DR and BDR Election in OSPF
Question
R1 is an OSPF router with a priority of 100 and has been elected as the designated router (DR). R2 is the backup designated router (BDR) with a priority of 50. A third router, R3, comes online with a priority of 200.
Which routers will be the DR and BDR after R3 comes online?
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D.A
In OSPF, the designated router (DR) is responsible for sending multicast traffic and maintaining the topology database for a broadcast or non-broadcast network. The backup designated router (BDR) is responsible for taking over the DR role if the DR fails.
When a new router comes online, OSPF will run an election process to determine which router will become the DR and BDR based on their OSPF priority. OSPF priority is a value between 0 and 255, with the default value being 1. A higher priority value indicates a higher likelihood of becoming the DR or BDR.
In this scenario, R1 has a priority of 100 and has already been elected as the DR. R2 has a priority of 50 and has been elected as the BDR. When R3 comes online with a priority of 200, OSPF will run another election process to determine the new DR and BDR.
Since R3 has the highest priority, it will become the new DR. R1 will remain in the network as a router, but it will no longer be the DR. R2 will remain as the BDR since it has the second-highest priority. Therefore, the correct answer is option B, R3 will be the DR and R1 will be the BDR.
So, after R3 comes online, the new DR and BDR will be:
- DR: R3
- BDR: R1
