Patent Publication Number: US-2005117905-A1

Title: Optical transponder which can be reconfigured in accordance with various types of client networks

Description:
This application claims the priority of Korean Patent Application No. 2003-84984, filed on Nov. 27, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an optical transponder having a unified platform which can be reconfigured in accordance with various types of client networks, and more particularly, to an optical transponder which receives client signals including a synchronous digital hierarchy/synchronous optical network (SDH/SONET) signal, a gigabit Ethernet (GbE) signal, and a storage area network (SAN) signal.  
      2. Description of the Related Art  
       FIG. 1  shows a configuration of a conventional optical transponder which converts an STM-64/OC-192 signal that is most widely used, into an OTU2 signal and transmits the OTU2 signal. Referring to  FIG. 1 , the conventional optical transponder, which cannot be reconfigured in accordance with various types of client networks and receives the STM-64/OC-192 signal, includes an STM-64 interface transceiver  110 , a digital wrapper unit  120 , an OTN interface transceiver  130 , and a supervision/ control unit  140 .  
      The STM-64 interface transceiver  110  is a unit into which an STM-64/OC-192 signal is input or which outputs the STM-64/OC-192 signal. The STM-64 interface transceiver  110  includes an optic/electric conversion block  112 , a multiplexing/demultiplexing block  114 . The optic/electric conversion block  112  optic-to-electric converts the STM-64/OC-192 signal. The multiplexing/demultiplexing block  114  converts a 9.958 Gb/s serial electric signal into 16×622 MHz parallel data and a 622 MHz clock signal.  
      The digital wrapper unit  120  maps or demaps the STM-64/OC-192 signal into the OTU2 signal. The digital wrapper unit  120  includes an OTN clock generation block  122 , an SDH clock generation block  126 , and a digital wrapper  124 . The OTN clock generation block  122  generates a clock signal for mapping, and the SDH clock generation block  126  generates a clock signal for demapping. The digital wrapper  124  maps the STM-64/OC-192 signal into the OTU2 signal or demaps the OTU2 signal into the STM-64/OC-192 signal.  
      The OTN interface transceiver  130  is a unit into which the OTU2 optical signal is input or which outputs the OUT2 optical signal. The supervision/control unit  140  controls the operation of each element constituting the STM-64 interface transceiver  110  and supervises a performance or abnormality thereof. The OTN interface transceiver  130  includes a multiplexing/demultiplexing block  132  and an optic/electric conversion block  134 . The multiplexing/demultiplexing block  132  converts 16×669 MHz parallel data and a 669 MHz clock signal input from the digital wrapper unit  120  into a 10.7 Gb/s serial electric signal. The optic/electric conversion block  134  optic-to-electric converts the 10.7 Gb/s serial electric signal.  
      Each of the STM-64 interface transceiver  110  and the OTN interface transceiver  130  includes 300-pin multisource agreement (MSA) standard connectors  116  and  136 . 16 parallel data, one clock signal, and a supervision/control signal are exchanged with one another via the 300-pin MSA standard connectors  116  and  136 , and a power source is supplied to a transceiver via the 300-pin MSA standard connections  116  and  136 . A method of exchanging the 16 parallel data and the one clock signal are exchanged with each other via the 300-pin MSA standard connectors  116  and  136  is defined in an optical internetworking forum (OIF) and is referred to as a serdes framer interface level 4 (SFI-4) connection standard.  
      However, in the aforementioned conventional optical transponder, types of optical transponders are different according to types of client networks. Thus, when a connected client signal should be changed, a system operator should replace an optical transponder with another one and a manufacturer should manufacture and manage various types of optical transponder PCBs.  
     SUMMARY OF THE INVENTION  
      The present invention provides an optical transponder which can be reconfigured and reused by replacing only the client network interface board and then re-provisioning the transponder when an interfaced client signal varies.  
      According to an aspect of the present invention, there is provided an optical transponder comprising: a client network interface transceiver multiplexing a client signal transmitted from a client network or demultiplexing a signal transmitted from an optical transport network and outputting the multiplexed signal and the demultiplexed signal; a digital wrapper mapping an STM-64/OC-192 signal or a plurality of STM-16/OC-48 signals input from the client network interface transceiver into an OTU2 signal or demapping the OTU2 signal into the STM-64/OC-192 signal or the plurality of STM-16/OC-48 signals, including a plurality of client network clock generation units to provide a second clock signal needed in the client network interface transceiver; an OTN interface transceiver transmitting the OTU2 signal input from the optical transport network to the digital wrapper or transmitting the OTU2 signal input from the digital wrapper to the optical transport network; and a supervision/control unit initializing and resetting hardware according to types of client signals input into the client network interface transceiver from the client network and supervising performance of each element and occurrence of errors, wherein the client network interface transceiver includes a connector comprising a first connection terminal providing a unit transmitting and receiving a plurality of first clock signals, a plurality of second clock signals, and a plurality of data signals to and from the digital wrapper; a second connection terminal providing a unit transmitting and receiving a supervision/control signal and a CPU-related signal to and from the supervision/controlling unit; and a power source terminal providing a unit to which a power source is supplied and is combined to be attached or detached to or from the digital wrapper and the supervision/controlling unit.  
      Thus, a functional unit commonly needed in the optical transponder is shared and only the client network interface board according to types of client signals is replaced with another one so that communication service provider and equipment manufacturer can reduce costs. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above aspects and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:  
       FIG. 1  shows a configuration of a conventional optical transponder which converts an STM-64/OC-192 signal that is most widely used, into an OTU2 signal and transmits the OTU2 signal;  
       FIG. 2  shows a configuration of a wavelength division multiplexing (WDM) optical transmission equipment using an optical transponder which can be reconfigured in accordance with various types of client networks, according to the present invention  
       FIG. 3  is a block diagram showing a configuration of an optical transponder which can be reconfigured in accordance with various types of client networks, according to an embodiment of the present invention; and  
       FIGS. 4 through 6  show a detailed configuration of the optical transponder and connection between elements when a client signal input from a client network is an STM-64/OC-192 signal, an STM-16/OC-48 signal, and a GbE/SAN signal, respectively. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.  
       FIG. 2  shows a configuration of a wavelength division multiplexing (WDM) optical transmission equipment using an optical transponder which can be reconfigured in accordance with various types of client networks, according to the present invention. The WDM optical transmission equipment is a device which dramatically increases the efficiency of a bandwidth utilization of an optical fiber link, that is, transmission capacity, by multiplexing and transmitting optical signals divided into different wavelengths in an optical transmission network.  
      Referring to  FIG. 2 , the WDM optical transmission equipment includes an optical channel block  220 , an optical multiplexing block  230 , and an optical amplifier block  240 , an optical demultiplexing block  260  and an optical channel block  270 . The optical multiplexing block  230  and the optical demultiplexing block  260  are connected to each other via an optical fiber link  290 .  
      The optical channel block  220  converts a client signal input from an external client network  210  into a WDM optical channel having the wavelength stipulated in accordance with ITU-T recommendation. The optical multiplexing block  230  multiplexes the optical signal input from the optical channel block  220 . The optical amplifier block  240  amplifies the optical signal multiplexed by the optical multiplexing block  230  via an optical fiber. The optical signal amplified by the optical amplifier block  240  is transmitted to the optical demultiplexing block  260  via the optical fiber link  290 . The optical demultipexing block  260  demultiplexes the optical signal transmitted via the optical fiber link  290 . The optical channel block  270  converts the optical signal demultiplexed for each WDM optical channel by the optical demultiplexing block  260  into a client signal of the external client network  280 .  
      Client signals which the WDM optical transmission equipment receives include a synchronous digital hierarchy/synchronous optical network (SDH/SONET) signal  212  including an STM-16/OC-48 signal and an STM-64/OC-192 signal, a gigabit Ethernet signal  214  including a GbE signal and a 10GbE signal, and an SAN signal  216  including a fiber channel (FC) signal and enterprise systems connectivity (ESCON) signal. In  FIG. 2 , #N is the maximum number of optical channels which the WDM optical transmission equipment receives, and N has values of 8, 16, 32, 40, and 160.  
      The optical transponder which can be reconfigured in accordance with various types of client networks according to the present invention, belongs to the optical channel blocks  220  and  270  of the WDM optical transmission equipment shown in  FIG. 2  and connects the external client network  210  or  280  to the optical multiplexing block  230  or the optical demultiplexing block  260 . An optical transponder in the conventional WDM optical transmission equipment has developed to receive the SDH/SONET signal, such as the STM-16/OC-48 signal and the STM-64/OC-192 signal. However, due to the recent and explosive increase in data communication traffic, demands for interfacing various clients signal, such as GbE, FC, and ESCON increase. In addition, as the speed of an optical channel of the WDM optical transmission equipment increases from 2.5 Gb/s to 10 Gb/s, four STM-16/OC-48 signals are multiplexed, or a plurality of GbE and SAN signals are multiplexed into a 10 Gb/s OTN (OTU2) signal to transmit them so that researches on the improvement of the efficiency of an optical channel bandwidth exploitation of the WDM optical transmission equipment has been progressed.  
       FIG. 3  is a block diagram showing a configuration of an optical transponder which can be reconfigured in accordance with various types of client networks, according to an embodiment of the present invention. The optical transponder  300  of  FIG. 3  includes a client network interface transceiver  310 , a digital wrapper unit  320 , an OTN interface transceiver  330 , and a supervision/control unit  340 . The client network interface transceiver  310  is combined with the optical transponder  300  to be replaced, and transceivers having different configurations are used in response to signals input from client networks. The client network interface transceiver  310  includes an optic/electric conversion block  312 , a multiplexing/demultiplexing block  314 , and a connector  316 . The optic/electric conversion block  312  optic-to-electric converts a client signal input from a client network. The multiplexing/demultiplexing unit block  314  converts an electric signal input from the optic/electric conversion block  312  into a parallel data signal and a clock signal. The connector  316  includes a first connection terminal which provides a unit transmitting and receiving a plurality of first clock signals (clock signals output to the OTN clock generation block  322 ), a plurality of second clock signals (clock signals input from a client network clock generation block  326 ), and a plurality of data signals to and from the digital wrapper unit  320 , a second connection terminal which provides a unit transmitting and receiving a supervision/control signal and a CPU-related signal to and from the supervision/control unit  340 , and a power source terminal which provides a unit to which a power source is supplied.  
       FIGS. 4 through 6  show the detailed configuration of the optical transponder  310  and connection between elements when a client signal input from a client network is an STM-64/OC-192 signal, an STM-16/OC-48 signal, and a GbE/SAN signal, respectively.  
      Referring to  FIG. 4 , when an STM-64 interface transceiver  410  as the client network interface transceiver  310  is mounted on the optical transponder  300 , 16 data and one clock signal are transmitted to a digital wrapper unit  420  and a supervision/control unit  440  according to a serdes framer interface level 4 (SFI-4) connection standard. Only a clock signal generated by one client network clock generation unit of the four client network clock generation units  423  of the digital wrapper unit  420  is used. Three clock signals and a CPU-related signal indicated by dotted lines of  FIG. 4  are not used.  
      In addition, referring to  FIG. 5 , when an STM-16 interface transceiver  510  as the client network interface transceiver  310  is mounted on the optical transponder  300 , four signals can be input into an STM-16 interface transceiver  510 . Thus, 16 data and four clock signals are transmitted to a digital wrapper unit  520  and a supervision/control unit  540 . Since the four signals are in an asynchronous state, the four clock signals and a client network clock generation unit  523  are used. A CPU-related signal indicated by a dotted line of  FIG. 5  is not used.  
      In addition, referring to  FIG. 6 , when a GbE/SAN interface transceiver  610  including an STM-64/OC-192 mapping block  614  as the client network interface transceiver  310  is mounted on the optical transponder  300 . The STM-64/OC-192 mapping block  614  maps N GbE or SAN signals having a comparatively low speed into an STM-64/OC-192 signal by performing a generic framing procedure (GFP) and a concatenation procedure. The 16 data and the one clock signal mapped and multiplexed into the STM-64/OC-192 signal are transmitted from the STM-64/OC-192 mapping block  614  to the digital wrapper unit  620  and a supervision/control unit  640 . Thus, as shown in  FIG. 6 , only one client network clock generation unit of the four client network clock generation units  623  is used, and a CPU-related signal is used.  
      As described above, six data and four clock signals are connected between the client network interface transceiver  310  and the digital wrapper unit  320 , so as to receive various types of client signals. In addition, a supervision/control signal and the CPU-related signal are connected between the client network interface transceiver  310  and the supervision/controlling unit  340 . Furthermore, various types of client signals can be received by designing a connection unit of the client network interface transceiver  310  so that a power source is supplied to the client network interface transceiver  310 .  
      The digital wrapper unit  320  may be used in two cases: one case where an STM-64/OC-192 signal is input into the digital wrapper unit  320  and the other case where four STM-16/OC-48 signals are input thereinto. When the STM-64/OC-192 signal is input into the digital wrapper unit  320 , each one of the OTN clock generation block  322  and an SDH clock generation block  324  is necessary. However, when the four STM-16/OC-48 signals are input into the digital wrapper unit  320 , the STM-16/OC-48 signal is in an asynchronous state. Thus, four client network clock generation blocks are necessary. Thus, when the digital wrapper unit  320  is designed to have four client network clock generation blocks, the digital wrapper unit  320  is designed to use one client network clock generation block among the four client network generation blocks when interfacing the STM-64/OC-192 signal. In this case, the OTN clock generation block  322  generates a clock signal for mapping, and the client network clock generation block  326  generates a clock signal for demapping.  
      The OTN interface transceiver  330  is a unit into which the OTU2 optical signal is input or which outputs the OTU2 optical signal. The OTN interface transceiver  330  includes a multiplexing/demultiplexing block  332 , an optic/electric conversion block  334 , and a connector  336 . The configuration and operation of the OTN interface transceiver  330  are similar to those of the client network interface transceiver  310 , and thus detailed descriptions thereof will be omitted.  
      The supervision/control unit  340  supervises/controls the operation of each element even when the STM-16/OC-48 signal and the GbE/SAN signal as well as the STM-64/OC-192 signal are input into the supervision/control unit  340 . In addition, the supervision/control unit  340  makes CPU communication with the client network interface transceiver  310  by receiving the CPU-related signal from the client network interface transceiver  310 . In addition, firmware of the supervision/controlling unit is used to re-provisioning hardware according to types of client signals.  
      As described above, in the optical transponder which can be reconfigured in accordance with various types of client networks according to the present invention, a functional unit commonly needed in the optical transponder is shared and only a client network interface transceiver is replaced from the optical transponder according to types of client signals such that hardware is re-provisioned in response to the client signals, thereby configuring a new optical transponder. Thus, a communication service provider purchases not the entire optical transponder but the client network interface transceiver when the optical transponder should be replaced with another one owing to changed demand in interfacing client signal such that purchasing costs are reduced. In addition, an optical transponder manufacturer can reduce costs for manufacturing and managing various types of optical transponder PCBs.  
      While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the following claims.