This feature will allow the user to select whether port mirror destinations of type GRE tunnel include the optional “key” field in the GRE header on certain platforms. The key field allows the user to uniquely identify a particular packet flow. The feature also allows the user to specify the value of the 32 bit key field. The format of the key field within the GRE header can be seen in RFC 1701 - Generic Routing Encapsulation (GRE).