User is unable to attach to Magma
Description: This document describe the steps triage issues when a user is unable to attach to the network, AGW is rejecting the attach request.
Environment: AGW and Orc8r deployed.
Affected components: AGW, Orchestrator
- APN configuration has been done in Orc8r
- AGW has been successfully registered in Orc8r
- User has been registered in Orc8r with the correct parameters( Authentication and APN)
- eNB has been successfully integrated with AGW
- Run the command sudo mobility_cli.py get_subscriber_table, the output will show the list of subscribers(by IMSI) that are currently attached to the network. If the user is showing in the list, it means the attach request was successfully completed. If the IMSI is not showing there, proceed with the next step
- Verify in the pcap trace or NMS logs the reason of attach reject.
a. To obtain a pcap trace in AGW you can run the following command
sudo tcpdump -i any sctp -w <destination path>b. To verify the logs in NMS you can go in NMS to Equipment->Select the AGW-> Logs->Search logs
The attach request flow should follow below signal flow, where sctpd, mme, subscriberdb, mobilityd and sessiond are used services in the AGW:
Below you will find possible causes of why the Attach Request could be rejected by AGW.
Causes related to invalid messages or Unknown messages
UE may include in the Attach Request a parameter Magma doesn’t support. Magma will reject the request with the following cause:
Identify which parameter the UE is sending in the Attach Request and compare with the ones Magma support. You can find which parameters magma is currently supported from the code. https://github.com/magma/magma/blob/master/lte/gateway/c/core/oai/tasks/nas/emm/msg/AttachRequest.cpp
Note: Make sure to select the branch you are currently have in your network(v1.1, v1.2, v1.3 , etc)
Once you identify the parameter, verify with the UE/CPE vendor if you can disable it. If you can't disable, file a feature request.
Misconfiguration of APN
Using the pcap trace, verify the APN configured in NMS/Orc8r matches the APN sent by UE.
- You will find the APN sent by UE in the “PDN connectivity request”( Attach Request) or in the “ESM information transfer”
- Make sure the APN matches the one configured in Orc8r for this user
Cause related to subscription options If the user is not correctly provisioned in the NMS/Orc8r, the attach request will be rejected with the following causes:
- Double check with the Auth Key and OPC are correctly set for this user
- Verify the Auth Key and OPC values with the SIM vendor
- If issue still persists, please file github issues or ask in our support channels https://magmacore.org/join-the-open-source-community/