Gugrajah_Yuvaan_ Ramesh_2003.pdf

Simulation ofa Load Balancing Routing Protocol
Chapter 3
Chapter]
SIMULATION OF A LOAD BALANCING ROUTING
PROTOCOL
3.1. Introduction
The results of simulations comparing on-demand routing protocols for ad hoc
networks to the proactive table-driven routing protocols [Broch98], [Johannson99],
[Camp02] show that the table-driven protocols struggle to maintain valid global state
information in ad hoc networks with high mobility. The resulting overhead causes
network congestion and increased delay. The on-demand protocols discussed in
Chapter 2 also do not account for load balancing to avoid congestion and often use
the shortest path or the first path found by a route request procedure. While the
shortest path is likely to result in decreased delay, using the shortest path may
actually increase delay in situations where traffic load is high. Certain nodes may
become overburdened due to their respective locations in the network and as a result
the packet buffers overflow, throughput performance deteriorates and delay
increases.
With reference to a simple example in Figure 3-1, node 6 becomes overburdened
because of its position in the network. The shortest path algorithms would frequently
employ node 6 as a node along the shortest route to some other node on the opposite
side of node 6. However, congestion at node 6 would eventually result in longer
delays. By avoiding node 6 and routing traffic along the outer ring when node 6 is
congested, network throughput and delay will be improved. The configuration in
Figure 3-1 is purely for demonstrating the problem of load balancing; however
mobility and the resulting topologies can always result in similar topologies and even
more complicated topologies where this unfavourable condition could arise.
3-1