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Alteon OS Application Guide
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Chapter 12: OSPF 42C4911, January 2007
Types of OSPF Routing Devices
As shown in Figure 12-2, OSPF uses the following types of routing devices:
Internal Router (IR)—a router that has all of its interfaces within the same area. IRs main-
tain LSDBs identical to those of other routing devices within the local area.
Area Border Router (ABR)—a router that has interfaces in multiple areas. ABRs maintain
one LSDB for each connected area and disseminate routing information between areas.
Autonomous System Boundary Router (ASBR)—a router that acts as a gateway between
the OSPF domain and non-OSPF domains, such as RIP, BGP, and static routes.
Figure 12-2 OSPF Domain and an Autonomous System
Backbone
Area 0
Area 3
Area 2
Area 1
Inter-Area Routes
(Summary Routes)
ABR
ABR
ABR
ASBR
Internal
Router
ASBR
External
Routes
BGP
RIP
OSPF Autonomous System