Software controlled clock synchronization for network devices

A synchronous communication system includes a plurality of network communication devices, one of which is designated as a root device and others are designated as slave devices. Each network communication device includes one or more ports and communication circuitry that processes communication signals received by the one or more ports in order to recover a respective remote clock from each signal. Synchronization circuitry is integrated in a root device and provides a root clock signal that is communicated over a clock link to a slave device. The host processor selects one of the ports of one of the network communication devices as a master port, finds a clock difference between the root clock signal and a corresponding remote clock recovered from the master port, and outputs a control signal that causes the synchronization circuit to adjust the root clock signal in response to the clock difference. 同步通信系统包括多个网络通信设备，其中一个被指定为根设备而其他被指定为从设备。每个网络通信设备包括一个或多个端口和通信电路，该通信电路处理由一个或多个端口接收的通信信号以便从每个信号恢复相应的远程时钟。同步电路集成在根设