For our networking tests we connect the test system up to our Intel Gigabit enabled ASUS Rampage IV Extreme X79 motherboard test system through the ASUS RT-AC68U router and run our tests. We opted for this over a direct point-to-point connection because we wanted to simulate real world performance.
LAN Speed Test Lite
LAN Speed Test was designed from the ground up to be a simple but powerful tool for measuring file transfer, hard drive, USB Drive, and Local Area Network (LAN) speeds (wired & wireless). It does this by building a file in memory, then transfers it both ways (without effects of windows file caching) while keeping track of the time. Download the free Lan Speed Test Lite utility from here.
Passmark Performance Test 8
The PassMark Advanced Network Test (which is part of PerformanceTest) is designed to test the data transfer rate between two computers both of which must be running PerformanceTest. One of the computers must act as the server and will sit waiting for a connection. The other computer acts as a client. It connects to the server machine and sends data to it for the duration of the test. You can download a trial version of PerformanceTest from here.