Abstract:
An optical transmission apparatus to which an optical module having optical module information stored therein is attachable, the optical module information being manufacturing information about the optical module, includes a certification rank table configured to a list, with respect to each of a plurality of optical modules, the optical module information regarding an optical module and a rank indicative of a range of guarantee for the corresponding optical module, and a ranking unit configured to refer to the certification rank table by use of the optical module information stored in an optical module attached to the optical transmission apparatus so as to determine the rank indicative of a range of guarantee for the attached optical module, wherein the determined rank is reported to an exterior of the apparatus.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to optical transmission apparatuses, and particularly relates to an optical transmission apparatus using an optical module that is pluggable to the optical transmission apparatus.  
         [0003]     2. Description of the Related Art  
         [0004]     Optical transceivers (optical modules) used in optical transmission apparatuses provided for backbone networks as typified by SONET, SDH, WDM, etc., are developed by makers and manufacturers using their own designs and interfaces, and thus do not possess universal applicability. Against this background, the MSA (Multi-Source Agreement) has been established as an industry standard for the optical module industry for the purpose of achieving cost advantage and revitalizing the optical module industry. This has resulted in the spread of optical modules having universal applicability based on standardized design and interface. Among such standardized optical modules (MSA modules), those with pluggable structure such as SFP (Small Form Factor Pluggable) and XFP (10 Gigabit Small Form Factor Pluggable) have been becoming mainstream.  
         [0005]     As the market penetration of such pluggable modules is made, communication carriers who utilize optical transmission apparatuses to provide services are now demanding the use of optical modules purchased through their own purchase channels for the benefit of cost advantage, and are also demanding the reduction of repair cost by making it possible to replace only a pluggable module upon failure. Because of this, the optical transmission apparatuses employing standardized pluggable optical modules are now required to have such a structure as to allow optical modules to be freely replaced.  
         [0006]     When pluggable optical modules are employed for optical transmission modules, the main issue is how to keep balance between the reliability of the apparatuses and the convenience of the pluggable optical modules (high availability, easy maintenance, low cost, and so on). In the following, three examples of the related-art usage of a pluggable optical module will be described.  
         [0007]      FIG. 1A  is a drawing showing a first usage type. A pluggable optical module  1  is fixedly mounted in an optical transmission apparatus  2 . In this configuration, only those which have passed the test by the manufacturers at the time of shipment from factory are mounted. This can avoid use of poor-quality products, thereby making it possible to ensure the reliability of the apparatuses.  
         [0008]      FIG. 1B  is a drawing showing a second usage type. A pluggable optical module  3  is freely pluggable to an optical transmission apparatus  4 , which provides for easy maintenance at the time of failure or the like. Also, clients can make their own choice to select inexpensive optical modules, so that the manufacturers can provide cost advantage to the clients.  
         [0009]      FIG. 1C  is a drawing showing a third usage type. A pluggable optical module  5  has such a structure as to be pluggable to an optical transmission apparatus  6 . A CPU  7  of the optical transmission apparatus  6  checks the optical module by comparing the module code read from the optical module  5  via a DDM (Digital Diagnostics Monitor) interface  8  with the module code of an operable optical module stored in a memory  9 . If a module having a wrong code is mounted, an alarm is issued to a monitoring control apparatus so as to prevent the use of the optical module  5 .  
         [0010]     Patent Document 1 discloses transmitting a membership number read from a membership card by a hall-installed apparatus to a management computer, which reads a membership classification flag stored in memory in response to the membership number for transmission to the hall-installed apparatus, so that the hall-installed apparatus displays the membership class of the member as indicated by the membership classification flag.  
         [0011]     Patent Document 1  
         [0012]     Japanese Patent Application Publication No. 10-156022  
         [0013]     The first usage type cannot make use of the convenience of a pluggable optical module such as the fact that it is pluggable, and, also, cannot allow a client to use an optical module that the client obtained through his/her own channel.  
         [0014]     The second usage type raises concern that a pluggable optical module not suitable to the apparatus or a poor-quality module may be used. In the worst case, there is a possibility of having a situation in which the communication channel fails while it is used. That is, the reliability of the apparatus may not be guaranteed.  
         [0015]     The third usage type allows only exactly the same product as specified by the manufacture to be used when replacing the pluggable optical module  5  upon failure of the pluggable optical module  5 , and does not allow the use of a pluggable optical module having the same characteristics if it is not the type as specified. Further, it is not possible for a client (communication carrier) using the apparatus to make its own choice to select an inexpensive pluggable optical module. That is, no cost merit is provided to clients.  
         [0016]     Further, if an inexpensive pluggable optical module that is not fully supported by the manufacture is chosen, there is a need to check, before putting this pluggable optical module into operation, whether this module properly operates in the optical transmission apparatus and whether this module has sufficient characteristics for operation of the communication channel. A test that is currently conducted by the manufacturers for the purpose of checking a pluggable optical module for certification is performed by assuming the worst conditions (in terms of ambient temperature, transmission distance, etc.) in which the pluggable optical module is operated. Only those which passed this rigorous test are certified. This is the same when a client makes its own choice to select a pluggable optical module. That is, there are needs to determine product specifications by assuming the worst conditions for operation, to prepare a dedicated measurement device to conduct an optical-characteristic test, a transmission test, etc, and to actually perform various test items. In this manner, a large number of process steps are required in order to select a pluggable optical module.  
         [0017]     In reality, however, the conditions of use, transmission distance, etc., differ from communication line to communication line, and not all the optical modules are used in the worst conditions. Conducting tests by determining product specifications based on the worst conditions serves to narrow the range of choices of an pluggable optical module to be used. Further, a large number of optical module venders rigorously develop and update new pluggable optical modules to sell inexpensive optical modules. Against this background, the reduction of a number of process steps for product certification is an important issue.  
         [0018]     Accordingly, there is a need for an optical transmission apparatus that can clearly specify the range of product guarantee while offering ease of maintenance and cost advantage, and that can widen the range of choices of pluggable optical modules to be used.  
       SUMMARY OF THE INVENTION  
       [0019]     It is a general object of the present invention to provide an optical transmission apparatus that substantially obviates one or more problems caused by the limitations and disadvantages of the related art.  
         [0020]     Features and advantages of the present invention will be presented in the description which follows, and in part will become apparent from the description and the accompanying drawings, or may be learned by practice of the invention according to the teachings provided in the description. Objects as well as other features and advantages of the present invention will be realized and attained by an optical transmission apparatus particularly pointed out in the specification in such full, clear, concise, and exact terms as to enable a person having ordinary skill in the art to practice the invention.  
         [0021]     To achieve these and other advantages in accordance with the purpose of the invention, the invention provides an optical transmission apparatus to which an optical module having optical module information stored therein is attachable, the optical module information being manufacturing information about the optical module, includes a certification rank table configured to a list, with respect to each of a plurality of optical modules, the optical module information regarding an optical module and a rank indicative of a range of guarantee for the corresponding optical module, and a ranking unit configured to refer to the certification rank table by use of the optical module information stored in an optical module attached to the optical transmission apparatus so as to determine the rank indicative of a range of guarantee for the attached optical module, wherein the determined rank is reported to an exterior of the apparatus.  
         [0022]     According to at least one embodiment of the present invention, the optical transmission apparatus can clearly define the range of product guarantee while providing ease of maintenance and cost advantage, and can widen the range of choices of pluggable optical modules to be used. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]     Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings, in which:  
         [0024]      FIGS. 1A through 1C  are drawings showing the usage types of a related-art pluggable optical module;  
         [0025]      FIG. 2  is a drawing showing the configuration of an embodiment of a network system that is constructed by use of an optical transmission apparatus of the present invention;  
         [0026]      FIG. 3  is a drawing showing a certification rank table;  
         [0027]      FIG. 4  is a drawing showing the configuration of an embodiment of a pluggable optical module and optical transmission apparatus;  
         [0028]      FIG. 5  is a flowchart of a process performed by the optical transmission apparatus to which the pluggable optical module is mounted; and  
         [0029]      FIG. 6  is a drawing showing the configuration of an embodiment of a communication line test. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]     In the following, embodiments of the present invention will be described with reference to the accompanying drawings.  
         [0031]     Network Configuration  
         [0032]      FIG. 2  is a drawing showing the configuration of an embodiment of a network system that is constructed by use of an optical transmission apparatus of the present invention. In  FIG. 2 , optical transmission apparatuses  11 ,  12 ,  13 , and  14  constitute a network  15 . A network monitoring and controlling apparatus  16  monitors the operation states of the apparatuses and the performance of channels between the apparatuses so as to control the apparatuses according to the situations.  
         [0033]     By the same token, optical transmission apparatuses  21 ,  22 , and  23  constitute a network  25 , which is operated by a network monitoring and controlling apparatus  26 , Each of the optical transmission apparatuses and network monitoring and controlling apparatuses has a certification rank table that lists the certification ranks of pluggable optical modules such as SFP modules. Each of the network monitoring and controlling apparatuses  16  and  26  is connectable via the Internet to a certification-rank-table master server  28  provided at a optical transmission apparatus maker.  
         [0034]     Certification Rank Table  
         [0035]     As shown in  FIG. 3 , each certification rank table includes the name of usage (Transceiver code) as defined by the MSA standard, the name of a pluggable optical module vender (Vender ID), the name of a pluggable optical module type (Vender Parts Number) as defined by the pluggable optical module vender, the version number of the pluggable optical module (Vender Revision), and rank 1, 2, 3, or 4 as defined by the apparatus maker according to its own ranking standard. These items are associated with each other in the table. The ranking is provided according to the apparatus maker&#39;s own standard based on the data accumulated over the years regarding the results of certification tests and experienced failures. Each rank is intended to mean the following.  
         [0036]     Rank 1: A product having this rank is fully guaranteed by the apparatus maker in terms of its operation and characteristics (i.e., certified apparatus).  
         [0037]     Rank 2: A product having this rank is guaranteed by the apparatus maker in terms of its operation only (i.e., certified apparatus with some limitation to its ability).  
         [0038]     Rank 3: A product having this rank has not been subjected to a certification test by the apparatus maker, but can be put into operation according to the user&#39;s decision since the code read from the optical module suggests that its operation is proper.  
         [0039]     Rank 4: A product having this rank has failed the certification test conducted by the apparatus maker, or has been determined as not operable based on the memory code and thus cannot be used.  
         [0040]     The certification rank table may contain different data amount depending on the positions where the server and apparatuses are situated. This is because the higher the frequency of uses of an optical module in the network is, or the higher the risk of failure of an optical module is, the closer its data is to the optical transmission apparatus. This is intended to reduce the time required for a certification process, which will later be described, and also to take into account the limitation of the table capacity that can be stored in the apparatus.  
         [0041]     Moreover, there is a need to keep the certification rank table up to date everyday while hundreds of, thousands of optical module venders in the word are developing and updating new pluggable optical modules everyday. In order to keep the certification rank table of each optical transmission apparatus up to date, the network monitoring and controlling apparatuses  16  and  26  access the certification-rank-table master server  28  at constant intervals, and download the latest ranking data of the pluggable optical modules currently used in their respective local networks or of the pluggable optical modules likely to be used in the future, thereby keeping the certification rank tables in the network monitoring and controlling apparatuses  16  and  26  up to date. Further, if data of the most importance optical modules such as one that could create disastrous consequences is registered in the master server, the certification-rank-table master server  28  initiates a contact to prompt the network monitoring and controlling apparatuses  16  and  26  to update the table data.  
         [0042]     Further, the network monitoring and controlling apparatuses  16  and  26  transmits to each transmission apparatus only the certification rank data that is specialized to the pluggable optical modules currently used in their respective local networks and/or the pluggable optical modules highly likely to be used in the future. The updating of the rank table in each transmission apparatus is performed in this manner so as to achieve a high speed certification process and the reduction of table capacity.  
         [0043]     Configuration of Pluggable Optical Module and Optical Transmission Apparatus  
         [0044]      FIG. 4  is a drawing showing the configuration of an embodiment of a pluggable optical module and optical transmission apparatus. In  FIG. 4 , a pluggable optical module  30  such as an SFP module is mounted in an optical transmission apparatus  40 . The pluggable optical module  30  includes a receiver  31  for receiving optical signals, a transmitter  32  for transmitting optical signals, and a DDM unit  33  for storing therein optical module information such as manufacturing information about the optical module including the name of usage, the name of the pluggable optical module vender, the name of the pluggable optical module type, and the version number of the pluggable optical module.  
         [0045]     The optical transmission apparatus  40  includes a DDM interface  41 , a CPU  42  for controlling the entirety of the apparatus, a switch unit  43  for providing cross-connects, test selectors  44  and  45  situated between the pluggable optical module  30  and the switch unit  43 , an optical-input-break detecting unit  46  for detecting a break of an optical input at the receiver  31 , an optical-output-break controlling unit  47  for controlling a break of an optical output at the transmitter  32 , a test-mode selecting unit  48  for selecting a test mode, and a test pattern unit  49  for generating and detecting a test pattern.  
         [0046]     The CPU  42  includes a memory  51  for storing software, a certification rank table, and various standard values, a comparison unit  52 , a test controlling unit  53 , and a test-result collecting unit  54 .  
         [0047]     Operation of Optical Transmission Apparatus upon Implementation  
         [0048]      FIG. 5  is a flowchart of a process performed by the optical transmission apparatus to which the pluggable optical module is mounted.  
         [0049]     At step S 1 , the CPU  42  detects the insertion of the pluggable optical module  30 . At step S 2 , the CPU  42  reads the name of usage, the name of the pluggable optical module vender, the name of the pluggable optical module type, and the version number of the pluggable optical module from the DDM unit  33  of the pluggable optical module  30  via the DDM interface  41 .  
         [0050]     At step S 3 , a check is made as to whether the name of usage of the pluggable optical module  30  is the same as a usage name that conforms to the optical transmission apparatus  40 . If the usage name does not match, the pluggable optical module  30  is determined as unusable. At step S 4 , the CPU  42  reports rank  4  to a network monitoring and controlling apparatus  56  for display of this rank. At step S 8 , the CPU  42  takes measures to prevent optical output and to stop the operation of the pluggable optical module  30 .  
         [0051]     If the usage names match, the name of the pluggable optical module vender, the name of the pluggable optical module type, and the version number of the pluggable optical module of the pluggable optical module  30  are compared by the comparison unit  52  with the name of the pluggable optical module vender, the name of the pluggable optical module type, and the version number of the pluggable optical module listed in the certification rank table of the optical transmission apparatus  40  stored in the memory  51 . If the certification rank table contains a matched data item, the rank of this data item is displayed (steps S 5  through S 7 ).  
         [0052]     If no matched data item is found, the certification rank table of the network monitoring and controlling apparatus of  FIG. 2  is referred to. If no matched data item is found even in this certification rank table, an upper-order certification-rank master server is referred to. If no match is found even in this server, the module is determined as having a matching usage name but not certified. Rank 3 is reported to the network monitoring and controlling apparatus  56  for display of the rank.  
         [0053]     If match is detected in the checking of any certification rank tables, the rank obtained as a result of the check is reported to the network monitoring and controlling apparatus  56  for display of the rank. A check as to whether the module is usable or unusable is made as described above, thereby performing a first-stage selection process.  
         [0054]     If certification as rank 1 is obtained, this means that the apparatus maker guarantees the functions and characteristics. At step S 9 , thus, the apparatus is put into operation as usual. If determination as rank 4 is obtained, this means that the module cannot be used. At step S 8 , thus, a measure such as the measure to prevent signal outputting is performed.  
         [0055]     If certification as rank 3 is obtained, a check is made at step S 10  to determine whether a test process is to be performed. In this example, if a test of the pluggable optical module has been conducted, the test process is skipped. If such a test has not been conducted, a standalone test for determining whether the pluggable optical module properly operates is performed at step S 11 . At step S 12 , further, a network test is conducted. At step S 13 , the test results are reported to the network monitoring and controlling apparatus  56  for display of the test results. Thereafter, a check is made at step S 14  to determine whether to start operation. If the operation is possible, the apparatus is put into operation at step S 15 .  
         [0056]     If certification as rank 2 is obtained, a check is made at step S 17  to determine whether a test process is to be performed. In this example, if a test of the pluggable optical module has been conducted, the test process is skipped. If such a test has not been conducted, a network test for determining whether the pluggable optical module properly operates is performed at step S 18 . Since the standalone operation is already checked by the maker in the case of rank 2, no standalone test is performed. At step S 19 , the test results are reported to the network monitoring and controlling apparatus  56  for display of the test results. Thereafter, a check is made at step S 20  to determine whether to start operation. If the operation is possible, the apparatus is put into operation at step S 21 .  
         [0057]     Standalone Test  
         [0058]     A standalone test will now be described by referring to  FIG. 4 . A standalone test is performed by providing a loopback between the receiver  31  and transmitter  32  of the pluggable optical module  30  via an optical fiber  60 , and includes a signal communication test, an optical-output-break test, and an optical-input-break detection test.  
         [0059]     In response to the instruction to perform a standalone test from the network monitoring and controlling apparatus  56 , the CPU  42  enters a signal communication test mode. In the signal communication test mode, under the control of the test controlling unit  53 , the test selectors  44  and  45  are switched from the operating communication line to the test pattern line, and the test pattern unit  49  supplies a test pattern to the transmitter  32  of the pluggable optical module  30 . The test pattern returning through the optical fiber  60  is supplied to the test pattern unit  49  via the receiver  31  of the pluggable optical module  30  and the test selector  44 .  
         [0060]     The results of test pattern detection are reported from the test pattern unit  49  to the CPU  42 . In response, the system software of the CPU  42  reports “signal communication test NG” to the network monitoring and controlling apparatus  56  if an error is found in the test pattern. If no error is detected in the test pattern, the mode for optical-output-break functionality test and optical-input-break functionality test is entered.  
         [0061]     In the mode for optical-output-break functionality test and optical-input-break functionality test, the optical-output-break controlling unit  47  performs optical-output-break control with respect to the transmitter  32  of the pluggable optical module  30 , and the receiver  31  of the pluggable optical module  30  performs optical-input-break detection with respect to the output of the transmitter  32  via the loopback of the optical fiber  60 . The results of the optical-input-break detection are reported to the CPU  42 . The system software of the CPU  42  reports “optical-output-break-functionality/optical-input-break-detection-functionality NG” to the network monitoring and controlling apparatus  56  if the optical input break is not properly detected. The system software of the CPU  42  reports the “standalone test OK” to the network monitoring and controlling apparatus  56  if the optical input break is properly detected.  
         [0062]     The standalone test conducted in the manner as described above makes it possible for the user (communication carrier) using the apparatus to check whether the pluggable optical module  30  (rank 3) having undergone no certification test by the apparatus maker properly operates in the optical transmission apparatus. This helps to significantly reduce the number of process steps required for test preparation and test operation.  
         [0063]     Communication Line Test  
         [0064]      FIG. 6  is a drawing showing the configuration of an embodiment of a communication line test. For a communication line test, the optical transmission apparatus  40  is connected to a pluggable optical module  70  of a counterpart apparatus  80  via operating lines  65  that are actually used in practice, and performs a signal communication test and an optical-input-level check test.  
         [0065]     The instruction to perform a communication line test is supplied from the network monitoring and controlling apparatus  56  to the optical transmission apparatus  40  and the optical transmission apparatus  80  that are connected to each other. In response to the instruction, the CPUs  42  of the optical transmission apparatuses  40  and  80  enter the signal communication test mode, so that the test selectors  44  and  45  of the optical transmission apparatuses  40  and  80  are switched from the operating communication line to the test pattern line, and the test pattern units  49  of the optical transmission apparatuses  40  and  80  supply a test pattern to the transmitters  32  of the pluggable optical modules  30  and  70 , respectively. The test patterns are supplied through the operating lines  65  to the test pattern units  49  via the receivers  31  of the pluggable optical modules  70  and  30  of the optical transmission apparatuses  80  and  40 , respectively.  
         [0066]     The results of test pattern detection are reported to the CPUs  42  of the optical transmission apparatuses  80  and  40 . In response, the system software of the CPU  42  of the optical transmission apparatus  40  or  80  reports the “signal communication test NG” to the network monitoring and controlling apparatus  56  if an error is found in the test pattern. If no error is detected in the test pattern, then, an input-level-check test mode is entered.  
         [0067]     In the optical-input-level check test mode, the CPU  42  of each of the optical transmission apparatuses  40  and  80  reads the power of an optical input received by the receiver  31  via the DDM interface  41  from the DDM unit  33  of each of the pluggable optical modules  30  and  70 , respectively. The optical reception power that is read in this manner is compared by the comparison unit  52  of the CPU  42  with the optical input standard level of the pluggable optical module  30  or  70  stored in the memory  51 . If the optical input power is not within the optical input standard level, the system software of the CPU  42  reports an “optical-input-level check test NG” and the detected optical input power to the network monitoring and controlling apparatus  56 . If the optical input power is within the optical input standard level, the system software of the CPU  42  reports to the network monitoring and controlling apparatus  56  a “communication test OK” and an indication of how much dB margin exists between the detected optical input power and the optical input standard level.  
         [0068]     The communication test conducted in the manner as described above makes it possible for the communication carrier using the optical transmission apparatus to readily determine whether the pluggable optical module that does not satisfy the required specifications can be used in the operating line and also to readily determine the margin of the communication line. The number of process steps required for test preparation and test operation can thus be reduced, and installing a new pluggable optical module becomes easier.  
         [0069]     Further, even if the pluggable optical module is not guaranteed by the apparatus maker, such pluggable optical module can be used in individual communication lines despite of some limitation. This widens the choices of pluggable optical modules so as to make it possible to use a less expensive optical module, thereby providing a cost advantage.  
         [0070]     In this manner, the replacement of a pluggable optical module becomes easier, thereby allowing such replacement to be made locally and allowing an optical module different from the original one to be used as a replacement. This improves the ease of maintenance. Moreover, a communication line test is performed by use of operating communication lines, thereby making it possible to check the usability on a communication-line-specific basis independently of the guarantee provided by the apparatus maker. This widens the range of choices of pluggable optical modules, and thus allows the use of less expensive pluggable optical modules.  
         [0071]     Further, a standalone test and real communication line test are performed to make it easier to perform a certification test with respect to a pluggable optical module. This helps to reduce the cost of introducing a new optical module and the period required for such introduction. Since the mechanism is provided to keep the certification rank table up to date at all times, the introduction of a state-of-the-art pluggable optical module becomes easier. Since the certification of pluggable optical modules is introduced, plugging-in and plugging-out can be freely made while preventing the use of a poor-quality product.  
         [0072]     Further, the present invention is not limited to these embodiments, but various variations and modifications may be made without departing from the scope of the present invention.  
         [0073]     The present application is based on Japanese priority application No. 2005-282095 filed on Sep. 28, 2005, with the Japanese Patent Office, the entire contents of which are hereby incorporated by reference.