Switching system of optical transmission lines for protecting from trouble

A system for optical communication between optical terminal stations automatically and selectively switchable between normal and protection modes, comprising:

• first and second optical terminal stations;
• a plurality of working optical transmission lines, each connecting said first and second optical terminal stations and operable in the normal mode for transmitting optical signals in two opposite directions between said first and second optical terminal stations;
• a protection optical transmission line, provided as a standby bidirectional optical transmission for at least some of said working optical transmission lines, connecting said first and second optical terminal stations and operable in the protection mode for transmitting an optical signal between said first and second optical terminal stations;
• each of said first and second optical terminal stations comprising:
• a protection piece of optical terminal equipment connected to said protection optical transmission line and operable in the protection mode for transmitting and receiving signals over the protection optical transmission line,
• a plurality of groups of working pieces of optical terminal equipment, respective working pieces of optical terminal equipment in said plurality of groups being connected to corresponding said working optical transmission lines, the respective working pieces of optical terminal equipment in each group being concurrently connectable to said protection piece of optical terminal equipment in the protection mode, a sum of maximum transmission rates of the working optical transmission lines corresponding to the working pieces of optical terminal equipment in each of the groups being not more than a transmission rate of said protection transmission line,
• a plurality of bidirectional optical signal paths connected to the respective groups, each operatively connecting the working pieces of optical terminal equipment in each of the groups corresponding to said each bidirectional optical signal path with said protection piece of optical terminal equipment in the protection mode for signal transmission therebetween, and
• a control unit which maintains the normal mode of each of the plurality of working pieces in the absence of any trouble occurring on the respective working optical transmission lines and which is responsive to a trouble occurring in one of the plurality of working optical transmission lines for disabling the normal mode and enabling the protection mode of operation of the respective working piece and of the protection piece;
• each of said working pieces of optical terminal equipment comprising:
• at least one bidirectional tributary port inputting and outputting tributary signals therethrough,
• first and second bidirectional optical ports, each for inputting and outputting optical signals, said first bidirectional optical port being connected to one of the working optical transmission lines corresponding to said each of said plurality of working pieces of optical terminal equipment, and said second bidirectional optical port being connected to one of the bidirectional optical signal paths corresponding to one of the groups in which said each of said working pieces of optical terminal equipment is included,
• first receiving means, connected to said at least one tributary port, for receiving tributary signals from said at least one tributary port,
• first converting means, connected to said first receiving means, for converting the tributary signals to optical signals,
• first transmitting means, connected to said first converting means and said first bidirectional optical port and operable in the normal mode for transmitting the optical signals, converted from the tributary signals, through said first bidirectional optical port and the corresponding working optical transmission line to the other of said first and second optical terminal stations,
• second transmitting means, connected to said first converting means and said second bidirectional optical port and operable in the protection mode, for transmitting the optical signals, converted from said received tributary signals, through said one of the second bidirectional optical ports and the corresponding bidirectional optical signal path to said protection piece of optical terminal equipment,
• second receiving means, connected to said first bidirectional port, for receiving optical signals transmitted in the normal mode from said other of said first and second optical terminal stations through said first bidirectional optical port,
• third receiving means, connected to said second bidirectional optical port, for receiving optical signals transmitted in the protection mode from said protection piece of optical terminal equipment through the corresponding bidirectional optical signal path and said second bidirectional port,
• second converting means, selectively connected to said second receiving means in said normal mode and to said third receiving means in said protection mode, for converting the optical signals received by said second and third receiving means to tributary signals to be output from said at least one bidirectional tributary port, and
• third transmitting means, connected to said second converting means and said at least one bidirectional tributary port, for transmitting the tributary signals converted by said second converting means to said at least one bidirectional tributary port;
• and
• said protection piece of optical terminal equipment comprising:
• a third bidirectional optical port inputting and outputting optical signals therethrough, said third bidirectional optical port being connected to said protection optical transmission line,
• a plurality of fourth bidirectional optical ports, provided for the respective groups, each inputting and outputting optical signals therethrough, said plurality of fourth bidirectional optical ports being operatively connectable to said plurality of bidirectional optical signal paths, respectively,
• fourth receiving means, connected to said plurality of fourth bidirectional optical ports, for receiving optical signals transmitted in the protection mode through said plurality of fourth bidirectional optical ports from said plurality of groups of working pieces of optical terminal equipment,
• multiplexing means, connected to said fourth receiving means, operative in the protection mode for multiplexing signals received through said plurality of fourth bidirectional optical ports to generate a multiplexed optical signal and output the multiplexed optical signal to fourth transmitting means,
• said fourth transmitting means, connected to said multiplexing means, being operative in the protection mode for transmitting the multiplexed optical signals through said protection optical transmission line to said other of said first and second optical terminal stations,
• fifth receiving means, connected to said third bidirectional optical port, operative in the protection mode for receiving optical signals from said other of said first and second optical terminal stations through said third bidirectional optical port,
• demultiplexing means operative in the protection mode for demultiplexing signals received through said third bidirectional optical port into a plurality of demultiplexed signals and outputting the demultiplexed signals to fifth transmitting means, and
• said fifth transmitting means, connected to said demultiplexing means, being operative in the protection mode for transmitting the demultiplexed optical signals through said plurality of fourth bidirectional optical ports to said plurality of working pieces of optical terminal equipment.

A system for optical communication between optical terminal stations automatically and selectively switchable between normal and protection modes, comprising:

• first and second optical terminal stations;
• a plurality of working optical transmission lines, each connecting said first and second optical terminal stations and operable in the normal mode, for transmitting optical signals in two opposite directions between said first and second optical terminal stations;
• a protection optical transmission line, provided as a stand by bidirectional optical transmission line for at least some of said working optical transmission lines, connecting said first and second optical terminal stations and operable in the protection mode for transmitting an optical signal between said first and second optical terminal stations;
• each of said first and second optical terminal stations comprising:
• a protection piece of optical terminal equipment corresponding to said protection optical transmission line and operable in the protection mode for transmitting and receiving signals over the protection optical transmission line,
• a plurality of working pieces of optical terminal equipment respectively corresponding to said plurality of working optical transmission lines,
• a plurality of bidirectional optical signal paths, each connecting a respective said working piece of optical terminal equipment with said protection piece of optical terminal equipment and operable in the protection mode for signal transmission therebetween, and
• a control unit which maintains the normal mode of each of the plurality of working pieces in the absence of any trouble occurring on the respective working optical transmission lines and which is responsive to a trouble occurring in one of the plurality of working optical transmission lines for disabling the normal mode and enabling the protection mode of operation of the respective working piece and of the protection piece;
• each of said plurality of working pieces of optical terminal equipment comprising:
• at least one bidirectional tributary port inputting and outputting tributary signals therethrough,
• a first bidirectional optical port inputting and outputting optical signals therethrough, said first bidirectional optical port being connected to one of the working optical transmission lines corresponding to said each of said plurality of working pieces of optical terminal equipment,
• at least one second bidirectional optical port inputting and outputting optical signals therethrough, said at least one second bidirectional optical port being connected to at least one of said plurality of bidirectional optical signal paths,
• first receiving means, connected to said at least one tributary port, for receiving tributary signals from said at least one tributary port,
• first converting means, connected to said first receiving means, for converting the tributary signals to optical signals,
• first transmitting means, connected to said first converting means and said first bidirectional optical port and operable in the normal mode, for transmitting the optical signals, converted from the received tributary signals, through said first bidirectional optical port and operable in the protection mode to the other of said first and second optical terminal stations,
• second transmitting means connected to said first converting means and operable in the protection mode for transmitting the optical signals converted from said received tributary signals through said at least one second bidirectional optical port and the respective bidirectional optical signal path to said protection piece of optical terminal equipment,
• second receiving means, connected to said first bidirectional optical port, for receiving optical signals, transmitted in the normal mode from said other of said first and second optical terminal stations, through said respective working line and said first bidirectional optical port,
• third receiving means, connected to said at least one second bidirectional optical port, for receiving optical signals, transmitted in the protection mode from said protection piece of optical terminal equipment, through said at least one second bidirectional optical port from said corresponding bidirectional optical signal path,
• second converting means, selectively connected to said second receiving means in said normal mode and to said third receiving means in said protection mode, for converting the respective optical signals received by said second and third receiving means, to tributary signals to be output from said at least one bidirectional tributary port, and
• third transmitting means, connected to said second converting means and said at least one bidirectional tributary port, for transmitting the tributary signals converted by said second converting means to said at least one bidirectional tributary port;
• and
• said protection piece of optical terminal equipment comprising:
• a third bidirectional optical port inputting and outputting optical signals, said third bidirectional optical port being connected to said protection optical transmission line,
• a plurality of fourth bidirectional optical ports each inputting and outputting optical signals therethrough, each of said plurality of fourth bidirectional optical ports being operatively connectable to said at least one second bidirectional optical port in said working pieces of optical terminal equipment,
• fourth receiving means, connected to said plurality of fourth bidirectional optical ports, for receiving optical signals transmitted in the protection mode through said plurality of fourth bidirectional optical ports from at least one of said plurality of working pieces of optical terminal equipment,
• multiplexing means, connected to said fourth receiving means, operative in the protection mode for multiplexing signals received through said plurality of fourth bidirectional optical ports to generate a multiplexed optical signal and outputting the multiplexed signal to fourth transmitting means,
• said fourth transmitting means, connected to the multiplexing means, being operative in the protection mode for transmitting the multiplexed optical signals through said protection optical transmission line to said other of said first and second optical terminal stations,
• fifth receiving means, connected to said third bidirectional optical port, operative in the protection mode for receiving optical signals from said other of said first and second optical terminal stations through said third bidirectional optical port,
• demultiplexing means operative in the protection mode for demultiplexing signals received through said third bidirectional optical port into a plurality of demultiplexed signals to generate a demultiplexed optical signal and outputting the demultiplexed signals to fifth transmitting means,
• said fifth transmitting means, connected to said demultiplexing means, being operative in the protection mode for transmitting the demultiplexed optical signals through said plurality of fourth bidirectional optical ports, to said plurality of working pieces of optical terminal equipment, and
• said plurality of bidirectional optical signal paths corresponding to the respective second bidirectional optical ports of said working pieces of optical terminal equipment, each of said plurality of bidirectional optical signal paths operatively connecting the respective second bidirectional optical ports with said fourth bidirectional optical ports of said protection piece of optical terminal equipment for signal transmission therebetween in the protection mode and wherein a sum of maximum transmission rates of the plurality of bidirectional optical signal paths concurrently connected to the fourth bidirectional optical ports of the protection piece of optical terminal equipment is not more than a transmission rate of said protection transmission line.

A system for optical communication between optical terminal stations automatically and selectively switchable between normal and protection modes, comprising:

• associated pairs of local and remote working optical terminal equipment;
• plural working optical transmission lines interconnecting said local and remote working optical terminal equipment of each pair and operable in a normal mode to transmit corresponding optical signals in two opposite directions between said local and remote optical terminal equipment of each pair;
• a plurality of pairs of local and remote bidirectional optical signal paths respectively interconnected by said pairs of corresponding local and remote working optical terminal equipment and operative in the protection mode for providing bidirectional communications therebetween;
• at least one protection optical transmission line operable in the protection mode for providing bidirectional communications and selectively corresponding to at least one of said working optical transmission lines;
• at least one pair of local and remote protection units interconnected by the respective at least one protection optical transmission line and identically constructed as and corresponding to the local and remote working units, respectively, of at least one pair of said local and remote working optical terminal equipment, operative in the protection mode to transmit optical signals in two opposite directions on the respective, at least one interconnecting protection optical transmission line;
• a control unit which maintains the normal mode of each of the plurality of working pieces in the absence of any trouble occurring on the respective working optical transmission lines and which is responsive to a trouble occurring in one of the plurality of working optical transmission lines for disabling the normal mode and enabling the protection mode of operation of the respective working piece and the protection piece;
• and
• each of the local and remote protection units comprising:
• a first bidirectional optical port operatively connected in the protection mode to each local working unit corresponding thereto via a corresponding one of said bidirectional optical signal paths,
• first receiving means, connected to said first bidirectional optical port, operative in the protection mode for receiving the corresponding local and remote optical signals from the respective local and remote working units of a pair of said local and remote working optical terminal equipment corresponding thereto, over the corresponding one of the pair of local and remote bidirectional optical signal path,
• a second bidirectional optical port operatively connected to said at least one protection optical transmission line,
• first transmitting means, connected to said first receiving means and said second bidirectional optical port, operative in the protection mode for transmitting the local optical signals via said at least one protection optical transmission line to the associated remote protection unit of the pair thereof,
• second receiving means, connected to said second bidirectional optical port, operative in the protection mode for receiving remote optical signals from the associated remote protection unit of the pair thereof, and
• second transmitting means, connected to said second receiving means and said first bidirectional optical port, operative in the protection mode for transmitting the received, remote optical signals via said first bidirectional optical port to the respective one of the associated local and remote working units of the one pair of said working optical terminal equipment corresponding thereto over the corresponding bidirectional optical signal path.