Network and method for setting a time-base of a node in the network

A data communication network comprising:

• a first sub-network comprising:
• at least two master clocks, and
• a synchronisation system connected to said master clocks, for determining a time-base for said master clocks and controlling said master clocks according to said determined time-base;
• wherein said synchronisation system has an input for receiving clock data representing time base information from said at least two master clocks, and wherein said synchronisation system is arranged to determine a common time-base based on said time information from said master clocks and to control said master clocks based on the determined common time-base;
• wherein said first sub-network includes at least one slave synchronisation data source for generating slave clock synchronisation data derived from time information of at least one said master clocks;
• and
• 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 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.