Patent ID: 8204083

Claim:
A communication system, comprising: a grand master; and at least one sub-network, coupled to the grand master, comprising: at least one first node; and a network connection apparatus, coupled to and between the grand master and the at least one first node, wherein the network connection apparatus accepts a timing information from the grand master to achieve timing synchronization between the network connection apparatus and the grand master, and the network connection apparatus outputs a first timing synchronization request packet to the at least one first node based on the timing information of the network connection apparatus, to request the at least one first node to be in the timing synchronization with the network connection apparatus; wherein the network connection apparatus acts as a master to calculate a sync time and provide the sync time to the at least one first node and forces the at least one first node to be a slave and synchronized with the sync time; wherein the grand master and the network connection apparatus support a best master clock (BMC) algorithm for determining a master-slave relationship between the grand master and the network connection apparatus, when the at least one first node does not support the BMC algorithm, the network connection apparatus forces the at least one first node to be a slave without executing the BMC algorithm.