This object represents the network input interface on the
sender router where the synthetic packets are received from the
emulated endpoint source. This is used for path congruence with
correct feature processing at the sender router.
The user can get the InterfaceIndex number from ifIndex object
by looking up in ifTable. In fact, it should be useful to first
get the entry by the augmented table ifXTable which has ifName
object which matches the interface name used on the router or
switch equipment console.