Gugrajah_Yuvaan_ Ramesh_2003.pdf

Simulation ofa Load Balancing Routing Protocol
3.6. Traffic Model
Chapter 3
Two packet buffers are maintained at each node, each being buffer_length packets
long. One buffer contains data packets and the other routing information packets
(route requests, route replies and route error packets). Routing information packets
have the higher priority. Packets are dropped if they are in a queue for longer than
pkCtimeout seconds.
[Broch98], [Johannson99] and [DasOl] used constant bit rate (CBR) sources and
varied the number of sources for different simulation runs in order to determine the
effects of traffic load. The source nodes selected to be CBR sources were the only
nodes throughout the simulation that generated traffic and the associated destination
nodes for each source node also never changed. A different approach was
implemented for traffic generation for the simulations discussed herein in an attempt
to create stochastic behaviour.
Each node is assigned a random Packet Generation Time (POT), normally distributed
between 0 and a maximum packet generation time PGT. After POT seconds, the node
selects a destination node randomly and generates session_length packets each of
pkt_length bytes to be transmitted to the selected node. The packets are added to the
appropriate buffer and the node assigns itself a new POT.
3.7. Simulation Procedure
The custom built simulator was used to compare AODV to the four DLAR schemes
in terms of packet delivery ratio and delay. A total of 24 simulations were run for
each of the four routing protocols for 3600s of simulation time. By varying the pause
time from a low pause time to a high pause time, the network topology was varied
from highly dynamic topologies with constant node movement to slow changing
topologies with longer pause times. There were four different pause times used: 0,
25s, 50s and 150s. For each pause time the load was varied for six different values of
PGT: 0.25s, 0.5s, Is, 2s, 5s and 10s.
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