Simulation of Distance Vector Routing Algorithm
Java Code for Simulation of Link State Routing Algorithm
Code Explanation
This Java program simulates the Link State Routing Algorithm for a network of routers.
In this algorithm, each router shares information about its directly connected neighbors
with every other router in the network (using flooding). The goal is for each router to
build a map of the entire network and calculate the shortest paths to all other nodes.
Key Components:
1. Router Class:
- Maintains each router's ID, link state database, and shortest path table.
- Uses Dijkstra's algorithm to compute the shortest path to every other router.
2. LinkStateRoutingSimulation Class:
- Initializes multiple routers with specific connections and link costs.
- Uses a flooding mechanism to ensure that each router receives the link states of every
other router, enabling each router to compute the shortest paths.
- Displays the final routing table for each router, showing the shortest paths.
This setup includes specific connections and costs for simplicity, making it easier to
verify the shortest path calculation.
import java.util.*;
class Router {
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Simulation of Distance Vector Routing Algorithm
private String id;
private Map<String, Integer> linkStateDatabase; // Direct link costs to neighbors
private Map<String, Integer> shortestPaths; // Shortest path costs to all nodes
private Map<String, String> nextHop;
public Router(String id) {
this.id = id;
this.linkStateDatabase = new HashMap<>();
this.shortestPaths = new HashMap<>();
this.nextHop = new HashMap<>();
}
public void addLink(String neighbor, int cost) {
linkStateDatabase.put(neighbor, cost);
}
public void calculateShortestPaths(Set<Router> routers) {
// Implementation of Dijkstra's algorithm
PriorityQueue<String> queue = new PriorityQueue<>(Comparator.comparingInt(shortestPaths::get));
shortestPaths.put(id, 0);
queue.add(id);
while (!queue.isEmpty()) {
String current = queue.poll();
int currentDistance = shortestPaths.get(current);
for (Router router : routers) {
if (linkStateDatabase.containsKey(router.getId())) {
int distance = currentDistance + linkStateDatabase.get(router.getId());
if (distance < shortestPaths.getOrDefault(router.getId(), Integer.MAX_VALUE)) {
shortestPaths.put(router.getId(), distance);
nextHop.put(router.getId(), current.equals(id) ? router.getId() :
nextHop.get(current));
queue.add(router.getId());
}
}
}
}
}
public void printRoutingTable() {
System.out.println("Routing Table for Router " + id + ":");
for (String destination : shortestPaths.keySet()) {
System.out.println("Destination: " + destination + ", Distance: " + shortestPaths.get(destination)
+ ", Next Hop: " + nextHop.get(destination));
}
}
}
public class LinkStateRoutingSimulation {
public static void main(String[] args) {
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Simulation of Distance Vector Routing Algorithm
Router A = new Router("A");
Router B = new Router("B");
Router C = new Router("C");
Router D = new Router("D");
A.addLink("B", 1);
A.addLink("C", 3);
B.addLink("D", 4);
C.addLink("D", 2);
Set<Router> routers = new HashSet<>(Arrays.asList(A, B, C, D));
for (Router router : routers) {
router.calculateShortestPaths(routers);
router.printRoutingTable();
}
}
}
Sample Input and Output
Sample Input:
Initial links and costs between routers:
- Link cost from A to B: 1
- Link cost from A to C: 3
- Link cost from B to D: 4
- Link cost from C to D: 2
Sample Output:
Routing Table for Router A:
- Destination: A, Distance: 0, Next Hop: A
- Destination: B, Distance: 1, Next Hop: B
- Destination: C, Distance: 3, Next Hop: C
- Destination: D, Distance: 5, Next Hop: B
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Simulation of Distance Vector Routing Algorithm
Routing Table for Router B:
- Destination: A, Distance: 1, Next Hop: A
- Destination: B, Distance: 0, Next Hop: B
- Destination: C, Distance: 5, Next Hop: D
- Destination: D, Distance: 4, Next Hop: D
Routing Table for Router C:
- Destination: A, Distance: 3, Next Hop: A
- Destination: B, Distance: 5, Next Hop: A
- Destination: C, Distance: 0, Next Hop: C
- Destination: D, Distance: 2, Next Hop: D
Routing Table for Router D:
- Destination: A, Distance: 5, Next Hop: B
- Destination: B, Distance: 4, Next Hop: B
- Destination: C, Distance: 2, Next Hop: C
- Destination: D, Distance: 0, Next Hop: D
Explanation:
Each router calculates the shortest path to all other nodes using link state information,
building a complete network map.
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