Information
An IP directed broadcast is an IP packet whose destination address is a valid broadcast address for an IP subnet, but which originates from a node that is not itself a part of that destination subnet.
Rationale:
Directed broadcasts can be abused in several ways:
a volumetric DOS attack against the NX-OS switch itself, the sent volume of data can be much larger than the received request
a volumetric DOS attack against a third party (often called a 'smurf attack')
a single-packet reconnaissance of a local subnet
We recommend that you disable the ip directed-broadcast command on any interface where they are not required for some reason.
Solution
switch(config-if)# no ip directed-broadcast