To simulate Next Hop routing protocol projects in NS2, has needs to concentrate on configures a simple network in which each node forwards packets to the next hop up to the packet reaches the destination. In many cases, next-hop routing is an integral part of routing protocols such as AODV, DSR, and others that utilize hop-by-hop forwarding. For a custom Next Hop protocol, we will describe on how nodes discover and choose the next hop in terms of proximity, connectivity, or predefined routes.
Here’s a step-by-step guide on how to simulate a Next Hop routing protocol in NS2:
Steps to Simulate Next Hop Protocol Projects in NS2
- Install NS2
Make sure that NS2 is installed on the system. You can download it from the NS2 official page.
- Set up Basic Network Topology
In the Next Hop routing protocol, each node identifies only the next hop towards the destination. The routing is simplified, and each node forwards packets according to the next-hop information. We can physically describe routing tables with the next hop for each node or replicate a dynamic discovery process.
Example TCL Script for a Basic Network with Next Hop Routing:
# Create a new simulator instance
set ns [new Simulator]
# Define trace and nam files for logging and visualization
set tracefile [open next_hop_simulation.tr w]
$ns trace-all $tracefile
set namfile [open next_hop_simulation.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]
# Create duplex links between the nodes
$ns duplex-link $n0 $n1 1Mb 10ms DropTail
$ns duplex-link $n1 $n2 1Mb 10ms DropTail
$ns duplex-link $n2 $n3 1Mb 10ms DropTail
$ns duplex-link $n3 $n4 1Mb 10ms DropTail
# Set up node positions (optional if mobility is not needed)
$n0 set X_ 50; $n0 set Y_ 50; $n0 set Z_ 0.0
$n1 set X_ 100; $n1 set Y_ 100; $n1 set Z_ 0.0
$n2 set X_ 200; $n2 set Y_ 150; $n2 set Z_ 0.0
$n3 set X_ 300; $n3 set Y_ 200; $n3 set Z_ 0.0
$n4 set X_ 400; $n4 set Y_ 250; $n4 set Z_ 0.0
- Implement Next Hop Routing Logic
To replicate a Next Hop protocol, we can weather:
- Manually define static routing tables in which each node forwards packets to the next hop, or
- Simulate dynamic next-hop discovery using reactive or proactive routing methods, like AODV or DSR.
Example: Manually Define Next Hop Routing
We can physically describe routes for each node so that they identify which node is their next hop towards the destination.
# Enable static routing
$ns rtproto Static
# Define next hop routes
$n0 add-route $n4 via $n1 ;# n0 forwards packets to n1 for n4
$n1 add-route $n4 via $n2 ;# n1 forwards packets to n2 for n4
$n2 add-route $n4 via $n3 ;# n2 forwards packets to n3 for n4
$n3 add-route $n4 via $n4 ;# n3 directly sends packets to n4
In this setup:
- n0 forwards packets to n1 as the next hop towards n4.
- n1 forwards packets to n2, and so on, until n4 is reached.
- Set up Traffic between Nodes
We can utilize TCP or UDP traffic to replicate data transfer among nodes. Here’s how to configure TCP and UDP traffic.
Example for TCP Traffic:
# Set up TCP connection between node 0 and node 4
set tcp0 [new Agent/TCP]
set sink0 [new Agent/TCPSink]
$ns attach-agent $n0 $tcp0
$ns attach-agent $n4 $sink0
$ns connect $tcp0 $sink0
# Create FTP traffic over TCP
set ftp0 [new Application/FTP]
$ftp0 attach-agent $tcp0
$ns at 2.0 “$ftp0 start”
$ns at 10.0 “$ftp0 stop”
Example for UDP Traffic (CBR):
# Set up UDP communication between node 1 and node 3
set udp0 [new Agent/UDP]
set null0 [new Agent/Null]
$ns attach-agent $n1 $udp0
$ns attach-agent $n3 $null0
# Generate CBR traffic over UDP
set cbr0 [new Application/Traffic/CBR]
$cbr0 set packetSize_ 512
$cbr0 set rate_ 100kb
$cbr0 attach-agent $udp0
$ns at 3.0 “$cbr0 start”
$ns at 12.0 “$cbr0 stop”
- Run the Simulation
Once we have configured the network, traffic, and routing, we can execute the simulation. Save your TCL script (e.g., next_hop_simulation.tcl) and execute it using NS2:
ns next_hop_simulation.tcl
This will create a trace file (.tr) and a NAM file (.nam) for evaluation and envisioned in Network Animator (NAM).
- Analyse the Simulation Results
We can evaluate key parameters like Packet Delivery Ratio (PDR), End-to-End Delay, and Routing Overhead. Here’s an instance AWK script to estimate the Packet Delivery Ratio:
BEGIN { sent = 0; received = 0; }
{
if ($1 == “s” && $4 == “AGT”) { sent++; }
if ($1 == “r” && $4 == “AGT”) { received++; }
}
END {print “Packet Delivery Ratio = “, received/sent*100, “%”; }
We can also envision the packet forwarding and route selection in NAM to see how packets hop from one node to the next.
- Example Project Ideas for Next Hop Protocol Simulation
- Performance Comparison Between Next Hop Routing and AODV:
- Replicate both next hop routing and AODV to relate their performance based on packet delivery, routing overhead and end-to-end delay.
- Energy Efficiency in Next Hop Routing:
- Measure the energy consumption of each node in a next hop routing environment and measure its effectiveness in sensor or mobile networks.
- Next Hop Routing in Mobile Networks:
- Mimic a mobile network with next hop routing and evaluate on how node mobility impacts the routing performance and path discovery.
- Scalability of Next Hop Routing:
- Replicate a large-scale network with next hop routing and measure its scalability by evaluate packet delivery ratio, latency, and overhead as the network size increases.
In this manual, we clearly explained the concepts about how to simulate and install the environment for Next Hop routing protocol projects in ns2 tool and also we offered the simulation procedures, sample snippets and the extension for this project with the project ideas. If you want to know more details feel free to ask!
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