US Patent 7561559 Hardware time stamping and processor synchronization

Hardware time stamping is disclosed. In a method, a transmit time stamp may be added to an outgoing data unit in hardware prior to transmitting the outgoing data unit over a communications medium. The outgoing data unit may be received from a processor and may be intended for a node. The outgoing data unit may be transmitted over the communications medium to the node. An incoming data unit may be received over the communications medium. A receive time stamp may be added to the incoming data unit in hardware before the incoming data unit is provided to the processor. The method may be achieved on a hardware device included on a board in a network testing system.