3Com CoreBuilder 2500 User Manual page 85

7
R
OUTING WITH
This chapter describes Open Shortest Path First (OSPF) routing, including:
Elements of OSPF Routing
How OSPF Routing Works
The OSPF link-state protocol dynamically responds to changes in network
topology that occur within a group of networks and routers called an
autonomous system. OSPF tracks the states of links and routers in each
autonomous system, and when a change occurs, calculates new routes
based on the new topology. The OSPF protocol responds to network
topology changes with a minimum of administrator involvement and
routing traffic.
All OSPF routers within an autonomous system build and synchronize
databases of the autonomous system's network topology. Using its
database, each router calculates the shortest path trees to every
destination within the autonomous system. With this dynamic table of
shortest paths, OSPF converges on an optimum route faster than other
routing algorithms, such as the Routing Information Protocol (RIP).
Routers that use a distance-vector protocol like RIP periodically exchange
all or a portion of their tables, but only to their neighbors. Routers using a
link-state protocol like OSPF send small portions of their tables
throughout the network by flooding.
Figure 7-1 illustrates a typical OSPF application.
OSPF