How to Calculate Network Intermediate Delay in NS2
To calculate the Network Intermediate Delay in ns2 encompasses to compute the delay experienced by packets at the intermediate nodes (routers or other hops) when they move from the source to the destination. It is useful while measuring how long packets take to process at or dispatched by intermediate nodes that contains queuing delay, processing delay and transmission delay. The following manual will help you to compute it in ns2:
Steps to Calculate Intermediate Delay in NS2
To compute intermediate delay, we need to record the time when a packet enters and exits an intermediate node, or several nodes if you want to estimate delay over numerous hops.
- Set Up NS2 Simulation:
First, build a network with at least three nodes, so we can compute the intermediate delay amongst the nodes.
Example TCL Script for a Multi-hop Network:
# Create the simulator
set ns [new Simulator]
# Define the nodes: source, intermediate, and destination
set node_(0) [$ns node] ;# Source
set node_(1) [$ns node] ;# Intermediate node
set node_(2) [$ns node] ;# Destination
# Create duplex links between the nodes (1 Mbps bandwidth, 10ms delay)
$ns duplex-link $node_(0) $node_(1) 1Mb 10ms DropTail
$ns duplex-link $node_(1) $node_(2) 1Mb 10ms DropTail
# Attach UDP agents to nodes for sending and receiving data
set udp0 [new Agent/UDP]
set sink [new Agent/Null]
$ns attach-agent $node_(0) $udp0
$ns attach-agent $node_(2) $sink
$ns connect $udp0 $sink
# Set up CBR traffic on the UDP agent
set cbr0 [new Application/Traffic/CBR]
$cbr0 attach-agent $udp0
$cbr0 set packetSize_ 512 ;# Packet size in bytes
$cbr0 set rate_ 1Mb ;# Transmission rate
# Start and stop the traffic
$ns at 1.0 “$cbr0 start”
$ns at 10.0 “$cbr0 stop”
# Set up tracing to capture packet events, including intermediate hops
set tracefile [open out.tr w]
$ns trace-all $tracefile
# End the simulation after 12 seconds
$ns at 12.0 “finish”
proc finish {} {
global ns tracefile
$ns flush-trace
close $tracefile
exit 0
}
# Run the simulation
$ns run
- Run the Simulation:
Execute the simulation using the below command:
ns your_simulation_script.tcl
This will produce a trace file (out.tr) containing logs of all packet events as well as when packets enter and leave the intermediate node (node_(1)).
- Analyze the Trace File:
To measure intermediate delay, we need to look at the timestamps when packets enter (s for sent) and exit (r for received) the intermediate node (node_(1)) and subtract the two to acquire the delay.
Sample Trace File Entries:
s 1.000000000 _0_ AGT — 512 cbr 0 0.0 1.0 1.0
r 1.010000000 _1_ AGT — 512 cbr 0 0.0 1.0 1.0
s 1.020000000 _1_ RTR — 512 cbr 0 0.0 1.0 1.0
r 1.030000000 _2_ AGT — 512 cbr 0 0.0 1.0 1.0
- s: Packet sent event.
- r: Packet received event.
- 1: Intermediate node.
- Calculate Intermediate Delay Using AWK Script:
Use AWK script to calculate the intermediate delay by estimating the time difference amongst when a packet is obtained at the intermediate node and when it is moved to the next hop.
AWK Script to Calculate Intermediate Delay:
BEGIN {
total_delay = 0;
packet_count = 0;
}
# Capture the packet reception at the intermediate node (_1_)
$1 == “r” && $4 == “_1_” && $7 == “cbr” {
arrival_time[$10] = $2; # Store the time the packet was received at the intermediate node
}
# Capture the packet transmission from the intermediate node (_1_)
$1 == “s” && $4 == “_1_” && $7 == “cbr” {
if (arrival_time[$10] > 0) {
delay = $2 – arrival_time[$10]; # Calculate the intermediate delay
total_delay += delay;
packet_count++;
}
}
END {
if (packet_count > 0) {
avg_delay = total_delay / packet_count;
print “Average Intermediate Delay: ” avg_delay ” seconds”;
} else {
print “No packets processed by the intermediate node!”;
}
}
- Run the AWK Script:
Store the AWK script as intermediate_delay.awk and execute it on the trace file created by NS2:
awk -f intermediate_delay.awk out.tr
- Interpreting the Results:
The output of the AWK script will deliver the average intermediate delay:
Example Output:
Average Intermediate Delay: 0.01 seconds
This denotes that, on average, packets took 0.01 seconds to be processed and dispatched by the intermediate node.
- Conclusion:
To calculate Intermediate Delay in NS2:
- Configure the simulation with traffic flowing over an intermediate node.
- Execute the simulation to develop a trace file.
- Analyze the trace file to extract the time when packets are obtained at and deliver from the intermediate node.
- Use an AWK script to compute the time difference between these events and measure the average intermediate delay.
In conclusion, we successfully concentrated on how to compute the Intermediate Delay in the ns2 simulation by tracking the time taken for the packets both to enter and leave the intermediate node. If you want any information about this calculation, we will offer it.
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