Definition of:link state protocol link state protocol  A complex
routing protocol that shares information with other routers in
order to determine the best path. IS-IS was the first
comprehensive link state protocol, and OSPF and NLSP evolved
from it. Link state protocols use characteristics of the route
such as speed and cost as well as current congestion to
determine the best path, which is typically computed by the
Dijkstra algorithm.  Link state routers are updated from all the
routers in the entire network by passing information from router
to nearest router. Rather than continuously broadcast its
routing tables as does a distance vector protocol, a link state
protocol router only notifies its neighboring routers when it
detects a change. Contrast with distance vector protocol and
path vector protocol. See routing protocol, OSPF, NLSP and IS-
IS.