To simulate Path Vector Routing in NS2, we will require adjusting NS2 to manage the routing protocols, which maintain path information in their routing updates. Path Vector Routing is generally connected with the Border Gateway Protocol (BGP), in which each router advertises the whole path it knows to attain a destination, rather than just the distance.
While NS2 doesn’t have a built-in implementation of BGP then we can replicate a same idea utilizing custom modifications, or we can mimic a simplified path vector protocol by building upon existing distance vector or link state routing mechanisms and inserting the path tracking.
Following is a common procedure on how we can simulate Path Vector Routing in NS2 by making a custom protocol, which simulates the path vector behavior.
Steps to Simulate Path Vector Routing in NS2
- Install NS2
Make certain NS2 is installed on the machine. If not, we can download and install it from the NS2 Official Website.
- Define Path Vector Routing Protocol
NS2 has built-in support for protocols such as AODV, DSDV, and DSR. But, to replicate a Path Vector protocol, we will require describing the custom protocol, which will:
- Keep track of the path (sequence of nodes) to the destination.
- Exchange path data with neighbors, rather than just distance parameters.
- Create a TCL Script for Path Vector Routing Simulation
Below script outlines how to replicate a network with simple path vector functionality. We can change it to encompass path tracking (where each node records the sequence of nodes taken to reach the destination).
Example TCL Script for Path Vector Routing:
# Create a simulator object
set ns [new Simulator]
# Define trace and NAM files for analysis and visualization
set tracefile [open “path_vector_trace.tr” w]
set namfile [open “path_vector_simulation.nam” w]
$ns trace-all $tracefile
$ns namtrace-all $namfile
# Create network topology and nodes
set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]
set n4 [$ns node]
# Define links between nodes with bandwidth and delay
$ns duplex-link $n0 $n1 1Mb 10ms DropTail
$ns duplex-link $n1 $n2 1Mb 20ms DropTail
$ns duplex-link $n2 $n3 1Mb 30ms DropTail
$ns duplex-link $n3 $n4 1Mb 10ms DropTail
$ns duplex-link $n0 $n2 1Mb 25ms DropTail
$ns duplex-link $n1 $n3 1Mb 15ms DropTail
# Custom Path Vector Protocol initialization (pseudo code for path vector)
# You would need to write custom routing logic here, based on path vector protocol.
# For now, we simulate standard routing
for {set i 0} {$i < 5} {incr i} {
$ns at 0.0 “$n$i start-dv-routing” # Example of Distance Vector start
}
# Define a UDP agent and attach it to node 0 (source)
set udp0 [new Agent/UDP]
$ns attach-agent $n0 $udp0
# Define a CBR (Constant Bit Rate) traffic generator for the UDP agent
set cbr0 [new Application/Traffic/CBR]
$cbr0 set packetSize_ 512
$cbr0 set rate_ 1Mb
$cbr0 attach-agent $udp0
# Attach a UDP sink agent to node 4 (destination)
set udp1 [new Agent/UDP]
$ns attach-agent $n4 $udp1
# Connect the source and destination agents
$ns connect $udp0 $udp1
# Schedule the traffic flow
$ns at 1.0 “$cbr0 start”
$ns at 4.5 “$cbr0 stop”
# Define the finish procedure
proc finish {} {
global ns tracefile namfile
$ns flush-trace
close $tracefile
close $namfile
exit 0
}
# End the simulation at 5 seconds
$ns at 5.0 “finish”
# Run the simulation
$ns run
- Run the Simulation
We can save the script as path_vector_simulation.tcl, and execute it in NS2:
ns path_vector_simulation.tcl
- Visualize the Simulation
We can open the generated .nam file to envision the network in the Network Animator (NAM):
nam path_vector_simulation.nam
- Analyze the Trace File
The trace file (path_vector_trace.tr) includes information of the packet transmissions, routing decisions, and other parameters we can utilize to examine the performance of the Path Vector Routing simulation.
- Extend the Protocol for Path Vector Behavior
We can further modify the script by inserting a protocol, which logs the whole path (vector of nodes) as part of routing updates. It will include changing the source code in NS2 to execute the path vector logic or incorporating an existing BGP-like behavior if obtainable within NS2 or third-party modules.
Optional Enhancements:
- Path Loop Prevention: Insert logic to avoid the routing loops by verifying if a node is previously in the path vector.
- Failure Handling: Replicate node or link failures and monitor how the path vector protocol responds by recalculating paths.
- Performance Comparison: Relate the performance of Path Vector Routing with other protocols like Distance Vector or Link State.
These projects provide a comprehensive exploration of Path Vector Routing using NS2, covering performance, enhancements, and basic path vector functionality. We will also be offered further information related to these projects, if necessary.
Provide us with your information, and we will help you enhance your project performance on Path Vector Routing Projects utilizing the NS2 tool.
