Refer to the exhibit.
Why are two OSPF designated routers identified on Core-Router?
A.
Core-Router is connected to more than one multi-access network.
B.
The router at 208.149.23.130 is a secondary DR in case the primary fails.
C.
Two router IDs have the same OSPF priority and are therefore tied for DR election
D.
The DR election is still underway and there are two contenders for the role.
ased on the network type, OSPF router can elect one router to be a Designated Ruter (DR) and one router to be a Backup Designated Router (BDR). For example, on multiaccess broadcast networks (such as LANs) routers defaults to elect a DR and BDR. DR and BDR serve as the central point for exchanging OSPF routing information. Each non-DR or non-BDR router will exchange routing information only with the DR and BDR, instead of exchanging updates with every router on the network segment. DR will then distribute topology information to every other router inside the same area. This greatly reduces OSPF traffic.
To send routing information to a DR or BDR the multicast address of 224.0.0.6 is used. DR sends routing updates to the multicast address of 224.0.0.5. If DR fails, BDR takes over its role of redistributing routing information.
Every router on a network segment establish a full neighbor relationship with the DR and BDR. Non-DR and non-BDR routers establish a two way neighbor relationship between themselves.
NOTE – on point-to-point links a DR and BDR are not elected since only two routers are directly connected.
On LANs, DR and BDR have to be elected. Two rules are used to elect a DR and BDR:
1. router with the highest OSPF priority will become a DR. By default, all routers have a priority of 1
2. if there is a tie, a router with the highest router ID wins the election
The router with the second highest OSPF priority or router ID will become a BDR.
0
0
A core router is a router designed to operate in the Internet backbone, or core. To fulfill this role, a router must be able to support multiple telecommunications interfaces of the highest speed in use in the core Internet and must be able to forward IP packets at full speed on all of them.
0
0