What does Quality of Service Mean?
Quality of Service (QoS) in networking terms refers to the ability of a network to give guaranteed performance based on some metric usually by prioritizing traffic. For example, certain types of network traffic such as VoIP can be prioritized on a network to ensure that a certain minimum level of quality is always obtained.
QoS is the defined measure of performance in a system. For example, the maximum response time to complete a transaction must be no longer than 10 seconds.
Because dedicated channels were set up between parties, the plain old telephone system (POTS) delivered the highest QoS for years. Since data is now broken into packets that travel through routers in a LAN or WAN, QoS mechanisms are used to give higher priority to real-time data, such as voice over IP (VoIP), than to non-real-time data, such as file downloads. Another option in packet switching is to overbuild the network, ensuring that it will accommodate all traffic fed to it. Today, everything is built around IP, and there are a variety of methods competing to provide QoS in IP networks.