US Patent 9432456 Mechanism for clock synchronization

A method and apparatus for synchronizing time between a master device and a target device arranged across a network, wherein the target device communicates to the master device through a PCIe interconnect includes transmitting a first message at a first time from the master device to the target device, the first message including a message indicator; and receiving a reply message at a subsequent time from the target device to the master device, the reply message including the message indicator.