How to Start Hot Potato Routing Projects Using NS2

To create a Hot Potato Routing project using NS2 (Network Simulator 2), follow these detailed steps. Hot Potato Routing is a routine procedure in which the packets are sending to many available for the next hop deprived of holding them in a queue, goal for minimal delay.

Steps to Start Hot Potato Routing Projects Using NS2

Step 1: Set Up NS2 Environment

  1. Install NS2:
    • Download and install NS2 from the NS2 Official Website.
    • Validate the installation:

ns -version

  1. Familiarize with NS2 Basics:
    • Recognize the Tcl scripting for NS2, has includes the node creation, connection definition, and congestion generation.
    • Analysis for the sample from ns-allinone-2.x/examples/.

Step 2: Understand Hot Potato Routing

  1. What is Hot Potato Routing?
    • A packet-switching technique in which the packets are transmitted to the next hop once they arrive, even it is not the optimal path.
    • Nodes are prioritizing to minimizing the queuing latency.
  2. Use Cases:
    • Networks by low buffer capacity for the use case.
    • Environments need the minimal packet for a holding time.
  3. Challenges:
    • It can lead to suboptimal paths.
    • Improved the probability for the packet drops in congested networks.

Step 3: Design Network Topology

  1. Create a Topology:
    • Model a network through several nodes and connection to assign the non-optimal routing paths.

Example:

set ns [new Simulator]

# Create nodes

set n1 [$ns node]

set n2 [$ns node]

set n3 [$ns node]

set n4 [$ns node]

# Create links with bandwidth and delay

$ns duplex-link $n1 $n2 10Mb 5ms DropTail

$ns duplex-link $n2 $n3 10Mb 10ms DropTail

$ns duplex-link $n3 $n4 10Mb 15ms DropTail

$ns duplex-link $n1 $n3 5Mb 20ms DropTail

  1. Validate Topology:
    • Assure the several paths exist for packets to income the non-optimal routes.

Step 4: Implement Hot Potato Routing

Hot Potato Routing is not natively implemented in NS2. We will necessary to replicate the behavior or extend NS2 by alter the logic.

Option 1: Simulate Hot Potato in Tcl

  1. Define Routing Logic:
    • Transmit the packets for many possible neighbor according to the round-robin or random methods:

proc hotPotatoRoute {src neighbors} {

# Randomly select a next hop

set nextHop [lindex $neighbors [expr int(rand() * [llength $neighbors])]]

return $nextHop

}

  1. Forward Packets Dynamically:
    • Invoke the hotPotatoRoute operates at every hop to decide the next hop.

Option 2: Custom Hot Potato Agent in C++

  1. Extend the Agent Class:
    • Execute the Hot Potato logic in a alter routing agent.

Example:

class HotPotatoAgent : public Agent {

public:

HotPotatoAgent();

void recv(Packet* p, Handler* h);

private:

std::vector<int> neighbors;

int selectNextHop();

};

void HotPotatoAgent::recv(Packet* p, Handler* h) {

int nextHop = selectNextHop();

if (nextHop != -1) {

send(p, nextHop);

} else {

Packet::free(p); // Drop the packet if no next hop

}

}

int HotPotatoAgent::selectNextHop() {

return neighbors[rand() % neighbors.size()];

}

  1. Compile and Link:
    • Improve the new agent to the NS2 Makefile.
    • Recompile NS2:

make clean && make

Step 5: Add Traffic Sources

  1. Define Traffic Flows:
    • Assign the congestion sources and sinks to the nodes:

# Attach agents

set udp [new Agent/UDP]

$ns attach-agent $n1 $udp

set sink [new Agent/Null]

$ns attach-agent $n4 $sink

$ns connect $udp $sink

# Add CBR application

set cbr [new Application/Traffic/CBR]

$cbr attach-agent $udp

$cbr set packetSize_ 512

$cbr set interval_ 0.05

$ns at 1.0 “$cbr start”

  1. Monitor Packet Flow:
    • Monitor on how the packets are transmitted according to the Hot Potato routing.

Step 6: Simulate and Analyze

  1. Run the Simulation:
    • Store your script as hot_potato_routing.tcl and implement:

ns hot_potato_routing.tcl

  1. Visualize in NAM:
    • Used i9n the envision for NAM (Network Animator) we follow on the routing behavior:

nam hot_potato_routing.nam

  1. Analyze Trace File:
    • Important parameter metrics to calculate:
      • Packet delivery ratio.
      • Average delay.
      • Packet drops due to suboptimal routing.

Step 7: Enhance Hot Potato Routing

  1. Dynamic Topology Changes:
    • The nodes are replicate or connection failures and monitor on how the Hot Potato routing adapts.
  2. Load Balancing:
    • Improve the logic we balance the load with several paths instead of purely choose the random.
  3. Comparison with Other Protocols:
    • Replicate the AODV or DSR and associate them by Hot Potato routing.
  4. Energy Efficiency:
    • Intended for wireless networks, calculate and improve the energy usage below Hot Potato routing.

In the above manual, we demonstrate the comprehensive procedures to simulate and execute the Hot Potato Routing that has simulation procedures explanation, sample snippets and modification were given to execute in ns2 tool. Additional specific details regarding the Hot Potato Routing will be provided.