MicroNugget: How to Troubleshoot GNS3 Error 206

In this video, Keith Barker covers how to troubleshoot one of the most common and most frustrating errors in GNS3: Error 206 UDP N10. The error comes about when some ports are already in use, and GNS3 is trying to tell us which ones they are.

The issue behind the UDP N10 error is that GNS3 is trying to use some ports that are already in use by the local device. It's also trying to tell the user what kinds of ports are taken up.

By investigating the ports being used by the computer hosting GNS3 and comparing those to the details of the network file itself, you can deconflict the underlying problem.

Right-click the network file itself and choose edit. Then identify the TCP and UDP ports that the file is trying to instantiate in GNS3.

After that, view all open and listening ports on the computer at that moment by performing a netstat -an via the command line. With that information, you can compare the TCP and UDP ranges identified in the network file and see whether they're in conflict.

From there, it's a short few steps to deconflict the values and get your GNS3 file running.

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[BismillahCollege]

keith! thank you very very much for your being gns3 expert. coz i benefited alot from u.
i am doing ccnp route now, so i created many different labs. one day i tried to open to see how i configured again. but no luck to open.
you helped open my dear topologies.
thank

[notomab]

Thanks Keith, I have learned a lot from you.

[KeithBarker]

You may want to open the .net files, and take a look. If the IOS image path has changed, that would be one reason for the failure.

[IrzFzeArouWXhiRxhBx]

Yes, port in use is the reason in most cases. But not always.