OSPF DR/BDR election help, please!

Empathy

So I'm trying to force a DR/BDR election between 3 routers, and even after setting the priority on the router I want to force to be the DR to 255, I can't make that router "win" the election.

here's the output from "show ip ospf neighbor detail" from the router that keeps winning the election:

Crarion2620#sh ip ospf neighbor detail
Neighbor 10.1.1.3, interface address 10.1.1.3
In the area 0 via interface FastEthernet0/0
Neighbor priority is 255, State is FULL, 12 state changes
DR is 10.1.1.1 BDR is 10.1.1.2
Options is 0x42
Dead timer due in 00:00:37
Neighbor is up for 00:24:12
Index 2/2, retransmission queue length 0, number of retransmission 0
First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
Last retransmission scan length is 0, maximum is 0
Last retransmission scan time is 0 msec, maximum is 0 msec
Neighbor 10.1.1.2, interface address 10.1.1.2
In the area 0 via interface FastEthernet0/0
Neighbor priority is 1, State is FULL, 6 state changes
DR is 10.1.1.1 BDR is 10.1.1.2
Options is 0x2
Dead timer due in 00:00:32
Neighbor is up for 00:33:53
Index 1/1, retransmission queue length 0, number of retransmission 1
First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
Last retransmission scan length is 1, maximum is 1
Last retransmission scan time is 0 msec, maximum is 0 msec

Any ideas of what I'm missing? Thanks!

mikej412

Set the other routers priority to 0

The election isn't preemptive, so the first router to boot up usually will win, unless you tell the other routers not to participate in the election process.

Or you could always just manually boot that router first and let it win.... then boot the other routers. That way you'd have a backup in case the first router dies.

nice343

once the election is done, the only way to apply changes made is to clear the ospf process


use this command

clear ip ospf process

Empathy

mikej412 wrote:

Set the other routers priority to 0

Thanks, I'll try that.

Empathy

nice343 wrote:

once the election is done, the only way to apply changes made is to clear the ospf process


use this command

clear ip ospf process

Actually, I used

debug ip ospf adj

on all 3 routers, changed the priority of the interface on the router I wanted to win the election to 255, then

shutdown

and

no shutdown

the interface, and it appeared to force the election to take place again, without clearing the ospf process.

dtlokee

The "clear ip ospf process" can be hit and miss because you need to clear them all at the exact same time (remember when a router sends a hello to a new neighbor it will advertise the current DR). Changing the priority of the ones you don't want to be the DR to 0 will ensure they don't become the DR. Shutting down the interfaces after setting the priority seems to yeild the best results. I always try to set the priority before I establish the neighbors if I know that is what I am going to do as part of the implementation.

Rack1R6#clear ip ospf proc
Reset ALL OSPF processes? [no]: y
Rack1R6#
*Mar  2 17:13:05.642: OSPF: Send hello to 224.0.0.5 area 168 on FastEthernet0/0 from 148.1.6.6
*Mar  2 17:13:06.390: OSPF: Send hello to 224.0.0.5 area 168 on FastEthernet1/0 from 148.1.68.6
Rack1R6#
*Mar  2 17:13:07.238: OSPF: Interface Loopback0 going Down
*Mar  2 17:13:07.238: OSPF: 150.1.6.6 address 150.1.6.6 on Loopback0 is dead, state DOWN
*Mar  2 17:13:07.238: OSPF: Interface FastEthernet1/0 going Down
*Mar  2 17:13:07.238: OSPF: 150.1.6.6 address 148.1.68.6 on FastEthernet1/0 is dead, state DOWN
*Mar  2 17:13:07.238: OSPF: Neighbor change Event on interface FastEthernet1/0
*Mar  2 17:13:07.238: OSPF: DR/BDR election on FastEthernet1/0 
*Mar  2 17:13:07.238: OSPF: Elect BDR 0.0.0.0
*Mar  2 17:13:07.238: OSPF: Elect DR 150.1.8.8
*Mar  2 17:13:07.238: OSPF: Elect BDR 0.0.0.0
*Mar  2 17:13:07.238: OSPF: Elect DR 150.1.8.8
*Mar  2 17:13:07.242:        DR: 150.1.8.8 (Id)   BDR: none 

It basically just re-elected the same DR