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How to predict link failure in the AODV routing protocol using NS2?

Description

Each node along an active source route scans the received hello packet signals from its nexthop hop node. When a node found that the Received Signal Strength (RSS) value of the received packet from its nexthop goes below the threshold and is still decreasing after two successive measurements, the node will realize that the link between it and its nexthop will have a link breakage soon. Then it will update its route table by marking the current nexthop as link breaking node.

Sample Code

p = source node
q = nexthop node
Threshold = 200;
if ((threshold < current_distance[p][q]) && (w_flag[p][q]==2)) {
l_flag[p][q]=1;
}
else if (threshold < current_distance[p][q] ) {
w_flag[p][q]=w_flag[p][q]+1;
}
else {
prev_distance[p][q]=current_distance[p][q];
}


Screenshots


Before Link failure case

 

3 – 12 – 7 – 0 – 5

Link failure case

Link failure between node 12 and node 7.


After Link Failure

Link Predication based Path Selection

Source node send data to new path

3 – 12 – 2 – 1 – 9 – 5