How to Calculate Network Transmission Speed in NS2
To calculate the network transmission speed in NS2 has includes controlling how fast data is routed among nodes. Transmission speed is usually expressed in bits per second (bps) that can be resulting from the throughput, which is the amount of data effectively transferred per unit of time.
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The below are the techniques to achieve this in ns2:
Steps to Calculate Network Transmission Speed:
- Set Up the Simulation: State the nodes, traffic types (UDP, TCP, or CBR), and packet sizes in NS2 simulation. This will permit to monitor the transmission events during the simulation.
- Generate a Trace File: NS2 creates a trace file that logs all packet transmission, reception, and dropping events. By evaluating the sent and received packets from this trace file, we can estimate the transmission speed.
- Analyse the Trace File: Utilize the trace file to classify the amount of data routed among the nodes and estimate the time taken for the transmission. Transmission speed is estimated as the total number of bits transmitted divided by the time duration.
- Formula for Transmission Speed:
Transmission Speed (bps)=Total Data Transmitted (bits)Transmission Time (seconds)\text{Transmission Speed (bps)} = \frac{\text{Total Data Transmitted (bits)}}{\text{Transmission Time (seconds)}}Transmission Speed (bps)=Transmission Time (seconds)Total Data Transmitted (bits)
Example Tcl Script for NS2 Simulation:
Below is an sample Tcl script for configuring a simple network simulation in which two nodes interacted using UDP, and we estimated the transmission speed by evaluating the trace file.
# Create a new simulator instance
set ns [new Simulator]
# Open trace file to record events
set tracefile [open trace.tr w]
$ns trace-all $tracefile
# Define two nodes
set node1 [$ns node]
set node2 [$ns node]
# Define UDP agents and traffic source
set udp [new Agent/UDP]
set null [new Agent/Null]
$ns attach-agent $node1 $udp
$ns attach-agent $node2 $null
# Connect the nodes
$ns connect $udp $null
# Define CBR traffic source (constant bit rate)
set cbr [new Application/Traffic/CBR]
$cbr attach-agent $udp
$cbr set packetSize_ 512
$cbr set rate_ 1Mb
# Schedule traffic start and stop times
$ns at 1.0 “$cbr start”
$ns at 5.0 “$cbr stop”
# Define finish procedure
proc finish {} {
global ns tracefile
$ns flush-trace
close $tracefile
exit 0
}
# Schedule end of simulation
$ns at 6.0 “finish”
# Run the simulation
$ns run
- Trace File Analysis:
Once the simulation is done, we can evaluate the trace file (trace.tr) to estimate the transmission speed. The trace file records events like packet transmissions, receptions, and drops.
- Sent Packets: Marked by s in the trace file.
- Received Packets: Marked by r in the trace file.
Each packet includes the data like the packet size and the time of the event, that will support to estimate the transmission speed.
Example Trace File Output:
s 1.0 _1_ AGT — 512 [0 0 0 0] ——- [1:0 2:0 32 0]
r 1.1 _2_ AGT — 512 [0 0 0 0] ——- [1:0 2:0 32 0]
- The s line denoted a packet sent by node1.
- The r line signifies a packet received by node2.
- The value 512 denotes the packet size in bytes.
- Calculate Transmission Speed:
Bash Script to Calculate Transmission Speed:
We can utilize a basic Bash script to estimate the total number of packets routed, their size, and the time interval to estimate the transmission speed.
# Count the number of packets sent by node1
sent_packets=$(grep “^s” trace.tr | grep “_1_” | wc -l)
# Packet size in bytes (512 bytes)
packet_size=512
# Convert packet size to bits (1 byte = 8 bits)
packet_size_bits=$(echo “$packet_size * 8” | bc)
# Calculate total data transmitted in bits
total_data_transmitted=$(echo “$sent_packets * $packet_size_bits” | bc)
# Calculate transmission time (difference between first and last packet timestamps)
start_time=$(grep “^s” trace.tr | head -n 1 | awk ‘{print $2}’)
end_time=$(grep “^s” trace.tr | tail -n 1 | awk ‘{print $2}’)
transmission_time=$(echo “$end_time – $start_time” | bc)
# Calculate transmission speed in bits per second (bps)
if [ $(echo “$transmission_time > 0” | bc) -eq 1 ]; then
transmission_speed=$(echo “scale=2; $total_data_transmitted / $transmission_time” | bc)
echo “Transmission Speed: $transmission_speed bps”
else
echo “Transmission time is zero, unable to calculate speed.”
fi
Example Calculation:
Let’s assume:
- Sent Packets: 100 packets
- Packet Size: 512 bytes = 4096 bits
- Transmission Time: 4 seconds
Using these values:
- Total Data Transmitted:
100×4096 bits=409,600 bits100 \times 4096 \text{ bits} = 409,600 \text{ bits}100×4096 bits=409,600 bits
- Transmission Speed:
Transmission Speed=409,600 bits4 seconds=102,400 bps\text{Transmission Speed} = \frac{409,600 \text{ bits}}{4 \text{ seconds}} = 102,400 \text{ bps}Transmission Speed=4 seconds409,600 bits=102,400 bps
Thus, the network transmission speed would be 102.4 kbps.
Summary of Steps:
- Run the NS2 simulation with the preferred traffic pattern and nodes.
- Analyse the trace file to extract the number of sent packets, the packet size, and the time difference among the first and last packet transmission.
- Calculate transmission speed using the formula: Transmission Speed (bps)=Total Data Transmitted (bits)Transmission Time (seconds)\text{Transmission Speed (bps)} = \frac{\text{Total Data Transmitted (bits)}}{\text{Transmission Time (seconds)}}Transmission Speed (bps)=Transmission Time (seconds)Total Data Transmitted (bits)
By following these steps, we can compute the transmission speed for any network setup simulated in NS2. Let me know if you need further details or help with this!
In this module, we had clearly understood the computation procedures, sample snippets were given to enforce the network transmission speed with the help of ns2 tool. We also deliver further significant information regarding the network transmission speed will be provided.