Clock signal synchronization among computers in a network

1. A method of clock signal synchronization among computers in a network, the method comprising:

designating, as a primary clock signal for all the computers in the network, a clock signal from one of the computers in the network, each computer in the network comprising a clock signal generator having as an output a clock signal capable of coordinating operations among the computers in the network and also capable of interconnection to each of the other computers through a multiplexer in each computer and a narrow-bandwidth phase locked loop in each computer;

providing the primary clock signal, simultaneously and in parallel, from the computer whose clock signal is designated as the primary clock signal to all the other computers in the network; and

providing the primary clock signal, simultaneously and in parallel, from each computer in the network to all computers in the network through the multiplexers and the phase locked loops, with the primary clock signal locked in phase across all the computers by the phase locked loop on each computer.

2. The method of claim 1 wherein each narrow-bandwidth phase locked loop has a loop bandwidth of at least 1 hertz and not more than 10 hertz.

3. The method of claim 1 wherein designating a clock signal as a primary clock signal further comprises:

assigning to each computer in the network a different clock signal priority; and

designating, by all the computers in the network as the primary clock signal, a clock signal from the computer in the network having the highest clock signal priority.

4. The method of claim 1 wherein providing the primary clock signal, simultaneously and in parallel, from the computer whose clock signal is designated as the primary clock signal to all the other computers in the network further comprises:

fanning out the primary clock signal from an output of the multiplexer on the computer whose clock signal is designated as the primary clock signal through the phase locked loop on the computer whose clock signal is designated as the primary clock signal through a multiplicity of driver circuits and cable conductors, one driver circuit driving each such cable conductor with a fanned out primary clock signal, each driven cable conductor connected from the computer whose clock signal is designated as the primary clock signal to a separate one of the other computers in the network.

5. The method of claim 1 wherein providing the primary clock signal, simultaneously and in parallel, from each computer in the network to all computers in the network through the multiplexers and the phase locked loops, with the primary clock signal locked in phase across all the computers by a phase locked loop on each computer, further comprises:

fanning out the primary clock signal from an output of the multiplexer on each computer in the network through the phase locked loop on each computer in the network through a multiplicity of driver circuits and cable conductors, one driver circuit driving each such cable conductor with a fanned out primary clock signal, each driven cable conductor connected from each computer in the network to a separate one of the other computers in the network.

6. The method of claim 1 further comprising:

receiving, by a first computer in the network, the primary clock signal from a second computer in the network;

detecting by the first computer a loss of lock on the primary clock signal by the first computer's phase locked loop;

switching, by the first computer through the first computer's multiplexer, to receiving the primary clock signal from a third computer in the network; and

relocking the first computer's phase locked loop on the primary clock signal as received from the third computer.

7. The method of claim 6 wherein:

the second computer is the computer whose clock signal is designated as the primary clock signal; and

the method further comprises designating as the primary clock signal a clock signal from one of the other computers in the network.

8. An apparatus for clock signal synchronization among computers in a network, the apparatus comprising logic circuitry, the logic circuitry including a computer processor and a computer memory, the logic circuitry operating the apparatus to carry out the steps of:

designating, as a primary clock signal for all the computers in the network, a clock signal from one of the computers in the network, each computer in the network comprising a clock signal generator having as an output a clock signal capable of coordinating operations among the computers in the network and also capable of interconnection to each of the other computers through a multiplexer in each computer and a narrow-bandwidth phase locked loop in each computer;

providing the primary clock signal, simultaneously and in parallel, from the computer whose clock signal is designated as the primary clock signal to all the other computers in the network; and

providing the primary clock signal, simultaneously and in parallel, from each computer in the network to all computers in the network through the multiplexers and the phase locked loops, with the primary clock signal locked in phase across all the computers by the phase locked loop on each computer.

9. The apparatus of claim 8 wherein each narrow-bandwidth phase locked loop has a loop bandwidth of at least 1 hertz and not more than 10 hertz.

10. The apparatus of claim 8 wherein designating a clock signal as a primary clock signal further comprises:

assigning to each computer in the network a different clock signal priority; and

designating, by all the computers in the network as the primary clock signal, a clock signal from the computer in the network having the highest clock signal priority.

11. The apparatus of claim 8 wherein providing the primary clock signal, simultaneously and in parallel, from the computer whose clock signal is designated as the primary clock signal to all the other computers in the network further comprises:

fanning out the primary clock signal from an output of the multiplexer on the computer whose clock signal is designated as the primary clock signal through the phase locked loop on the computer whose clock signal is designated as the primary clock signal through a multiplicity of driver circuits and cable conductors, one driver circuit driving each such cable conductor with a fanned out primary clock signal, each driven cable conductor connected from the computer whose clock signal is designated as the primary clock signal to a separate one of the other computers in the network.

12. The apparatus of claim 8 wherein providing the primary clock signal, simultaneously and in parallel, from each computer in the network to all computers in the network through the multiplexers and the phase locked loops, with the primary clock signal locked in phase across all the computers by a phase locked loop on each computer, further comprises:

fanning out the primary clock signal from an output of the multiplexer on each computer in the network through the phase locked loop on each computer in the network through a multiplicity of driver circuits and cable conductors, one driver circuit driving each such cable conductor with a fanned out primary clock signal, each driven cable conductor connected from each computer in the network to a separate one of the other computers in the network.

13. The apparatus of claim 8 further comprising the logic circuitry operating the apparatus to carry out the steps of:

receiving, by a first computer in the network, the primary clock signal from a second computer in the network;

detecting by the first computer a loss of lock on the primary clock signal by the first computer's phase locked loop;

switching, by the first computer through the first computer's multiplexer, to receiving the primary clock signal from a third computer in the network; and

relocking the first computer's phase locked loop on the primary clock signal as received from the third computer.

14. The apparatus of claim 13 wherein:

the second computer is the computer whose clock signal is designated as the primary clock signal; and

the apparatus further comprises the logic circuitry operating the apparatus to carry out the step of designating as the primary clock signal a clock signal from one of the other computers in the network.

15. A computer program product for clock signal synchronization among computers in a network, the computer program product embodied upon a computer-readable non-transmission medium, the computer program product comprising computer program instructions capable of:

designating, as a primary clock signal for all the computers in the network, a clock signal from one of the computers in the network, each computer in the network comprising a clock signal generator having as an output a clock signal capable of coordinating operations among the computers in the network and also capable of interconnection to each of the other computers through a multiplexer in each computer and a narrow-bandwidth phase locked loop in each computer;

providing the primary clock signal, simultaneously and in parallel, from the computer whose clock signal is designated as the primary clock signal to all the other computers in the network; and

providing the primary clock signal, simultaneously and in parallel, from each computer in the network to all computers in the network through the multiplexers and the phase locked loops, with the primary clock signal locked in phase across all the computers by the phase locked loop on each computer.

16. The computer program product of claim 15 wherein designating a clock signal as a primary clock signal further comprises:

assigning to each computer in the network a different clock signal priority; and

designating, by all the computers in the network as the primary clock signal, a clock signal from the computer in the network having the highest clock signal priority.

17. The computer program product of claim 15 further comprising computer program instructions capable of:

receiving, by a first computer in the network, the primary clock signal from a second computer in the network;

detecting by the first computer a loss of lock on the primary clock signal by the first computer's phase locked loop;

switching, by the first computer through the first computer's multiplexer, to receiving the primary clock signal from a third computer in the network; and

relocking the first computer's phase locked loop on the primary clock signal as received from the third computer.

18. The computer program product of claim 17 wherein:

the second computer is the computer whose clock signal is designated as the primary clock signal; and

the computer program product further comprises computer program instructions capable of designating as the primary clock signal a clock signal from one of the other computers in the network.