DHCP Dora process got stuck in Discover and Offer

Technical Support
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Hello Community,

I’m using the Apalis iMX8 QuadPlus with Yocto Dunfell on our custom board. While the unit generally functions well, there are times when it fails to obtain an IP address from the DHCP server. We’ve used tcpdump on both the server and client sides for analysis. The client continuously sends DHCP Discover packets, which the server receives and responds to with DHCP Offer packets. However, these Offer packets are not visible on the client side. As a result, the client keeps sending additional Discover packets, causing the process to stall and preventing it from acquiring an IP address. This situation persists until the unit is power-cycled or the eth0 interface is brought down and then back up.

Client Side

Client_Broadcasting_DISCOVER_Message
Client_Broadcasting_DISCOVER_Message1366×768 69.4 KB

Server Side

Server_Replying2Discover_OfferWithUnicast
Server_Replying2Discover_OfferWithUnicast719×678 15.1 KB

Any guidance on resolving this issue promptly would be greatly appreciated.

Thank you,
Muthyam D.

2

Hi, I’m the Toradex AI Assistant. The Toradex Support team will follow up with you shortly!

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:+1: :-1:

Hello Muthyam,

Thank you for reaching out to the community with your DHCP issue on the Apalis iMX8 QuadPlus. It sounds like a challenging situation, but let’s see if we can work through it together.

Here are some steps you can take to address the problem:

  1. Network Configuration Check: Double-check the network configurations on both the DHCP server and the client. Ensure that the server is set up correctly to respond to requests from your client device.

  2. Firewall and Filtering: Investigate any firewall rules or network policies that might be blocking the DHCP Offer packets. Make sure the network path between the server and client is free of any filtering that could prevent these packets from reaching the client.

  3. Tcpdump Analysis: Continue using tcpdump to capture network traffic on both the client and server sides. This can help pinpoint where the Offer packets are being lost. Look for any discrepancies in the packet flow that might indicate the source of the issue.

  4. Temporary Workarounds: As a temporary measure, you can power-cycle the unit or reset the eth0 interface to restore network functionality. However, it’s important to address the root cause for a permanent solution.

By systematically addressing these areas, you should be able to identify and resolve the issue causing the DHCP process to stall. If the problem persists, further investigation into the network environment may be necessary.

I hope this helps, and please feel free to reach out if you have any more questions.

Best regards,
Toradex AI Assistant

Please, also check if these links can help you solve your problem:

iMX7D second ethernet issue with systemd-networkd.