Testing is an important means to ensure the performance of wiring links, and network debugging cannot be used to test the performance of links. The test standards for cabling systems are constantly changing with the development of network technology. The standards that have been used successively are:

TSB-67 on-site test standard, TSB95 on-site test standard, TIA-568-A-5-2000 Gigabit network test standard for super five-line cable, GB/T 50312-2000 Building and building complex integrated wiring system engineering acceptance specification.

The TIA-568-B standard passed in 2001, which integrates the contents of TIA/EIA-568-A, TSB 72, 75, 95 and other standards, has become a new wiring and testing standard. This standard abandons the basic link mode (Basiclink) in the original test standard and adopts the permanent link connection mode.

The permanent link model eliminates the influence of the test cable connecting the tester and the circuit under test at both ends of the link on the circuit test results, so that the test is carried out according to this model and the test is passed, then use the original manufacturer's qualified user cable and Once the network equipment is connected, a qualified link can be obtained and put into use directly. (ACR): refers to the difference between near-end crosstalk loss and attenuation. ACR(dB)=NEXT(dB)- A(dB)

ACR is a very important physical quantity and a form of signal-to-noise ratio on a line pair. ACR=0 indicates that the signal transmitted on the pair will be submerged by noise, so the higher the frequency point corresponding to ACR=0, the better. A high ACR value means that the received signal is greater than crosstalk.