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Can i have a question on OSPF DR and DBR election
have been very puzzling with the DR and BDR election in a OSPF area network. as predetermined, the first condition of being a DR is the parameter "priority". however, if all the routers were having the same priority number such as 1, the router with the higher router ID would be the DR. also, the router ID is based on the highest numerical active ip address. Therefore, based on the all those understanding, here comes a example....
router A f0: 10.4.0.2 /16
f0:10.4.0.1/16 Router B f0:10.5.0.1 /16
Router C f1: 10.5.0.2 /16
(Assume that all the routers are having same priority)
as shown above, two network are known, they are the 10.4.0.0 and 10.5.0.0 /16. the election of DR and DBR would be as following:
network 10.4.0.0: router A is the DR(its address is numerically higher than the other), Router B is the BDR
network 10.5.0.0: Router C is the DR(same as above), Router B is the BDR
However, as the answer given, my thought was proved to be wrong. the answer is router A is the BDR, router B is DR, Router C is DR.
Finally, my question is: any 1 can tell me where i m wrong???
thnx so much[/img]
Hi
have been very puzzling with the DR and BDR election in a OSPF area network. as predetermined, the first condition of being a DR is the parameter "priority". however, if all the routers were having the same priority number such as 1, the router with the higher router ID would be the DR. also, the router ID is based on the highest numerical active ip address. Therefore, based on the all those understanding, here comes a example....
router A f0: 10.4.0.2 /16
f0:10.4.0.1/16 Router B f0:10.5.0.1 /16
Router C f1: 10.5.0.2 /16
(Assume that all the routers are having same priority)
as shown above, two network are known, they are the 10.4.0.0 and 10.5.0.0 /16. the election of DR and DBR would be as following:
network 10.4.0.0: router A is the DR(its address is numerically higher than the other), Router B is the BDR
network 10.5.0.0: Router C is the DR(same as above), Router B is the BDR
However, as the answer given, my thought was proved to be wrong. the answer is router A is the BDR, router B is DR, Router C is DR.
Finally, my question is: any 1 can tell me where i m wrong???
thnx so much[/img]
That's why your Router B is elected DR over Router A.
-i have question regarding ospf priority-
My understanding about ospf priority is that the lowest priority number will have the highest priority value such that if I set the priority number of Router A to 1 and Router B to 5, then Router A will have the highest priority.
Am i correct?
Dove
OSPF priority ranges from 0 to 255, where
0 = Router will never be elected DR
1= Default priority
The HIGHER the priority, the higher the elecitive value.
Your Router B will be DR.
www.cisco.com/warp/public/104/17.html#priority