that switch is a dumb one. completely unmanaged.

The IP scanner is nice, but it wont let you find all of the devices on a network, just the ones responding to PING. All the scanner does is ping every IP in a range that you provide. It won't let you find devices configured for an IP outside the range you specify. The best way to find all types of devices using all protocol types (provided they are sending out something) is with a sniffer or packet capture device. The better ones are hardware based and will show all packets. The linix ones for the most part wont catch the error/runt/collision packets that will indicate a problem with the network unless the card it is working with can be set not to filter them at the hardware level prior to passing them up the stack to the application. You may get a flag that it saw an error or runt, but not the content which lets you find the problem.

edit was to change a wrong word.

About me:
8 years of network support
7 years IT field service

Always looking for the next project to be done.