As per the online Help, you can enter a fixed link propagation delay (in milliseconds) that emulates the distance of the subnets involved. To this delay, you can also add a Delay Variation that emulates the queuing and processing delay at intermediate hops in the internet/network. The sum of these two delays is the total delay used per packet. You can configure these delays on a per subnet basis for outgoing and incoming traffic separately (that is, Receive Side and Send Side of the interface).