Abstract:
There is provided a line card configured to mount a module in which a signal transmitted on a line is processed, the line card including a memory, and a processor coupled to the memory and the processor configured to receive information on transmission quality of the signal to be transmitted through the module to be mounted on the line card, extract a combination satisfying the transmission quality among combinations of error correction processing schemes applicable to the module and a framer circuit for performing a signal processing for the signal to be transmitted, and estimate a combination of a range in which temperatures of each of the module and the framer circuit do not exceed a predetermined temperature when the module and the framer circuit are operated by applying the error correcting processing schemes of the combination extracted.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2016-084291, filed on Apr. 20, 2016, the entire contents of which are incorporated herein by reference. 
       FIELD 
       [0002]    The embodiments discussed herein are related to a line card within an optical transmission device. 
       BACKGROUND 
       [0003]    In recent years, with the increase of Internet traffic, there have been demands for large capacity, miniaturization, and cost reduction in an optical communication system, and various types of optical pluggable (detachable) modules (hereinafter, simply referred to as “modules”) are mounted on each line card within an optical transmission device. The various types of modules are, for example, a 10G small form-factor pluggable (XFP) module and a 100G form-factor pluggable (CFP) module. Each module mounted on the line card processes a signal transmitted through the module connected with a transmission line. 
         [0004]    As to the structure of a cage on which a module is mounted and the shape of the module, for example, INF-8077i is defined as a standard specification in the case of XFP, and CFP-MSA is defined as a standard specification in the case of CFP. Therefore, a module in compliance with a standard function may be detachably mounted on a mounting port in the cage. 
         [0005]    However, each module includes various types of modules depending on support states such as a transmission distance and internal functions. For example, in the case of XFP, the power consumption amount thereof is in the range of, for example, 1 Watt (W) to 6 W, depending on the specifications. In the case of CFP, the power consumption amount thereof is in the range of, for example, 8 W to 32 W, depending on specifications. Further, there is a tendency that the power consumption increases as the functionality of a module becomes high. 
         [0006]    As a technique for supporting a longer transmission distance, a process of correcting a bit error for a signal received in a reception terminal of a transmission line is performed by applying an error correction code. A circuit module, such as a large scale integration (LSI) performing such error correcting process performs a more complicated operation as the error correction capability improves. For this reason, the power consumption of the circuit module that performs the error correcting process tends to increase as the gate size increases. 
         [0007]    There is known a technique for enlarging the range of device guarantee while providing maintenance and cost superiority to the optical transmission device and widening the choice options of optical pluggable modules that can be used (see, for example, Patent Document 1). 
         [0008]    There is known a monitoring control device capable of estimating, in advance, an environment temperature after triggering of a mounted module, before the triggering of the mounted module (see, for example, Patent Document 2). 
         [0009]    Related technologies are disclosed in, for example, Japanese Laid-Open Patent Publication No. 2007-096640 that is the Patent Document 1 and No. 2014-235721 that is the Patent Document 2. 
       SUMMARY 
       [0010]    According to an aspect of the invention, a line card is configured to mount a module in which a signal transmitted on a line is processed, the line card includes a memory, and a processor coupled to the memory and the processor configured to receive information on transmission quality of the signal to be transmitted through the module to be mounted on the line card, extract a combination satisfying the transmission quality among combinations of error correction processing schemes applicable to the module and a framer circuit for performing a signal processing for the signal to be transmitted, and estimate a combination of a range in which temperatures of each of the module and the framer circuit do not exceed a predetermined temperature when the module and the framer circuit are operated by applying the error correcting processing schemes of the combination extracted. 
         [0011]    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. 
         [0012]    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 DRAWINGS 
         [0013]      FIG. 1  is a diagram for describing an example of an optical transmission device; 
           [0014]      FIG. 2  is an explanatory view schematically illustrating an example of a line card; 
           [0015]      FIG. 3  is a view for describing an example of a thermal coefficient table; 
           [0016]      FIG. 4  is a view for describing an example of a power consumption amount table; 
           [0017]      FIG. 5  is a view for describing an example of a specified temperature table; 
           [0018]      FIG. 6A  is a flowchart for describing a process by a card controller according to the present disclosure; 
           [0019]      FIG. 6B  is a flowchart for describing a process by a card controller according to the present disclosure; 
           [0020]      FIG. 6C  is a flowchart for describing a process by a card controller according to the present disclosure; 
           [0021]      FIG. 6D  is a flowchart for describing a process by a card controller according to the present disclosure; 
           [0022]      FIG. 6E  is a flowchart for describing a process by a card controller according to the present disclosure; 
           [0023]      FIG. 7A  is a flowchart for describing an exemplary process by an estimation unit; 
           [0024]      FIG. 7B  is a flowchart for describing an exemplary process by an estimation unit; and 
           [0025]      FIG. 8  is a flowchart for describing an example of an extracting method in an FEC scheme satisfying a transmission quality. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0026]    The optical pluggable modules mounted on a line card within an optical transmission device have different power consumption amounts depending on the support states such as an optical transmission distance and internal functions. Further, although the scheme of correcting an error (forward error correction (FEC) scheme) in an LSI or a module may be selected according to a transmission distance, the power consumption amount increases when the FEC scheme with a high error correction capability is selected. 
         [0027]    Therefore, in a case where a module with the high power consumption and an FEC scheme with the high correction capability are combined with each other to be used for the line card, the environment temperature inside the transmission device may exceed a specified temperature when a plurality of modules is mounted on a line card and triggered. 
         [0028]    Hereinafter, with reference to the drawings, descriptions will be made on an embodiment of a technology for enabling a mounting arrangement suitable for practical operation by performing a temperature monitoring on the line card and selecting FEC schemes in a line card on which various types of pluggable modules are mounted. 
         [0029]      FIG. 1  is a diagram for describing an example of an optical transmission device.  FIG. 2  is an explanatory view schematically illustrating an example of a line card. An optical transmission device  100  illustrated in  FIG. 1  includes a line card  1000 , a device management card  2000 , and a management terminal  3000 . 
         [0030]    The line card  1000  enables mounting of, for example, M XFP modules, and includes a mounting portion  1100 , a temperature sensor  1200 , a framer LSI  1300 , a temperature sensor  1400 , a connection connector  1700 , a power supply connector  1800 , a memory  1500 , and a card controller  1600 . A module  5  is mounted on the mounting portion  1100 , and the mounting portion  1100  includes a cage  1100 A having a mounting port  1100 B which detachably mounts the module  5 , and a heat sink  1100 C arranged on the upper surface of the cage  1100 A (see, for example,  FIG. 2 ; however,  FIG. 2  does not illustrate the module  5 ). The heat sink  1100 C is a heat radiation component having heat radiation pins that radiate heat of the module  5  mounted on the mounting port  1100 B. 
         [0031]    The M framers LSI  1300  are mounted on the line card  1000 . Each framer LSI  1300  has a function of efficiently grouping various client signals and converting the signals into a signal frame format of an optical transmission network having an error correcting function. As illustrated in  FIG. 2 , the framer LSI  1300  includes a heat sink  1300 A on the upper surface thereof. The heat sink  1300 A is a heat radiation component having heat radiation pins that radiate heat of the framer LSI  1300 . 
         [0032]    The module  5  has a soft decision (SD) FEC function and enables a soft decision error correcting process. Meanwhile, the framer LSI  1300  has a hard decision (HD) FEC function and enables a hard decision error correcting process. 
         [0033]    The temperature sensor  1200  is arranged near each corresponding cage  1100 A to measure an environment temperature of a windward side and detect the environment temperature as a surrounding environment temperature T a @Temp_Sensor_MDL of the cage  1100 A. Hereinafter, the surrounding environment temperature T a @Temp_Sensor_MDL of the cage  1100 A, which is measured by the temperature sensor  1200  will be referred to as “T a @Temp_Sensor_MDL.” The temperature sensor  1400  is arranged near each corresponding framer LSI  1300  to measure an environment temperature of a windward side and detect the environment temperature as a surrounding environment temperature T a @Temp_Sensor_LSI of the framer LSI  1300 . Hereinafter, the surrounding environment temperature T a @Temp_Sensor_LSI of the cage  1100 A, which is measured by the framer LSI  1300  will be referred to as “T a @Temp_Sensor_LSI.” 
         [0034]    The connection connector  1700  is a connector to be connected to the device management card  2000 . The power supply connector  1800  is a connector to be connected to a power supply (not illustrated). The card controller  1600  entirely controls the line card  1000 . The card controller  1600  collects the surrounding environment temperature T a @Temp_Sensor_MDL from the temperature sensor  1200  for each cage  1100 A and the surrounding environment temperature T a @Temp_Sensor_LSI from the temperature sensor  1400  for each framer LSI  1300 . Also, the card controller  1600  notifies the management terminal  3000  of information on for example, usable mounting ports or FEC schemes. 
         [0035]    The card controller  1600  is configured to include a processor that reads out various programs from the memory  1500  and executes various processes as functions based on the programs. The card controller  1600  includes, as functions, a reception unit  1610 , a collection unit  1620 , an estimation unit  1630 , a controller  1640 , an extraction unit  1650 , and a notification unit  1660 . The reception unit  1610  receives information on a transmission quality required for a port to be added, from the management terminal  3000 . The collection unit  1620  collects temperature information from the module  5 , the temperature sensor  1200 , the framer LSI  1300 , and the temperature sensor  1400 . The extraction unit  1650  extracts, from combinations of SD-FEC scheme types operated by a module to be connected to the port to be added and HD-FEC scheme types operated by a framer LSI, a combination exceeding (satisfying) the transmission quality. When it is assumed that the module and the framer LSI are operated in the extracted combination, the estimation unit  1630  estimates whether the module and the framer LSI exceed the specified temperature. The controller  1640  controls the FEC schemes operated by the module and the famer LSI. 
         [0036]    As described above, the card controller  1600  according to the present disclosure may estimate the combinations of the FEC schemes operated by the framer LSI and the pluggable module in the range in which an environment temperature within the device does not exceed the specified temperature. 
         [0037]    Next, a process by the line card according to the present disclosure will be described. An environment temperature directly above the heat sink  1100 C mounted on each module will be referred to as “T a @Pluggable_Module.” The module  5  may acquire a module case temperature through a control interface. The module case temperature will be referred to as “T c @Pluggable_Module.” Further, a thermal resistance (C/W) of the cage  1100 A and the heat sink  1100 C will be referred to as “θ ca @MDL.” A power consumption amount (W) of the module  5  will be referred to as “P@MDL.” The card controller  1600  may calculate the environment temperature T a @Pluggable_Module directly above the heat sink  1100 C based on the following equation. 
         [0000]      ( T   a @Pluggable_Module)=( T   c @Pluggable_Module)−(θ ca   @MDL )*( P@MDL )
 
         [0038]    Accordingly, the card controller  1600  may acquire, in advance, the surrounding environment temperature T a @Temp_Sensor_MDL of the cage  1100 A and the environment temperature T a @Pluggable_Module directly above the heat sink  1100 C. Also, the card controller  1600  calculates a difference ΔT a @MDL between the surrounding environment temperature T a @Temp_Sensor_MDL of the cage  1100 A and the environment temperature T a @Pluggable_Module directly above the heat sink  1100 C. 
         [0039]    In a case where the thermal resistance θ ca @MDL is acquired in advance, and information on a power consumption amount of a certain module  5  corresponding to the FEC schemes may be acquired, the card controller  1600  may estimate the module case temperature T c @Pluggable_Module when the module  5  is triggered. 
         [0040]    In addition, with respect to an influence of heat generated in the module  5  on the leeward side, the card controller  1600  estimates an environment temperature variation “ΔT a   _   UP @MDL” of a mounting position of a leeward-side module  5 . The card controller  1600  estimates the environment temperature variation ΔT a   _   UP @MDL by using the module power consumption amount P@MDL. Here, the relationship between the power consumption amount and the environment temperature variation may be measured in advance and acquired as table information (which will be described later with reference to  FIGS. 3 and 4 ). The relationship between the power consumption amount and the environment temperature variation may be determined by a thermal design simulation. 
         [0000]      Δ T   a   _   UP   @MDL=f ( P@MDL )
 
         [0041]    Similarly, the temperature sensor  1400  is arranged near each corresponding framer LSI  1300  to measure an environment temperature of the windward side and detect the environment temperature as a surrounding environment temperature T a @Temp_Sensor_LSI of the framer LSI  1300 . An environment temperature directly above the heat sink  1300 A mounted on the framer LSI  1300  will be referred to as “T a @Framer_LSI.” The framer LSI  1300  may acquire a junction temperature through a control interface. This junction temperature will be referred to as “T j @Framer_LSI.” Further, a thermal resistance (C/W) of the framer LSI  1300  and the heat sink  1300 A will be referred to as “θ ja @LSI.” The power consumption amount (W) of the framer LSI  1300  will be referred to as “P@LSI.” The card controller  1600  may calculate the environment temperature T a @Framer_LSI directly above the heat sink  1300 A based on the following equation. 
         [0000]      ( T   a @Framer_ LSI )=( T   j @Framer_ LSI )−(θ ja   @LSI )*( P@LSI )
 
         [0042]    Therefore, the card controller  1600  may acquire, in advance, the surrounding environment temperature T a @Temp_Sensor_LSI of the framer LSI  1300  and the environment temperature T a @Framer_LSI directly above the heat sink  1300 A. Further, the card controller  1600  may calculate the difference ΔT a @LSI between the surrounding environment temperature T a @Temp_Sensor_LSI of the framer LSI  1300  and the environment temperature T a @Framer_LSI directly above the heat sink  1300 A. In a case where the thermal resistance θ ja @LSI is acquired in advance, and information on a power consumption amount of a certain framer LSI  1300  corresponding to the FEC scheme is acquired, the card controller  1600  may estimate the junction temperature T j @Framer_LSI when the framer LSI  1300  is triggered. 
         [0043]    In addition, with respect to an influence of heat generated in the framer LSI  1300  on the leeward side, the card controller  1600  estimates an environment temperature variation “ΔT a   _   UP @LSI” of a mounting position of a leeward-side framer LSI  1300 . The card controller  1600  estimates the environment temperature variation ΔT a   _   UP @LSI by using the power consumption amount P@LSI of the framer LSI  1300 . The relationship between the power consumption amount and the environment temperature variation may be measured in advance and acquired as table information (which will be described later with reference to  FIGS. 3 and 4 ). The relationship between the power consumption amount and the environment temperature variation may be determined by a thermal design simulation. 
         [0000]        T   a @Framer_ LSI=f ( P@LSI ) 
         [0044]    Each piece of information (e.g., ΔT a , θ ja , θ ca , or ΔT a   _   UP ) varies depending on the mounting positions of the module  1100  and the framer LSI  1300  on the line card  1000 . Thus, the card controller  1600  acquires each piece of information (e.g., ΔT a , θ ja , θ ca , or ΔT a   _   UP ) from each of the module  1100  and the framer LSI  1300 . 
         [0045]    The wind flow on the line card  1000  is not changed by the mounting/unmounting of the module  1100  and the framer LSI  1300 . The wind flow is determined by the structure of a cage for the module  5  and is not affected by the presence/absence of a module to be mounted within the cage and the triggering state of the module. 
         [0046]      FIG. 3  is a view for describing an example of a thermal coefficient table. The thermal coefficient table  3100  includes items of a type, a port, a thermal resistance, a difference, and a leeward-side environment temperature variation. The type is information representing a module and a framer LSI. The port is information representing port numbers  1  to M for the module  1100  and the framer LSI  1300 . 
         [0047]    The thermal resistance item of the thermal coefficient table of  FIG. 3  represents a thermal resistance amount of each of the module and the framer LSI. The thermal resistance amount of the module  1100  is represented as θ ca @MDL, and the thermal resistance amount of the framer LSI  1300  is represented as θ ja @LSI. Since the thermal resistance amount of the module  1100  and the thermal resistance amount of the framer LSI  1300  at each port are different from each other, a port number is assigned behind θ ca @MDL and θ ja @LSI in the form of “_number” in  FIG. 3 . 
         [0048]    The difference item includes the difference on the side of the module  1100  and the difference on the side of the framer LSI  1300 . The difference on the side of the module  1100  is information representing the difference between the temperature of the temperature sensor  1200  arranged near the module  1100  (the surrounding environment temperature) and the environment temperature directly above the heat sink  1100 C. The difference on the side of the module  1100  is represented as ΔT a @MDL. The difference on the side of the framer LSI  1300  is information representing the difference between the surrounding environment temperature of the framer LSI  1300  and the environment temperature directly above the heat sink  1300 A. The difference on the side of the framer LSI  1300  is represented as ΔT a @LSI. In  FIG. 3 , a port number is assigned behind ΔT a @MDL and ΔT a @LSI in the form of “_number.” 
         [0049]    The item of the leeward-side environment temperature variation includes a leeward-side environment temperature variation of the module  1100  side and a leeward-side environment temperature variation of the framer LSI  1300  side. The leeward-side environment temperature variation of the module  1100  side represents an environment temperature variation which is an influence imposed by the heat generated by a windward-side module  5  itself on an adjacent leeward-side module  5 . The leeward-side environment temperature variation of the framer LSI  1300  represents an environment temperature variation which is an influence imposed by the heat generated by a windward-side framer LSI  1300  itself on an adjacent leeward-side framer LSI  1300 . The leeward-side environment temperature variation of the module  5  side is represented as ΔT a   _   UP @MDL. The leeward-side environment temperature variation of the framer LSI  1300  side is represented as ΔT a   _   UP @LSI. In  FIG. 3 , a port number is assigned behind ΔT a   _   UP @MDL and ΔT a     —UP   @LSI in the form of “_number.” The Ports  1  of the module  1100  and the framer LSI  1300  have no environment temperature variation because there are no other leeward-side module and framer LSI which are affected by the module  1100  and the framer LSI  1300  of the Ports  1 . 
         [0050]      FIG. 4  is a view for describing an example of a power consumption amount table. The power consumption amount table  4100  includes items of an FEC type, an operation state, a power consumption amount, and a correction capability. The FEC type is represented by information indicating an SD-FEC mounted in the module  5  and an HD-FEC mounted in the framer LSI  1300 . 
         [0051]    The power consumption amount table  4100  includes information indicating ON and OFF states as the operational state of the SD-FEC function mounted in the module  5 . The power consumption amount table  4100  includes information indicating an OFF state as the operational state of the HD-FEC function mounted in the framer LSI  1300  and standards such as G.709 FEC and EFEC as the operational state (standard) of the HD-FEC function. 
         [0052]    The power consumption amount table  4100  includes information indicating a power consumption amount in the ON and OFF states of the SD-FEC function, and the OFF state and the standards of the HD-FEC function. Further, the power consumption amount table  4100  includes information indicating a correction capability amount in the ON and OFF states of the SD-FEC function, and the OFF state and the standards of the HD-FEC function. The correction capability amount is represented by a gain value. 
         [0053]      FIG. 5  is a view for describing an example of a specified temperature table. The specified temperature table  4200  provides a module specified temperature “T c   _   MAX @MDL” acceptable for the operation of the module  5  and an LSI specified temperature “T j   _   MAX @LSI” acceptable for the operation of the framer LSI  1300 . 
         [0054]    The process by the line card  1000  according to the present disclosure, using the data of the various tables of  FIGS. 3 to 5  will be described sequentially. 
         [0055]    (A1) When a module is newly added, the reception unit  1610  within the line card controller  1600  controlling the line card  1000  receives information on a transmission quality required for a service or a system, from the management terminal  3000 . The transmission quality is represented by, for example, a bit error rate (BER). 
         [0056]    (A2) The collection unit  1620  collects the module case temperature (T c @Pluggable_Module_ 1 -M) of each module and the surrounding environment temperature (T a @Temp_Sensor_MDL_ 1 -M) of the module. Further, the collection unit  1620  collects the junction temperature (T j @Framer_LSI_ 1 -M) of each framer LSI  1300  and the surrounding environment temperature (T a @Temp_Sensor_LSI_ 1 -M) of the framer LSI. 
         [0057]    (A3) The extraction unit  1650  extracts, from the combinations of SD-FEC scheme types supported by the module  5  side and HD-FEC scheme types supported by the framer LSI  1300  side, a combination satisfying the transmission quality received in (1). A plurality of combinations satisfying the transmission quality may exist. 
         [0058]    (A4) The estimation unit  1630  estimates a temperature variation when the module and the framer LSI are triggered in the combinations extracted in the process of (A3), for module-unmounted ports. Further, the estimation unit  1630  determines whether the estimated temperatures of the module and the framer LSI exceed the specified temperature of the specified temperature table  4300 . The process s of (A4) will be described in detail later in (B1) to (B10). 
         [0059]    (A5) The estimation unit  1630  repeatedly performs the process of (A4) for all the combinations extracted in (A3). 
         [0060]    (A6) The estimation unit  1630  repeatedly performs the processes of (A4) and (A5) for all the module-unmounted ports. 
         [0061]    (A7) The estimation unit  1630  determines whether an operable port of the module  5  and the framer LSI  1300  exists, based on the results of (A4) to (A6). 
         [0062]    (A8) When it is determined in (A7) that a usable port exists, the notification unit  1660  notifies the management terminal  3000  of both the usable port and the combinations of the FEC schemes. An operator selects triggering contents (port and FEC schemes to be used) from the menus. 
         [0063]    (A9) The controller  1640  triggers the module and the framer LSI according to instruction contents (a port and FEC scheme to be used) received from the operator in (A8). 
         [0064]    (A10) When it is determined in (A7) that there is no usable port, the estimation unit  1630  checks the presence/absence of a margin of the transmission quality, for module-triggered ports. Specifically, the estimation unit  1630  extracts a combination satisfying the transmission quality, other than the SD-FEC scheme and the HD-FEC scheme which are currently being operated. Details will be described in (C1) to (C3). In addition, the transmission quality for a triggered port may be a transmission quality stored in a memory when the corresponding port is added, or may be newly acquired from the operator. 
         [0065]    (A11) The estimation unit  1630  performs the process of (A10) for all the module-triggered ports. 
         [0066]    (A12) The estimation unit  1630  determines whether a module-triggered port having a margin of the transmission quality exists as a result of (A10) and (A11). 
         [0067]    (A13) When it is determined in (A12) that a port having the margin does not exist, the notification unit  1660  notifies the management terminal  3000  of the nonexistence of an addible port (The card controller  1600  terminates the process according to the present embodiment). 
         [0068]    (A14) The estimation unit  1630  estimates a temperature variation in the case of applying the combination of the SD-FEC scheme and the HD-FEC scheme extracted in (A10), for the triggered port which is determined to have the margin in (A10). The difference (ΔT a   _   UP ) between the environment temperature variations (variations of the surrounding temperature) calculated from power consumptions before and after the change of the FEC schemes, respectively, is the leeward-side environment temperature variation. The estimation unit  1630  adds the leeward-side environment temperature variation (ΔT a   _   UP ) to the case temperature and the surrounding environment temperature of each leeward-side module, and the junction temperature and the surrounding environment temperature of each leeward-side framer LSI. Here, the power consumption amounts of the module and the framer LSI corresponding to the SD-FEC scheme and the HD-FEC scheme which are currently being operated are referred to as P@MDL_N_Current and P@LSI_N_Current, respectively. In addition, it is assumed that the power consumption amounts after the change of the SD-FEC scheme and the HD-FEC scheme are P@MDL_N_Change and P@LSI_N_Change, respectively. The leeward-side environment temperature variation is represented by the following equations. 
         [0000]      Δ T   a   _   UP   @MDL _ N=f ( P@MDL _ N _Current)− f ( P@MDL _ N _Change)
 
         [0000]      Δ T   a   _   UP   @LSI _ N=f ( P@LSI _ N _Current)− f ( P@LSI _ N _Change)
       For example, as to a leeward-side port temperature variation when FEC schemes of port N+1 are changed, in a case where a plurality of ports changing the FEC schemes exists, the leeward-side environment temperature variation (ΔT a   _   UP ) for each of the changing ports is added at a leeward-side port.       
 
         [0070]    (A15) The estimation unit  1630  estimates a temperature variation when the module and the framer LSI are triggered in the combinations extracted in (A3), for module-unmounted ports, based on a temperature after the change of the FEC schemes estimated in (A14), and determines whether the module and the framer LSI exceed the specified temperature. The process of (A15) will be described in detail later in (B1) to (B10). 
         [0071]    (A16) The estimation unit  1630  repeatedly performs the process of (A15) for all the combinations of the FEC schemes extracted in (A3). 
         [0072]    (A17) The estimation unit  1630  repeatedly performs the processes of (A15) and (A16) for all the mounted ports with the margin extracted in (A10) and the combinations of the FEC schemes. 
         [0073]    (A18) The estimation unit  1630  determines whether an operable port of the module and the framer LSI exists as a result of (A15) to (A17). 
         [0074]    (A19) When it is determined in (A18) that there is no usable port, the notification unit  1660  notifies the management terminal  3000  that there is no addible port (The card controller  1600  terminates the process according to the present embodiment). 
         [0075]    (A20) When it is determined in (A18) that there is a usable port, the notification unit  1660  notifies the management terminal  3000  of the usable mounted port and the combinations of the FEC schemes. At this time, the notification unit  1660  further notifies a condition that the FEC schemes of the triggered port be also changed. The operator selects triggering contents (e.g., the port or the FEC schemes) from the menus. 
         [0076]    (A21) The controller  1640  changes the FEC schemes of the triggered port based on the contents received in (A20) and triggers the added module and operates the framer LSI. 
         [0077]    As described above, the line card according to the present disclosure may estimate the combinations of the FEC schemes operated by the framer LSI and the pluggable module, in the range in which the environment temperature inside the device does not exceed the specified temperature. Further, for example, combinations of the FEC schemes considering, for example, an already triggered module, as well as a module to be newly added, may also be estimated. 
         [0078]    Subsequently, the process by the estimation unit  1620  in the processes of (A4) and (A15) will be described in detail. 
         [0079]    (B1) Herein, it is assumed that a port to be subject to the processes of (A4) and (A15) is a port N. The estimation unit  1620  estimates the module case temperature T c @Pluggable_Module when the module is triggered with the SD-FEC scheme. The module case temperature T c @Pluggable_Module may be estimated by numbers. The estimation unit  1620  uses the various parameters of the thermal coefficient table  3100  ( FIG. 3 ) stored in the memory. 
         [0000]        T   c @Pluggable_Module_ N=Ta@ Temp_Sensor_ MDL _ N+ΔTa@MDL _ N+θca@MD L _ N*P@MDL _ N   
         [0080]    (B2) The estimation unit  1620  determines whether the case temperature T c @Pluggable_Module_N at the port N estimated in (B1) exceeds the module specified temperature T c   _   MAX @MDL. The estimation unit  1620  may obtain the module specified temperature from the specified temperature table  4200  of  FIG. 5 . 
         [0081]    (B3) When it is determined that the case temperature does not exceed the module specified temperature, the estimation unit  1620  estimates an environment temperature variation of a module arranged on the side further leeward than the port N. 
         [0000]      Δ T   a   _   UP   @MDL=f ( P@MDL )
 
         [0082]    (B4) The estimation unit  1620  determines whether the case temperature at each of all ports on the side further leeward than the port N exceeds the module specified temperature T c   _   MAX @MDL, based on the environment temperature variation estimated in (B3). 
         [0083]    (B5) When it is determined that the case temperature at each of all the leeward-side ports does not exceed the module specified temperature, the estimation unit  1620  estimates the junction temperature T j @Framer_LSI when the framer LSI is operated by the port N and the HD-FEC scheme. The junction temperature may be estimated according to the following equation. The estimation unit  1620  uses the various parameters in the thermal coefficient table  3100  ( FIG. 3 ) stored in the memory. 
         [0000]        T   j @Framer_ LSI _ N=T   a @Temp_Sensor_ LSI _ N+ΔT   a   @LSI _ N+θ   ja   @LSI _ N*P@LSI _ N   
         [0084]    (B6) The estimation unit  1620  determines whether the junction temperature T j @Framer_LSI_N at the port N estimated in (B5) exceeds the LSI specified temperature T j   _   MAX @LSI. 
         [0085]    (B7) When it is determined that the junction temperature does not exceed the LSI specified temperature, the estimation unit  1620  estimates the environment temperature variation ΔT a   _   UP @LSI_N of a framer LSI arranged at a port on the side further leeward than the port N. 
         [0000]      Δ T   a   _   UP   @LSI _ N=f ( P@LSI _ N )
 
         [0086]    (B8) The estimation unit  1620  determines whether the junction temperature at each of all ports on the side further leeward than the port N exceeds the LSI specified temperature, based on the environment temperature variation ΔT a   _   UP @LSI_N estimated in (B7). 
         [0087]    (B9) When it is determined that the junction temperature at each of all the leeward-side ports does not exceed the LSI specified temperature, the estimation unit  1620  determines that the port N and the FEC schemes may be used. Thereafter, the card controller  1600  performs the process from (A5). 
         [0088]    (B10) When it is determined in the processes of (B2), (B4), (B6), and (B8) that the temperatures exceed the specified temperature, the estimation unit  1620  determines that the port N and the FEC schemes may not be used. Thereafter, the card controller  1600  performs the process from (A5). 
         [0089]    Subsequently, the process by the estimation unit  1620  in the process of (A10) will be described in detail. 
         [0090]    (C1) Herein, it is assumed that a port to be subject to the process of (A10) is a port X. The collection unit  1620  collects an SD-FEC monitor and an HD-FEC monitor of the port X. Examples of the SD-FEC monitor and the HD-FEC monitor to be collected are described below. 
         [0000]      SD-FEC Corrected Bit_X (the number of SD-FEC corrected bits) 
         [0000]      SD-FEC Un-Corrected Block_X (the number of SD-FEC un-corrected blocks) 
         [0000]      HD-FEC Corrected Bit_X (the number of HD-FEC corrected bits) 
         [0000]      HD-FEC Un-Corrected Block_X (the number of SD-FEC un-corrected blocks) 
         [0091]    (C2) The estimation unit  1620  estimates the BER before FEC correction from the FEC monitor values collected in (C1) and elapsed time. The estimation unit  1620  estimates, from correction capability, BER after FEC correction in the case of applying a combination of the SD-FEC scheme and an FEC scheme other than the HD-FEC scheme, with respect to BET before the estimated FEC correction. 
         [0092]    (C3) The card controller stores the combination of the SD-FEC scheme and the HD-FEC scheme satisfying the transmission quality in a memory and continuously performs the process from (A11). 
         [0093]    In addition, the module according to the present disclosure is not limited to the SFP, the XFP, or the CFP. In addition, various types of modules may exist together on the line card. In the present disclosure, the temperature sensors are provided near the module and the framer LSI. However, the positions of the temperature sensors are not limited. 
         [0094]      FIGS. 6A to 6E  are flowcharts for describing the process by the card controller according to the present disclosure. When a module is newly added, the reception unit  1610  within the line card controller  1600  controlling the line card  1000  receives information on a transmission quality required for a service or a system, from the management terminal  3000  (operation S 101 ). The collection unit  1620  collects temperature information from various modules such as each module, a temperature sensor near the module, the framer LSI  1300 , and a temperature sensor near the framer LSI (operation S 102 ). The extraction unit  1650  extracts the combinations of the SD-FEC scheme and the HD-FEC scheme satisfying the transmission quality (operation S 103 ). 
         [0095]    The estimation unit  1630  estimates the FEC schemes of a module and a framer LSI which are usable in the range that does not exceed the specified temperature, for the extracted combinations of the FEC schemes and module-unmounted ports (operation S 104 ). The estimation unit  1630  determines whether the process of operation S 104  has been performed for all the combinations extracted in operation S 103  (operation S 105 ). When it is determined that the process of operation S 104  has not been performed for all the extracted combinations (No in operation S 105 ), the estimation unit  1630  repeatedly performs the process from operation S 104 . When it is determined that the process of operation S 104  has been performed for all the extracted combinations (YES in operation S 105 ), the estimation unit  1630  determines whether the processes of operation S 104  and operation S 105  have been completed for all the module-unmounted ports (operation S 106 ). 
         [0096]    The estimation unit  1630  determines whether an operable port of the module  5  and the framer LSI  1300  exists, based on the results of operations S 104  to S 106  (operation S 107 ). When it is determined that an operable port exists (YES in operation S 107 ), the notification unit  1660  notifies the management terminal  3000  of all the usable port and the combinations of the FEC schemes, and receives an input of triggering contents (a port and an FEC scheme to be used) from an operator (operation S 108 ). The controller  1640  triggers the module and the framer LSI according to instruction contents (a port and an FEC scheme to be used) received from the operator in operation S 108  (operation S 109 ). When the process of operation S 109  is completed, the card controller  1600  terminates the process according to the present disclosure. 
         [0097]    When it is determined that no operable port exists (NO in operation S 107 ), the estimation unit  1630  checks the presence/absence of a margin for the transmission quality, for module-triggered ports (operation S 110 ). Further, in the process of operation S 110 , the extraction unit estimates the combinations of changeable SD-FEC schemes and HD-FEC schemes in the range in which the requirement for the transmission quality is satisfied in the corresponding ports. The estimation unit  1630  determines whether the process of operation S 110  has been performed for all the module-triggered ports (operation S 111 ). When it is determined that the process of operation S 110  has not been performed for all the module-triggered ports (No in operation S 111 ), the estimation unit  1630  repeatedly performs the process from operation S 111 . 
         [0098]    When it is determined that the process of operation S 110  has been performed for all the module-triggered ports (YES in operation S 111 ), the estimation unit  1630  determines whether a module-triggered port which has the margin of the transmission quality exists (operation S 112 ). When it is determined that there is no module-triggered port which has the margin of the transmission quality (NO in operation S 112 ), the notification unit  1660  notifies the management terminal  3000  that there is no addible port (operation S 113 ). When the process of operation S 113  is completed, the card controller  1600  terminates the process according to the present embodiment. 
         [0099]    When it is determined that there is a module-triggered port which has the margin of the transmission quality (YES in operation S 112 ), the estimation unit  1630  estimates a temperature variation in the case of applying the combination of the SD-FEC scheme and the HD-FEC scheme extracted in operation S 110 , for the triggered port which is determined to have the margin (operation S 114 ). The estimation unit  1630  estimates a temperature variation when the module and the framer LSI are triggered in the combinations extracted in operation S 103 , for module-unmounted ports based on the temperature after the change of the FEC schemes, and determines whether the module and the framer LSI exceed the specified temperature (operation S 115 ). The estimation unit  1630  determines whether the process of operation S 115  has been performed for all the combinations of the FEC schemes extracted in operation S 103  (operation S 116 ). When it is determined that the process of operation S 115  has not been performed for all the combinations of the FEC schemes extracted in operation S 103  (No in operation S 116 ), the estimation unit  1630  selects another combination of the FEC schemes and repeatedly performs the process from operation S 115 . When it is determined that the process of operation S 115  has been performed for all the combinations of the FEC schemes extracted in operation S 103  (YES in operation S 116 ), the estimation unit  1630  determines whether the processes of operation S 114  and operation S 115  have been completed for all the mounted ports with the margin which are extracted in operation  5110  (operation S 117 ). When it is determined that the processes of operation S 114  and operation S 115  have not been completed for all the mounted ports with the margin (NO in operation S 117 ), the estimation unit  1630  repeatedly performs the process from operation S 114  for other mounted ports with the margin. 
         [0100]    The estimation unit  1630  determines whether an operable port of the module and the framer LSI exists, based on the results of operations S 115  to S 117  (operation S 118 ). When it is determined that there is no operable port (NO in operation S 118 ), the notification unit  1660  notifies the management terminal  3000  that there is no addible port (operation S 119 ). The card controller  1600  terminates the process according to the present embodiment. When it is determined that a usable port exists (YES in operation S 118 ), the notification unit  1660  notifies the management terminal  3000  of the usable mounted port and the combinations of the FEC schemes (operation S 120 ). The controller  1640  changes the FEC schemes of the triggered port according to an input of an operator on the side of the management terminal  3000  and triggers the added module and operates the framer LSI (operation S 121 ). 
         [0101]    As described above, the line card according to the present disclosure may estimate the combinations of the FEC schemes operating by a framer LSI and a pluggable module, in the range in which the environment temperature inside the device does not exceed the specified temperature. Further, the combinations of FEC schemes considering, for example, an already triggered module, as well as a module to be newly added, may also be estimated. 
         [0102]      FIGS. 7A and 7B  are flowcharts for describing an example of the process by the estimation unit. The flowcharts of  FIGS. 7A and 7B  are an example of the specific processes of operations S 104  and S 115 . The estimation unit  1620  estimates the module case temperature T c @Pluggable_Module in the case of triggering the module with the SD-FEC scheme (operation S 201 ). The estimation unit  1620  determines whether the module case temperature exceeds the module specified temperature (operation S 202 ). When it is determined that the module case temperature does not exceed the module specified temperature, the estimation unit  1620  estimates the environment temperature variation of a module arranged on the side further leeward than the port N (operation S 203 ). The estimation unit  1620  determines whether the case temperature at each of all ports on the side further leeward than the port N exceeds the module specified temperature, based on the environment temperature variation estimated in operation S 203  (operation S 204 ). 
         [0103]    When it is determined that the case temperature at each of all the leeward-side ports does not exceed the module specified temperature (NO in operation S 204 ), the estimation unit  1620  estimates the junction temperature when the framer LSI is operated at the port N and in the HD-FEC scheme (operation S 205 ). The estimation unit  1620  determines whether the junction temperature T@Framer_LSI_N at the port N estimated in operation S 205  exceeds the LSI specified temperature T j   _   MAX @LSI (operation S 206 ). When it is determined that the junction temperature does not exceed the LSI specified temperature (NO in operation S 206 ), the estimation unit  1620  estimates the environment temperature variation ΔT a   _   UP @LSI_N of a framer LSI arranged at a port on the side further leeward than the port N. (operation S 207 ). The estimation unit  1620  determines whether the junction temperature at each of all ports on the side further leeward than the port N exceeds the LSI specified temperature (operation S 208 ). When it is determined that the junction temperature at each of all the leeward-side ports does not exceed the LSI specified temperature (NO in operation S 208 ), the estimation unit  1620  determines that the port N and the FEC schemes may be used (operation S 209 ). Thereafter, the card controller  1600  terminates the processes of  FIGS. 7A and 7B  and performs the processes from operations S 105  and S 116 . 
         [0104]    When it is determined that the module case temperature exceeds the module specified temperature (YES in operation S 202 ), or the case temperature at each of all ports on the side further leeward than the port N exceeds the module specified temperature (YES in operation S 204 ), the estimation unit  1620  determines that the port N and the FEC schemes may not be used (operation S 210 ). Further, when it is determined that the junction temperature at the port N exceeds the LSI specified temperature (YES in operation S 206 ), or the junction temperature at each of all ports on the side further leeward than the port N exceeds the LSI specified temperature (YES in operation S 208 ), the estimation unit  1620  performs the process of operation S 210 . 
         [0105]      FIG. 8  is a flowchart for describing an exemplary method of extracting the FEC schemes satisfying the transmission quality.  FIG. 8  is a flowchart for specifically describing the process of operation  110  of  FIG. 7B . The collection unit  1620  collects the SD-FEC monitor and the HD-FEC monitor of the port X (operation S 301 ). The estimation unit  1620  estimates the BER before the FEC correction from the collected FEC monitor values and elapsed time (operation S 302 ). The card controller stores a combination of the SD-FEC scheme and the HD-FEC scheme satisfying the transmission quality in a memory and continuously performs the process from operation S 111  (operation S 303 ). 
         [0106]    As described above, the line card according to the present disclosure may estimate the combinations of the FEC schemes operated by a framer LSI and a pluggable module, in the range in which the environment temperature of the device does not exceed the specified temperature. Further, the combinations of FEC schemes in consideration of, for example, an already triggered module, as well as a module to be newly added, may also be estimated. Therefore, in the line card on which various types of different pluggable modules are mounted, by monitoring the temperature on the line card and selecting the FEC schemes, mounting/arrangement suitable for a practical operation may be implemented. Further, it is possible to determine whether an unmounted pluggable module is mounted or implement an optical transmission suitable for practical operation. 
         [0107]    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 an illustrating of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.