How can I ping point to point, or ethernet to ethernet when there is no IP address assigned? Is that possible? I tried using a MAC address with Ping but that did not work. In this case its a PC to a ethernet to 100BaseF (fiber) conversion and I want to send pings to test the link (no other routers or switches involved, just point to point). Any insight appreciated

Ping is a function of TCP/IP. You can't "Ping" without an IP address. Even without a router, you can still set a manual IP address on each computer. -Ryan Adams Free Computer Tips and more:http://RyanTAdams.com Paid Tech Support: Black Diamond

If you are using TCP/IP then there must be an IP address to establish communication. You cannot Ping an MAC address as Ethernet is not part of the TCP/IP protocol. Ping is part of the TCP/IP protocol. In fact the MAC addresses are communicating with each other all the time a cable is connected. It is what keeps the link light lit on network hardware. If the link light is lit then there is a link. Stuart

Understood. I can add a IP addressable device on the other end. How do people test ethernet without TCP/IP then?

They don't. "Ethernet" is generally used as a term for the hardware, software (protocols) for computer communication. Without the software/protocols in place, you don't even have "Ethernet" you just have some wires (or fiber cable). If you want to test wires, there you can use a multimeter or a special cat5 tester. They also make fiber optic testers, but these are usually expensive. -Ryan Adams Free Computer Tips and more:http://RyanTAdams.com Paid Tech Support: Black Diamond

I told you, the link light. That's what it is there for. There is no other was of testing that the Ethernet link is working. Stuart

They also make fiber optic testers, but these are usually expensive. We have two testers where I work. They are capable of testing both copper and fibre. Not only do they test, they certify as well. I've tested many many cables with them and will be testing some more in the next month or so after we finish renovating our library. My coworker and I will be pulling, terminating and testing all our cables ourselves. The expensive one is worth around $10,000.00 brand new and the less expensive one is around $1,500.00