Link-State Routing Protocols and Split Horizon

Link-state routing protocols and distance vector protocols are two different types of routing protocols used in networking. OSPF is an example of a link-state routing protocol, while RIP is an example of a distance vector protocol. One key difference between these two types of protocols is how they handle the concept of split horizon.

What is Split Horizon?

Split horizon is a technique used in distance vector routing protocols to prevent routing loops. The basic idea is that a router will not advertise a route back out the interface that it was learned on. For example, if router A learns about a route to network X from router B, it will not advertise that route back out to router B.

Why Link-State Routing Protocols Don't Use Split Horizon

Link-state routing protocols, on the other hand, do not use split horizon. Instead, they rely on a different technique called the "link-state database" or LSA. In OSPF, routers build a complete picture of the network by exchanging LSAs with one another. Each router constructs a map of the entire network, which includes information about all the links and routers in the network.

This approach has several advantages over distance vector protocols like RIP. For one thing, link-state protocols are more efficient and accurate at calculating the best path to a destination. They also scale better in larger networks, since they don't suffer from the same routing loops and other issues that can plague distance vector protocols.

Conclusion

In summary, link-state routing protocols like OSPF do not use split horizon, since they rely on a different mechanism for preventing routing loops. Instead, OSPF routers build a complete map of the network using LSAs, which allows them to calculate the most efficient path to a destination.