Ospf Routing Components; Autonomous Systems - Cisco ASR 9000 Series Routing Configuration Manual

OSPF Routing Components

Tip Understanding hierarchical CLI and CLI inheritance saves you considerable configuration time. See
Configuring Authentication at Different Hierarchical Levels for OSPF Version 2, on page 443
how to implement these fundamentals. In addition, Cisco IOS XR Software examples are provided in
Configuration Examples for Implementing OSPF , on page
OSPF Routing Components
Before implementing OSPF, you must know what the routing components are and what purpose they serve.
They consist of the autonomous system, area types, interior routers, ABRs, and ASBRs.
This figure illustrates the routing components in an OSPF network topology.
Figure 17: OSPF Routing Components

Autonomous Systems

The autonomous system is a collection of networks, under the same administrative control, that share routing
information with each other. An autonomous system is also referred to as a routing domain.
Routing Components, on page 410
can consist of one or more OSPF areas.
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.3.x
410
491.
shows two autonomous systems: 109 and 65200. An autonomous system
Implementing OSPF
to understand
Figure 17: OSPF