1. A method comprising: receiving in a processor in a network card an instruction to transmit a data unit with a payload of dummy data the processor sending header information to a network communications unit preparing in the network communications unit an outgoing data unit having dummy data in a payload of the outgoing data unit, including the network communications unit computing validation information and placing the validation information in a header in the outgoing data unit the network communications unit transmitting the outgoing data unit onto a communications medium.