Abstract:
In a testing apparatus for an optical access network, a converting unit converts an optical signal received through the optical access network into an electrical signal to create  10   b  coded data. A protocol processing unit performs a processing according to a protocol of the optical access network on the  10   b  coded data, and records a plurality of different protocol processing data corresponding to protocol information assigned to a plurality of ONUs. A memory unit stores the  10   b  coded data output from the converting unit. A CPU analyzes the  10   b  coded data in the memory unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2005-284459, filed on Sep. 29, 2005, the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a testing apparatus for testing a relay device in an optical access network according to a gigabit Ethernet (GbE).  
         [0004]     2. Description of the Related Art  
         [0005]     The IEEE802.3ah is an optical access network standard. A testing apparatus for a relay device conforming to the IEE802.3ah standard has not yet been available in the market. Due to this, a test for such relay device has conventionally been carried out as follows.  
         [0006]      FIG. 7  is a block diagram of a conventional testing system. An optical line terminal (OLT)  1  shown in  FIG. 7  is a relay device to be tested. The OLT  1  is a gigabit-Ethernet passive-optical network (GE-PON) device on a station side. An Ethernet tester (or a server)  2  is connected to the OLT  1  via an Ether network  3  (for example, Japanese Patent Laid-Open Publication No. 2005-20420).  
         [0007]     Optical network units (ONU)  4  are GE-PON devices, on a subscriber side, connected to the OLT  1  via a GbE optical-access network  5 . Ethernet testers (or a personal computers (PC))  6  are connected to the ONU  4  via an Ether network  7 . The Ethernet testers  6  are testers for testing Ethernet.  
         [0008]     As shown in  FIG. 7 , to test a single unit of the OLT  1 , a plurality of ONUs  4  are connected to one unit of the OLT  1  via the GbE optical-access network  5  in a similar manner as an actual operation in the market. To confirm data communication between a backbone network and a subscriber, an Ethernet tester, a personal computer (PC), or a work station (WS) is connected to each of the ONUs  4 .  
         [0009]      FIG. 8  is a block diagram of the ONU  4 . As shown in  FIG. 8 , the ONU  4  includes an optical-electrical/electrical-optical (OE/EO) unit  11 , an encoding unit  12 , an IEEE802.3ah-protocol processing unit  13 , and an Ethernet INF unit  14 .  
         [0010]     The OE/EO unit  11  is connected to the GbE optical-access network  5  via an interactive optical fiber cable  8 . The OE/EO unit  11  receives optical signals transmitted from the OLT  1  via the GbE optical-access network  5  and the optical fiber cable  8 , and converts received optical signals into electrical signals. The OE/EO unit  11  also converts electrical signals into optical signals to transmit to the OLT  1  via the GbE optical-access network  5 . The encoding unit  12  encodes  10   b  coded serial data output from the OE/EO unit  11  into  8   b  coded parallel data. The encoding unit  12  also decodes  8   b  coded parallel data output from the IEEE802.3ah-protocol processing unit  13  into  10   b  coded serial data.  
         [0011]     The IEEE802.3ah-protocol processing unit  13  carries out an IEEE802.3ah protocol processing on  8   b  coded data that are output by the encoding unit  12 . The Ethernet interface (INF)  14  connects the ONU  4  to the Ethernet tester (or PC)  6  that serves the ONU  4 .  
         [0012]     The IEEE802.3ah-protocol processing unit  13  includes a preamble identifying unit  15 , a medium-access-control (MAC)-layer identifying unit  16 , a fixed-preamble generating unit  17 , a fixed-MAC generating unit  18 , a fixed-data generating unit  19 , a data inserting unit  20 , a MAC inserting unit  21 , and a preamble inserting unit  22 . The preamble identifying unit  15  identifies a preamble area of IEEE802.3ah  8   b  coded frame data that are transmitted from the encoding unit  12 .  
         [0013]     The MAC-layer identifying unit  16  identifies a MAC layer of the IEEE802.3ah frame data that is transmitted from the preamble identifying unit  15 . The fixed-preamble generating unit  17  generates preamble data in  8   b  code that are fixedly allocated to a single unit of the ONU  4  during the IEEE802.3ah protocol processing. The fixed-MAC generating unit  18  generates a MAC header in  8   b  code that are fixedly set during the IEEE802.3ah protocol processing.  
         [0014]     The fixed-data generating unit  19  generates  8   b  coded frame data that are fixedly set during the IEEE802.3ah protocol processing. The data inserting unit  20  inserts the frame data to a transmission frame. The MAC inserting unit  21  inserts the MAC header to the transmission frame. The preamble inserting unit  22  inserts the preamble data to the transmission frame. Thus, the transmission frame is assembled.  
         [0015]     In the ONU  4 , the OE/EO unit  11  receives the optical signals that are input from the GbE optical-access network  5  and converts the received optical signals into electrical signals of  10   b  coded frame data. The encoding unit  12  converts the received frame data in  10   b  code into  8   b  coded data. The  8   b  coded data is subjected to the IEEE802.3ah protocol processing in the IEEE802.3ah-protocol processing unit  13 . During transmission, the encoding unit  12  converts the  8   b  coded data into  10   b  coded transmission frame data. The OE/EO unit  11  converts the transmission frame data into optical signals, and outputs the optical signals to the GbE optical-access network  5 .  
         [0016]     However, when a test is performed simultaneously at each of the ONU  4  and each of the Ethernet tester  6  in the conventional testing system, plural units of the ONUs  4  and plural units of the Ethernet testers  6  are required for a single unit of the OLT  1 . Therefore, cost and a scale of the testing system increase.  
         [0017]     When the scale increases, for example, a factory is required to prepare a large space to install the testing system to perform a test before shipment. If a plural units of the OLT  1  is to be tested, the number of the ONUs  4  and the Ethernet testers  6  required for the test significantly increases.  
       SUMMARY OF THE INVENTION  
       [0018]     It is an object of the present invention to at least solve the above problems in the conventional technology.  
         [0019]     A testing apparatus according to one aspect of the present invention is for testing a device that is connected to the testing apparatus via an optical access network. The testing apparatus includes a converting unit configured to convert an optical signal received through the optical access network into an electrical signal to create  10   b  coded data; a protocol processing unit configured to perform a processing according to a protocol of the optical access network on the  10   b  coded data; and an encoding unit configured to encode the  10   b  coded data to  8   b  coded data.  
         [0020]     The other objects, features, and advantages of the present invention are specifically set forth in or will become apparent from the following detailed description of the invention when read in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  is a block diagram of a testing apparatus for an optical access network according to an embodiment of the present invention;  
         [0022]      FIG. 2  is a schematic of a protocol processing table and a search key;  
         [0023]      FIG. 3  is a schematic for illustrating a frame format of the IEEE802.3ah standard;  
         [0024]      FIG. 4  is a schematic for illustrating a frame format of a DIX specification;  
         [0025]      FIG. 5  is a block diagram of a testing system that uses the testing apparatus for the optical access network according to the embodiment;  
         [0026]      FIG. 6  is a flowchart of a frame processing in a test executed by the testing apparatus according to the embodiment;  
         [0027]      FIG. 7  is a block diagram of a conventional testing system; and  
         [0028]      FIG. 8  is a block diagram of an ONU shown in  FIG. 7 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]     Exemplary embodiments according to the present invention are explained in detail below with reference to the accompanying drawings.  
         [0030]      FIG. 1  is a block diagram of a testing apparatus for an optical access network according to an embodiment of the present invention. As shown in  FIG. 1 , a testing apparatus  100  includes an OE/EO unit  111 , an IEEE802.3ah-protocol processing unit  112 , an encoding unit  113 , an Ethernet-upper-layer testing unit  114 , a capture memory  115 , and a central processing unit (CPU)  116  that are connected to each other via control paths  117 .  
         [0031]     The OE/EO unit  111  is connected to the GbE optical access network  5  (see  FIG. 5 ) via an interactive optical fiber cable  8 . The OE/EO unit  111  receives optical signals that are transmitted via the GbE optical-access network  5  and the optical fiber cable  8 , and converts the received optical signals into electrical signals to generate received frame data formed with  10   b  coded serial data. The received frame data is transmitted to the IEEE802.3ah-protocol processing unit  112  in the form of  10   b  code. The OE/EO unit  111  converts into optical signals, transmission frame data formed with  10   b  coded serial data that are transmitted from the IEEE802.3ah-protocol processing unit  112 , and outputs the converted optical signals to the GbE optical-access network  5  via the optical fiber cable  8 .  
         [0032]     The IEEE802.3ah-protocol processing unit  112  includes a protocol identifying unit  118 , a protocol processing table  119 , and an IEEE802.3ah-frame processing unit  120 . The IEEE802.3ah-protocol processing unit  112  carries out an IEEE802.3ah protocol processing on the received frame data in the form of  10   b  code. The protocol identifying unit  118  analyzes the received frame data that are transmitted from the OE/EO unit  111 , and identifies whether the received frame data is a frame data of an IEEE802.3ah protocol or an IEEE802.3 frame.  
         [0033]     If the received frame data is of the IEEE802.3ah standard, the protocol identifying unit  118  generates an identification code for a protocol processing, and combines the identification code with a testing code to generate a search key. The search key is used to select protocol data from the protocol processing table  119 . The CPU  116  sets the testing code. If the received frame data is not a frame data of the IEEE802.3ah standard, the protocol identifying unit  118  does not generate the search key.  
         [0034]     Furthermore, if the received frame data is a frame data of the IEEE802.3ah standard, the protocol identifying unit  118  does not transfer the received frame data to the encoding unit  113 . If the received frame data is any other type of frame data, the protocol identifying unit  118  transfers the received frame data in the form of  10   b  code to the encoding unit  113 . The CPU  116  controls whether to transfer the received frame data to the encoding unit  113 .  
         [0035]     The protocol processing table  119  includes multiple entries of protocol data and frame data corresponding to the IEEE802.3ah protocol and the IEEE802.3 frame respectively. Based on the search key, an appropriate entry is selected from among the entries in the protocol processing table  119 . The protocol processing table  119  is rewritable by the CPU  116 .  
         [0036]     The IEEE802.3ah-frame processing unit  120  obtains protocol data of the entry selected based on the search key. By using a preamble, a MAC header, and response data, the IEEE802.3ah-frame processing unit  120  assembles response frame data conforming to the proper IEEE802.3ah standard, and outputs the response frame data via the OE/EO unit  111  to the GbE optical-access network  5  at predetermined timing. The response frame data is transmitted either within a transmission timing that is stipulated by received electrical signals and the IEEE802.3ah standard, or at a timing indicated in timing data set in the protocol processing table  119 .  
         [0037]     The encoding unit  113  encodes  10   b  coded serial data that passes through the protocol identifying unit  118  into  8   b  coded parallel data, and transmits the  8   b  coded parallel data to the Ethernet-upper-layer testing unit  114 . The encoding unit  113  decodes the  8   b  coded parallel data that are transmitted from the Ethernet-upper-layer testing unit  114  into  10   b  coded serial data, and transmits the  10   b  coded serial data to the IEEE802.3ah-frame processing unit  120 . The IEEE802.3ah-frame processing unit  120  transmits the parallel data in the form of  10   b  code that are transmitted from the Ethernet-upper-layer testing unit  114  to the OE/EO unit  111 .  
         [0038]     The Ethernet-upper-layer testing unit  114  is controlled by the CPU  116  and carries out testing of an Ethernet upper-layer packet. The Ethernet-upper-layer testing unit  114  is provided with an upper-layer frame generating function that enables the Ethernet-upper-layer testing unit  114  to generate the Ethernet upper-layer packet, and to transmit the Ethernet upper-layer packet to the GbE optical-access network  5  via the encoding unit  113 , the IEEE802.3ah-frame processing unit  120 , and the OE/EO unit  111 .  
         [0039]     The capture memory  115  includes a memory unit  121  that stores in the form of  10   b  code the received frame data that is received from the GbE optical-access network  5 , a filtering unit  122  that sorts data for storing in the memory unit  121  according to specified filtering conditions, and a control function that controls the memory unit  121  and the filtering unit  122 . The CPU  116  specifies the filtering conditions. Logic to avoid filtering can also be set in the filtering unit  122 .  
         [0040]     The CPU  116  controls the entire testing apparatus  100 . The CPU  116  can communicate with a not shown external computer. The CPU  116  can read and analyze data that is captured in the memory unit  121 . The data captured in the memory unit  121  can also be read by the CPU  116 , transmitted to the not shown external computer or display device, and analyzed by the personal computer or displayed in the display device.  
         [0041]      FIG. 2  is a schematic of the protocol processing table.  FIG. 3  is a schematic for illustrating a frame format of the IEEE802.3ah standard and  FIG. 4  is a schematic for illustrating a frame format of a DIX specification. As shown in  FIG. 2 , a search key  130  includes an identification code  131  that is generated from the IEEE802.3ah frame, and a testing code  132  that is set by the CPU  116 .  
         [0042]     For example, the identification code  131  includes a MAC-DA  133 , a Type  134 , an LLID [15:8]  135 , an LLID [7:0]  136 , and an Opcode  137 . The MAC-DA  133 , the Type  134 , the LLID [15:8]  135 , the LLID [7:0]  136 , and the Opcode  137  of the identification code  131  correspond respectively to a MAC-DA  203 , a Type  204 , an LLID [15:8]  201 , an LLID [7:0]  202 , and an Opcode  205  that are assigned to an IEEE802.3ah frame format  200  shown in  FIG. 3 .  
         [0043]     The LLID [15:8]  201  and the LLID [7:0]  202  indicate upper 8 bits and lower 8 bits respectively of a 2 byte LLID. LLID is an abbreviation of local link identification (ID), and Opcode is an abbreviation of operation code.  
         [0044]     The testing code  132  is provided to determine whether the searched data is regular protocol data or testing protocol data. For example, a protocol processing table  140  is provided with a regular frame entry area  141 , a testing frame entry area  1  ( 142 ), and a testing frame entry area  2  ( 143 ). The CPU  116  sets entry data of the regular frame entry area  141 , the testing frame entry area  1  ( 142 ), and the testing frame entry area  2  ( 143 ).  
         [0045]     Multiple entries  144  of regular protocol data corresponding to the IEEE802.3ah protocol are stored in the regular frame entry area  141 . Multiple entries  145  of testing protocol data corresponding to the IEEE802.3ah protocol are stored in the testing frame entry area  1  ( 142 ). Storing standard violating data or  10   b  coded data defects as testing protocol data enables to increase testing variation.  
         [0046]     Multiple entries  146  of protocol data corresponding to a DIX specification format are stored in the testing frame entry area  2  ( 143 ). This enables the IEEE802.3ah-frame processing unit  120  to generate a testing frame corresponding to the DIX specification format, thus enabling to correspond to data frames other than data frames that conforming to the IEEE802.3ah standard. The IEEE802.3ah standard and the DIX specification are identified from a value of the Type  134 . The Type  134  of the identification code  131  corresponds to a Type  301  that is assigned to a DIX specification format  300  shown in  FIG. 4 .  
         [0047]     As shown in  FIG. 3  and  FIG. 4 , SPD, PRE, CRC, and SFD are abbreviations corresponding to start of packets, preamble, cyclic redundancy check, and start of packet delimiter respectively. The numerals inside brackets shown in  FIG. 2  through  FIG. 4  represent the number of bytes.  
         [0048]      FIG. 5  is a block diagram of a testing system that uses the testing apparatus  100 . As shown in  FIG. 5 , the testing apparatus  100  is connected via the GbE optical-access network  5  to an OLT  1  that is tested. An Ethernet tester (or a server)  2  is connected the OLT  1  via an Ether network  3 .  
         [0049]      FIG. 6  is a flowchart of a frame process by the IEEE802.3ah-protocol processing unit  112  that executes a test with the testing system shown in  FIG. 5 . As shown in  FIG. 6 , the OE/EO unit  111  receives frame data of optical signals that are transmitted from the OLT  1  via the GbE optical-access network  5 . The OE/EO unit  111  converts the received optical signals into electrical signals to generate received frame data in  10   b  code, and transmits the received frame data in the form of  10   b  code to the protocol identifying unit  118 .  
         [0050]     The protocol identifying unit  118  obtains the received frame data from the OLT  1  via the OE/EO unit  111  (step S 1 ), and identifies protocol of the received frame data according to the IEEE802.3ah standard (step S 2 ). Next, the protocol identifying unit  118  determines whether the received frame data is a frame data of the IEEE802.3ah standard (step S 3 ).  
         [0051]     If the received frame data is a frame data of the IEEE802.3ah standard (“YES” at step S 3 ), the protocol identifying unit  118  extracts an identification code for the protocol processing (step S 4 ). Next, the protocol identifying unit  118  combines the identification code with the testing code that is set by the CPU  116  to generate the search key (step S 5 ). The protocol identifying unit  118  transmits the generated search key to the protocol processing table  119 , and controls not to transfer the received frame data to the encoding unit  113 .  
         [0052]     The protocol processing table  119  obtains the search key from the protocol identifying unit  118 , and searches the protocol processing table  140  for an entry that is specified by the search key (step S 6 ). Next, the protocol processing table  119  selects protocol processing data (protocol data) from the entry based on the search key (step S 7 ), and transmits the selected protocol processing data to the IEEE802.3ah-frame processing unit  120 .  
         [0053]     The IEEE802.3ah-frame processing unit  120  obtains the protocol processing data from the protocol processing table  119 , and uses the protocol processing data to assemble response frame data of the regular IEEE802.3ah standard (step S 8 .). Next, the IEEE802.3ah-frame processing unit  120  determines whether a processing to be performed on the response frame data is a regular frame processing or a testing frame processing (step S 9 ).  
         [0054]     If the processing to be performed is the testing frame processing (“TESTING FRAME PROCESS” at step S 9 ), based on the received electrical signals and timing data in the protocol processing data, the IEEE802.3ah-frame processing unit  120  computes transmission timing, and transmits the response frame data to the GbE optical-access network  5  via the OE/EO unit  111  (step S 10 ). Thus, a series of process by the IEEE802.3ah-protocol processing unit  112  is finished.  
         [0055]     If the processing to be performed is the regular frame process (“REGULAR FRAME PROCESS” at step  9 ), based on the received electrical signals and transmission timing specified by the IEEE802.3ah standard, the IEEE802.3ah-frame processing unit  120  transmits the response frame data at the specified timing to the GbE optical-access network  5  via the OE/EO unit  111  (step S 11 ). Thus, a series of process by the IEEE802.3ah-protocol processing unit  112  is finished.  
         [0056]     If the received frame data is not a frame data of the IEEE802.3ah standard at step S 3  (“NO” at step S 3 ), the protocol identifying unit  118  transfers the received frame data to the Ethernet-upper-layer testing unit  114  via the encoding unit  113  (step S 12 ). Thus, a series of process by the IEEE802.3ah-protocol processing unit  112  is finished.  
         [0057]     Upon receiving the response frame data, which is not a frame data of the IEEE802.3ah standard from the protocol identifying unit  118 , the Ethernet-upper-layer testing unit  114  transmits the response frame data to the CPU  116 . The CPU  116  analyzes the response frame data, and displays the analysis result in the not shown external display device.  
         [0058]     The response data received from the protocol identifying unit  118  can also be analyzed in the not shown hard circuit and the analysis result can be displayed in the not shown external display device. The response frame data received from the protocol identifying unit  118  can also be displayed in the not shown external display device.  
         [0059]     In the testing apparatus  100  according to the embodiment, multiple IEEE802.3ah protocol data are stored in the protocol processing table  140 , thereby maintaining the protocol data that are fixedly allocated to multiple ONUs, and enabling to construct an environment equivalent to the environment in which multiple ONUs are connected to the OLT  1  via the GbE optical-access network  5 . Thus, the GbE optical-access network  5  can be tested with a simple structure. Thus, it is possible to reduce the cost and space for testing.  
         [0060]     Standard-violating protocol processing data or  10   b  coded data defects is set in the protocol processing table  140 , and transmission frame data that is based on the standard-violating protocol data or the  10   b  coded data defects is transmitted to the GbE optical-access network  5 , thereby providing a variety of verification patterns for the OLT  1 . Thus, it is possible to judge whether the GbE optical-access network  5  conforming to the IEEE802.3ah standard is normal or defective.  
         [0061]     Furthermore, the Ethernet-upper-layer testing unit  114  is provided in the testing apparatus  100 . Therefore, it is possible to carry out verification of Ethernet. Thus, it is possible to judge whether the GbE optical-access network  5  conforming to the Ethernet interface standard is normal or defective.  
         [0062]     The IEEE802.3ah-protocol processing unit  112  handles  10   b  coded data, stores in the capture memory  115  the received frame data in the form of  10   b  code, and analyzes the stored received frame data. Therefore, it is possible to identify an error that occurs in the GbE optical-access network  5 , and to analyze optical circuit noise in  10   b  code.  
         [0063]     The received frame data that is stored in the capture memory  115  is analyzed by using the CPU  116 , the external display device, or the hard circuit, thereby enabling to detect defective codes in  10   b  code due to an optical circuit noise. Furthermore, the CPU  116  reads the received frame data that is stored in the capture memory  115  and displays the read received frame data in the external display device, thereby enabling to confirm the frame data that flows through the optical circuits.  
         [0064]     The CPU  116  executes software to rewrite the protocol processing table  140 . Therefore, it is possible to generate illegal data in the physical layer, thereby increasing types of verification data. Thus, generation of testing frames and variation in testing can be increased.  
         [0065]     The filtering unit  122  in the capture memory  115  enables to capture only specific received frame data in the memory unit  121  and to analyze the captured received frame data. Therefore, it is possible to detect a defect early and to efficiently use the memory space in the memory unit  121 .  
         [0066]     The present invention is not limited to the above embodiments, and various modifications can be applied. For example, the testing apparatus  100  need not be provided with the inbuilt Ethernet-upper-layer testing unit  114 . Instead of providing the Ethernet-upper-layer testing unit  114 , an interface can be provided that-connects the testing apparatus  100  to an external Ethernet tester (or a personal computer). The Ethernet tester (or the personal computer) can be connected to the interface when carrying out a test.  
         [0067]     According to the embodiments described above, it is possible to test an optical access network with a simple structure. Moreover, it is possible to judge whether a GbE optical-access network conforming to the IEEE802.3ah standard is normal or defective. Furthermore, it is possible to judge whether the GbE optical-access network conforming to the Ethernet interface standard is normal or defective.  
         [0068]     Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.