Changing OSPF DR/BDR routers.

[tjskier69]

Hey folks,

I have a query that if dr/bdr elction proecess has already taken place but the dr/bdr routers need to be moved to others on the LAN, can you just use the priority command to select the dr etc you want and then dr is re-elected to that router as I have read conflicting info that a router would have to be rebooted to 'lose' its dr status?

Thanks, Tony

[pkhatri]

Hi Tony,

If you change the DR priority for a router to be zero, the DR election will be re-held. Therefore, if you no longer want a router to be a DR or BDR, set its priority to be zero. Note that just setting it to a lower priority will not help; you will have to make it zero.

The documentation you have read is probably correct because it is potentially referring to the case where you add routers with higher priorities on segments with DR/BDR already elected. In such cases, the existing DR/BDr continue in that role.

Hope that helps - pls rate the post if it does.

Paresh

[pkhatri]

A bit more info...

The idea behind this behaviour is to prevent DR/BDR churn on networks. Once a router is elected DR/BDR, it is there for life. It cannot be displaced by another router with a higher priority. This provides a bit of stability in LAN environments and prevents the situation where type-2 LSAs are flooded by the election of new DRs.

Hope that helps - pls rate the post if it does.

Paresh

[tjskier69]

Thanks Paresh, that certainly clears that up :)