Signal routing in a node of a 1:N automatic protection switching network

1. A data communication node, comprising:

a plurality of channel devices, each comprising:

an input port;

an output port;

a data receive port configured to receive a channel data signal;

a data send port configured to provide a transmit data signal to a data communication channel; and

a signal routing arrangement configured to route data from said input port to said output port or to said data send port, and to route data from said data receive port to said output port or to said data send port;

a plurality of links, each establishing a data path from said output port of one of said channel devices to said input port of another one of said channel devices; and

a processor connected to said channel devices, said processor controlling said signal routing arrangement of each channel device to provide automatic protection switching for said data communication node;

said processor being configured to respond to channel performance metrics; and

said channel performance metrics indicating whether said data communication node functions in a normal operating mode or in a protection mode;

wherein, in said protection mode:

one of said channel devices functions as a protection channel device, one of said channel devices is a protected channel device, and each of the remaining channel devices functions as a working channel device;

said data receive port of said protection channel device receives a null data signal;

said data receive port of said protected channel device receives a channel data signal; and,

said processor controls said signal routing arrangement of each of said channel devices to route said null data signal to said input port of said protected channel device, and to route said channel data signal to said data send port of said protection channel device.

2. A data communication node according to claim 1 , wherein the number of said links equals the number of said channel devices.

3. A data communication node according to claim 1 , wherein said processor is configured to generate control signals that control the operation of said signal routing arrangement of each channel device.

4. A data communication node according to claim 3 , wherein each of said channel devices further comprises a control signal port configured to receive one of said control signals.

5. A data communication node according to claim 1 , wherein, in said normal operating mode, said signal routing arrangement of each of said channel devices routes data from its data receive port to its data send port.

6. A data communication node according to claim 5 , wherein, in said normal operating mode, said signal routing arrangement of each of said channel devices routes data from its input port to its output port.

7. A data communication node according to claim 1 , wherein said data send port of said protection channel device is coupled to a protection data communication channel.

8. A data communication node according to claim 1 , wherein said data communication node comprises a transmit node.

9. A data communication node according to claim 1 , wherein said data communication node comprises a receive node.

10. An automatic protection switching method comprising:

in a normal operating mode:

receiving a null data signal at a data receive port of a first channel device;

generating, at a data send port of said first channel device, a first transmit data signal based on said null data signal;

receiving a channel data signal at a data receive port of a second channel device; and

generating, at a data send port of said second channel device, a second transmit data signal based on said channel data signal; and

in a protection mode:

generating, at an output port of said first channel device, a first output data signal based on said null data signal; and

generating, at an output port of said second channel device, a second output data signal based on said channel data signal.

11. A method according to claim 10 , further comprising, in said normal operating mode:

receiving a first input data signal at an input port of said first channel device;

generating, at said output port of said first channel device, a third output data signal based on said first input data signal;

receiving a second input data signal at an input port of said second channel device; and

generating, at said output port of said second channel device, a fourth output data signal based on said second input data signal.

12. A method according to claim 10 , further comprising, in said protection mode:

receiving, at an input port of said first channel device, a first input data signal based on said second output data signal; and

generating, at said data send port of said first channel device, a third transmit data signal based on said first input data signal.

13. A method according to claim 10 , further comprising, in said protection mode, passing said first output data signal through a working channel device connected between said first channel device and said second channel device.

14. A method according to claim 13 , wherein passing said first output data signal comprises:

receiving said first output data signal at an input port of said working channel device; and

routing said first output data signal from said input port of said working channel device to an output port of said working channel device.

15. A method according to claim 10 , further comprising, in said protection mode, passing said second output data signal through a working channel device connected between said first channel device and said second channel device.

16. A method according to claim 15 , wherein passing said second output data signal comprises:

receiving said second output data signal at an input port of said working channel device; and

routing said second output data signal from said input port of said working channel device to an output port of said working channel device.