Dell PowerConnect B-RX - Designated Routers in Multi-Access Networks; Designated Router Election in Multi-Access Networks

680 BigIron RX Series Configuration Guide
53-1002253-01
Overview of OSPF (Open Shortest Path First)
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FIGURE 101 OSPF operating in a network
Designated routers in multi-access networks
In a network that has multiple routers attached, OSPF elects one router to serve as the designated
router (DR) and another router on the segment to act as the backup designated router (BDR). This
arrangement minimizes the amount of repetitive information that is forwarded on the network by
forwarding all messages to the designated router and backup designated routers responsible for
forwarding the updates throughout the network.
Designated router election in multi-access networks
In a network with no designated router and no backup designated router, the neighboring router
with the highest priority is elected as the DR, and the router with the next largest priority is elected
as the BDR, as shown in Figure 102
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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