Multiplex communications – Fault recovery
Reexamination Certificate
1997-07-11
2002-11-19
Ton, Dang (Department: 2661)
Multiplex communications
Fault recovery
C370S225000, C370S535000
Reexamination Certificate
active
06483803
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to communications systems and specifically to fault tolerant fiber optic communication networks.
2. Description of the Related Art
Fiber optic communication systems are traditionally deployed in a point-to-point terminal configuration along a single path. A problem occurs if the connection path is somehow interrupted either due to equipment failure or a physical disruption in the connection.
Sonet self healing ring architectures may be a solution that protects against service disruption and node failure along a given primary path. Referring to
FIG. 1
, a ring architecture is presented, with nodes
120
,
130
,
140
and
150
all residing on ring
110
. If a message to be transmitted from node
150
to node
130
clockwise along path A-B of ring
110
cannot be completed due to a failure in path B, then the message is routed counter-clockwise along alternate path D-C. In fact, in this architecture messages from node
120
intended for any node are also routed counter-clockwise to the intended destination node.
Drawbacks to the above system include the requirement for having expensive add/drop multiplexers and associated support equipment present in each node.
Most installed networks are point-to-point systems. Balancing traffic around a ring can be difficult. Further, managing an all-ring network and provisioning demands across several interconnected rings is more difficult and expensive than in a point to point network.
There is accordingly a need for a new method and apparatus for inexpensively and easily rerouting traffic between nodes in a communication network when a given path becomes unusable in order to solve or ameliorate one or more of the above-described problems.
SUMMARY OF THE INVENTION
According to a preferred embodiment of the present invention, a system and method for connecting traffic along a communications network is accomplished by rerouting traffic upon the detection of a fault condition along a primary connection path.
In an embodiment of the present invention, wavelengths are divided into different regions labeled red and blue, respectively. The wavelength bands between transmit and receive channels are alternated between red and blue band regions and then combined, multiplexed or “bundled” together by a non wavelength specific wideband wavelength division multiplexer in a single transmission medium for connection to a single uni-directional Optical Cross Connect System (OCCS) port. The different number of regions may be any even number of regions as long as the wavelengths are alternated.
Additionally, the receiving end of a single medium is connected to a wavelength division demultiplexer which unbundles the combined red and blue band signals upon reception.
In other words, a red band signal is bundled with a blue band signal for transmission through a single medium where it is received and then unbundled into its red and blue components by a wavelength division multiplexer at the receiver.
An analogous method and apparatus is used to transmit a signal in the opposite direction when and if required for full duplex operation.
Further features of the above-described invention will become apparent from the detailed description hereinafter.
The foregoing features together with certain other features described hereinafter enable the overall system to have properties differing not just by a matter of degree from any related art, but offering an order of magnitude more efficient use of processing time and resources.
Additional features and advantages of the invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate preferred embodiments of the apparatus and method according to the invention and, together with the description, serve to explain the principles of the invention.
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Yutaka Katsuyama et al. “Survivable Optical Fiber Architecture Employing Ultra-Wavelegth-Insensitive Switch and Coupler”, Journal of Lightwave Technology, vol. 11 No. 12, Dec. 1, 1993, pp. 2177-2181.
IEEE Journal of Lightwave Technology, “Multiwavelength Survivable Ring Network Architectures” A.F. Elrefaie, Bellcore, Red Bank, NJ 07701, USA, Pub: May 23,1993, pp. 1245-1251.
Bullock Paul Arthur
Elahmadi Siraj Nour
Nagaraj Kesavamurthy
Nguyen Brian
Ton Dang
Withrow & Terranova, P.L.L.C.
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