When vRiaBcastAddrFormat is set to 'allOnes', the
255.255.255.255 address is used for local broadcast.
When vRiaBcastAddrFormat is set to 'hostOnes', the
<prefix>-1 address is used for the local broadcast.
For example for subnet 10.10.16.0/20 the <prefix>-1
address is 10.10.31.255.