 01/31/2024 10:12 AM
wireshark_enb_attach_identity_request.png View wireshark_enb_attach_identity_request.png 59.9 KB jolly, 01/31/2024 10:12 AM
wireshark_enb_attach_identity_response.png View wireshark_enb_attach_identity_response.png 77.4 KB jolly, 01/31/2024 10:12 AM
attach_detach.pcapng attach_detach.pcapng 57.9 KB PCAP of attachment and detachment jolly, 01/31/2024 02:04 PM
wireshark_epc_attach.png View wireshark_epc_attach.png 82.2 KB jolly, 02/01/2024 10:07 AM
enb_attach.msc enb_attach.msc 769 Bytes jolly, 02/01/2024 11:20 AM
enb_attach.png View enb_attach.png 40.3 KB jolly, 02/01/2024 11:20 AM
enb_detach.msc enb_detach.msc 231 Bytes jolly, 02/01/2024 11:20 AM
enb_detach.png View enb_detach.png 10.6 KB jolly, 02/01/2024 11:20 AM
epc_attach.msc epc_attach.msc 786 Bytes jolly, 02/01/2024 11:21 AM
epc_attach.png View epc_attach.png 40.6 KB jolly, 02/01/2024 11:21 AM

Updated by jolly 4 months ago · 22 revisions

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