To simulate a Ring-Mesh Hybrid Topology in NS2 (Network Simulator 2) has includes integrating the two topological structures: Ring and Mesh. This hybrid topology can be utilized in networks in which the nodes are arranged in a ring for easy traversal however with some extra mesh-like links to upsurge redundancy and fault tolerance.
Here is a procedure on how to replicate the Ring-Mesh Hybrid Topology in NS2
Steps to Simulate Ring Mesh Hybrid Topology Projects in NS2
Step 1: Understand the Ring-Mesh Hybrid Topology
In a Ring-Mesh Hybrid Topology:
- Ring Topology: Nodes are organized in a circular structure, with each node associated to two neighbours (one on each side). These types of network effective for communication, however it can suffer if a single link miscarries.
- Mesh Topology: Nodes have multiple connections to each other that deliver multiple paths for redundancy and fault tolerance.
- The hybrid integrates both characteristics by organizing some nodes in a ring since incorporates additional mesh-like connections to some of the nodes to upsurge flexibility and communication resilience.
Step 2: Design the Network
We will mimic a Ring-Mesh Hybrid Topology where:
- Nodes are organized in a ring structure, with each node associates to its immediate neighbour.
- Additional mesh-like links are incorporated among non-adjacent nodes for increased redundancy and to deliver multiple paths among nodes.
Step 3: Create an NS2 TCL Script for Simulating a Ring-Mesh Hybrid Topology
Below is an NS2 TCL script which replicates a Ring-Mesh Hybrid Topology with a circular arrangement of nodes and some additional links to construct a mesh.
Example: Ring-Mesh Hybrid Topology Simulation in NS2
# Create a new NS2 simulator object
set ns [new Simulator]
# Define the number of nodes for the ring and mesh
set num_nodes 6 ;# Total number of nodes (adjust as needed)
# Create the nodes (hosts)
set nodes {}
for {set i 0} {$i < $num_nodes} {incr i} {
set node [$ns node]
lappend nodes $node
}
# Connect nodes in a ring topology (each node connected to its next and previous neighbors)
for {set i 0} {$i < $num_nodes} {incr i} {
set next_idx [expr ($i + 1) % $num_nodes] ;# Next node in the ring (wrap around)
set prev_idx [expr ($i – 1 + $num_nodes) % $num_nodes] ;# Previous node in the ring
# Create duplex links for the ring structure
$ns duplex-link [lindex $nodes $i] [lindex $nodes $next_idx] 1Mb 10ms DropTail
}
# Add additional mesh-like links to increase redundancy (connect non-adjacent nodes)
# Example: connect node 0 to node 2 and node 3 to node 5 for a partial mesh
$ns duplex-link [lindex $nodes 0] [lindex $nodes 2] 1Mb 10ms DropTail
$ns duplex-link [lindex $nodes 3] [lindex $nodes 5] 1Mb 10ms DropTail
# Attach UDP agents to the nodes for communication
set udp1 [new Agent/UDP]
set udp2 [new Agent/UDP]
$ns attach-agent [lindex $nodes 0] $udp1
$ns attach-agent [lindex $nodes 5] $udp2
# Attach Null agents to act as sinks at the opposite nodes
set null1 [new Agent/Null]
set null2 [new Agent/Null]
$ns attach-agent [lindex $nodes 5] $null1
$ns attach-agent [lindex $nodes 0] $null2
# Connect the UDP agents to their respective sinks
$ns connect $udp1 $null1
$ns connect $udp2 $null2
# Create CBR traffic from node 0 to node 5 and vice versa
set cbr1 [new Application/Traffic/CBR]
$cbr1 set packetSize_ 512
$cbr1 set interval_ 0.1
$cbr1 attach-agent $udp1
set cbr2 [new Application/Traffic/CBR]
$cbr2 set packetSize_ 512
$cbr2 set interval_ 0.1
$cbr2 attach-agent $udp2
# Start the traffic flows
$ns at 1.0 “$cbr1 start”
$ns at 1.5 “$cbr2 start”
# Create trace and nam files for recording the simulation events
set tracefile [open “ring_mesh_hybrid.tr” w]
$ns trace-all $tracefile
set namfile [open “ring_mesh_hybrid.nam” w]
$ns namtrace-all $namfile
# Define the finish procedure to close files and start NAM
proc finish {} {
global ns tracefile namfile
$ns flush-trace
close $tracefile
close $namfile
exec nam ring_mesh_hybrid.nam &
exit 0
}
# Finish the simulation after 10 seconds
$ns at 10.0 “finish”
# Run the simulation
$ns run
Step 4: Explanation of the Script
- Network Setup:
- Six nodes are generated in a circular (ring) arrangement. Each node is associated to its immediate neighbour, generating a simple ring topology.
- Two additional mesh-like links are incorporated: one between nodes 0 and 2 and another among nodes 3 and 5. This delivers alternate communication paths, accumulative redundancy and fault tolerance.
- Communication Setup:
- UDP agents are associated to nodes 0 and 5 to replicate communication among them.
- CBR (Constant Bit Rate) traffic is created among these nodes to replicate constant data transfer.
- Link Characteristics:
- All links are set up with a bandwidth of 1Mb and a latency of 10ms. We can adapt these metrics to design different network conditions.
- Tracing and Visualization:
- A trace file (ring_mesh_hybrid.tr) is created to log network events, like packet transmissions, receptions, and drops.
- A NAM file (ring_mesh_hybrid.nam) is created for envisioning the network topology and traffic flows.
Step 5: Run the Simulation
- Save the script as ring_mesh_hybrid.tcl.
- Execute the script in NS2:
ns ring_mesh_hybrid.tcl
This will create two files:
- ring_mesh_hybrid.tr: A trace files which logs packet-level information.
- ring_mesh_hybrid.nam: A NAM file for envision the network in NAM.
Step 6: Visualize the Simulation Using NAM
To envision the Ring-Mesh Hybrid Topology in NAM:
nam ring_mesh_hybrid.nam
In NAM, we will see:
- The nodes organized in a ring and the additional mesh-like links among non-adjacent nodes.
- Packet transmissions among nodes as traffic flows between node 0 and node 5.
Step 7: Analyse the Trace File
The trace file (ring_mesh_hybrid.tr) logs all network events, like:
- Packet transmissions and receptions among the nodes.
- Packet drops or delays because of network congestion or link conditions.
We can utilize tools such as AWK, Python, or custom scripts to measure the trace file and extract key parameters like:
- Packet delivery ratio (PDR).
- End-to-end delay among nodes.
- Network throughput and link utilization.
Step 8: Enhance the Simulation
Here are some ways to prolonged or optimize the simulation:
- Add More Nodes: Add the amount of nodes and links to generate a larger and more complex ring-mesh hybrid topology.
- Simulate Link Failures: Establish link failures to learn on how the mesh-like links deliver redundancy and enable the network to sustain connectivity.
- Dynamic Routing: Execute a routing protocol such as AODV to enthusiastically route packets over different paths according to network conditions.
- Measure Performance Metrics: Measure parameters like latency, throughput, and packet loss in different traffic loads or failure environment.
In this configuration, we have been clearly understood the concepts and learn the essential procedures to simulate the Ring-Mesh Hybrid Topology project that has encompass the installation procedures and generating the network topology and then envisioned the outcomes via ns2 analysis too. Further details will be provided later.
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