WDM optical network with passive pass-through at each node

• US 6,529,300 B1
• Filed: 08/12/1999
• Issued: 03/04/2003
• Est. Priority Date: 08/27/1997
• Status: Expired due to Term

• Current Assignee: Ciena Corporation
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Milton, David, Liu, Kexing, Valis, Tomas, Pigeon, Michel, Totti, Gino
• Primary Examiner(s): NEGASH, KINFE MICHAEL
• Application Number:
  US09/372,575
• Time in Patent Office: 1,300 Days
• Field of Search: 359/119, 359/123, 359/128, 359/139, 370/452
• US Class Current: 398/59
• CPC Class Codes: H04J 14/0206 Express channels arrangements
• CPC Class Codes: H04J 14/0209 Multi-stage arrangements, e.g. by cascading multiplexers or demultiplexers
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]
• CPC Class Codes: H04J 14/0213 Groups of channels or wave bands arrangements
• CPC Class Codes: H04J 14/0226 Fixed carrier allocation, e.g. according to service
• 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 14/0246 using one wavelength per ONU
• CPC Class Codes: H04J 14/025 using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
• CPC Class Codes: H04J 14/028 WDM bus architectures
• CPC Class Codes: H04J 14/0282 WDM tree architectures
• CPC Class Codes: H04J 14/0283 WDM ring architectures
• CPC Class Codes: H04J 14/0284 WDM mesh architectures
• CPC Class Codes: H04J 14/0289 Optical multiplex section protection
• CPC Class Codes: H04J 14/0291 Shared protection at the optical multiplex section (1:1, n:m)
• CPC Class Codes: H04J 14/0298 with sub-carrier multiplexing [SCM]
• CPC Class Codes: H04Q 11/0062 Network aspects

Abstract

A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.

Claims

1. A distributed packet switch comprising:

a plurality of switching components distributed over a geographical area;

a fiber optic wavelength division multiplexed ring interconnecting said switching components, said fiber optic ring carrying a plurality of wavelengths organized into bands; and

means for adding/dropping a band at each switching component associated therewith, said adding/dropping means passively forwarding other bands;

wherein pairs of said switching components forming part of said switch directly communicate on wavelengths in bands associated therewith.

2. A distributed packet switch as claimed in claim 1, wherein said switch is an ATM switch.

3. A distributed packet switch comprising:

a plurality of switching components distributed over a geographical area;

a fiber optic wavelength division multiplexed ring interconnecting said switching components, said fiber optic ring carrying a plurality of wavelengths organized into bands; and

an interface at each switching component that operates to add/drop a band associated therewith, said interfaces passively forwarding other bands;

wherein pairs of said switching components forming part of said switch directly communicate on wavelengths in bands associated therewith.

4. A distributed packet switch as claimed in claim 3, wherein said switch is an ATM switch.