To simulate an Interior Gateway Protocols (IGPs) using MATLAB requires creating a routing protocols design and examines that utilized in an autonomous system (AS). General IGPs contains RIP (Routing Information Protocol), OSPF (Open Shortest Path First), and EIGRP (Enhanced Interior Gateway Routing Protocol). The simple ideas in replicating IGP protocols turn around how routers distribute routing data and how paths are computed in the network. To get best simulation needs for your research then we will guide you.
Below is a step-by-step technique to simulate IGP protocols such as OSPF and EIGRP in MATLAB:
Steps to Simulate IGP Protocol Projects in MATLAB
- Network Topology Definition
Initially, we can describe the network topology as an adjacency matrix in which nodes denote the routers and links signify direct connections amongst them. It is the initial point for most routing protocols.
Example: Defining a Network Topology
% Number of routers
numRouters = 6;
% Define the adjacency matrix for the network (Inf = no direct connection)
adjMatrix = [
0 2 Inf 1 Inf Inf; % Router 1 connections
2 0 3 Inf Inf Inf; % Router 2 connections
Inf 3 0 2 Inf 1; % Router 3 connections
1 Inf 2 0 4 Inf; % Router 4 connections
Inf Inf Inf 4 0 3; % Router 5 connections
Inf Inf 1 Inf 3 0 % Router 6 connections
];
disp(‘Network Adjacency Matrix:’);
disp(adjMatrix);
- Dijkstra’s Algorithm for OSPF
Open Shortest Path First is a link-state protocol which uses Dijkstra’s algorithm to determine the shortest path for each destination. OSPF routers sustain a comprehensive map of the network and then compute the shortest path to all other router.
Implementing Dijkstra’s Algorithm
Dijkstra’s algorithm evaluates the shortest path from a source router to every other router by discovering the minimum cumulative link cost.
% Dijkstra’s Algorithm to calculate shortest path in OSPF
function [distances, previous] = dijkstra(adjMatrix, source)
numRouters = size(adjMatrix, 1);
distances = Inf(1, numRouters); % Initialize distances to infinity
previous = NaN(1, numRouters); % Previous node in the optimal path
distances(source) = 0; % Distance from source to itself is 0
unvisited = 1:numRouters; % All nodes are initially unvisited
while ~isempty(unvisited)
% Find the unvisited node with the smallest distance
[~, idx] = min(distances(unvisited));
currentNode = unvisited(idx);
unvisited(idx) = []; % Mark current node as visited
% Update the distances to neighboring nodes
for neighbor = 1:numRouters
if adjMatrix(currentNode, neighbor) < Inf % Neighbor exists
alt = distances(currentNode) + adjMatrix(currentNode, neighbor);
if alt < distances(neighbor)
distances(neighbor) = alt;
previous(neighbor) = currentNode;
end
end
end
end
end
% Simulate OSPF by running Dijkstra’s algorithm from each router
for routerID = 1:numRouters
[distances, previous] = dijkstra(adjMatrix, routerID);
disp([‘Router ‘, num2str(routerID), ‘ – Shortest distances to all routers:’]);
disp(distances);
end
- Routing Table Construction in OSPF
After executing the Dijkstra’s algorithm, we can build the routing tables for each router that will involve the next hop and the cost to attain each destination.
Example: Constructing Routing Tables
% Function to construct routing table from Dijkstra’s algorithm output
function routingTable = constructRoutingTable(previous, source)
numRouters = length(previous);
routingTable = NaN(numRouters, 2); % First column: Next hop, Second column: Total cost
for dest = 1:numRouters
if dest == source
continue; % Skip the source router itself
end
% Backtrack to find the next hop
nextHop = dest;
while ~isnan(previous(nextHop)) && previous(nextHop) ~= source
nextHop = previous(nextHop);
end
routingTable(dest, 🙂 = [nextHop, previous(dest)];
end
end
% Simulate OSPF routing tables for each router
for routerID = 1:numRouters
[distances, previous] = dijkstra(adjMatrix, routerID);
routingTable = constructRoutingTable(previous, routerID);
disp([‘Router ‘, num2str(routerID), ‘ – Routing Table:’]);
disp(‘Destination | Next Hop | Total Cost’);
disp([(1:numRouters)’, routingTable]);
end
- Simulating EIGRP (Distance Vector Protocol)
EIGRP is a distance-vector protocol, which aggregates the advantages of both distance-vector and link-state protocols. EIGRP routers distribute its routing tables along with neighbors and select the optimal path according to the several parameters such as bandwidth, delay, load, reliability. We can replicate the EIGRP by designing the exchange of routing data among the routers.
Simplified EIGRP Distance Vector Update
In this simulation, we will concentrate on the simple distance-vector update process.
% Initialize routing tables (initially, each router knows only its neighbors)
routingTablesEIGRP = cell(numRouters, 1);
for i = 1:numRouters
routingTablesEIGRP{i} = adjMatrix(i, :); % Initialize with direct neighbors
end
% Function to update EIGRP routing table based on neighbors
function updatedRoutingTable = eigrpUpdate(currentTable, neighborTable, neighborID)
updatedRoutingTable = currentTable;
numRouters = length(currentTable);
% Update based on the neighbor’s table
for dest = 1:numRouters
if neighborTable(dest) < Inf
newCost = neighborTable(dest) + currentTable(neighborID);
if newCost < updatedRoutingTable(dest)
updatedRoutingTable(dest) = newCost;
end
end
end
end
% Simulate EIGRP updates for several iterations
numIterations = 5;
for iter = 1:numIterations
disp([‘EIGRP Iteration ‘, num2str(iter), ‘:’]);
for routerID = 1:numRouters
for neighborID = 1:numRouters
if adjMatrix(routerID, neighborID) < Inf && routerID ~= neighborID
% Perform EIGRP update with neighbor
routingTablesEIGRP{routerID} = eigrpUpdate(routingTablesEIGRP{routerID}, routingTablesEIGRP{neighborID}, neighborID);
end
end
end
% Display updated routing tables
for routerID = 1:numRouters
disp([‘Router ‘, num2str(routerID), ‘ – Routing Table:’]);
disp(routingTablesEIGRP{routerID});
end
end
- Handling Failures
Replicating the network failures like a link going down that is a significant portion of any routing protocol simulation. We can launch the failures within the network and observe how protocols such as OSPF and EIGRP manage them by recalculating the routes.
Example: Simulating Link Failure in OSPF or EIGRP
% Simulate a link failure between Router 3 and Router 6
disp(‘Simulating link failure between Router 3 and Router 6’);
adjMatrix(3, 6) = Inf;
adjMatrix(6, 3) = Inf;
% Re-run OSPF or EIGRP after the failure
disp(‘Re-running OSPF after link failure:’);
for routerID = 1:numRouters
[distances, previous] = dijkstra(adjMatrix, routerID);
disp([‘Router ‘, num2str(routerID), ‘ – Shortest distances to all routers after failure:’]);
disp(distances);
end
- Visualization of the Network Topology
Envision the network topology, which encompassing the routers and links, to offer details into how the network is associated and how the routing tables move ahead over time.
Example: Plotting the Network Topology
% Define positions of routers for visualization
routerPositions = [
0 0; % Router 1
1 0; % Router 2
2 0; % Router 3
1 1; % Router 4
2 1; % Router 5
3 0 % Router 6
];
% Plot the network topology
figure;
gplot(adjMatrix < Inf, routerPositions, ‘-o’);
for i = 1:numRouters
text(routerPositions(i, 1), routerPositions(i, 2), [‘R’, num2str(i)], ‘FontSize’, 12);
end
title(‘Network Topology’);
Example Projects for IGP Protocol Simulation:
- Simulate OSPF in a Large Network: Execute the OSPF within a larger network topology and examine the convergence time and path calculations.
- Simulate EIGRP with Multiple Metrics: Prolong the EIGRP simulation deliberating the parameters like bandwidth, delay, and reliability.
- Handling Link Failures in OSPF and EIGRP: Replicate link failures and relate how OSPF and EIGRP manage the route recalculations.
- Comparing Convergence Times: Mimic OSPF and EIGRP within the similar network and after a network modify or failure, compare the convergence times.
These projects concentrate on how to simulate IGP protocols such as OSPF and EIGRP and how to model and analysis the routing protocols using MATLAB environment. We are equipped to expand it with addition information.
