PowerConnect B-Series FCX Configuration Guide 923
53-1002266-01
Overview of OSPF
29
An Autonomous System Boundary Router (ASBR) is a router that is running multiple protocols and
serves as a gateway to routers outside an area and those operating with different protocols. The
ASBR is able to import and translate different protocol routes into OSPF through a process known
as redistribution. For more details on redistribution and configuration examples, refer to “Enabling
route redistribution” on page 953.
FIGURE 138 OSPF operating in a network
OSPF point-to-point links
One important OSPF process is Adjacency. Adjacency occurs when a relationship is formed
between neighboring routers for the purpose of exchanging routing information. Adjacent OSPF
neighbor routers go beyond the simple Hello packet exchange; they exchange database
information. In order to minimize the amount of information exchanged on a particular segment,
one of the first steps in creating adjacency is to assign a Designated Router (DR) and a Backup
Designated Router (BDR). The Designated Router ensures that there is a central point of contact,
thereby improving convergence time within a multi-access segment.
Area 0.0.0.0 Backbone
Area 192.5.1.0
Area 200.5.0.0
Area 195.5.0.0
Router A
Router B
Router C
Router D
Router E
Router F
Router G
208.5.1.1
Area Border
Router (ABR)
Virtual Link
Area Border
Router (ABR)
Autonomous System
Border Router (ASBR)
RIP Router
206.5.1.1
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