An administrator is configuring a router that will act as the hub in a Frame Relay hub-and-spoke
topology. What is the advantage of using point-to-point subinterfaces instead of a multipoint
interface on this router?
A.
Only a single physical interface is needed with point-to-point subinterfaces, whereas a
multipoint interface logically combines multiple physical interfaces.
B.
Only one IP network address needs to be used to communicate with all the spoke devices.
C.
It avoids split-horizon issues with distance vector routing protocols.
D.
Point-to-point subinterfaces offer greater security compared to a multipoint interface
configuration.
Explanation:
Frame Relay supports two types of interfaces: point-to-point and multipoint. The one you choose
determines whether you need to use the configuration commands that ensure IP address to datalink connection identifier (DLCI) mappings. After configuring the PVC itself, you must tell the router
which PVC to use in order to reach a specific destination. Let’s look at these options: Point-topoint subinterface – With point-to-point subinterfaces, each pair of routers has its own subnet. If
you put the PVC on a point-to-point subinterface, the router assumes that there is only one pointto-point PVC configured on the subinterface. Therefore, any IP packets with a destination IP
address in the same subnet are forwarded on this VC. This is the simplest way to configure the
mapping and is therefore the recommended method. Use the frame-relay interface-dlci command
to assign a DLCI to a specified Frame Relay subinterface. On partially meshed Frame Relay
networks, the problem of split horizon can be overcome by using point to point frame relay
subinterfaces. Multipoint networks – Multipoint networks have three or more routers in the same
subnet. If you put the PVC in a point-to-multipoint subinterface or in the main interface (which is
multipoint by default), you need to either configure a static mapping or enable inverse Address
Resolution Protocol (ARP) for dynamic mapping.