Date Added: Jan 2010
QoS mechanisms can be categorized into two groups based on how the application traffic is treated: traffic handling mechanisms, and bandwidth management mechanisms. The lowest service level that a network can provide is best effort service which does not provide QoS support. In best effort service, all traffic is handled equally regardless of the application or host that generated the traffic. However, some applications need QoS support, requiring better than best effort service such as differentiated or guaranteed service. For a network to provide selective services to certain applications, first of all, the network requires a Classification mechanism that can differentiate between the different applications.