Patent ID: 8130014

Claim:
A data communication network comprising: a first sub-network comprising: at least two master clocks, and a synchronisation system connected to said at least two master clocks, comprising an input for receiving clock data representing time base information from said at least two master clocks, wherein said synchronisation system is arranged to determine a common time-base based on said time base information from said at least two master clocks and to control said at least two master clocks based on the determined common time-base; and at least one slave synchronisation data source for generating slave clock synchronisation data derived from said time base information of at least one of said at least two master clocks; wherein said network includes a second sub-network connected to said first sub-network, said second sub-network including: at least one slave clock; and a slave clock time-base controller connected to said at least one slave synchronisation data source, for receiving said slave clock synchronisation data and controlling at least one of said at least one slave clock in accordance with the slave clock synchronisation data.