Question 33

Evaluate the statements for the large network:

• [S1]: 'The computational overhead in link state protocols is higher than in distance vector protocols.'
  Link state protocols require each router to maintain full network topology and run Dijkstra's shortest path algorithm ($O(V \log V + E)$), which demands significantly more CPU and memory than distance vector's local Bellman-Ford vector exchanges. Thus S1 is TRUE.

• [S2]: 'A distance vector protocol (with split horizon) avoids persistent routing loops, but not a link state protocol.'
  Split horizon prevents simple two-node loops, but does NOT prevent loops involving 3 or more nodes (count-to-infinity problem still occurs). In contrast, link state protocols maintain a global topology map and compute a shortest path tree from each node, which is inherently loop-free. Thus S2 is FALSE.

• [S3]: 'After a topology change, a link state protocol will converge faster than a distance vector protocol.'
  Link state floods Link State Advertisements (LSAs) immediately upon detecting a change, allowing fast convergence across the entire network. Distance vector propagates updates hop-by-hop in periodic intervals, which converges much slower. Thus S3 is TRUE.

Therefore, S1 and S3 are true, but S2 is false (Option D).