ATM networks have been touted as “one of the few
networks that can provide the real-time and quality
of service guarantees required for new multimedia
data types”. However, as the networks become
larger, busier and more complex, fulfilling this
quality of service guarantee will not be a simple
task. What are the end effects or the service layer
effects if the quality of service (QoS) is less than
expected? If cells are lost in a data communications
application, retransmission may be required. If
cells are delayed, timers may expire causing even
more delays. In a video-on-demand service, if the
cell delay variation in the ATM network increases
due to congestion, the buffers in a set-top box may
begin to underflow causing blanking or jagged
movements.