Ospf Configuration; Ospf Configuration Examples; Configuring Ospf On An S-Series Operating As An Inter-Area Router - Dell Force10 S2410-01-10GE-24P Configuration Manual

OSPF Configuration

For larger networks, Open Shortest Path First (OSPF) is generally used in preference to RIP. OSPF offers
several benefits to the administrator of a large and/or complex network:
• Less network traffic:
• Routing table updates are sent only when a change has occurred.
• Only changed part of the table is sent.
• Updates are sent to a multicast, not a broadcast, address.
• Hierarchical management, allowing the network to be subdivided
The top level of the hierarchy of an OSPF network is known as an autonomous system (AS) or routing
domain, and is a collection of networks with a common administration and routing strategy. The AS is
divided into areas: intra-area routing is used when a source and destination address are in the same area,
and inter-area routing across an OSPF backbone is used when they are not. An inter-area router
communicates with border routers in each of the areas to which it provides connectivity.
The S-Series operating as a router, and running OSPF, will determine the best route, using the assigned
cost and the type of the OSPF route. The order for choosing a route, if more than one type of route exists,
is as follows:
1. Intra-area
2. Inter-area
3. External Type 1: The route is external to the AS.
4. External Type 2: The route was learned from other protocols such as RIP.

OSPF Configuration Examples

The examples in this section show you how to configure the S-Series first as an inter-area router and then
as a border router. They show two areas, each with its own border router connected to one inter-area router.

Configuring OSPF on an S-Series operating as an inter-area router

The first diagram shows a network segment with an inter-area router connecting areas 0.0.0.2 and 0.0.0.3.
The example shows the commands used to configure the S-Series as the inter-area router in the diagram by
enabling OSPF on port 0/2 in area 0.0.0.2 and port 0/3 in area 0.0.0.3.
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