Configuring OSPF Priority in Cisco

The Open Shortest Path First (OSPF) protocol belongs to a family of IP routing protocols and is an internal protocol for the Internet used to send IP routing information through a single Autonomous System (AS) and distribute it across IP networks. Gateway Protocol (GP). Priority in OSPF is used in the DR/BDR election process. DR/BDR election is done per multi-segment, not per area.

Configuration:

Consider the following topology:

In this topology, we can tell just by looking that R4 is the DR and R3 is the BDR and the rest are DRO. The first criterion in DR/BDR election is the priority. So, If we change R1 f0/0 priority it should become the DR. First, Let’s look at the DR/BDR election from R4 perspective

Now let’s change R1 f0/0 OSPF priority and clear the OSPF process (on R4 and R3)

ip ospf priority 255
clear ip ospf process

Let’s check DR/BDR election from R4’s perspective, If we change the priority of an interface to 0 then the router can not participate in DR/BDR election So, now let’s change R1 f0/0 OSPF priority to 0

ip ospf priority 0

And again check DR/VDR election from R4 perspective

show ip ospf neighbor

As we can see now R3 is the BDR and R4 is the new DR. We, do not need to clear the OSPF process when we change interface priority to 0.