Cisco Network Assistant and “Could not create Java machine”

The Cisco Network Assistant (CNA) is software that provides a more richly featured GUI interface to a low-medium range IOS Cisco switch. You can use the CLI of course, and there is a web interface (if you have not upgraded your switch and blown away the HTML files).

I was running version 5.4 though I had not used it for ages. When I had tried to start it I got a “Could not create a Java machine” error from my XP machine


I figured I had installed so much software in between that I had broken something or it didn’t like the newer versions of Java, or just that I really shouldn’t still be running XP.

So I decided to upgrade it to 5.8.2 but afterwards I got the same error.

Poking around, I saw that the real issue was that I didn’t have the memory free that Java wanted when it started the application. It greedily expects to grab a Gig for itself! However you can change this quite easily using a text editor by modifying the entry in the properties file for CNA (normal risks apply when editing system startup files – only do this if you have a clue).

The file exists in C:\Program Files\Cisco Systems\Cisco Network Assistant\startup\


Change the value of

as shown here:


You should now be able to start the application. On my small network, I didn’t see an issue by reducing the startup memory size.


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