How to Implement Network Monitoring in NS2
To implement the Network Monitoring in NS2, we have to continuously gather and analyze the performance metrics like its packet transmission, delay and throughput, packet loss, jitter and link status. By doing this, we can detect the problems like congestion, packet loss or degraded performance, permitting for dynamic alterations to enhance the network.
In below, you can see a step-by-step guide on how to implement Network Monitoring in NS2:
Step-by-Step Guide to Implement Network Monitoring in NS2
- Set Up the Basic Network Topology:
- Begin by defining a network topology that contains nodes, links and communication flows to observe the network’s performance.
Example OTcl script for setting up a simple network topology:
set ns [new Simulator]
set nf [open out.tr w]
$ns trace-all $nf
set namfile [open out.nam w]
$ns namtrace-all $namfile
# Create nodes
set node0 [$ns node] ;# Source node
set node1 [$ns node] ;# Intermediate node
set node2 [$ns node] ;# Destination node
# Create duplex links between nodes
$ns duplex-link $node0 $node1 1Mb 10ms DropTail
$ns duplex-link $node1 $node2 1Mb 10ms DropTail
# Define TCP communication between node0 and node2
set tcp [new Agent/TCP]
set sink [new Agent/TCPSink]
$ns attach-agent $node0 $tcp
$ns attach-agent $node2 $sink
$ns connect $tcp $sink
set ftp [new Application/FTP]
$ftp attach-agent $tcp
# Start FTP traffic at 1.0 seconds and stop at 5.0 seconds
$ns at 1.0 “$ftp start”
$ns at 5.0 “$ftp stop”
# Run the simulation
$ns at 6.0 “finish”
proc finish {} {
global ns nf namfile
$ns flush-trace
close $nf
close $namfile
exec nam out.nam &
exit 0
}
$ns run
- This script sets up a basic TCP communication flow from node0 to node2 via node1.
- Implement Packet Monitoring:
- Observe the packet transmission, receipt, and drop events. NS2 trace files log detailed information about these events, which can later be processed for analysis by using the NS2’s built-in tracing functionality.
Example OTcl script to trace packets:
# Enable per-link tracing to monitor packets at each link
$ns trace-queue $node0 $node1 “queue.tr” ;# Trace between node0 and node1
$ns trace-queue $node1 $node2 “queue.tr” ;# Trace between node1 and node2
- This enables monitoring of the queues amongst nodes, logging information like queue length and packet drops to the file queue.tr.
- Monitor Performance Metrics:
To perform network monitoring, you need to track key metrics like throughput, delay, packet loss, and jitter.
3.1 Throughput Monitoring:
- Throughput can be measured as the rate of data successfully delivered to the destination. You can compute it by summing up the bytes received over a given period.
Example AWK script to calculate throughput:
awk ‘{
if ($1 == “r” && $4 == “TCP”) {
total_bytes += $6
}
} END {
print “Throughput: “, total_bytes / 5, “bytes per second”
}’ out.tr
- This script see how many bytes were received over a 5-second simulation, then estimates the throughput.
3.2 Packet Delay Monitoring:
- Packet Delay is the time a packet takes to traverse the network from source to destination.
Example AWK script to calculate packet delay:
awk ‘{
if ($1 == “s” && $4 == “TCP”) {
start_time[$11] = $2
}
if ($1 == “r” && $4 == “TCP”) {
end_time[$11] = $2
total_delay += end_time[$11] – start_time[$11]
packet_count++
}
} END {
print “Average Delay: “, total_delay / packet_count, “seconds”
}’ out.tr
- This script measures the average delay for TCP packets from the time they were delivered to when they were obtained.
3.3 Packet Loss Monitoring:
- Packet Loss happens when packets are dropped because of network issues like blockage or faulty links.
Example AWK script to calculate packet loss:
awk ‘{
if ($1 == “s” && $4 == “TCP”) {
sent_packets++
}
if ($1 == “r” && $4 == “TCP”) {
received_packets++
}
} END {
packet_loss = sent_packets – received_packets
print “Total Packet Loss: “, packet_loss
}’ out.tr
- This script tracks the count of packets sent by the source and the number acquired by the destination, then calculates the total packet loss.
3.4 Jitter Monitoring:
- Jitter is the variation in packet delay and is vital for realistic applications.
Example AWK script to calculate jitter:
awk ‘{
if ($1 == “r” && $4 == “TCP”) {
if (prev_time != 0) {
delay_diff = $2 – prev_time
jitter += (delay_diff > 0) ? delay_diff : -delay_diff
}
prev_time = $2
packet_count++
}
} END {
print “Average Jitter: “, jitter / packet_count, “seconds”
}’ out.tr
- This script calculates the jitter by calculating the variation in packet delay amongst successive packets.
- Log Network Events for Analysis:
- Log crucial network events like packet transmission, receipt, drops, and queue lengths with the help of trace files. This permits for post-simulation analysis of network behavior.
Example OTcl script for logging network events:
# Enable trace logging for packets sent, received, and dropped
proc log_packet_events {node} {
puts “Node $node event: Packet Sent, Received, or Dropped”
}
# Monitor packet events at node1
$ns at 1.0 “log_packet_events $node1”
- This script logs the packet events (sent, received, or dropped) at node1.
- Run the Simulation and Collect Data:
- After configuring network monitoring, execute the simulation and assess the output trace file (out.tr) to aggregate data on packet transmission, delays, losses, and other key events.
To execute the simulation:
ns your_script.tcl
- The trace file (out.tr) will log all network activities as well as packet transmission, reception, drops, and delays.
- Analyze Performance Metrics Using AWK Scripts:
- Use the AWK scripts offered above to estimate throughput, delay, jitter, and packet loss from the trace file.
Example command to calculate throughput:
awk -f throughput.awk out.tr
- Similarly, run the other AWK scripts to extract other performance metrics from the trace file.
- Visualize Network Monitoring in NAM:
- Visualize the network activity in real-time by using NAM (Network Animator). You can see the transmission of packets, queue lengths, and packet drops in the animation.
To launch NAM:
nam out.nam
- NAM permits you to see how packets are transmitted amongst nodes and where congestion or packet loss happens, giving you a visual indication of network performance.
In conclusion, we have presented the valuable insights for you to know and understand the techniques and its implementation about the Network monitoring in the simulation by defining the network topology and then monitor the behaviors of the network using ns2 simulator tool. If you want to implement Network Monitoring in the NS2 tool effectively, you can count on us. Don’t hesitate to reach out if you need expert help! We have all the resources to offer you the best topics and support you in a timely and efficient manner.