Optical network

• US 6,643,041 B1
• Filed: 07/01/1999
• Issued: 11/04/2003
• Est. Priority Date: 07/01/1998
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ikeda, Hiroki, Kanetake, Tatsuo
• Primary Examiner(s): SWARTHOUT, BRENT
• Application Number:
  US09/345,747
• Time in Patent Office: 1,587 Days
• Field of Search: 359/110, 359/123, 359/124, 359/128, 359/135, 359/180, 359/119
• US Class Current: 398/79
• CPC Class Codes: H04J 14/0206 Express channels arrangements
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]
• CPC Class Codes: H04J 14/0283 WDM ring architectures
• CPC Class Codes: H04J 14/0295 Shared protection at the optical channel (1:1, n:m)
• CPC Class Codes: H04J 2203/006 Fault tolerance and recovery

Abstract

A first object of the invention of the present application is to provide an optical network capable of flexibly performing a choice of protection optical paths upon the occurrence of a failure without depending on an installation form of an optical transmission line, e.g., an optical fiber. A second object of the invention of the present application is to allow an improvement in the efficiency of use of an optical transmission line, e.g., an optical fiber employed in an optical network. The invention of the present application provides a wavelength division multiplexing transmission optical network having at least a plurality of pieces of transmission equipment and a plurality of optical paths connecting the transmission equipment and wherein wavelengths of predetermined transmission light are assigned to the optical paths and a transmission frame having overhead information is at least used to perform digital transmission.

Claims

1. An optical network, comprising at least:

a plurality of pieces of transmission equipment having switching information; and

a plurality of optical paths which connect said plurality of pieces of transmission equipment to one another;

wherein said optical paths are used as working optical paths or protection optical paths,

and wavelengths of predetermined transmission light are assigned to said optical paths to perform wavelength division multiplexing digital transmission, and

said plurality of optical paths have optical paths which connect said plurality of pieces of transmission equipment in a straight chain form, and

wherein the switching information includes at least numbers of working optical paths highest in importance, numbers of transmission equipment which transmitted the switching information, and switched states of the transmission equipment.

2. The optical network according to claim 1, further including at least optical paths connecting said transmission equipment in a ring form and wherein said optical paths are capable of being used as protection optical paths.

3. The optical network according to claim 1, further including at least optical paths connecting said transmission equipment in a straight chain form, and wherein said optical paths are capable of being used as protection optical paths.

4. The optical network according to claim 1,

wherein a ring network constructed by said working optical paths is provided at least two.

5. The optical network according to claim 2, wherein said optical paths connect a plurality of said transmission equipment in form of mesh-like and said optical paths are served as a working line.

6. The optical network according to claim 3,

wherein said optical paths connect plurality of said transmission equipments in form of mesh-like and said optical paths are served as a working line.

7. The optical network according to claim 1,

wherein the switching information includes at least wavelength addresses for working optical paths and switched states of transmission equipment.

8. The optical network according to claim 1,

wherein the switching information includes at least wavelength addresses for working optical paths highest in importance and switching states of transmission equipment.

9. The optical network according to claim 1, wherein each transmission equipment has memory means constituting a wavelength address map for storing therein at least information of wavelength addresses on said respective optical paths and failure information on said respective optical paths, and is constructed such that when a failure occurs in a working optical path, optical-path switching is done based on switching control information about the failure, the wavelength address information and the failure information on the optical paths and the switching control information includes a determination concerning an automatic protection switching byte of overhead information.

10. A time-division multiplex transmission optical network, comprising at least:

a plurality of pieces of transmission equipment having switching information; and

a plurality of optical paths which connect said plurality of pieces of transmission equipment to one another;

wherein said optical paths are used as working optical paths or protection optical paths,

and said plurality of optical paths are assigned predetermined time division multiplex signals and at least a transmission frame having overhead information is used to perform digital transmission, and

said plurality of optical paths include optical paths which connect said plurality of pieces of transmission equipment in a straight chain form;

wherein the switching information includes at least numbers of working optical paths highest in importance, numbers of transmission equipment which transmitted the switching information, and switched states of the transmission equipment.

11. The optical network according to claim 10, further including at least optical paths connecting said plurality of pieces of transmission equipment in a ring form, and wherein said optical paths are capable of being used as protection optical paths.

12. The optical network according to claim 10, further including at least optical paths connecting said plurality of pieces of transmission equipment in a straight chain form, and wherein said optical paths are capable of being used as protection optical paths.

13. The optical network according to claim 10, wherein a ring network constructed by said working optical paths is provided at least two.

14. The optical network according to claim 11,

wherein said optical paths connect plurality of said transmission equipments in form of mesh-like and said optical paths are served as a working line.

15. The optical network according to claim 12,

wherein said optical paths connect plurality of said transmission equipments in form of mesh-like and said optical paths are served as a working line.

16. A wavelength division multiplexing optical network, comprising at least:

a plurality of pieces of transmission equipment having switching information; and

optical paths which connect said plurality of pieces of transmission equipment to one another;

wherein said optical paths are assigned wavelengths of predetermined transmission light and at least a transmission frame having overhead information is used to perform digital transmission,

said overhead information has switching control information about a failure, and

said each transmission equipment has memory means constituting a wavelength address map for storing therein at least information of wavelength addresses on said respective optical paths and failure information on said respective optical paths, and is constructed such that when a failure occurs in a working optical path, optical-path switching is done based on the switching control information about the failure, the wavelength address information and the failure information on the optical paths;

wherein the switching information includes at least numbers of working optical paths highest in importance, numbers of transmission equipment which transmitted the switching information, and switched states of the transmission equipment.

18. The optical network according to claim 16 or 17, which is a SONET (Synchronous Optical Network) network.

19. The optical network according to claim 16 or 17, further including at least optical paths connecting said transmission equipment in a ring form, and wherein said optical paths are capable of being used as protection optical paths.

20. The optical network according to claim 16, further including at least two optical paths connecting said transmission equipment in a straight chain form, and wherein said optical paths are capable of being used as protection optical paths.

21. The optical network according to claim 16 or 17, wherein the two or more of said optical paths are placed in one optical transmission line.

22. The optical network according to claim 16 or 17, wherein a ring network constructed by said working optical paths is provided at least two.

23. The optical network according to claim 19,

wherein said optical paths connect plurality of said transmission equipments in form of mesh-like and said optical paths are served as a working line.

24. The optical network according to claim 20,

wherein said optical paths connect plurality of said transmission equipments in form of mesh-like and said optical paths are served as a working line.

25. The optical network according to claim 16, wherein the switching control information includes a determination concerning an automatic protection switching byte of the overhead information.

26. The optical network according to claim 16 or 17, which is a SDH (Synchronous Digital Hierarchy) network.

17. A wavelength division multiplexing optical network, comprising at least:

a plurality of pieces of transmission equipment having switching information; and

optical paths which connect said plurality of pieces of transmission equipment to one another;

wherein said optical paths are used as working optical paths or protection optical paths and are assigned wavelengths of predetermined transmission light, and at least a transmission frame having overhead information is used to perform digital transmission,

said overhead information has switching control information about a failure, and

said each transmission equipment has memory means constituting a wavelength address map for storing therein at least information of wavelength addresses on said respective optical paths and failure information on said respective optical paths, and is constructed such that when a failure occurs in a working optical path, the working optical path is switched to a protection optical path, based on the switching control information about the failure, the wavelength address information and the failure information on the optical paths;

wherein the switching information includes at least numbers of working optical paths highest in importance, numbers of transmission equipment which transmitted the switching information, and switched states of the transmission equipment.

27. An optical network, comprising at least:

a plurality of pieces of transmission equipment having switching information; and

a plurality of optical paths which connect said plurality of pieces of transmission equipment to one another;

wherein at least two of said optical paths are placed in one optical transmission line and at least a transmission frame having overhead information is used to perform digital transmission, thereby allowing signal multiplexing transmission, and

said plurality of optical paths include a plurality of optical paths connecting said plurality of pieces of transmission equipment in a straight chain form;

wherein the switching information includes at least numbers of working optical paths highest in importance, numbers of transmission equipment which transmitted the switching information, and switched states of the transmission equipment.

28. A wavelength division multiplexing survival network, comprising at least:

several pieces of transmission equipment having switching information;

working optical paths which connect said transmission equipment to one another and are assigned optical wavelengths; and

protection optical paths which connect said transmission equipment and are assigned optical wavelengths;

wherein said each transmission equipment has memory means constituting a wavelength address map for storing therein at least information of wavelength addresses and failure information on said respective optical paths, and performs digital transmission by using at least a transmission frame having overhead information;

wherein the switching information includes at least numbers of working optical paths highest in importance numbers of transmission equipment which transmitted the switching information, and switched states of the transmission equipment; and

wherein said network is constructed so as to be capable of performing the following switching determining steps;

(1) a step 1 for determining whether an automatic protection switching byte of said overhead information shows a failure pattern,

(2) a step 2 for determining whether the automatic protection switching byte of said overhead information is destined for the transmission equipment which received the same,

(3) a step 3 for starting a switching operation when the automatic protection switching byte is destined for the transmission equipment which received the same, and

(4) a step 4 for transferring the automatic protection switching byte when the automatic protection switching byte is undestined for the transmission equipment which received the same.