A centralized routing protocol depends on specially designated nodes to compute and then distribute routing tables. Routing updates are sent by a switch only to directly connected switches. Flooding is used to send each switch s routing table to every network switch. Hold-down makes it possible for a network to more quickly react to information that a link or switch has gone down. Use of split horizon means that a switch does not send information about a destination to the switch from which it received its current route for the destination.
Distance vector is preferred to link state in networks with long paths.
The SPF algorithm no longer is used by link state protocols. Each switch receives information about both ends of each network link. Link state is preferred to distance vector when there is minimal network congestion. Hold-down plays a roll for link state analogous to its role in distance vector. Different routes may be computed for different service types.