Patent Publication Number: US-2011064417-A1

Title: Communication system

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2009-210193, filed on Sep. 11, 2009, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiment discussed herein is related to a communication system that performs information communication. 
     BACKGROUND 
     An optical transceiver has a photoelectric conversion function and is an optical module that realizes high-speed optical data communication, thus drawing attention as a key component of an optical communication system. In the optical transceiver, specifications of outlines and electrical interfaces are set based on the International Standard Specifications called an MSA (Multi Source Agreement). In particular, a standard of an XFP (10 Gbps Small Form-factor Pluggable) compliant with the MSA becomes mainstream in an optical communication of 10 Gbps. 
     The optical transceiver has a pluggable configuration in which removal and exchange operations are facilitated, and is capable of replacing optical transceivers of the user side with respect to an apparatus of the host side. This process permits a function enhancement and a specification change to be easily performed. 
     As a conventional technique, a technique in which unauthorized optical data links are excluded is provided (see, for example, Japanese Laid-open Patent Publication No. 2006-325030). A technique in which a two-way dialogue is performed between apparatuses and an authentication is performed is provided (see, for example, Published Japanese Translation of a PCT application No. 2005-534089). 
     As can be seen from the above discussion, the optical transceiver has a significant advantage that an exchange can be easily performed. However, when an exchange can be performed on the user side, a user can use modules (for example, inexpensive modules except an optical transceiver authorized on the vendor side of a host apparatus) except an optical transceiver to be originally inserted into a host apparatus, and incorrectly perform communication. Therefore, there is the possibility that characteristics and quality of communication fail to be maintained, and the reliability threatens to be reduced. 
     On the other hand, optical transceivers represented by an XFP type exchange information with the host apparatus using general-purpose I 2 C communication (Inter-Integrated Circuit: a serial communication system with a peripheral device by a protocol for realizing high-speed communication mainly with a memory IC). 
     The optical transceiver is conventionally authenticated using the I 2 C communication between the host apparatus and the optical transceiver such that a normal communication is not performed between the host apparatus and the above-described unauthorized optical transceiver. 
     However, the I 2 C communication protocol is disclosed, and therefore, there is the possibility that an I 2 C signal is illegally monitored and authentication data is detected and reproduced. As a result, the conventional authentication method does not definitely prevent the use of the unauthorized optical transceiver. 
     SUMMARY 
     According to one aspect of the present invention, there is provided a communication system to perform information communication. This communication system includes: a communication module including an operation controller that controls an operation of itself based on a control signal having no general-purpose communication protocol; and a communication apparatus including a signal processor that generates the control signal and transmits the generated control signal to the communication module inserted into itself, wherein: the signal processor: transmits, when causing the communication module to perform a predetermined operation, the control signal at a predetermined level, and changes, when authenticating the communication module, a level of the control signal into an authentication pattern and transmits the control signal; and the operation controller: performs, when a level of the received control signal is the predetermined level, the predetermined operation, and performs, when a level of the received control signal is the authentication pattern, authentication control by matching or comparing the authentication pattern with a previously recognized pattern. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWING(S) 
         FIG. 1  illustrates a configuration example of a communication system; 
         FIG. 2  illustrates a configuration example of an optical transceiver; 
         FIG. 3  illustrates a configuration at the time when a plurality of optical transceivers are inserted into a communication apparatus; 
         FIG. 4  illustrates an authentication pattern at the time of authenticating the optical transceiver; 
         FIG. 5  illustrates the authentication pattern at the time of authenticating the optical transceiver; 
         FIG. 6  illustrates a monitor pattern at the time of performing monitor control of the optical transceiver; and 
         FIG. 7  illustrates one example of the monitor pattern. 
     
    
    
     DESCRIPTION OF EMBODIMENT(S) 
     Preferred embodiments of the present invention will now be described in detail below with reference to the accompanying drawings, wherein like reference numerals refer to like elements throughout.  FIG. 1  illustrates a configuration example of a communication system. The illustrated communication system  1  includes a communication apparatus  10  and a communication module  20 , and is a system that inserts the communication module  20  into the communication apparatus  10  and performs information communication between the communication apparatus  10  and the communication module  20 . 
     The communication apparatus  10  includes a communication unit  11   a  and a signal processor  11   b . The communication unit  11   a  communicates with the communication module  20  using a general-purpose communication protocol (for example, I 2 C communication protocol). The signal processor  11   b  generates a control signal and transmits the generated control signal to the communication module  20  inserted into itself. 
     The communication module  20  includes a communication unit  21   a  and an operation controller  21   b . The communication unit  21   a  communicates with the communication apparatus  10  using the general-purpose communication protocol. The operation controller  21   b  controls an operation of itself based on a control signal having no general-purpose communication protocol. 
     The control signal having no general-purpose communication protocol means, for example, a control signal that does not depend, when the general-purpose communication protocol is an I 2 C communication protocol, on a communication format using the I 2 C communication protocol. 
     Here, when causing the communication module  20  to perform a predetermined operation, the signal processor  11   b  sets a level of a control signal to a predetermined constant level and transmits the control signal to the communication module  20  (to transmit a signal having an H level or an L level for a given length of time). When authenticating the communication module  20 , the signal processor  11   b  changes a level of the control signal into a previously set authentication pattern and transmits the control signal. Further, when monitoring various functions of the communication module  20 , the signal processor  11   b  changes a level of the control signal into a previously set monitor pattern and transmits the control signal. 
     On the other hand, the operation controller  21   b  receives the control signal transmitted from the signal processor  11   b  and, when a level of the received control signal is a predetermined level, performs a predetermined operation corresponding to the level. 
     When a level of the received control signal is a level change pattern of the authentication pattern, the operation controller  21   b  performs an authentication control by matching or comparing the level change pattern with a previously recognized pattern. Further, when a level of the received control signal is a level change pattern of the monitor pattern, the operation controller  21   b  performs a monitor control in order to perform a function monitor of itself corresponding to each pattern of the monitor pattern and inform the communication apparatus  10  of the monitor results. 
     Next, as an example of the communication system  1 , suppose that the communication module  20  is an XFP type pluggable optical transceiver module. A configuration and operations at the time when the optical transceiver is inserted into the communication apparatus  10  and then the communication is performed will be described in detail. 
       FIG. 2  illustrates a configuration example of an optical transceiver. The illustrated optical transceiver  20   a  includes a CPU (Central Processing Unit)  21 , a CDR (Clock Data Recovery) unit  22 , an E/O unit  23   a , and an O/E unit  23   b . The CPU  21  includes a communication unit  21   a  and an operation controller  21   b . The CPU  21  performs operation control of the entire module except the communication unit  21   a  and the operation controller  21   b.    
     The communication unit  21   a  communicates with the communication apparatus  10  using the I 2 C communication protocol. The operation controller  21   b  performs the operation control of itself based on a Pdown Rest (Power down Reset) signal, a TX DIS (TX Disable) signal, and a Mod ABS (Module Absence) signal as a control signal having no I 2 C communication protocol. 
     Here, the Pdown Rest signal sets and releases the optical transceiver  20   a  to and from the standby state as a predetermined operation of the optical transceiver  20   a . The Pdown Rest signal is transmitted from the signal processor  11   b  of the communication apparatus  10  to the optical transceiver  20   a , and reaches a Pdown Rest pin of the optical transceiver  20   a.    
     For example, when the Pdown Rest signal having the H level of 10 μs or more reaches the Pdown Rest pin of the optical transceiver  20   a , the operation controller  21   b  reduces power consumption of the optical transceiver  20   a  up to a constant level using the Pdown Rest signal, thus setting the optical transceiver  20   a  to a standby state (power down mode) for stopping an operation of the I 2 C communication or optical communication. 
     On the other hand, when Pdown Rest signal reaches the Pdown Reset pin at the L level, the operation controller  21   b  releases the optical transceiver  20   a  from a standby state using the Pdown Rest signal, thus performing a normal operation of the optical transceiver  20   a  (the operation controller  21   b  releases the optical transceiver  20   a  from the standby state and moves the optical transceiver  20   a  to a normal operation mode by a falling edge from the H level to the L level of the Pdown Rest signal). 
     A TX DIS signal causes the optical transceiver  20   a  to perform output and stop of signal light (corresponding to communication data) as a predetermined operation of the optical transceiver  20   a . The TX DIS signal is transmitted from the signal processor  11   b  of the communication apparatus  10  to the operation controller  21   b  of the optical transceiver  20   a , and reaches a TX DIS pin of the optical transceiver  20   a.    
     For example, when the TX DIS signal reaches the TX DIS pin at the H level, the operation controller  21   b  drives an E/O  23   a  and causes the E/O  23   a  to generate signal light and output the generated signal light to the outside (via an optical fiber) using the TX DIS signal. On the other hand, when the TX DIS signal reaches the TX DIS pin at the L level, the operation controller  21   b  stops the driving of the E/O  23   a  and causes the E/O  23   a  to stop the output of the signal light. 
     A Mod ABS signal indicates whether the optical transceiver  20   a  is inserted into the communication apparatus  10 . When the optical transceiver  20   a  is inserted into the communication apparatus  10 , the output signal of the Mod ABS pin of the optical transceiver  20   a  becomes the L level (the operation controller  21   b  outputs the Mod ABS signal having the L level). 
     When the optical transceiver  20   a  is detached from the communication apparatus  10 , the output signal of the Mod ABS pin of the optical transceiver  20   a  becomes the H level (the operation controller  21   b  outputs the Mod ABS signal having the H level). The communication apparatus  10  can recognize an insertion state of the optical transceiver  20   a  from a level of the output signal of the Mod ABS pin. 
     On the other hand, the CDR unit  22  receives a data signal and extracts a clock signal, thus realizing a retiming of the data signal. The E/O unit  23   a  converts the data signal to signal light and outputs the converted signal light to the outside. The O/E unit  23   b  receives signal light transmitted from the outside and converts the received signal light to an electric signal. The operation controller  21   b  controls the driving of the E/O unit  23   a  and the O/E unit  23   b.    
       FIG. 3  illustrates a configuration at the time when a plurality of optical transceivers are inserted into the communication apparatus  10 . The optical transceivers  20   a - 1  to  20   a - n  in the number of n are inserted into the communication apparatus  10 . The CPU  11  of the communication apparatus  10  includes the communication unit  11   a  and signal processor  11   b  illustrated in  FIG. 1 . Further, the optical transceivers  20   a - 1  to  20   a - n  includes CPUs  21 - 1  to  21 - n , respectively. 
     The I 2 C communication is performed between the communication unit  11   a  of the CPU  11  and the communication units  21   a  of the CPUs  21 - 1  to  21 - n . Further, the control signals (the Pdown Rest signals, the TX DIS signals, and the Mod ABS signals) are exchanged between the signal processor  11   b  of the CPU  11  and the operation controllers  21   b  of the CPUs  21 - 1  to  21 - n.    
     Operations at the time of authenticating the optical transceiver  20   a  will be described below.  FIG. 4  illustrates an authentication pattern at the time of authenticating the optical transceiver  20   a . When authenticating whether the optical transceiver  20   a  inserted into the communication apparatus  10  is a normal optical transceiver, the signal processor  11   b  changes a level of the Pdown Rest signal into the authentication pattern and transmits the changed Pdown Rest signal to the optical transceiver  20   a.    
     Referring now to  FIG. 4 , suppose, for example, that a pattern “10010101” is the authentication pattern. The signal processor  11   b  changes a level of the Pdown Rest signal into this authentication pattern and transmits the changed Pdown Rest signal to the optical transceiver  20   a.    
     The operation controller  21   b  of the optical transceiver  20   a  compares a level change pattern of the received Pdown Rest signal and the previously recognized authentication pattern (“10010101”). If a level change pattern of the Pdown Rest signal is a pattern “10010101” and matched with the previously recognized authentication pattern, the operation controller  21   b  starts an activation operation of the optical transceiver  20   a  (the operation controller  21   b  may inform the communication apparatus  10  that the level change pattern of the Pdown Rest signal is matched with the previously recognized authentication pattern). If the level change pattern of the Pdown Rest signal fails to be matched with the previously recognized authentication pattern, the operation controller  21   b  does not start an activation operation of the optical transceiver  20   a  (the operation controller  21   b  may inform the communication apparatus  10  that the level change pattern of the Pdown Rest signal fails to be matched with the previously recognized authentication pattern). 
     When providing the authentication pattern for the Pdown Rest signal, the signal processor  11   b  generates the authentication pattern of the H level having a period shorter than or equal to 10 μs. The reason is that when a period of the H level is longer than 10 μs, the Pdown Rest signal performs an original operation (setting of the standby state). 
     Accordingly, when setting the optical transceiver  20   a  to the standby state, the signal processor  11   b  sets the Pdown Rest signal to have the H level with a period of 10 μs or longer, whereas when releasing the optical transceiver  20   a  from the standby state, the signal processor  11   b  sets the Pdown Rest signal to have the L level for a given length of time. 
     When authenticating the optical transceiver  20   a , the signal processor  11   b  changes a level of the Pdown Rest signal into the authentication pattern and transmits the changed Pdown Rest signal to the optical transceiver  20   a  (sets the Pdown Rest signal to have the H level with a period shorter than or equal to 10 μs). As can be seen from the above discussion, the proposed communication system  1  uses one Pdown Rest signal for both the setting and release of the standby state of the optical transceiver  20   a  and the authentication of the optical transceiver  20   a.    
     This process permits the optical transceiver  20   a  to be authenticated using the Pdown Rest signal being one control signal not dependent on the I 2 C communication and therefore, illegal use of the unauthorized optical transceiver can be definitely prevented. Since using the existing Pdown Rest signal eliminates the need to add circuits, the communication system  1  can efficiently perform the authentication control. 
     Operations at the time of authenticating the optical transceiver  20   a  using two control signals of the Pdown Rest signal and the TX DIS signal will be described below.  FIG. 5  illustrates the authentication pattern at the time of authenticating the optical transceiver  20   a . The signal processor  11   b  performs the authentication in combination of the Pdown Rest signal and the TX DIS signal when authenticating whether the optical transceiver  20   a  inserted into the communication apparatus  10  is an unauthorized optical transceiver. 
     The signal processor  11   b  outputs the Pdown Rest signal having the H level with a period of 10 μm or longer and sets the optical transceiver  20   a  to the standby state. Further, the signal processor  11   b  provides the TX DIS signal with a level of the authentication pattern and transmits the TX DIS signal at the time of a time band of the H level of the Pdown Rest signal. 
     Here, when the signal processor  11   b  transmits only the TX DIS signal with the authentication pattern, the optical transceiver  20   a  outputs or stops signal light in accordance with a level change of the TX DIS signal (activates an original optical communication operation). 
     As compared with the above-described process, after setting the optical transceiver  20   a  to the standby state using the Pdown Rest signal, the signal processor  11   b  transmits the TX DIS signal with the authentication pattern. This process permits the optical transceiver  20   a  to be authenticated in the state where the optical transceiver  20   a  stops the signal light (in  FIG. 5 , the authentication pattern is set to a pattern “01010101”). 
     As can be seen from the above discussion, the communication system  1  uses one TX DIS signal for both the output and stop of the signal light from the optical transceiver  20   a  and the authentication of the optical transceiver  20   a  (note that when authenticating the optical transceiver  20   a , the signal transceiver  11   b  sets the optical transceiver  20   a  to the standby state using the Pdown Rest signal and then provides the TX DIS signal with the authentication pattern). 
     This process permits the optical transceiver  20   a  to be authenticated using the TX DIS signal being one control signal not dependent on the I 2 C communication. As a result, illegal use of the unauthorized optical transceiver can be definitely prevented. Further, since using the existing TX DIS signal eliminates the need to add circuits, the communication system  1  can efficiently perform the authentication control. 
     Operations at the time of performing a monitor control of the optical transceiver  20   a  using three control signals of the Pdown Rest signal, the TX DIS signal, and the Mod ABS signal will be described below.  FIG. 6  illustrates a monitor pattern at the time of performing the monitor control of the optical transceiver  20   a . When monitoring a function of the optical transceiver  20   a  inserted into the communication apparatus  10 , the signal processor  11   b  specifies a function to be monitored for the optical transceiver  20   a  in combination of the Pdown Rest signal and the TX DIS signal. 
     The signal processor  11   b  outputs the Pdown Rest signal having the H level with a period of 10 μs or longer and sets the optical transceiver  20   a  to the standby state. Further, the signal processor  11   b  provides the TX DIS signal with a level of the monitor pattern (a pattern different from the authentication pattern) and transmits the TX DIS signal at the time of a time band of the H level of the Pdown Rest signal. 
     Here, when the signal processor  11   b  transmits only the TX DIS signal with the monitor pattern, the optical transceiver  20   a  outputs or stops the signal light in accordance with a level change of the TX DIS signal (activates an original optical communication operation). 
     As compared with the above-described process, the signal processor  11   b  sets the optical transceiver  20   a  to the standby state using the Pdown Rest signal and then transmits the TX DIS signal with the monitor pattern. This process permits the signal processor  11   b  to specify a function to be monitored within the optical transceiver  20   a  in accordance with the monitor pattern in the state where the optical transceiver  20   a  stops the signal light. 
     On the other hand, the optical transceiver  20   a  is set to the standby state by the Pdown Rest signal. When receiving the TX DIS signal with the monitor pattern at the time of the standby state, the optical transceiver  20   a  monitors a function to be specified by the monitor pattern. Further, the optical transceiver  20   a  informs the communication apparatus  10  of monitor results using, for example, the Mod ABS signal in a time band of the standby state. 
     Here, examples of the monitor content of the functions of the optical transceiver  20   a  include TX bias data, laser wavelength data, LD (laser diode) driver bias data, and LD driver amplification data. 
     The TX bias data is data on a control bias applied to the E/O unit  23   a . The laser wavelength data is data on an output wavelength of the LD. The LD driver bias data is bias data on a driving signal of the LD driver. The LD driver amplification data is amplification data on a driving signal of the LD driver in the E/O unit  23   a.    
     MSA has a provision regarding a monitor of the TX bias data, and specifically, the MSA restricts the number of bits (the number of bits of the read current) at the time of informing the communication apparatus  10  of monitor results. However, when using the above-described Mod ABS signal, the optical transceiver  20   a  can eliminate the need for the restriction of the number of bits and inform the communication apparatus  10  of more detailed information (the MSA has the restriction that the optical transceiver  20   a  informs the communication apparatus  10  of information using a signal of two bytes, and on the other hand, when using the Mod ABS signal, the optical transceiver  20   a  can inform the communication apparatus  10  of the information using a signal of two bytes or more). 
     Also, the MSA has provisions regarding a monitor of the laser wavelength data, and specifically, the MSA has the restriction that the accuracy at the time of informing the communication apparatus  10  of monitor results is 10 pm units. However, when using the above-described Mod ABS signal, the optical transceiver  20   a  can inform the communication apparatus  10  of more detail information (for example, 1 pm unit). 
     The MSA has no provisions regarding a monitor of the LD driver bias data and the LD driver amplification data. When knowing transmission characteristics, it is effective to know these monitor information units. As can be seen from the above discussion, the optical transceiver  20   a  can monitor also a function monitor a provision of which is absent in the MSA. 
       FIG. 7  illustrates one example of a monitor pattern. A pattern P 1  is a monitor pattern example at the time of monitoring the TX bias data. A pattern P 2  is a monitor pattern example at the time of monitoring the laser wavelength data. 
     A pattern P 3  is a monitor pattern example at the time of monitoring the LD driver bias data. A pattern P 4  is a monitor pattern example at the time of monitoring the LD driver amplification data. As described above, since freely associating a function to be monitored and a monitor pattern with each other, the optical transceiver  20   a  can flexibly expand a monitoring function. 
     As described above, the proposed communication system  1  permits the communication apparatus  10  to change a level of the control signal to a predetermined level and transmit the control signal when causing the communication module  20  to perform a predetermined operation, change a level of the control signal to the authentication pattern and transmit the control signal when authenticating the communication module  20 , and change a level of the control signal to the monitor pattern and transmit the control signal when monitoring the communication module  20 . 
     Further, the communication module  20  is configured to perform a predetermined operation when a level of the received control signal is a predetermined level, perform authentication control by matching or comparing the authentication pattern with a previously recognized pattern when a level of the received control signal is the authentication pattern, and perform monitor control in order to perform a function monitor corresponding to each pattern of the monitor patterns and inform the communication apparatus  10  of the monitor result when a level of the received control signal is the monitor pattern. 
     This communication system  1  makes it possible to use existing control signals and perform a two-way communication that is not restricted in the provisions of the general-purpose communication protocol between the communication apparatus  10  and the communication module  20  by a communication format different from the general-purpose communication protocol. Therefore, the communication system  1  permits authentication accuracy of the communication module  20  to be improved. Further, the communication system  1  permits the communication module  20  to perform monitoring with accuracy and improve monitoring accuracy. 
     The proposed communication system  1  permits the communication quality and the reliability to be improved. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiment(s) of the present inventions has (have) been described in detail, it should be understood that various changes, substitutions and alterations could be made hereto without departing from the spirit and scope of the invention.