Optical Transport Switching Node with Framer

• US 20120250580A1
• Filed: 10/20/2009
• Published: 10/04/2012
• Est. Priority Date: 10/20/2009
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Antonio D'errico, Francesco Testa
• Inventors: Testa, Francesco, D'errico, Antonio
• Granted Patent: US 8,861,402 B2
• Time in Patent Office: Days
• US Class Current: 370/254
• CPC Class Codes: H04J 14/0201 Add-and-drop multiplexing
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]
• CPC Class Codes: H04J 14/0241 Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
• CPC Class Codes: H04J 14/0267 Optical signaling or routing
• CPC Class Codes: H04J 14/0273 using optical overhead, e.g. overhead processing
• CPC Class Codes: H04J 14/0287 Protection in WDM systems
• CPC Class Codes: H04Q 11/0005 Switch and router aspects

Abstract

A switching node for an optical communication system has an electrical switch, coupled to switch electrical signals from an input converter to a selected one of the outputs, and has a framer for reading or writing optical transport overhead information from or to the electrical signals. A bypass path is provided so that at least some of the signals being switched can bypass the framer. This can enable each node to be more efficient or handle more signals, since the framer no longer has to process all the signals. A reduction in power consumption can result. A method of configuring the switching node can involve a management system receiving information about the network, determining a new wavelength routing configuration and sending control signals to the node to configure the switches and control which signals use the bypass path.

Claims

1. A switching node for an optical communication system, the switching node comprising:

an optical input path, and an optical output path, and at least one other output, of optical or other type;

an input converter to convert optical signals on the optical input path to electrical input signals;

an output converter to convert output electrical signals to output optical signals;

an electrical switch, coupled to switch electrical signals from the input converter to a selected one of the outputs; and

a framer for reading or writing optical transport overhead information from or to the electrical signals,

wherein the framer is coupled so as to provide a bypass path so that at least some of the signals being switched by the electrical switch can be switched selectively onto the bypass path to bypass the framer and be output without reading or writing of their optical transport overhead information.

2. The switching node of claim 1, comprising a regenerator for analog regeneration of at least some of the electrical signals switched onto the bypass path.

3. The switching node of claim 2, the regenerator being arranged to retime pulses of at least some of the electrical signals.

4. The switching node of claim 1, arranged as a reconfigurable add drop multiplexer and having an add/drop interface,

wherein the electrical switch is coupled to the input converter to selectively add electrical signals from the add/drop interface to the output converter, or to drop the electrical input signals to the add/drop interface, or to pass the electrical input signals through to the output converter.

5. The switching node of claim 4, wherein the framer is coupled at an add drop interface side of the electrical switch to read or write optical transport framing information from or to at least some of the electrical signals being added or dropped, and wherein the bypass path comprises a path for the electrical signals being passed through the add drop multiplexer without being added or dropped.

6. The switching node of claim 1, wherein the optical transport overhead information comprises any of forward error correction information, path monitoring information, quality of service information, tandem connection information, optical section information, optical subnetwork information, and protection switching information.

7. The switching node of claim 1 comprising a wavelength demultiplexer coupled to the optical input path for separating wavelengths from a wavelength multiplexed input optical signal.

8. The switching node of claim 7, wherein the electrical switch is arranged to switch the electrical signals to carry out wavelength routing of the separated wavelengths.

9. The switching node of claim 1, at least the input converter or output converter comprising a photonic integrated circuit.

10. The switching node of claim 1, having a monitor coupled to the electrical input signal for detecting optical characteristics of the input optical path based on the electrical input signal.

11. An optical communications system having multiple nodes, at least some of the nodes comprising a switching node according to claim 1.

12. A wavelength routing management system for an optical communications system having multiple nodes, at least some of the nodes including a switching node for an optical communication system, the switching node comprising:

an optical input path, and an optical output path, and at least one other output, of optical or other type;

an input converter to convert optical signals on the optical input path to electrical input signals;

an output converter to convert output electrical signals to output optical signals;

an electrical switch, coupled to switch electrical signals from the input converter to a selected one of the outputs; and

a framer for reading or writing optical transport overhead information from or to the electrical signals,

wherein the framer is coupled so as to provide a bypass path so that at least some of the signals being switched by the electrical switch can be switched selectively onto the bypass path to bypass the framer and be output without reading or writing of their optical transport overhead information,

wherein the wavelength routing management system is coupled to a switching node of the optical communications system to receive information based on optical transport overhead information received at the node, or optical characteristics monitored at the node, the wherein the wavelength routing management system is also arranged to send control signals to configure the switching node to configure which of the electrical signals are added or dropped or passed through.

13. A subsystem comprising:

an add/drop interface;

an electrical switch, coupled to switch electrical signals from an input converter to a selected one of a plurality of outputs, wherein the input converter converts optical to electrical signals, and wherein the electrical switch is coupled to selectively add electrical signals from the add/drop interface to an output converter, or to drop the electrical input signals to the add/drop interface, or to pass the electrical signals through to the output converter;

a framer, coupled to the add/drop interface, for reading or writing optical transport overhead information from or to the electrical signals; and

an interface for coupling the framer to the electrical switch, so that the framer can read or write optical transport overhead information of signals added or dropped, and signals that are passed through by the electrical switch can bypass the framer and pass through without reading or writing of their optical transport overhead information.

14. A method of configuring a switching node, in an optical communications system having multiple nodes, at least some of the nodes comprising a switching node that comprises:

an optical input path, and an optical output path, and at least one other output, of optical or other type;

an input converter to convert optical signals on the optical input path to electrical input signals;

an output converter to convert output electrical signals to output optical signals;

an electrical switch, coupled to switch electrical signals from the input converter to a selected one of the outputs; and

a framer for reading or writing optical transport overhead information from or to the electrical signals,

wherein the framer is coupled so as to provide a bypass path so that at least some of the signals being switched by the electrical switch can be switched selectively onto the bypass path to bypass the framer and be output without reading or writing of their optical transport overhead information,

the method comprising the steps of;

receiving information based on optical transport overhead information received at the node, or optical characteristics monitored at the node; and

sending control signals to configure the switching node to configure which of the electrical signals are switched to bypass the framer.