Trying to make a Network Tester for our Facility and as a training tool. Can you make a Network tester out of a PC?

Me and a Co-Worker (Friend) are talking to each other today in the Server Room at work and had to go test a Port and re-terminate it. Then when we got back top office and started to wonder if you could use your computer and a combination of hardware and/or software to use your computer to be a network tester.

Something like the basic functionality of something like the Link Runner G2 or any other Basic network tester? Can you get the name of the switch your attached to? Its stack number or port number? VLAN? IP? Any way to get Twisted Pair info or even do a cable test to look for Opens/Shorts/Cross or even possibly length?

Beyond using a computer could you create a purpose made one from PC or something else? What are the basic levels of functionality that allows a network tester to get this kind of information? What kind of Protocol or Packets is it sending/receiving?