How to Simulate Dijkstra’s Link State Routing Using MATLAB

To simulate Dijkstra’s Link-State Routing USING MATLAB, we can configure a network in which each node (router) utilizes Dijkstra’s algorithm to discover the shortest path to each other node according to the link-state data. This replication will include the network topology configuration, executing Dijkstra’s algorithm from each node, and modernizing routes if the network modifications.

We will show you through the series of steps on  how to simulate and build a link-state routing simulation using Dijkstra’s algorithm in MATLAB.

Steps to Simulate Dijkstra’s Link-State Routing in MATLAB

  1. Define Network Topology:
    • Utilize an adjacency matrix or graph object to denote the nodes (routers) and weighted links.
    • The weights signify the cost of each link that could be rely on distance, latency, or other metrics.
  2. Initialize Link-State Databases (LSDBs):
    • Every single node sustains a link-state database comprising data regarding their directly associated neighbors.
    • Nodes periodically swap link-state data to construct a global view of the network.
  3. Run Dijkstra’s Algorithm for Shortest Path Calculation:
    • Each node independently executes Dijkstra’s algorithm on their LSDB to compute the shortest paths to every other node.
    • Save the calculated paths within a routing table for packet forwarding.
  4. Simulate Packet Forwarding:
    • Packets are sent depends on the routing table derived from Dijkstra’s algorithm.
    • If a link flops or the network topology changes then replay Dijkstra’s algorithm and modernize the routing tables.
  5. Visualize and Analyze Results:
    • Design the network topology, which emphasising paths computed by Dijkstra’s algorithm.
    • Monitor parameters such as path length, packet delay, and amount of hops.

Example Code Outline

Below is an outline of MATLAB code to replicate the link-state routing with Dijkstra’s algorithm.

% Define network topology as an adjacency matrix with link weights

adjMatrix = [

0 2 0 0 7;

2 0 3 8 0;

0 3 0 1 6;

0 8 1 0 4;

7 0 6 4 0

];

numNodes = size(adjMatrix, 1);

% Dijkstra’s algorithm function for finding shortest path from source

function [dist, prev] = dijkstra(adjMatrix, source)

numNodes = size(adjMatrix, 1);

dist = inf(1, numNodes);  % Initialize distances to infinity

dist(source) = 0;          % Distance to itself is 0

visited = false(1, numNodes);

prev = NaN(1, numNodes);   % Previous node in optimal path

for i = 1:numNodes

% Find the unvisited node with the smallest distance

[~, u] = min(dist + visited * inf);

visited(u) = true;

% Update distances to neighboring nodes

for v = 1:numNodes

if adjMatrix(u, v) > 0 && ~visited(v)  % Check for edge and if unvisited

alt = dist(u) + adjMatrix(u, v);

if alt < dist(v)

dist(v) = alt;

prev(v) = u;

end

end

end

end

end

% Set up link-state routing tables for each node

routingTables = cell(numNodes, 1);

for source = 1:numNodes

[~, prev] = dijkstra(adjMatrix, source);

routingTables{source} = prev;  % Store the previous node for each shortest path

end

% Display routing tables for all nodes

disp(‘Link-State Routing Tables:’);

for i = 1:numNodes

disp([‘Routing table for node ‘, num2str(i), ‘:’]);

disp(routingTables{i});

end

% Function to simulate packet forwarding based on the routing tables

function forwardPacket(src, dest, routingTables)

current = src;

path = [current];

while current ~= dest

nextHop = routingTables{current}(dest);

if isnan(nextHop)

disp(‘No path available.’);

return;

end

path = [path, nextHop];

current = nextHop;

end

disp([‘Packet path from ‘, num2str(src), ‘ to ‘, num2str(dest), ‘: ‘, num2str(path)]);

end

% Test packet forwarding from a source to destination

srcNode = 1;

destNode = 5;

disp(‘— Packet Transmission —‘);

forwardPacket(srcNode, destNode, routingTables);

% Visualize the network and shortest paths

G = graph(adjMatrix);

figure;

plot(G, ‘EdgeLabel’, G.Edges.Weight);

title(‘Network Topology’);

Explanation of the Code

  • Network Topology: The adjacency matrix adjMatrix describes the network, including nodes as routers and weighted links denoting the cost amongst nodes.
  • Dijkstra’s Algorithm: The dijkstra function computes the shortest path from an origin node to every other node by discovering the minimum path cost iteratively. It is the fundamental of the link-state routing method.
  • Routing Table Setup: The routingTables cell array saves each node’s routing table as a prev array in which each entry points to the previous node within the shortest path to a provided destination.
  • Packet Forwarding: The forwardPacket function mimics packet transmission from a source to a destination by following the next hops within the routing table.

Visualization and Analysis

To envision and examine the simulation:

  • Network Visualization: Utilize the MATLAB’s graph and plot functions to show the network topology with weights.
  • Packet Path Display: Monitor and indicate the path taken by a packet from origin to destination rely on the routing tables.

Extending the Simulation

For a more exhaustive link-state routing simulation:

  • Dynamic Link-State Updates: Replicate the periodic link-state updates and replay Dijkstra’s algorithm if the network topology modifications.
  • Link Failures and Repairs: Replicate link failures by setting link weights to infinity (inf) and then replay the algorithm to monitor routing table modifications.
  • Control Overhead Measurement: Monitor the amount of control messages exchanged to sustain the link-state data and update routing tables.

In this setup, we clearly learnt through the above simulation process on how to simulate Dijkstra’s link state routing projects and how to visualize and analyse its outcomes uisng MATLAB tool. More insights will be shared later as per your needs.

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