This class is used for emulating circuit switching. The cell rate is constant with time. CBR applications are quite sensitive to cell-delay variation. This class allows users to send traffic at a rate that varies with time depending on the availability of user information.
Statistical multiplexing is provided to make optimum use of network resources.
Depending upon the state of congestion in the network, the source is required to control its rate. The users are allowed to declare a minimum cell rate, which is guaranteed to the connection by the network.