A company has a Frame Relay WAN with one central-site router and 100 branch office
routers. A partial mesh of PVCs exists: one PVC between the central site and each of the
100 branch routers. Which of the following could be true about the number of EIGRP
neighborships?

A.
A partial mesh totaling 100: one between the central-site router and each of the 100
branches.

B.
A full mesh – (101 * 100) / 2 = 5050–One neighborship between each pair of routers.

C.
101–One between each router (including the central site) and its nearby PE router.

D.
None of the answers is correct.

Explanation:
EIGRP forms neighborships only when two routers can communicate directly over a data
link. As a result, with Frame Relay, EIGRP neighborships occur only between routers on the
ends of a PVC, so in this case, 100 neighborships exist.