Bit-Error-Rate (BER) is the ratio of incorrectly transmitted bits to all transmitted bits, over a given time period, from one active device to another. In BER testing, real sample data is transmitted over the appropriate protocol (e.g., 100BASE-T, 10GBASE-T, etc.). The BER test will show the true real-world performance of the network, inclusive of the active components. In contrast, the standard electrical tests performed on the permanent link or channel will provide performance values for the cable and passive components, exclusive of the active equipment. The parameters included in standard permanent link or channel tests include Near-End Crosstalk, Attenuation, Return Loss, Delay, etc. The advantage of the bit error rate test is that it will show how well your cable network really performs in combination with your active equipment. It is not unusual for a marginally passing cable network to exhibit bit errors when used in combination with lower quality active equipment. The electrical margin built into better performing cable and connectivity products helps overcome such factors.