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Abstract
Voice, data, and video traffic have radically different performance
requirements and they are very bursty in their nature. The bursty nature of
the traffic is the pnmary cause of congestion. Congestion results in
undesirable performance degradation such as long cell delay, high cell loss,
and large buffer requirements. Congestion control is the network function
that attempts to avoid or control congestion and limits its effects.
Congestion control is an essential part of B-ISDN in order to
guarantee its performance level. The high transmission rate of such networks
and the support of different services with divers traffic characteristics make
the congestion control problem more complicated and more challenging than
in the conventional networks.
Traffic shaping has been proposed as congestion control mechanism
to control the input rate and smooth the burstiness of the traffic. Shaping the
traffic when it enters the network makes the traffic smoother and more
predictable, thus reducing the probability of the congestion.
This thesis studies the effects of the conventional traffic shaping on
the performance of the network using OPNET simulator. An ATM based B-
ISON network model, a traffic ’model, and a shaper model are developed,
simulation results show that conventional traffic shaping can provide good
network level performance, i.e., low queuing delay and low cell loss inside
the network. However, user level is adversely affected. Conventional traffic
shaping is basically a conservative approach to the congestion control. With
conventional traffic shaping cell loss will be reduced but at the cost of extra
delay at the shaper. Conventional traffic shaping reduces, the buffer
requirements at the switches with the provision of an, input buffer at the
shaper.
, This thesis also studies the effects of a new proposed adaptive-rate
traffic shapingmodel. Simulation’ shows that shaping decreases the delay
from the user leveipersp~cti.ve, maximizes the utilization of the switch