Cisco Systems OL-4580-01 manual OSPF Routing Hierarchy

Chapter 3 Configuring Open Shortest Path First (OSPF)

OSPF Overview

OSPF Routing Hierarchy

The OSPF routing hierarchy includes the following functions:

•Autonomous systems

•Areas, including the backbone and stub areas

•Area Border Routers (ABRs)

•Autonomous System Boundary Routers (ASBRs) Figure 3-1illustrates an OSPF network topology.

Figure 3-1 Basic OSPF Network Topology

Autonomous System A (AS A)

						AS
					Boundry
					Router1
Router1			Router2
(CSS)
				Area 1.1.1.1
		Area
		Border
		Router1
				Router4
	Router3
			Router5
			Area 0.0.0.0 (backbone)
		Area
		Border
		Router2
		Area 1.1.1.2
		(stub area)

Autonomous System B (AS B)

AS

Boundry

Router2

49658

	Cisco Content Services Switch Routing and Bridging Configuration Guide
OL-4580-01		3-3