Compound optical circuit switch

1. A compound optical circuit switch to provide selectable optical connections between a plurality of input ports and a plurality of output ports, comprising:

two or more 1 st -tier switches, each of the plurality of input ports connected to a respective input of one of the 1 st -tier switches, and each of the plurality of output ports connected to a respective output of one of the 1 st -tier switches;

one or more 2 nd -tier switches coupled to the 1 st -tier switches; and

a compound connection controller configured to:

receive a global connection command identifying an input port from the plurality of input ports and an output port from the plurality of output ports to be connected through the compound switch;

when the identified input port and the identified output port are connected to the same 1 st -tier switch, issue a local command to that 1 st -tier switch to effect a simple connection between the identified input port and the identified output port, or

when the identified input port and the identified output port are connected to different 1 st -tier switches,

select a connection path from the identified input port to the identified output port through the 1 st -tier switch connected to the identified input port, 1 selected 2 nd -tier switch, and the 1 st -tier switch connected to the identified output port, the connection path selected based, in part, on an expected insertion loss of the connection path, and

issue local commands to the 1 st -tier switch connected to the identified input port, the selected 2 nd -tier switch, and the 1 st -tier switch connected to the identified output port to effect a compound connection along the selected connection path.

2. The compound optical circuit switch of claim 1 , wherein the compound connection controller comprises:

an expected loss table storing an expected insertion loss for at least some of the possible connections between an input and an output of each of 1 st -tier switches and each of the 2 nd -tier switches.

3. The compound optical circuit switch of claim 2 , wherein the compound connection controller is further configured to:

select the connection path from the input port to the output port based, in part, on a insertion loss target included in the global connection command.

4. The compound optical circuit switch of claim 2 , wherein the compound connection controller is further configured to:

select the connection path from the input port to the output port to equalize, to an extent possible, insertion losses of all compound connections.

5. The compound optical circuit switch of claim 4 , wherein the compound connection controller is further configured to:

select an available connection path having an insertion loss that is most nearly equal to an average expected insertion loss for all compound connections.

6. A method of making connection through a compound optical circuit switch including two or more 1 st -tier switches and one or more 2 nd -tier switches, the method comprising:

receiving a global connection command identifying an input port from a plurality of input ports and an output port from a plurality of output ports to be connected;

when the identified input port and the identified output port are connected to the same 1 st -tier switch, making a simple connection within the 1 st -tier switch; and

when the identified input port and the identified output port are connected to two different 1 st -tier switches,

selecting a connection path from the input port to the output port through the 1 st -tier switch connected to the identified input port, a selected 2 nd -tier switch, and the 1 st -tier switch connected to the identified output port, the selecting based, in part, on an expected insertion loss of the connection path, and

making a compound connection along the selected connection path.

7. The method of claim 6 , further comprising:

when the identified input port and the identified output port are connected to the same 1 st -tier switch, issuing a local command to that 1 st -tier switch to effect the simple connection between the identified input port and the identified output port, or

when the identified input port and the identified output port are connected to different 1 st -tier switches, issuing local commands to the 1 st -tier switch connected to the identified input port, the selected 2 nd -tier switch, and the 1 st -tier switch connected to the identified output port to effect the compound connection.

8. The method of claim 6 , further comprising:

storing an expected insertion loss for at least some of the possible connections between an input and an output of each of 1 st -tier switches and each of the 2 nd -tier switches in an expected loss table.

9. The method of claim 8 , wherein selecting the connection path further comprises:

selecting the connection path from the input port to the output port based, in part, on an insertion loss target included in the global connection command and the expected loss table.

10. The method of claim 8 , wherein selecting the connection path further comprises:

selecting the connection path from the input port to the output port based on the expect loss table to equalize, to extent possible, insertion losses of all compound connections.

11. The method of claim 10 , wherein selecting the connection path further comprises:

selecting an available connection path having an insertion loss that is most nearly equal to an average expected insertion loss for all compound connections.