How to Implement Hierarchical Routing in NS2

To implement the Hierarchical routing is a routing protocol in which the network is split into various regions or levels, like clusters or zones. Every region has inter-region communication and its own routing protocol is managed at a higher level. This routing approach supports to enhance the scalability and effectiveness, particularly in large networks. The simulation NS2 permits for the simulation of hierarchical routing, while we may want to manually describe zones or regions and handle routing among and in this regions.

Steps to Implement Hierarchical Routing in NS2

  1. Set Up NS2 Environment
    • Make sure that NS2 is installed and appropriately set up on the computer.
  2. Understand Hierarchical Routing
    • This routing normally splits the network into the clusters or zones. Routing inside a cluster is managed by an intra-cluster protocol, whereas the inter-cluster communication that was handled by a higher-level protocol. It can help minimizes the complexity of routing tables in large networks.
  3. Design the Network Topology
    • Create a network topology which can be split into various zones or regions. These nodes in each zone will be communicated using an intra-zone protocol, and gateways or border nodes will manage communication among various zones.
  4. Simulate Hierarchical Routing Using Clusters

The followings is an instance of how we might mimic a simple hierarchical routing protocol wiin NS2 using zones or clusters.

Example OTcl Script for Hierarchical Routing

# Define the simulation environment

set ns [new Simulator]

# Open the trace file for recording data

set tracefile [open out.tr w]

$ns trace-all $tracefile

# Define the finish procedure

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exec nam out.nam &

exit 0

}

# Create network nodes

set node1 [$ns node]  ;# Zone 1, Node 1

set node2 [$ns node]  ;# Zone 1, Node 2

set node3 [$ns node]  ;# Zone 1, Node 3 (Gateway to Zone 2)

set node4 [$ns node]  ;# Zone 2, Node 1

set node5 [$ns node]  ;# Zone 2, Node 2

# Define links within Zone 1

$ns duplex-link $node1 $node2 10Mb 10ms DropTail

$ns duplex-link $node2 $node3 10Mb 10ms DropTail

# Define links within Zone 2

$ns duplex-link $node3 $node4 5Mb 20ms DropTail  ;# Inter-zone link between Zone 1 and Zone 2

$ns duplex-link $node4 $node5 10Mb 10ms DropTail

# Define intra-zone routing protocol (for simplicity, we use static routing inside zones)

$node1 add-route $node2 1  ;# Inside Zone 1

$node2 add-route $node1 1

$node2 add-route $node3 1

$node3 add-route $node2 1  ;# Gateway in Zone 1

$node3 add-route $node4 1  ;# Gateway node to Zone 2

# Define inter-zone routing (between clusters)

$node4 add-route $node5 1  ;# Inside Zone 2

$node5 add-route $node4 1

# Attach TCP agents and applications to test routing

set tcp [new Agent/TCP]

$ns attach-agent $node1 $tcp

set sink [new Agent/TCPSink]

$ns attach-agent $node5 $sink

# Connect the TCP agent and sink

$ns connect $tcp $sink

# Create an FTP application and attach it to TCP

set ftp [new Application/FTP]

$ftp attach-agent $tcp

# Start the FTP application

$ns at 1.0 “$ftp start”

# Stop the simulation at 10.0 seconds

$ns at 10.0 “finish”

# Run the simulation

$ns run

Explanation of the Script:

  1. Network Topology: The script is configures two zones that containing various nodes. node1, node2, and node3 are portion of the Zone 1, whereas the node4 and node5 are part of Zone 2. Node3 performs as the gateway among the two zones.
  2. Intra-Zone Communication: Static routing is used in every zone. For specimen, node1 can directly communicate with the node2, then the node2 can communicate with node3 that is gateway.
  3. Inter-Zone Communication: The gateway node (node3) handles communication among the Zone 1 and Zone 2. Traffic that requires to move among the zones will pass over the gateway node.
  4. Traffic Generation: A TCP connection is determined among the node1 in Zone 1and node5 in Zone 2, which is using an FTP application to mimic data transfer.
  5. Simulation: The replication runs for 10 seconds, during that the FTP application transfers data from node1 to node5, representing the hierarchical routing.

Run the Simulation

  1. We can save the script to a file such as hierarchical_routing.tcl.
  2. Run the script using NS2:

ns hierarchical_routing.tcl

  1. The simulation will produce a Network Animator (NAM) file (out.nam), and a trace file (out.tr). We can use NAM that helps to visualize the simulation to examine how packets transfer among zones and within zones.

Analyse the Results

  1. Trace File: The trace file (out.tr) will include the data regarding the packet transmissions, latency, and routes. We can use these to check that packets are following the right intra-zone and inter-zone routes.
  2. NAM Visualization: We can use the NAM to visualize the flow of packets among the zones and the role of the gateway in easing the inter-zone communication.

Enhancements

  1. Dynamic Zone Creation: We can change this script to dynamically make or dissolve zones according to particular criteria, like node density or network conditions.
  2. Load Balancing: Launch several gateways among the zones and execute load balancing mechanisms to deliver traffic over the gateways.
  3. Inter-Zone Protocols: Execute various routing protocols for inter-zone communication, like using link-state for inter-zone routing, and distance vector for intra-zone routing.
  4. Mobile Nodes: Append mobility models to mimic node movement over the zones and examine how the hierarchical routing protocol adjusts to this changes.

At the end, you acquire the concepts regarding Hierarchical routing that helps to divide the network into various regions using the above approaches to implement it in the simulation tool ns2. Further informations will be offered in another manual based on your needs.

Seek assistance with the implementation of Hierarchical Routing in NS2, please feel free to contact ns2project.com. We are prepared to share exemplary project ideas for you.