Abstract:
A system and method for utilizing the optical service channel for secondary communications without impacting the system communications passing along the channel is disclosed. The secondary communications are combined with the system communications and injected onto the optical service channel. The system communications are given a higher priority than the secondary communications to ensure that the system communications are given the required bandwidth.

Description:
RELATED APPLICATIONS 
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     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
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     MICROFICHE APPENDIX 
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     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is related to the field of communications, and in particular, to communication network architectures and services. 
     2. Description of the Prior Art 
     Dense wavelength division multiplexer (DWDM) optical line amplifiers (also known as optical amplifiers) are used to amplify the optical signals in optical fibers. The Optical amplifiers are currently not meant to add or drop capacity to the DWDM composite stream. Typically the optical amplifiers are placed in locations where capacity demands are minimal or non-existent. The minimal demand typically does not justify the cost of a tributary service carrying element such as a terminal or an optical add-drop multiplexer. Many Optical amplifiers have an optical service channel service module that terminates an optical service channel. The optical service channel (OSC) is a discrete channel that typically operates at the 1510 nm wavelength and is typically electronically separated from the DWDM composite signal. This channel is currently used for system communications that may comprise operation, administration, maintenance and provisioning communications. The current optical service channel configuration is not designed to enable utilization of the channel for customer and internal user communications. Any communications added to the current optical service channel at an optical service channel service module may compete with and may delay the system communications. Typically the system communications do not require the full bandwidth of the optical service channel. It would be useful to access the excess bandwidth in the optical service channel without the danger of delaying the system communications. 
     Therefore there is a need for a system and method for utilizing the optical service channel for internal secondary communications without impacting the system communications passing along the channel. 
     SUMMARY OF THE INVENTION 
     A system and method for utilizing the optical service channel for secondary communications without impacting the system communications passing along the channel is disclosed. The secondary communications are combined with the system communications and injected onto the optical service channel. The system communications are given a higher priority than the secondary communications to ensure that the system communications are given the required bandwidth. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a prior art block diagram of a communication system. 
         FIG. 2  is a flow chart of a method of accessing an optical service channel in an example embodiment of the invention. 
         FIG. 3  is a block diagram of a communication system in an example embodiment of the invention. 
         FIG. 4  is a block diagram of a channel groomer in an example embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1-4  and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents. 
       FIG. 1  illustrates a prior art communication system  100 . Communication system  100  includes west terminal  102 , east terminal  104 , optical amplifiers  106  and  108 , and optical service channel (OSC) service module  110 . The east terminal  104  and the west terminal  102  are Dense Wavelength Division Multiplexer (DWDM) terminals, Wavelength Division Multiplexer (WDM) terminals, Wide Wavelength Division Multiplexer (WWDM) terminals, or the like. The west terminal  102  is optically connected to optical amplifier  106 . Optical amplifier  106  is optically connected with OSC service module  110  and with optical amplifier  108 . Optical amplifier  108  is optically connected with east terminal  104 . An optical service channel is accessed through the OSC service module linked to optical amplifier  106 . There may be numerous additional optical amplifiers between the east and west terminals of the system, however only two are shown for clarity. In use, system communications may be sent or received at the OSC service module, using the optical service channel. The system communications may comprise operation, administration, maintenance and provisioning communications. There may be a desire to send additional or secondary communications from the OSC service module using the optical service channel. An example of these secondary communications may be customer communications and/or internal user communications. Using the current system, the secondary communications may compete for bandwidth on the optical service channel with the system communications. The competition for bandwidth may occur at layer 3, the TCP/IP layer. Adding secondary communications to the optical service channel that may delay or displace the system communications may cause difficulties in the system. 
       FIG. 2  is a flow chart for one example embodiment of the current invention. At step  202 , secondary communications are combined with system communications in such a way as to give the system communications a higher priority than the secondary communications. Combining multiple communications streams into one communication stream utilizing different priorities for the different communications streams and segregating the multiple streams back into the different individual streams is known as grooming. At step  204  the combined communication streams are injected onto, or read from, the optical service channel at the OSC service module. The secondary communications may comprise customer communications and internal user communications. The customer communications and the internal user communications may also have different priorities that allow different access to the bandwidth of the optical service channel. 
       FIG. 3  is a block diagram of a system in an example embodiment of the current invention. System  300  includes west terminal  302 , east terminal  304 , optical amplifiers  306  and  308 , Channel Groomer (CG)  312 , and optical service channel service module (OSC-SM)  310 . The east terminal  104  and the west terminal  102  are Dense Wavelength Division Multiplexer (DWDM) terminals, Wavelength Division Multiplexer (WDM) terminals, Wide Wavelength Division Multiplexer (WWDM) terminals, or the like. One example DWDM system that may be used is the Ciena CoreStream DWDM system. The west terminal  302  is optically connected to optical amplifier  306 . Optical amplifier  306  is optically connected with OSC service module  310  and with optical amplifier  308 . Optical amplifier  308  is optically connected with east terminal  304 . Optical service channel service module  310  is connected with channel groomer  312 . There may be numerous additional optical amplifiers between the east and west terminals of the system, however only two are shown for clarity. 
     In operation CG  312  allocates the bandwidth of the optical service channel provided by the OSC service module  310 . The bandwidth of the optical service channel is divided between system communications and secondary communications with the system communications having the higher priority. The system communications may comprise operation, administration, maintenance and provisioning communications. The secondary communications may comprise customer communications and internal user communications. The customer communications and the internal user communications may also have different priorities that allow different access to the bandwidth of the optical service channel. In one example embodiment of the invention, the CSU maps the optical service channel at the TDM layer. 
       FIG. 4  is a block diagram of a Channel groomer in an example embodiment of the current invention. Channel groomer  412  comprises router  416 , Channel service unit (CSU)  414 , TDM ports  418 , TCP/IP ports  420 , and OC-3 ports  422 . TCP/IP ports  420  are connected to router  416 . Router  416  is connected to CSU  414 . TDM ports  418  and OC-3 ports  422  are connected to CSU  414 . 
     In operation, OC-3 ports  422  are connected to an optical service channel service module, allowing access to the incoming and outgoing DWDM optical service channel along an optical communication link. Customer communications and internal user communications would access the optical service channel through TDM ports  418 . Customer communications that require TCP/IP routing would access the optical service channel through TCP/IP ports  420  into router  416 . System communications may utilize OC-3 ports  422  into and out of CSU  414 . Any signals other than the system communications that access the optical service channel are considered secondary communications, for example the internal user communications and the customer communications. CSU  414  prioritizes communications coming from TDM ports  418  and from router  416  before injecting the signals onto the optical service channel through OC-3 ports  422 . CSU  414  would give the system communications a higher priority than the secondary communications. CSU  414  may give different priorities to the customer communications and the internal user communications. In another example embodiment of the invention, where TCP/IP routing is not needed, router  416  may be optional. Other port types may also be used dependant on the type of access required by the optical service channel service module.