Refer to the exhibit.
Two routers are connected by Frame Relay and are running OSPF between
them. Each router has been configured with the appropriate network statements under router ospf
1, but the routers are not forming an adjacency. Which of the following three commands could be
configured on each router to correct this problem? (Choose three.)
A.
RouterC(config-if )#ip ospf network broadcast
RouterD(config-if )#ip ospf network broadcast
B.
RouterC(config-if)#ip ospf network point-to-point
RouterD(config-if)#ip ospf network point-to-point
C.
RouterC(config-router)#neighbor 10.100.100.4
RouterD(config-router)#neighbor 10.100.100.3
D.
RouterC(config-router)#neighbor 10.255.255.254
RouterD(config-router)#neighbor 10.255.255.253
Explanation:
By default, Frame Relay is classified as a non-broadcast network, meaning it doesn’t send any
broadcasts/multicasts like RIP, OSPF or EIGRP updates across the network (hello packets of
OSPF are multicast to 224.0.0.5). Hence, in NBMA network, the neighbors are not discovered
automatically; they must be configured manually. There are two ways to simulate a broadcast
model on an NBMA network:
+ Define the network type as broadcast with the “ip ospf network broadcast” interface subcommand+ Configure the neighbor statements under router ospf mode (though configuring the
neighbor statement on one end is sufficient to form adjacency, it is a good practice to have it
configured on both the ends)
Besides these two ways, another way for making OSPF work with Frame Relay is configuring the
network as a Point-to-Point network (or Point-to-Multipoint, notice that OSPF treats Point-toMultipoint network as a collective of point-to-point links).Some information about Point-to-Multipoint (or Point-to-Point) network:
Note: Point-to-Multipoint networks do not maintain a DR/BDR relationship.