Symmetric optical multiplexing node

1. An optical add/drop multiplexer (OADM) node, comprising:

a first interface to a first number of fiber pairs connecting the OADM node to a first trunk station;

a second interface to a second number of fiber pairs connecting the OADM node to a second trunk station;

a third interface to a third number of fiber pairs connecting the first trunk station and the second trunk station with a branch station, wherein the third number of fiber pairs is equal to each of the second number of fiber pairs and the first number of fiber pairs; and

a plurality of filters configured to provide connectivity between the first trunk station, the second trunk station and the branch station;

wherein the first trunk station supports a first group of optical bands, the second trunk station supports a second group of optical bands, and the branch station supports the second group of optical bands; and

wherein the first trunk station is a legacy station with a lower bandwidth capability than the second trunk station or the branch station.

2. The OADM node of claim 1 , wherein the first group of optical bands includes a first optical band and a second optical band, and the second group of optical bands includes the first optical band, the second optical band, a third optical band, and a fourth optical band, wherein the first optical band carries data traffic between the branch station and the second trunk station, the second optical band carries data traffic between the branch station and the first trunk station, the third optical band carries data traffic between the first trunk station and the second trunk station, and the fourth optical band carries data traffic between the branch station and the second trunk station.

3. The OADM node of claim 1 , further comprising a plurality of bypass switches, wherein each switch is configured to bypass one or more filters when a fault has been detected on the first, second, or third number of fiber pairs.

4. The OADM node of claim 3 , wherein the plurality of bypass switches includes the same number of switches as optical bands supported by the first trunk station and the second trunk station.

5. The OADM node of claim 1 , wherein the first trunk station, the second trunk station and the branch station each support a first optical band, a second optical band and a third optical band.

6. The OADM node of claim 5 , wherein the first optical band carries data traffic between the branch station and the first trunk station, the second optical band carries data traffic between the first trunk station and the second trunk station, and the third optical band carries data traffic between the second trunk station and the branch station.

7. A system, comprising:

a first trunk station;

a second trunk station;

a branch station;

a first fiber pair;

a second fiber pair; and

an optical add/drop multiplexer (OADM) node, the OADM node comprising:

a first interface to a first number of fiber pairs connecting the OADM node to a first trunk station;

a second interface to a second number of fiber pairs connecting the OADM node to a second trunk station;

a third interface to a third number of fiber pairs connecting the first trunk station and the second trunk station with a branch station, wherein the third number of fiber pairs is equal to each of the second number of fiber pairs and the first number of fiber pairs; and

a plurality of filters configured to provide connectivity between the first trunk station, the second trunk station and the branch station;

wherein the first trunk station supports a first group of optical bands, the second trunk station supports a second group of optical bands, and the branch station supports the second group of optical bands; and

wherein the first trunk station is a legacy station with a lower bandwidth capability than the second trunk station or the branch station.

8. The OADM node of claim 7 , wherein the first group of optical bands includes a first optical band and a second optical band, and the second group of optical bands includes the first optical band, the second optical band, a third optical band, and a fourth optical band, wherein the first optical band carries traffic between the branch station and the second trunk station, the second optical band carries traffic between the branch station and the first trunk station, the third optical band carries traffic between the first trunk station and the second trunk station, and the fourth optical band carries traffic between the branch station and the second trunk station.

9. The system of claim 7 , wherein the OADM node further comprises:

a plurality of bypass switches, wherein each switch is configured to bypass one or more filters when a fault has been detected on the first, second, or third number of fiber pairs.

10. The OADM node of claim 9 , wherein the plurality of bypass switches includes the same number of switches as bands supported by the first trunk station and the second trunk station.

11. The OADM node of claim 7 , wherein the first trunk station, the second trunk station and the branch station each support a first optical band, a second optical band and a third optical band.

12. The OADM node of claim 11 , wherein the first optical band carries traffic between the branch station and the first trunk station, the second optical band carries traffic between the first trunk station and the second trunk station, and the third optical band carries traffic between the second trunk station and the branch station.

13. A method for providing optical communications, comprising:

receiving a first communication at an optical add/drop multiplexer (OADM) node from a first trunk station over a first fiber pair;

receiving a second communication at the OADM node from a second trunk station over the first fiber pair; and

routing the first communication and the second communication to a branch station over a second fiber pair;

wherein a first number of fiber pairs extending between the first trunk station and the OADM node is equal to each of a second number of fiber pairs extending between the OADM node and the second trunk station and a third number of fiber pairs extending between the OADM node and the branch station;

wherein the first trunk station supports a first group of optical bands, the second trunk station supports a second group of optical bands, and the branch station supports the second group of optical bands; and

wherein the first trunk station is a legacy station with a lower bandwidth capability than the second trunk station or the branch station.

14. The method of claim 13 , wherein the OADM node comprises a plurality of filters configured to provide connectivity between the first trunk station, the second trunk station and the branch station.

15. The method of claim 13 , wherein the OADM node comprises a plurality of bypass switches, wherein each switch is configured to bypass one or more filters when a fault has been detected on the first fiber pair or the second fiber pair.

16. The method of claim 13 , wherein the first trunk station, the second trunk station and the branch station each support a first optical band, a second optical band and a third optical band.

17. The method of claim 16 , wherein the first optical band carries traffic between the branch station and the first trunk station, the second optical band carries traffic between the first trunk station and the second trunk station, and the third optical band carries traffic between the second trunk station and the branch station.

18. The method of claim 13 , wherein the first group of optical bands includes a first optical band and a second optical band, and the second group of optical bands includes the first optical band, the second optical band, a third optical band, and a fourth optical band, wherein the first band carries traffic between the branch station and the second trunk station, the second band carries traffic between the branch station and the first trunk station, the third band carries traffic between the first trunk station and the second trunk station, and the fourth band carries traffic between the branch station and the second trunk station.