Multitech RouteFinder MTASR2-203, User Manual, Page: 31 / 90

Chapter 4 - RouteFinder Software
MTASR2-203 31
Open Shortest Path First (OSPF)
Open Shortest Path First (OSPF) is a common TCP/IP routing protocol that provides robust and
efficient routing support in the most demanding Internet environments. OSPF calculates routes using
the number of routers, the transmission speed, expected delays, and the cost of the route. Version 2
of the OSPF protocol is designed to be run internal to a single Autonomous System. Each OSPF
router maintains an identical database describing the topology of the Autonomous System. From this
database, a routing table is calculated by constructing a “shortest-path” tree.
OSPF recalculates routes quickly in the event of topological changes using a minimum of routing
protocol traffic.
Under OSPF, networks can be grouped together into “areas,” each of which is the generalization of an
IP subnetted network. The topology of an area is hidden from the rest of the Autonomous System. The
result is that information hiding enables a significant reduction in routing traffic. Also, routing within an
area is determined only by the area’s own topology, protecting the area from “bad” routing data.
All OSPF protocol exchanges are authenticated; i.e., only trusted routers can participate in the
Autonomous System’s routing. Furthermore, a variety of authentication schemes can be used; in fact,
separate authentication schemes can be configured for each IP subnet.
Click the OSPF button on the Advanced tab to open the General Setup dialog box.
The Router Identification field defines the IP address of the router.
The Autonomous System Border Router feature enables the RouteFinder as an Autonomous
System (AS) border router, capable of exchanging routing information with routers in other autonomous
systems. The AS border router then advertises external routes throughout its autonomous systems.
By default, this option is disabled (unchecked).
Items in the Message Printing Controls group can be enabled to generate messages in the
RouteFinder’s built-in terminal application. While these are helpful tools for diagnostics and trouble
shooting, they are generally left disabled (unchecked) to avoid possible degradation of router
performance. The Printf feature enables generation of print messages, the Alarm feature enables
generation of Alarm messages, and the Routing Table feature enables generation of messages relating
to the Routing Table used by IP and IPX routers.
The Areas button opens the Area Setup dialog box used to configure various parameters for OSPF
areas; The Ports button opens the OSPF Port Setup dialog box used to configure various parameters
relating to the OSPF ports; and, the Virtual Interface button opens the Virtual Interfaces dialog box
through which you can add, edit, and remove virtual interfaces.