Optical cross connect apparatus and optical transmission system

• US 20060018656A1
• Filed: 07/20/2005
• Published: 01/26/2006
• Est. Priority Date: 07/20/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi Communication Technologies, Ltd. (Hitachi, Ltd.)
• Inventors: Fukashiro, Yasuyuki, Tsushima, Hideaki, Nogi, Yoshio, Mori, Tomohiro
• Granted Patent: US 7,447,430 B2
• Time in Patent Office: Days
• US Class Current: 398/50
• CPC Class Codes: H04J 14/0227 Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
• CPC Class Codes: H04J 14/0241 Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
• CPC Class Codes: H04J 14/0278 WDM optical network architectures
• CPC Class Codes: H04J 14/0291 Shared protection at the optical multiplex section (1:1, n:m)
• CPC Class Codes: H04J 14/0295 Shared protection at the optical channel (1:1, n:m)
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0043 Fault tolerance

Abstract

Disclosed is an optical cross connect apparatus that is applicable to an end office node and relay node in a path. The optical cross connect apparatus includes an optical switch for generating plural optical output signals from plural optical input signals; an optical level monitor section for detecting the optical levels of the optical input signals; and a control section that is connected to the optical switch and the optical level monitor section, includes a path switching management section for retaining a path switching management table, references the path switching management table when the optical input signals detected by the optical level monitor section are found to be OFF, and judges whether the optical switch should be operated.

Claims

1. An optical cross connect apparatus for transmitting an optical signal to a WDM net, said optical cross connect apparatus comprising:

an optical switch for generating a plurality of optical output signals from a plurality of optical input signals;

an optical level monitor section for detecting the optical levels of the optical input signals; and

a control section that is connected to said optical switch and said optical level monitor section, includes a path switching management section for retaining a path switching management table, references said path switching management table when said optical input signals detected by said optical level monitor section are found to be OFF, and judges whether said optical switch should be operated.

3. The optical cross connect apparatus according to claim 1, wherein said path switching management table contains fault status information about each reception port, connection destination information, and “

selected/nonselected”

status information.

2. An optical cross connect apparatus comprising:

an optical switch for selecting a transmission port and transmitting an optical signal that is received by a reception port;

an optical level monitor section for detecting an optical level of said optical signal; and

a control section for controlling said optical switch in accordance with results of detection by said optical level monitor section,

wherein said control section includes a path switching management section for retaining a path switching management table, references said path switching management table when said optical level monitor section detects that said optical signal is OFF, and judges whether said optical switch should be operated.

4. The optical cross connect apparatus according to claim 2, wherein said path switching management table contains fault status information about each reception port, connection destination information, and “

selected/nonselected”

status information.

5. An optical cross connect apparatus for allocating optical signals from first to third reception ports to first and second transmission ports,

wherein, when an optical signal fed from the first reception port is found to be OFF, connection between the first reception port and the first transmission port is maintained, and

when an optical signal fed from the second reception port is found to be OFF, connection source for the second transmission port, which is connected to the second reception port, is changed from the second reception port to the third reception port.

6. The optical cross connect apparatus according to claim 5, wherein a reception port that maintains connection to a transmission port when an optical signal OFF state is detected and a reception port that changes the connection to a transmission port when an optical signal OFF state is detected can be arbitrarily defined.

7. The optical cross connect apparatus according to claim 5, further comprising:

an optical switch for associating optical signals fed from the first to third reception ports with the first and second transmissions ports;

an optical level monitor section for monitoring optical levels of said optical signals fed from the first to third reception ports; and

a control section for controlling said optical switch in accordance with results of monitoring by said optical level monitor section,

wherein said control section includes a path switching management section for recording a path switching management table, references said path switching management table when said optical level monitor section detects that one of optical input signals fed from the first to third reception ports is OFF, and judges whether said optical switch should be operated.

8. The optical cross connect apparatus according to claim 6, further comprising:

an optical switch for associating optical signals fed from the first to third reception ports with the first and second transmissions ports;

an optical level monitor section for monitoring optical levels of said optical signals fed from the first to third reception ports; and

a control section for controlling said optical switch in accordance with results of monitoring by said optical level monitor section,

wherein said control section includes a path switching management section for recording a path switching management table, references said path switching management table when said optical level monitor section detects that one of optical input signals fed from the first to third reception ports is OFF, and judges whether said optical switch should be operated.

9. An optical cross connect apparatus included in a first path and a second path,

wherein said optical cross connect apparatus serves as a relay node for the first path and maintains the connection of the first path when an optical signal input in the first path is found to be OFF, and

said optical cross connect apparatus serves as an end office node for the second path and switches the second path from a selected system to a nonselected system when an optical signal fed from an opposing end office node in the second path is found to be OFF.

10. An optical transmission system comprising:

a first optical cross connect apparatus for receiving an optical signal from a first client apparatus and transmitting said received optical signal to a first transmission path; and

a second optical cross connect apparatus for receiving an optical signal from the first transmission path and transmitting said received optical signal to a second client apparatus,

wherein said first optical cross connect apparatus and said second optical cross connect apparatus are interconnected via a second transmission path, a third transmission path, and a fourth transmission path,

said second optical cross connect apparatus receives an optical signal from said second client apparatus and transmits said received optical signal to said second transmission path,

said first optical cross connect apparatus receives an optical signal from the second transmission path and transmits said received optical signal to said first client apparatus,

when said optical signal received from the first transmission path is found to be OFF, said second optical cross connect apparatus switches the transmission path for reception from the first transmission path to the third transmission path and switches the transmission path for transmission from the second transmission path to the fourth transmission path, and

when said optical signal received from the second transmission path is found to be OFF, said first optical cross connect apparatus switches the transmission path for reception from the second transmission path to the fourth transmission path and switches the transmission path for transmission from the first transmission path to the third transmission path.