The goal of QoS is to provide guarantees on the ability of a network to deliver predictable results. Elements of network performance within the scope of QoS often include availability, bandwidth, latency, and error rate. The bandwidth-intensive applications stretch network capabilities and resources, but also make business processes more efficient.
When the expense of mechanisms to provide QoS is justified, network customers and providers can enter into a service level agreement (SLA) which guarantees the ability of a network to give guaranteed performance based on mutually agreed measures, usually by prioritizing network traffic.
QoS can be aimed at a network interface, concerning a given server or router’s performance, or in terms of specific applications. A network monitoring system must generally be installed as part of QoS, to insure that networks are performing at the desired level.