Procedures, apparatuses, systems, and computer programs for providing optical network channel protection

Abstract

A procedure for transferring wavelengths, and a system that operates in accordance with the procedure. The system comprises at least one network terminal, each including a switch and a controller. A plurality of wavelength sets are applied to the switch. The controller is arranged to operate the switch such that the switch (a) selects at least one wavelength from at least one of the plurality of wavelength sets, based on electrical monitoring at a port module external to the network terminal, and (b) outputs the at least one wavelength to an output of the at least one network terminal.

1 .- 20 . (canceled) 
     
     
         21 . A network terminal comprising:
 a first path through which at least one wavelength can be communicated between a first add-drop multiplexer and a first port module, the first path being a working path, and the first add-drop multiplexer and the first port module being external to the network terminal; and   a second path through which at least one wavelength can be communicated between a second add-drop multiplexer and a second port module, the second path being a protect path, and the second add-drop multiplexer and the second port module being external to the network terminal,   wherein the network terminal is arranged to:
 recognize a communication defect in the first path in response to at least one of (1) detecting the communication defect in the first path in an optical domain, (2) receiving an indication from the first add-drop multiplexer that the first add-drop multiplexer has detected the communication defect in the optical domain, or (3) receiving an indication from the first port module that the first port module has detected the communication defect in at least one of the optical domain or an electrical domain, and 
 select the second path in response to the communication defect being detected. 
   
     
     
         22 . The network terminal of  claim 21 , wherein the network terminal provides 1:n protection. 
     
     
         23 . The network terminal of  claim 21 , further comprising:
 a third path through which at least one other wavelength can be communicated between a third add-drop multiplexer and the first port module, the third add-drop multiplexer being external to the network terminal; and   a fourth path through which at least one further wavelength can be communicated between a fourth add-drop multiplexer and the second port module, the fourth add-drop multiplexer being external to the network terminal,   wherein the at least one network terminal is further arranged to:
 recognize a further communication defect in the third path in response to at least one of (1) detecting the further communication defect in the third path in the optical domain, (2) receiving an indication from the third add-drop multiplexer that the third add-drop multiplexer has detected the further communication defect in the optical domain, or (3) receiving an indication from the first port module that the port module has detected the further communication defect in at least one of the optical domain or the electrical domain, and 
 select the fourth path in response to the further communication defect being detected. 
   
     
     
         24 . The network terminal of  claim 23 , wherein the network terminal provides 1+n protection. 
     
     
         25 . The network terminal of  claim 21 , wherein the network terminal comprises a switch arranged to select the second path in response to the communication defect being detected in the first path. 
     
     
         26 . The network terminal of  claim 25 , wherein the network terminal comprises a splitter arranged to receive a wavelength from at least one of the first port module or the second port module, and to provide the wavelength to at least one of the first add-drop multiplexer or the second add-drop multiplexer. 
     
     
         27 . The network terminal of  claim 21 , wherein the at least one wavelength of the first path has a same wavelength value as the at least one wavelength of the second path. 
     
     
         28 . The network terminal of  claim 23 , wherein the at least one wavelength of the first path has a same wavelength value as the at least one wavelength of the second path, and the at least one wavelength of the third path has a same wavelength value as the at least one further wavelength of the fourth path. 
     
     
         29 . The network terminal of  claim 21 , wherein at least one of the first add-drop multiplexer or the second add-drop multiplexer is a reconfigurable add-drop multiplexer (ROADM). 
     
     
         30 . The network terminal of  claim 21 , further comprising at least one of a demultiplexer and an optical matrix interposed in at least one of the first path or the second path. 
     
     
         31 . A method for operating a network terminal, comprising:
 communicating at least one wavelength through a first path between a first add-drop multiplexer and a first port module, the first path being a working path in the network terminal, and the first add-drop multiplexer and the first port module being external to the network terminal;   recognizing a communication defect in the first path in response to at least one of (1) detecting the communication defect in the first path in an optical domain, (2) receiving an indication from the first add-drop multiplexer that the first add-drop multiplexer has detected the communication defect in the optical domain, or (3) receiving an indication from the first port module that the port module has detected the communication defect in at least one of the optical domain or an electrical domain;   selecting a second path of the network terminal, in response to the communication defect being recognized, the second path being between a second add-drop multiplexer and a second port module, the second path being a protect path, and the second add-drop multiplexer and the second port module being external to the at least one network terminal; and   communicating at least one wavelength through the second path from the second add-drop multiplexer and the second port module.   
     
     
         32 . The method of  claim 31 , wherein the network terminal provides 1:n protection. 
     
     
         33 . The method of  claim 31 , further comprising:
 communicating at least one other wavelength through a third path between a third add-drop multiplexer and the first port module, the third add-drop multiplexer being external to the network terminal;
 recognizing a further communication defect in the third path in response to at least one of (1) detecting the further communication defect in the third path in the optical domain, (2) receiving an indication from the third add-drop multiplexer that the third add-drop multiplexer has detected the further communication defect in the optical domain, or (3) receiving an indication from the first port module that the port module has detected the further communication defect in at least one of the optical domain or the electrical domain; 
   selecting a fourth path in response to the further communication defect being detected, the fourth path being between a fourth add-drop multiplexer and the second port module, the fourth add-drop multiplexer being external to the network terminal; and   communicating the at least one wavelength through the fourth path.   
     
     
         34 . The method of  claim 33 , wherein the network terminal provides 1+n protection. 
     
     
         35 . The method of  claim 31 , wherein the selecting includes operating a switch arranged to select the second path in response to the communication defect being detected in the first path. 
     
     
         36 . The method of  claim 31 , further comprising communicating, via a splitter, a wavelength received from at least one of the first port module or the second port module, to at least one of the first add-drop multiplexer or the second add-drop multiplexer. 
     
     
         37 . The method of  claim 31 , wherein the at least one wavelength of the first path has a same wavelength value as the at least one wavelength of the second path. 
     
     
         38 . The method of  claim 33 , wherein the at least one wavelength of the first path has a same wavelength value as the at least one wavelength of the second path, and the at least one wavelength of the third path has a same wavelength value as the at least one further wavelength of the fourth path. 
     
     
         39 . The method of  claim 31 , wherein at least one of the first add-drop multiplexer or the second add-drop multiplexer is a reconfigurable add-drop multiplexer (ROADM).