To simulate switching protocols projects using NS2, we would usually replicate network scenarios that contain packet switching, circuit switching, and variants such as virtual circuit switching. While NS2 mainly concentrates on packet-switched networks, replicating switching protocols will includes configuring nodes, links, and traffic sources to act as based on the switching approaches you’re simulating.
Here’s a step-by-step guide on how to simulate switching protocols using NS2:
Steps to Simulate Switching Protocols Projects in NS2
- Install NS2
Make sure that NS2 is installed on the system.
- Define the Network Topology for Switching Protocols
Packet Switching Protocol Simulation
In packet switching, data is broken into small packets that are routed independently. Each packet can take a diverse path to reach the destination.
Here is how to configure packet switching in NS2:
# Create a new simulator instance
set ns [new Simulator]
# Define output files for trace and nam visualization
set tracefile [open packet_switch.tr w]
$ns trace-all $tracefile
set namfile [open packet_switch.nam w]
$ns namtrace-all $namfile
# Create nodes
set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]
set n4 [$ns node]
# Define packet-switched duplex links between nodes
$ns duplex-link $n0 $n1 2Mb 10ms DropTail
$ns duplex-link $n1 $n2 1.5Mb 20ms DropTail
$ns duplex-link $n2 $n3 1Mb 10ms DropTail
$ns duplex-link $n3 $n4 1.5Mb 10ms DropTail
# Configure TCP connection to simulate packet-switched data flow
set tcp0 [new Agent/TCP]
set sink [new Agent/TCPSink]
$ns attach-agent $n0 $tcp0
$ns attach-agent $n4 $sink
$ns connect $tcp0 $sink
# Generate FTP traffic over TCP
set ftp0 [new Application/FTP]
$ftp0 attach-agent $tcp0
$ns at 1.0 “$ftp0 start”
$ns at 10.0 “$ftp0 stop”
# Define end of simulation
$ns at 20.0 “finish”
# Run the simulation
$ns run
Circuit Switching Protocol Simulation
Circuit switching reserves a dedicated communication path for the complete duration of the transmission. Since NS2 is mostly intended for packet-switched networks, we can implement circuit switching by introducing a static, non-disruptive connection among nodes.
Here’s a way to replicate circuit switching behaviour in NS2:
# Create the simulator
set ns [new Simulator]
# Define trace and nam files
set tracefile [open circuit_switch.tr w]
$ns trace-all $tracefile
set namfile [open circuit_switch.nam w]
$ns namtrace-all $namfile
# Create nodes
set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]
# Circuit-switched link configuration (fixed link capacity)
$ns duplex-link $n0 $n1 1.5Mb 5ms DropTail
$ns duplex-link $n1 $n2 1.5Mb 5ms DropTail
$ns duplex-link $n2 $n3 1.5Mb 5ms DropTail
# Generate TCP traffic simulating reserved bandwidth (dedicated channel)
set tcp0 [new Agent/TCP]
set sink [new Agent/TCPSink]
$ns attach-agent $n0 $tcp0
$ns attach-agent $n3 $sink
$ns connect $tcp0 $sink
set ftp0 [new Application/FTP]
$ftp0 attach-agent $tcp0
$ns at 1.0 “$ftp0 start”
$ns at 9.0 “$ftp0 stop”
# End of simulation
$ns at 10.0 “finish”
# Run the simulation
$ns run
Virtual Circuit Switching Protocol Simulation
In virtual circuit switching, a logical connection is introduced, and all packets in the session follow the same path. We can replicate this by set up nodes to route all traffic along a predefined path.
# Create simulator instance
set ns [new Simulator]
# Define trace and nam files
set tracefile [open vc_switch.tr w]
$ns trace-all $tracefile
set namfile [open vc_switch.nam w]
$ns namtrace-all $namfile
# Create nodes
set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]
set n4 [$ns node]
# Define links between nodes (representing the virtual circuit)
$ns duplex-link $n0 $n1 2Mb 10ms DropTail
$ns duplex-link $n1 $n2 1Mb 15ms DropTail
$ns duplex-link $n2 $n3 1.5Mb 10ms DropTail
$ns duplex-link $n3 $n4 2Mb 10ms DropTail
# Establish TCP connection (fixed route for virtual circuit)
set tcp0 [new Agent/TCP]
set sink [new Agent/TCPSink]
$ns attach-agent $n0 $tcp0
$ns attach-agent $n4 $sink
$ns connect $tcp0 $sink
# Generate traffic
set ftp0 [new Application/FTP]
$ftp0 attach-agent $tcp0
$ns at 1.0 “$ftp0 start”
# End the simulation
$ns at 10.0 “finish”
# Run the simulation
$ns run
- Run the Simulation
Save the above scripts as .tcl files (e.g., packet_switch.tcl, circuit_switch.tcl, vc_switch.tcl). To execute the simulations, utilize the command:
ns packet_switch.tcl
ns circuit_switch.tcl
ns vc_switch.tcl
- Analyze the Output
- Trace Files (.tr): These files contain detailed logs of packet transmissions that can be utilized to measure parameters like packet delivery ratio, delay, and throughput.
- NAM Files (.nam): we can envision the network topology and traffic using the NS2 Network Animator (NAM) tool.
- Performance Metrics
Key parameters to evaluate in switching protocol simulations that involve:
- Throughput: Evaluate the amount of data transmitted successfully over the network.
- End-to-End Delay: Estimate the time taken for packets to travel from the source to the destination.
- Packet Loss: Monitor the number of packets that are dropped or lost in the course of transmission.
We can compose AWK scripts to execute the trace files for performance evaluation. For instance, here’s an AWK script to estimate throughput:
BEGIN {
recvBytes = 0;
startTime = 0;
endTime = 0;
}
# Calculate received bytes and time range
{
if ($1 == “r” && $4 == “AGT”) {
recvBytes += $7;
if (startTime == 0) startTime = $2;
endTime = $2;
}
}
END {
throughput = (recvBytes * 8) / (endTime – startTime) / 1024;
print “Throughput: “, throughput, ” Kbps”;
}
Example Project Ideas for Switching Protocol Simulation
- Packet Switching vs. Circuit Switching Performance: Relate the performance of packet switching and circuit switching based on delay, throughput, and scalability.
- Impact of Traffic Load on Switching Protocols: Mimic increasing traffic loads on packet-switched and circuit-switched networks to measure on how each switching approaches manage congestion.
- Virtual Circuit Switching in VoIP Networks: Replicate a virtual circuit-switching environment for VoIP applications and evaluate its effect on latency and jitter.
- Fault Tolerance in Circuit-Switched Networks: Examine the features of circuit-switched networks in failure conditions and relate it with packet-switched networks.
- Hybrid Switching Networks: Integrate circuit switching and packet switching in a hybrid simulation, in which voice traffic utilizes circuit switching and data traffic utilizes packet switching.
Here, we clearly discussed about the simulation procedures that were utilized to simulate the switching protocols projects using ns2 tool and it contains the essential information like step-by step procedure, explanation and extension for the simulation. If you need more details then feel free to ask!
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