The index value which uniquely identifies the interface to
which this entry is applicable. The interface identified by
a particular value of this index is the same interface as
identified by the same value of RFC 1573's ifIndex.
The value of the least-significant bit in the IP broadcast
address used for sending datagrams on the (logical)
interface associated with the IP address of this entry. For
example, when the Internet standard all-ones broadcast
address is used, the value will be 1. This value applies to
both the subnet and network broadcasts addresses used by the
entity on this (logical) interface.