How to Calculate Network Logging in NS2
To calculate and replicate the network logging using NS2 (Network Simulator 2), which refers to the procedure of logging numerous network events like packet transmissions, receptions, and drops for later analysis. These logs are usually captured in a trace file that stores the comprehensive data regarding every event, which happens within the network. By examining these logs, we can be computed several network performance metrics such as throughput, latency, packet loss, and other performance-related statistics. We follow the below procedure on how to compute and replicate the network logging in NS2:
Steps to Calculate Network Logging in NS2:
- Set up the NS2 Simulation with Logging
The initial step is to configure a simulation, which captures the network events in a trace file. If it is configured appropriately then the simulation environment NS2 automatically logs all network events to the trace file.
Example NS2 Script with Trace Logging
# Create NS2 simulator instance
set ns [new Simulator]
# Open trace file for logging network events
set tracefile [open out.tr w]
$ns trace-all $tracefile
# Define network nodes
set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
# Create duplex links between nodes
$ns duplex-link $n0 $n1 1Mb 10ms DropTail
$ns duplex-link $n1 $n2 1Mb 10ms DropTail
# Set up UDP traffic from n0 to n2
set udp0 [new Agent/UDP]
$ns attach-agent $n0 $udp0
set null0 [new Agent/Null]
$ns attach-agent $n2 $null0
$ns connect $udp0 $null0
set cbr0 [new Application/Traffic/CBR]
$cbr0 set packetSize_ 500
$cbr0 set interval_ 0.01
$cbr0 attach-agent $udp0
# Start and stop traffic
$ns at 0.5 “$cbr0 start”
$ns at 4.5 “$cbr0 stop”
# End simulation
$ns at 5.0 “finish”
proc finish {} {
global ns tracefile
$ns flush-trace
close $tracefile
exit 0
}
# Run the simulation
$ns run
Explanation of the Script:
- Trace File: The trace-all command is utilised to log all the network events to a file (out.tr).
- Traffic Setup: UDP traffic is configure from node n0 to node n2 using a Constant Bit Rate (CBR) application.
- Simulation Events: The simulation logs events like packet enqueue, dequeue, transmission, reception, and drops.
- Understand the Trace File Format
NS2 trace files encompass specified logs of network events. Each line in the trace file denotes an event (such as packet transmission or reception) and contains the details such as timestamp, node IDs, packet type, and packet size.
Example trace file entries:
+ 0.500000 0 1 udp 500 ——- 1 0.0 0.0 1.0
– 0.510000 0 1 udp 500 ——- 1 0.0 0.0 1.0
r 0.515000 1 2 udp 500 ——- 1 0.0 0.0 1.0
d 0.520000 1 2 udp 500 ——- 1 0.0 0.0 1.0
- +: Packet enqueued at a node.
- –: Packet dequeued for transmission.
- r: Packet received at a node.
- d: Packet dropped.
Each line gives data such as the timestamp, source and end node IDs, packet size, and packet type.
- Calculate Network Metrics from the Log
The trace file consist of all the data essential to compute key network performance metrics like throughput, latency, and packet loss.
Throughput Calculation
Throughput is the total amount of data effectively sent over a period of time. We can be computed it by adding the packet sizes of all successfully sent packets then dividing by the total simulation time.
Given below is an AWK script to estimate the throughput among two nodes:
awk ‘
{
if ($1 == “r” && $3 == “2”) { # Packet received at node 2
total_bytes += $6; # Sum the size of the received packets
}
}
END {
print “Throughput:”, total_bytes / 5.0, “bytes/sec”; # Divide by the simulation time (5 seconds)
}’ out.tr
This script evaluates the total number of bytes received by node2 then divides it by the simulation duration (5 seconds) to calculate the throughput in bytes for each second.
Latency Calculation
Latency is the time it takes for a packet to travel from the source to the end. We can be assessed it by comparing the time a packet is enqueued at the origin node and the time it is received at the end node.
Here’s an AWK script to estimate the average latency:
awk ‘
{
if ($1 == “+”) {
send_time[$7] = $2; # Record the time a packet is enqueued at the source node
}
if ($1 == “r” && $3 == “2”) {
if (send_time[$7] != “”) {
latency = $2 – send_time[$7]; # Calculate the latency (receive time – send time)
total_latency += latency;
count++;
}
}
}
END { print “Average Latency:”, total_latency / count, “seconds”; }’ out.tr
This script estimates the average latency by comparing the time a packet is transmitted including the time it is received at the end.
Packet Loss Calculation
Packet loss can estimate by counting the number of dropped packets. Dropped packets are marked by the d symbol within the trace file.
The following is an AWK script to assess the packet loss:
awk ‘
{
if ($1 == “d”) { # Count dropped packets
dropped_packets++;
}
}
END { print “Total Dropped Packets:”, dropped_packets; }’ out.tr
This script counts how many packets were dropped in the course of the simulation.
- Custom Logging and Filtering
As well as the default logging delivered by NS2, we cab execute custom logging and filtering to capture particular events. For instance, we may require to log only packets of a particular type or only log events related to particular nodes.
Example: Log Only UDP Packets
We can be changed the trace file logging to capture only UDP packets by summing a filter:
set udp_only_trace [open udp_trace.tr w]
$ns trace-all $udp_only_trace
proc udp_filter {src dst type} {
if {$type == “UDP”} {
return 1; # Log only UDP packets
}
return 0; # Ignore other types of packets
}
$ns at 0.5 “$ns set-forwarding-filter udp_filter”
This script will log only UDP packets and filtering out other kinds of traffic.
- Visualize the Results
When we have processed the trace file and computed the metrics such as throughput, latency, and packet loss then we can be visualized these outcomes using tools such as Python (matplotlib) or Excel.
Example Python Plot for Latency:
import matplotlib.pyplot as plt
# Example data for latency over time
time = [0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5]
latency = [0.01, 0.012, 0.015, 0.013, 0.014, 0.017, 0.016, 0.014, 0.013] # Example latency data (seconds)
plt.plot(time, latency, marker=’o’)
plt.title(‘Latency Over Time’)
plt.xlabel(‘Time (seconds)’)
plt.ylabel(‘Latency (seconds)’)
plt.grid(True)
plt.show()
Summary
To compute the network logging in NS2:
- Set up logging: We can be used the trace-all command to log all network events to a trace file.
- Analyze the trace file: Describe the trace file to assess key performance metrics such as throughput, latency, and packet loss using AWK scripts or same tools.
- Custom filtering: Execute the filters to capture particular kinds of traffic or events in the trace file.
- Visualize the results: We can use the tools such as Python or Excel to envision the outcomes and acquire insights into network performance.
We thoroughly carried out a comprehensive process on Network Logging, calculate and analyse done through the simulation tool NS2. Additional informations about this topic will be shared, if required.
Share your specific parameters with us, and we’ll help you out with a performance analysis. Reach out for details on your Network Logging in the NS2 tool, and you can get some fresh project ideas and topics together.