Designated Router Election In Multi-Access Networks - Dell PowerConnect B-RX Configuration Manual

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
If the DR goes off-line, the BDR automatically becomes the DR. The router with the next highest
priority becomes the new BDR. This process is shown in
NOTE
Priority is a configurable option at the interface level. You can use this parameter to help bias one
router as the DR.
FIGURE 103
If two neighbors share the same priority, the router with the highest router ID is designated as the
DR. The router with the next highest router ID is designated as the BDR.
BigIron RX Series Configuration Guide
53-1001810-01
Figure 102
Designated and backup router election
Designated Backup Router
priority 5
Router C
Backup designated router becomes designated router
Designated Backup Router
priority 5
Router C
Overview of OSPF (Open Shortest Path First)
priority 10
Router A
Designated Router
priority 20
Figure 103.
Designated Router
priority 10
Router A
priority 20
Router B
Router B
X
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