QUALITY OF SERVICES (QoS):
Network should support multimedia applications that are those combine audio, video, and data. For that it should provide sufficient bandwidth. The timeliness of delivery can be very important. The applications that is sensitive to the timeliness of data as real time applications. The data should be delivered correctly. A network that can provide these different levels of services is often said to be support quality of services.
RANDOM EARLY DETECTION (RED)
A second mechanism, called random early detection (RED), is similar to the DECbit scheme in that each router is programmed to monitor its own queue length, and when it detects that congestion is imminent, to notify the source to adjust its congestion window. RED, invented by Sally Floyd and Van Jacobson in the early 1990s, differs from the DECbit scheme in two major ways.