How do the insertion loss and return loss indicators of the keystone jack affect network performance?

When the signal passes through the keystone jack, the energy is attenuated due to factors such as conductor resistance, dielectric loss, and poor contact. The direct consequence of insertion loss is the continuous weakening of signal strength. This process is similar to the gradual decrease in pressure when water flows through a narrow valve in a water pipe. The signal is attenuated due to energy loss during transmission, which ultimately leads to the inability of the receiving end to accurately identify the data. For example, problems such as increased bit error rate, increased network latency, video playback freezes, or file transfer interruptions may occur during data transmission.

In addition, the accumulation of insertion loss will significantly shorten the effective transmission distance of the signal. For example, a network cable that theoretically supports 100 meters of transmission may actually shorten the effective transmission distance to 80 meters due to excessive keystone jack loss, thereby limiting the network coverage. In the PoE scenario, insertion loss will also share the power supply, causing terminal equipment to frequently shut down due to insufficient voltage, affecting system stability.

The signal is reflected at the keystone jack interface due to impedance mismatch, and the reflected signal is superimposed on the original signal to form interference. The core problem of return loss is signal distortion. When the reflected signal is superimposed on the original signal, the receiving end may not be able to correctly decode the data due to signal interference. For example, a "1" in a binary signal may be misjudged as a "0", resulting in an increase in the packet error rate. This interference will directly lead to an increase in packet retransmissions, thereby reducing the overall throughput of the network.

In addition, high-frequency signals are more sensitive to impedance mismatch. keystone jacks with poor return loss will cause high-frequency band signals to attenuate faster, making the actual network speed much lower than the theoretical value, and users may perceive the network as "stuck" or "slow". In the long run, repeated oscillations of reflected signals inside the device will cause chip overheating, accelerate hardware aging, and even shorten the service life of the device.