How to Implement Network Optical Fiber in NS2
To implement Optical Fiber Communication in NS2 has needs to include mimicking the communication process over optical links using fiber optic cables. Since NS2 primarily supports wired and wireless communication protocols, we can replicate optical communication by describing high-speed links with low delay, modelling the characteristics of optical fiber channels. Since NS2 does not have built-in support for complex optical communication models such as wavelength-division multiplexing or optical amplifiers, it can still be adjusted to mimic basic high-speed optical networks.
Here is a guide on how to achieve this process in ns2:
Steps to Implement Optical Fiber Communication in NS2:
- Set up the Simulation Environment
Initially, we need to describe the simulation environment, that has nodes, links (representing optical fibers), and the metrics like high bandwidth and low delay typical of optical fiber communication.
Example TCL Script for Basic Setup:
# Create a simulator instance
set ns [new Simulator]
# Set link parameters for optical fiber (high bandwidth, low delay)
set bw 10Gb ;# Bandwidth of optical fiber link (in Gbps)
set delay 2ms ;# Delay for optical fiber link (in milliseconds)
# Create nodes
set node1 [$ns node]
set node2 [$ns node]
set node3 [$ns node]
# Create optical fiber links between nodes
$ns duplex-link $node1 $node2 $bw $delay DropTail
$ns duplex-link $node2 $node3 $bw $delay DropTail
- Configure High-Speed Traffic Over Optical Links
Optical networks are usually used for high-speed communication, so we should setup the traffic generators such as TCP or UDP to mimic high data rates. We can use CBR (Constant Bit Rate) traffic sources to mimic continuous high-speed data transfers.
Example of Configuring High-Speed Traffic:
# Create UDP agent for node1 (source)
set udp1 [new Agent/UDP]
$ns attach-agent $node1 $udp1
# Create a CBR traffic generator to simulate high-speed data transfer
set cbr1 [new Application/Traffic/CBR]
$cbr1 set packet_size_ 1500 ;# Packet size in bytes
$cbr1 set rate_ 5Gb ;# Data rate (5 Gbps)
$cbr1 attach-agent $udp1
# Create a UDP sink (receiver) at node3
set null1 [new Agent/Null]
$ns attach-agent $node3 $null1
# Connect node1 to node3 through the optical link via node2
$ns connect $udp1 $null1
# Start and stop the traffic
$ns at 1.0 “$cbr1 start”
$ns at 10.0 “$cbr1 stop”
Here, node1 is sending high-speed data to node3 via an optical link via node2. The high data rate (5 Gbps) is typical of optical fiber communication.
- Simulate Optical Amplifiers (Optional)
Since NS2 doesn’t support explicit optical components such as amplifiers, we can replicate the impacts of amplification (to some extent) by adapting the latency and bandwidth based on the distance among nodes.
For instance, if optical link exceeds a certain distance, we can add an intermediate node that mimic the amplification process, minimizing the latency or increasing the effective bandwidth.
# Create an intermediate node to simulate an optical amplifier
set amplifier [$ns node]
# Create optical links with additional nodes simulating an amplifier
$ns duplex-link $node1 $amplifier $bw $delay DropTail
$ns duplex-link $amplifier $node2 $bw $delay DropTail
- Add Wavelength Division Multiplexing (WDM) Simulation (Optional)
To mimic Wavelength Division Multiplexing (WDM), in which multiple channels are supported over the same optical fibre, we can generate multiple parallel links among the nodes. Each link denotes a different wavelength, and different traffic flows can be allocated to diverse wavelengths.
# Create two parallel optical links to simulate WDM with two wavelengths
$ns duplex-link $node1 $node2 $bw $delay DropTail
$ns duplex-link $node1 $node2 $bw $delay DropTail ;# Second wavelength
# Create traffic for each wavelength
set udp2 [new Agent/UDP]
$ns attach-agent $node1 $udp2
set cbr2 [new Application/Traffic/CBR]
$cbr2 set packet_size_ 1500
$cbr2 set rate_ 3Gb
$cbr2 attach-agent $udp2
# Connect second wavelength traffic
$ns connect $udp2 $null1
$ns at 2.0 “$cbr2 start”
$ns at 12.0 “$cbr2 stop”
Here, two optical links mimic two wavelengths over the same physical fiber, with isolate traffic flows using diverse wavelengths.
- Monitor and Trace the Simulation
Enable tracing in NS2 to observe the performance of optical network, like packet transmissions, latency, losses, and throughput.
Enable Trace Files:
# Enable tracing for the simulation
set tracefile [open “optical_trace.tr” w]
$ns trace-all $tracefile
# Define a finish procedure to end the simulation and close the trace file
proc finish {} {
global ns tracefile
$ns flush-trace
close $tracefile
exit 0
}
# Set the simulation end time
$ns at 20.0 “finish”
The trace file will record all network events that have packet transmissions and latency, enable them to measure the performance of the optical network.
- Run the Simulation
Finally, execute the simulation to monitor the behaviour of high-speed optical communication links.
# Run the simulation
$ns run
Example Complete TCL Script for Optical Fiber Network Simulation
# Create a simulator instance
set ns [new Simulator]
# Set optical fiber link parameters
set bw 10Gb
set delay 2ms
# Create nodes
set node1 [$ns node]
set node2 [$ns node]
set node3 [$ns node]
# Create optical fiber links between nodes
$ns duplex-link $node1 $node2 $bw $delay DropTail
$ns duplex-link $node2 $node3 $bw $delay DropTail
# Create UDP agent for high-speed communication
set udp1 [new Agent/UDP]
$ns attach-agent $node1 $udp1
# Create a CBR traffic generator for high-speed data transfer
set cbr1 [new Application/Traffic/CBR]
$cbr1 set packet_size_ 1500
$cbr1 set rate_ 5Gb
$cbr1 attach-agent $udp1
# Create a UDP sink at node3
set null1 [new Agent/Null]
$ns attach-agent $node3 $null1
# Connect the source (node1) to the sink (node3)
$ns connect $udp1 $null1
# Start and stop the traffic
$ns at 1.0 “$cbr1 start”
$ns at 10.0 “$cbr1 stop”
# Enable tracing
set tracefile [open “optical_trace.tr” w]
$ns trace-all $tracefile
# End simulation
$ns at 20.0 “finish”
proc finish {} {
global ns tracefile
$ns flush-trace
close $tracefile
exit 0
}
# Run the simulation
$ns run
In the end of the replication, now we have some acquaintance about how the Optical Fiber Communication will perform in the network by using ns2 simulation tool. We will also intricate the additional supportive information about the Optical Fiber Communication in further upcoming manuals.
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