Optical transport network protection architecture, nodes and method

A communications network main node comprising:

• a plurality of optical transmitters configured to receive encapsulated downstream signals and to transmit downstream, DS, optical signals carrying the encapsulated downstream signals at downstream wavelengths;
• an optical multiplexer configured to multiplex the downstream optical signals carrying the encapsulated downstream signals;
• an optical demultiplexer configured to demultiplex upstream, US, optical signals carrying encapsulated upstream signals;
• a plurality of optical receivers configured to receive the demultiplexed upstream optical signals and output encapsulated upstream signals;
• and
• processing circuitry configured to perform working mode operations of:
• receiving downstream client signals and forming encapsulated downstream signals by encapsulating the downstream client signals and alignment data;
• extracting upstream client signals and alignment data from encapsulated upstream signals;
• receive status data indicative of a status relating to the node, the working mode operations further comprising inserting the status data into the header parts of the encapsulated downstream client signals;
• and
• perform protection mode operations of forming an encapsulated status signal and inserting the status data into a header part of the encapsulated status signal;
• and
• at least one of the optical transmitters being configured to receive the encapsulated status signal and to transmit at least one downstream optical signal carrying the encapsulated status signal.

An optical transport network comprising:

• a communications network remote node comprising:
• a downstream optical circuit configured to receive downstream, DS, optical signals at downstream wavelengths from an active main node and from a standby main node, the downstream optical circuit switchable between a working mode and a protection mode, in the working mode the downstream optical circuit is configured to demultiplex downstream optical signals carrying encapsulated client signals received from the active main node and in the protection mode the downstream optical circuit is configured to demultiplex downstream optical signals carrying encapsulated client signals received from the standby main node;
• a plurality of optical receivers configured to receive the demultiplexed downstream optical signals and output encapsulated downstream client signals;
• a plurality of optical transmitters configured to receive encapsulated upstream client signals and to transmit upstream, US, optical signals at upstream wavelengths carrying the encapsulated upstream client signals;
• an upstream optical circuit configured to multiplex the upstream optical signals carrying the encapsulated upstream client signals and to send the upstream optical signals to both the active main node and the standby main node;
• and
• processing circuitry configured to:
• extract downstream client signals and alignment data from encapsulated downstream client signals;
• and
• form encapsulated upstream client signals by encapsulating upstream client signals and alignment data;
• an active communications network main node, comprising:
• a plurality of optical transmitters configured to receive encapsulated downstream signals and to transmit downstream, DS, optical signals carrying the encapsulated downstream signals at downstream wavelengths;
• an optical multiplexer configured to multiplex the downstream optical signals carrying the encapsulated downstream signals;
• an optical demultiplexer configured to demultiplex upstream, US, optical signals carrying encapsulated upstream signals;
• a plurality of optical receivers configured to receive the demultiplexed upstream optical signals and output encapsulated upstream signals;
• and
• processing circuitry configured to perform working mode operations of:
• receiving downstream client signals and forming encapsulated downstream signals by encapsulating the downstream client signals and alignment data;
• and
• extracting upstream client signals and alignment data from encapsulated upstream signals;
• a standby communication network main node comprising:
• a plurality of optical transmitters configured to receive encapsulated downstream signals and to transmit downstream, DS, optical signals carrying the encapsulated downstream signals at downstream wavelengths;
• an optical multiplexer configured to multiplex the downstream optical signals carrying the encapsulated downstream signals;
• an optical demultiplexer configured to demultiplex upstream, US, optical signals carrying encapsulated upstream signals;
• a plurality of optical receivers configured to receive the demultiplexed upstream optical signals and output encapsulated upstream signals;
• and
• processing circuitry configured to perform working mode operations of:
• receiving downstream client signals and forming encapsulated downstream signals by encapsulating the downstream client signals and alignment data;
• and
• extracting upstream client signals and alignment data from encapsulated upstream signals;
• a first optical link between the active communications network main node and the communications network remote node;
• and
• a second optical link between the standby communications network main node and the communications network remote node.

A method of optical transport network failure protection, the method comprising:

• at an active main node:
• receiving downstream client signals and forming encapsulated downstream signals by encapsulating the downstream client signals and alignment data;
• transmitting downstream optical signals carrying the encapsulated downstream signals at downstream wavelengths;
• receiving upstream optical signals carrying encapsulated upstream signals;
• obtaining the encapsulated upstream signals from the upstream optical signals;
• and
• extracting upstream client signals and alignment data from the encapsulated upstream signals;
• at a standby main node:
• receiving status data indicative of a status relating to the standby main node;
• forming an encapsulated status signal and inserting the status data into a header part of the encapsulated status signal;
• and
• transmitting a downstream optical signal carrying the encapsulated status signal;
• and
• at a remote node:
• receiving downstream optical signals from the active main node and the standby main node;
• receiving the downstream signal carrying the encapsulated status signal;
• extracting the status data from the encapsulated status signal;
• demultiplexing downstream optical signals carrying encapsulated downstream client signals received from the active main node;
• obtaining the encapsulated downstream client signals from the downstream optical signals;
• extracting downstream client signals and alignment data from the encapsulated downstream client signals;
• forming encapsulated upstream client signals by encapsulating upstream client signals and alignment data;
• and
• transmitting upstream optical signals to both the active main node and the standby main node, the upstream optical signals having upstream wavelengths and carrying the encapsulated upstream client signals.