It is normal in broadcast media to have a 2-WAY state because not every router becomes adjacent on broadcast media. Every router enters into FULL state with the DR and the BDR.
In this example, there are only two routers on Ethernet; both are configured with priority 0. Priority 0 means that this router will not take part in DR/BDR election process. This configuration is useful when there are "low-end" routers on the segment and the desire is not to make those low-end routers DRs. For this purpose, you should configure priority 0. By default, the priority is set to 1. A router with the highest priority on a segment wins a DR election. If all priorities are kept to the default, the router with the highest router ID becomes the DR. For more information on DR and BDR election, refer to Chapter 8.
If all the routers on an Ethernet segment are configured with priority 0, no routers on the segment will be in FULL state with any other router. This creates problems. At least one router on the segment must have a priority that is not set to 0.
Figure 9-30 shows the network setup suffering from this problem.
Was this article helpful?