Which routing protocol is a link-state protocol commonly used in large networks?

Which routing protocol is a link-state protocol commonly used in large networks?

• A. RIP
• B. Open Shortest Path First
• C. Border Gateway Protocol
• D. Enhanced Interior Gateway Routing Protocol

Answer: (B)

OSPF is a link-state routing protocol designed for large networks. In this approach, every router floods information about its directly connected links to all other routers, building a complete map of the network's topology (the link-state database). Each router then runs Dijkstra’s shortest-path first algorithm on that shared topology to determine the best next hop for every destination. This method scales well because it supports hierarchical design with areas, including a central backbone area, which limits the scope of topology updates and makes large networks more manageable. OSPF also offers features useful in big environments, such as route summarization, fast convergence after topology changes, and support for variable-length subnet masks. RIP, by contrast, uses a distance-vector approach based on hop count, which limits scalability and convergence speed. BGP operates as a path-vector protocol for interdomain routing rather than an internal link-state protocol. EIGRP is fast and scalable but is not a pure link-state protocol and is primarily Cisco-centric. For these reasons, the protocol commonly used as a link-state solution in large networks is Open Shortest Path First.

OSPF is a link-state routing protocol designed for large networks. In this approach, every router floods information about its directly connected links to all other routers, building a complete map of the network's topology (the link-state database). Each router then runs Dijkstra’s shortest-path first algorithm on that shared topology to determine the best next hop for every destination.

This method scales well because it supports hierarchical design with areas, including a central backbone area, which limits the scope of topology updates and makes large networks more manageable. OSPF also offers features useful in big environments, such as route summarization, fast convergence after topology changes, and support for variable-length subnet masks.

RIP, by contrast, uses a distance-vector approach based on hop count, which limits scalability and convergence speed. BGP operates as a path-vector protocol for interdomain routing rather than an internal link-state protocol. EIGRP is fast and scalable but is not a pure link-state protocol and is primarily Cisco-centric. For these reasons, the protocol commonly used as a link-state solution in large networks is Open Shortest Path First.