Importance

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Abstract

A WDM add/drop module for use in a network node of an optical network, the module comprising an optical drop unit for dropping a first wavelength signal travelling along a first path in the optical network traffic, a trunk receiver unit for converting the first wavelength signal into a first electrical signal, a tributary optical transmitter unit for converting an electrical input signal into a first optical signal for transmission along a tributary optical connection, wherein the output of the trunk receiver unit is connected to the tributary optical transmitter unit and to a first interface port of the WDM drop module for interfacing with another WDM drop unit, an electrical switch unit arranged in a manner such that, in use, selectively either the first electrical signal or a second electrical signal received at a second interface port of the WDM add/drop module from another WDM add/drop module is through connected to the tributary transmitter unit for conversion and transmission along the tributary optical connection, a tributary optical receiver unit for converting a second optical signal received along a second tributary optical connection into a third electrical signal, a trunk transmitter unit for converting an electrical input signal into a second wavelength signal, an optical add unit for adding the second wavelength signal for transmission along the first path in the optical network traffic, a switch unit arranged in a manner such that, in use, selectively either the third electrical signal or a fourth electrical signal received at a third interface port of the WDM add/drop module from another WDM add/drop module is through connected to the trunk transmitter unit, and wherein the output of the tributary receiver unit is connected to the trunk transmitter unit and/or to a fourth interface port of the WDM add/drop module for interfacing with another WDM add/drop unit.

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First Claim