Abstract:
Determining the degree of satisfaction of a user of network services quantitatively is difficult. A service quality management model defining means for defining the service condition and network depending relation and evaluation conditions, a means for storing the model in a DB, a service condition monitoring means for monitoring the transition of the service condition, and a service quality calculating and evaluating means for calculating service availability and executing special service maintaining and relieving measures are provided.

Description:
This application claims priority from Japanese Patent Application No. 11-212174 filed Jul. 27, 1999, the entire contents of which are incorporated herein by reference for all purposes. 
   BACKGROUND OF THE INVENTION 
   This invention relates to service management techniques for carrying out the measurement, calculation and evaluation of the quality of services on the basis of a service level agreement concluded between a communication service user and a communication service provider. 
   As the utilization of local area networks and electronic commerce have become popular in recent years, the data flowing on the networks have been put to practical use as they are in business. Under such circumstances, new problems have arisen in addition to a stoppage of and a delay in the operations of the networks which constitute the problems of the related art techniques of this kind. The new problems include a decrease in the quality of services supplied onto the networks, which causes the degree of a satisfaction in the network services of a user (which will hereinafter be referred to simply as “user”) to decrease, and which possibly causes a working loss to occur. When the quality of the services decreases, a provider supplying network services (who will hereinafter be referred to simply as “provider”) loses his customers, and suffers a decrease in the equipment efficiency in some cases. Therefore, it has become insufficient for a provider to merely carry out specialized management, which he has heretofore practiced, of the networks, infrastructures. Namely, it has become important to measure and evaluate the performance of the services supplied to a user, and maintain the quality of the services. 
   The techniques for meeting such requirements include a method of carrying out MIB (Management Information Base) type collection of traffic on network connection by utilizing SNMP (Simple Network Management Protocol) disclosed in “Service Quality Display for Computer Networks” of Japanese Patent Laid-Open No. 205427/1997, and expressing the condition of fluctuation of the traffic by color and thickness of lines on a network construction diagram. Also, a method is known of measuring various kinds of quality data (delay time, packet loss rate and average band width) concerning point-to-point network connection by utilizing a passive probe disclosed in “Method of and Apparatus for Measuring Service Quality” of Japanese Patent Laid-Open No. 261254/1997. 
   The details of SNMP and MIB are given in RFC (Request for Comment)  1157  and RFC  1213  respectively. 
   A user has become able to selectively utilize a variety of service qualities in addition to the existing best effort type internet services and private line services in which only fixed band width assurance is given. Consequently, the following modes of services have become important. Namely, it has become important that a provider measures service qualities on the basis of what have been agreed upon in advance by users and the provider concerning how to maintain the service qualities, and supplies services in conformity with the contents of the agreement. 
   The following techniques are disclosed in “User Relieving Method and System” of Japanese Patent Laid-Open No. 244973/1997 as techniques for dealing with the above-mentioned matter. Namely, in these techniques, the degree of satisfaction concerning a service level agreement, of users who are influenced by the occurrence of troubles, is expressed in terms of a satisfaction percentage by comparing the measurement data obtained by a network monitoring operation with the contents of a service level agreement. Limitations of the utilization of services are then placed on users of a high degree of satisfaction, i.e. users having a satisfaction percentage in excess of 100%, and users of a low degree of satisfaction concerning the service level agreement, i.e. users having a satisfaction percentage of lower than 100% are relieved. These techniques constitute a method of maintaining the service quality without spending money on the duplication of equipment. 
   SUMMARY OF THE INVENTION 
   The measurement data on evaluation items obtained by a network monitoring operation are merely collected as respectively independent measurement data. Therefore, it is difficult to determine the quality of supplied services as a whole. 
   When the contents of a service level agreement are not strictly observed, a great influence is exerted on a user&#39;s business in some cases, and not so great an influence in some cases. In a related art system of this kind, the degrees of users&#39; satisfaction are calculated uniformly, and degrees of users&#39; satisfaction with consideration given to the individual circumstances of the respective users were not obtained. 
   Since a provider could not know the degrees of users&#39; satisfaction according to their individual circumstances, suitable steps could not be taken even when the degrees of users&#39; satisfaction concerning the service level agreement are low. 
   It is therefore an object of the present invention to provide a service management system which has a single index representing the degrees of users&#39; satisfaction determined with the individual circumstances of the users taken into consideration, and which is capable of obtaining the degrees of users&#39; satisfaction being determined on the basis of this index. 
   It is another object of the present invention to provide a service management system which is capable of giving instructions for carrying out a suitable step according to the mentioned determined degree of users&#39; satisfaction to some other existing system. 
   A first aspect of the invention which has been made so as to solve the above-mentioned first problems relates to a service management system provided with a server, plural user&#39;s terminals, and a service network formed of a network for connecting the server and plural user&#39;s terminals to each other, the server including service quality evaluation standard receiving means for receiving inputs of items for evaluating the quality of services supplied through the service network and evaluation standard for the information representative of the degree of the condition of services under the evaluation items; a service condition information obtaining means for obtaining information, which is representative of the degree of the service condition under the evaluation items, while services are supplied through the service network; and satisfaction degree-representing index calculating means for evaluating the obtained information, which represents the degree of the service condition, in accordance with the evaluation standard received by the service quality evaluation standard receiving means, and calculating a satisfaction degree-representing index indicating the degree of a user&#39;s satisfaction concerning the service quality. 
   A second aspect of the invention which has been made so as to solve the above-mentioned second problem relates to a service management system including in addition to the means as mentioned above to solve the first problems, satisfaction degree-representing index evaluation standard receiving means for receiving inputs of a range of satisfaction degree-representing indexes which the user can permit, and measures to be executed when the satisfaction degree-representing index is out of the range; means for comparing the calculated satisfaction degree-representing index and the permissible range of the satisfaction degree-representing index with each other; and means for giving instructions to execute the measures to be carried out practically which is received by the satisfaction degree-representing index evaluation standard receiving means, in a case where the results of the comparison made by the comparing means show that the satisfaction degree-representing index is out of the permissible range. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention will be described in detail on the basis of the following figures, wherein: 
       FIG. 1  illustrates functional blocks in embodiments of the system according to the present invention; 
       FIG. 2  illustrates the construction of hardware of the embodiments of the system according to the present invention; 
       FIG. 3  illustrates the construction of a system of a service provider who supplies IP telephone services and that of a system of a user in a first embodiment of the present invention; 
       FIG. 4  illustrates the construction of a system of a service provider who supplies private line services having plural service classes and that of a system of a user in a second embodiment of the present invention; 
       FIG. 5  is a general functional flow chart concerning a service quality management system according to the present invention; 
       FIG. 6  is a flow chart of a service quality evaluation model inputting operation according to the present invention; 
       FIG. 7  is a flow chart of a service availability evaluation policy inputting operation according to the present invention; 
       FIG. 8  is a flow chart of a service condition monitoring operation according to the present invention; 
       FIG. 9  is a flow chart of a service availability calculation operation in the present invention; 
       FIG. 10  is a flow chart of a service availability evaluation operation according to the present invention; 
       FIG. 11  illustrates a service quality evaluation model inputting screen in the first embodiment of the present invention; 
       FIG. 12  illustrates a service group quality evaluation model inputting screen in the second embodiment of the present invention; 
       FIG. 13  illustrates a service availability evaluation policy inputting screen in the first embodiment of the present invention; 
       FIG. 14  illustrates a service quality evaluation model defining table according to the present invention; 
       FIG. 15  illustrates a service evaluation item table according to the present invention; 
       FIG. 16  illustrates a service configuration table according to the present invention; 
       FIG. 17  illustrates a service availability evaluation policy table according to the present invention; 
       FIG. 18  illustrates a service condition transition history table according to the present invention; 
       FIG. 19  illustrates a service configuration inputting screen according to the present invention; and 
       FIG. 20  is a flow chart of a service configuration inputting operation according to the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention will now be described on the basis of embodiments thereof in which the present invention is used for a system for managing the quality of network communication services, and with reference to the accompanying drawings. 
     FIG. 3  is a construction diagram of the service management system in a first embodiment of the present invention. A provider A gives IP telephone services to a user B having plural positions. 
   A system  301  of the provider A includes a provider service network  305  adapted to supply IP telephone services; a management data transfer network  304  adapted to take and give management data from and to a network unit by using a protocol, such as SNMP: a network management system  303  adapted to monitor and control the network condition; a service management system  302  including a service quality management module  101  adapted to monitor the service condition in cooperation with the network management system  303 ; a trouble management system  312  adapted to carry out service trouble relieving and service restoring steps and deal with user&#39;s complaints; a billing system  313  adapted to impose service charge on the user, demand payment of service charge from the user and collect service charge; and a service order system  314  adapted to receive a user&#39;s request for the provider&#39;s presentation of services. 
   A system of the user B includes a head office system  306 , a branch office  1  system  307  and a branch office  2  system  308 . The head office system  306  and the two branch office systems  307 ,  308  are connected to access nodes  310 , which are provided in the provider&#39;s service network, by using VoIP (Voice Over IP) gateways  309  provided on the side of the user. This enables the head office and branch offices of user B to talk over the telephone with each other by using VoIP terminals  311  network-connected to the VoIP gateways  309 . 
     FIG. 2  is a construction diagram of hardware which can be used for attaining this system. A service quality management module  101  shown in  FIG. 1  can be formed on a computer provided with hardware including a CPU  201 , a memory  202 , an input-output interface  203 , a display  204 , an input unit  205 , a storage  206  and a network unit  207 . In this hardware, the service quality management module  101  is stored in the memory  202 , and materialized as a process. The service quality management module  101  is connected to an external management system  209  ( 106 - 109  in  FIG. 1 ) via the network unit  207 . 
   The system  301  of the provider A is formed of such functional blocks as shown in FIG.  1 . The system  301  includes the service quality management module  101  attaining the service management system  302  according to the present invention, a network management functional module  106 , a service order functional module  107 , a trouble management functional module  108 , and a billing functional module  109  which are external modules. The network management functional module  106  is mounted on the network management system  303 , the service order functional module  107  on the service order system  314 , the trouble management functional module  108  on the trouble management system  312 , and the billing module  109  on the billing system  313  respectively. 
   The service quality management module  101  is formed of a service quality management model defining block  102 , a service quality management model storage block  103 , a service quality calculation and evaluation block  104 , and a service condition monitoring block  105 . 
   The service quality management model defining block  102  provides an input screen for a service quality evaluation model, service configuration, and service availability evaluation policy (which will hereinafter be referred to as “SA evaluation policy”), and controls inputs and outputs into and from the screen. 
   The service quality evaluation model shows the standards on the basis of which a user evaluates the services supplied by a provider. A user inputs a signal into a service quality evaluation model input screen (which will hereinafter be referred to simply as “model input screen”)  10221  shown in FIG.  11 . 
   On the model input screen  10221  shown in  FIG. 11 , input fields for a customer&#39;s contract number  10222 , a kind  10223  of services, a service class  10224 , a speech delay  10225 , a degrading coefficient  10226  thereof, a usable number  10227  of calling channels, a degrading coefficient  10228  thereof, service supply starting date and time  10229  and service quality intervals  10230  are displayed, and this model input screen receives an input from the user. 
   The customer&#39;s contract number  10222  represents a number for identifying a contract directly. The kind  10223  of services represents the kind of services provided. In this embodiment, VoIP is selected. Other kinds of services include EDI service and e-mail. The service class  10224  indicates a class of service, and, in this embodiment, “Normal” is selected. Other service classes include band width assurance. The speech delay  10225  and usable number  10227  of calling channels are service evaluation items. The service evaluation items include a disuse ratio of cells, which a user can select. The degrading coefficients  10226 ,  10228  are coefficients representing the degree of deterioration of a service level on the side of a user. A value of this degree of deterioration is determined by a user. The service supply starting date and time  10229  are service starting date and time desired by a user. The service quality evaluation intervals  10230  represent time intervals at which a service quality evaluation process which will be described later is carried out. 
   In each of the service evaluation items, three grades of evaluation levels are set. Concerning the speech delay in this embodiment, a level  1  means a range ( 10225   a ) of 0-150 ms, a level  2  a range ( 10225   b ) of 150-400 ms and a level  3  a range ( 10225   c ) of not lower than 400 ms. The degrading coefficient  10226  is inputted as 0.5 ( 10226   a ) when the level changes from the level  1  to the level  2 , and as 0.1 ( 10226   b ) when the level changes from the level  1  to the level  3 . Inputting the degrading coefficient of 0.5 when the level changes from the level  1  to the level  2  means to a user who wants to receive the service of the level  1  that the value of the service which the user practically receives decreases 0.5 times in the level  2 . The above-mentioned inputted information is stored on a service quality evaluation model defining table  10301  shown in  FIG. 14 and a  service evaluation item table  10321  shown in FIG.  15 . 
   The service quality evaluation model defining table  10301  is formed of a customer&#39;s contract number  10302 , the kind of services  10303 , a service class  10304 , the name of service group (only when a service group is defined)  10305 , a weighting coefficient (only when a service group is defined) for the evaluation of the service group  10306 , names of service evaluation items  10307 - 10309 , service supply starting date and time  10310 , and service quality evaluation intervals  10311 . 
   Concerning the customer&#39;s contract number  10302 , the kind of services  10303 , service class  10304 , names of service evaluation items  10307 - 10309 , service supply starting date and time  10310  and service quality evaluation intervals  10311 , values inputted from the model input screen  10221  are stored. The name of a service group  10305  and weighting coefficient for the evaluation of service group  10306  will be described in a second embodiment. 
   A service evaluation item table  10321  of  FIG. 15  holds information concerning the service evaluation items out of a service quality evaluation model. Namely, this table holds a range value (for example, “0-150 ms”) ( 10323 - 10325 ) of an evaluation level and a degrading coefficient (for example, “0.5”) ( 10326 - 10328 ) for a service level decrease from a level  1  to some other level with respect to the name (for example, “speech delay”) of one service evaluation item. 
   Concerning the name of each service evaluation item, the name displayed on the model input screen  10221  is stored. Concerning the ranges ( 10225   a-c ,  10227   a-c ) of the evaluation level values and degrading coefficients ( 10226   a  and  b ,  10228   a  and b), what are inputted from the model input screen are stored under the corresponding items. Since one record is formed under one service evaluation item, two records are formed in the example of FIG.  11 . 
   A service configuration input screen  10381  shown in  FIG. 19  displays thereon input field of a customer&#39;s contract number  10302 , a name of service  10382 , a kind of service calculation  10383 , service calculation conditions  10384  and the name  10385  of a SA evaluation policy respectively. The kind of service calculation  10383  indicates a unit for the calculation of service availability. On this screen, either the kind of service or a unit group (which can be selected only when a service group is set) can be selected ( 10383   a ,  10383   b ). The service calculation conditions  10384  indicate the range of data to which the calculation of the service availability is directed. On this screen, either one of the quality evaluation interval unit and an accumulated total from the service supply starting time can be selected ( 10384   a ,  10384   b ). The details of a method of utilizing the kind of service calculation and service calculation condition will be described later. 
   A user inputs signals into this screen concerning all services the supply of which the user receives. The service configuration inputted during this time is stored by the name of services on the service configuration table  10331 . 
   The service configuration table  10331  shown in  FIG. 16  has the customer&#39;s contract number  10302 , the name of service  1   103382 , the kind  10333  of service  1  calculation, service  1  calculation condition  10334 , and the name  10335  of SA evaluation policy  1 . When there are plural services on the same customer&#39;s contract number, they are stored ( 10336 - 10343 ) continuously by the same format. 
   The SA evaluation policy is an evaluation standard for the service availability calculated by the procedure which will be described later. The SA evaluation policy is inputted by a user into the service availability evaluation policy input screen (which will hereinafter be referred to simply as “evaluation policy input screen”)  10241  shown in FIG.  13 . 
   The service availability represents an index indicative of the degree of a user&#39;s satisfaction concerning the service quality, which is expressed by a numerical value between 0 and 1. When the numerical value comes closer to 1, the service quality becomes higher, which indicates that the degree of the user&#39;s satisfaction is high. When the numerical value comes closer to 0, the service quality becomes lower, which indicates that the degree of the user&#39;s satisfaction is low. 
   The evaluation policy input screen  10241  is provided with a display field for the customer&#39;s contract number  10222 , degree of satisfaction restoring measures  10242  and names ( 10243 - 10245 ) of services, and an input field for measures execution threshold values ( 10243 - 10245 ) by the kind of services. 
   The degree of satisfaction restoring measures  10242  are measures to be taken by a provider so as to restore the degree of a user&#39;s satisfaction when the service availability decreases with the degree of the user&#39;s satisfaction at a low level. The measures include, for example, the issuance of trouble tickets and the compensation of service charge. The service names ( 10243 - 10245 ) are displayed with reference to those ( 10332 ,  10336 ,  10340 ) on the service configuration table  10331 . The measures execution threshold values ( 10243 - 10245 ) represent threshold values set so as to take the degree of satisfaction restoring measures when the service availability decreases to a level lower than the threshold values. Namely, the above-mentioned measures are taken when the service availability becomes lower than the measures execution threshold values. 
   In an example of  FIG. 13 , “demand for the issuance of trouble tickets” (measures execution threshold value: 0.95)  10243   a  and “customer&#39;s demand that the service charge be compensated” (measures execution threshold value: 0.75)  10243   c  are inputted as the degree of satisfaction restoring measures  10242  with respect to the name “SA1-int”  10243  of service. The measures of “performance report to a customer” are not executed since a measures execution threshold value therefor is not yet set (N/A)  10243   b.    
   The SA evaluation policy inputted in this example is held in the service quality management model storage block  103 , and stored in the SA evaluation policy table  10351  shown in FIG.  17 . 
   The SA evaluation policy table  10351  has a name of evaluation policy  10352 , a decision whether the degree of satisfaction restoring measures  1  should be applied or not  10353  (TRUE or FALSE), and a threshold value for the execution of the degree of satisfaction restoring measures  1   10354 . When there are plural evaluation policies for the same customer&#39;s contract number, they are stored continuously by the same format ( 10355 - 10358 ). In the example of  FIG. 13 , “SA1-int” for the name of evaluation policy  10352 , “TRUE” for the decision whether the degree of satisfaction restoring measures  1  should be applied or not  10353 , “lower than 0.95” for the threshold value for executing the degree of satisfaction restoring measures  1   10354 , “FALSE” for a decision whether the degree of satisfaction restoring measures  2  should be applied or not  10355 , “N/A” for a threshold value for executing the degree of satisfaction restoring measures  2   10354 , “TRUE” for a decision whether the degree of satisfaction restoring measures  3  should be applied or not, and “lower than 0.75” for a threshold value for executing the degree of satisfaction restoring measures  3  are stored in the form of one record. 
   In order to start supplying services by using this system of the above-described constitution, a user B and a provider A make a contract (service level agreement) with each other concerning the service quality. The contract may be made not only by writing or by word of mouth but also in a manner in which a terminal provided on a head office system of the user B is connected to the customers&#39; service management system  302  of the provider A by utilizing an internet  316  as a communication line to thereby input data necessary for the contract by an on-line system. 
   The procedure for making such a contract will now be described, and the procedure for managing the services for customers by this system will thereafter be described. 
     FIG. 5  is a flow chart showing a flow of a process as a whole carried out in this system. Prior to the starting of supplying new services, the user inputs a service quality evaluation model by using the model input screen  10221  given by the service quality management model defining block  102 . The contents of what are thus inputted are stored ( 10101 ) in the service quality evaluation model defining table  10301  held in the service quality management model storage block  103 . 
   The detailed procedure for inputting the service quality evaluation model will be described with reference to  FIGS. 6 and 11 . 
   First, the user selects ( 10201 ) the service evaluation items. In this example, the speech delay  10225  and usable number of calling channels  10227  are selected. The level classification by the ranges of measurement values is carried out with respect to each of the selected service evaluation items, and the results are inputted as evaluation levels into  10225   a - 10225   c . In this example, the levels  1 - 3  ( 10225   c ,  10225   b ,  10225   a ) of speech delay are inputted as “0-150 ms”, “150-400 ms”, “not lower than 400 ms” respectively. This means that the user expressed the user&#39;s desire to receive the supply of services of the level  1 , which is determined as a standard evaluation level. 
   The degrading coefficients used when the standard evaluation level changes are then determined and inputted ( 10202 ). In this example, a degrading coefficient  10226   a  used when the standard evaluation coefficient changes to the level  2 , and a degrading coefficient  10226   b  used when the standard evaluation level changes to the level  3  are inputted as 0.5 and 0.1 respectively. 
   The steps ( 10201 - 10202 ) are repeatedly carried out ( 10203 ) with respect to all of the services the supplying of which were requested, until this model has been defined. 
   When there are service groups having common network resources ( 10204 ), the user defines ( 10205 ) a weighting coefficient for evaluating plural services having the network resources in common. Since there are no service groups in this example, this step is not carried out. The inputted service quality evaluation model is stored on the service quality evaluation model defining table  10301  and service evaluation item table  10321  which are held in the service quality management model storage block  103 , to finish ( 10206 ) the service quality evaluation model inputting process. 
   When the service quality evaluation model inputting process finishes, the service configuration inputting screen  10381  is displayed. The procedure for carrying out the service configuration inputting process ( 10102 ) will be described with reference to  FIGS. 19 and 20 . First, a name of service is inputted ( 10601 ) as a name of the service quality evaluation model inputted latest. In this example, the service model is named “SA-lint”. The kind of service calculation and service calculation conditions are selected ( 10602 ,  10603 ). In this example, “the kind of service” and “interval unit” are selected respectively. Finally, a name of the SA evaluation policy is inputted ( 10604 ). The inputted service configuration is stored on the service configuration table  10331  held in the service quality management model storage block  103 , to finish the service configuration inputting process. 
   When the inputting of the service configuration finishes, the SA evaluation policy inputting screen  10241  is displayed. The procedure for inputting ( 10103 ) the SA evaluation policy will be described with reference to  FIGS. 7 and 13 . The user selects the degree of satisfaction restoring measures  10242  ( 10211 ) with respect to the names  10243 - 10245  of services. In this example, a demand for the issuance of trouble tickets  10242   a , a performance report to the user  10242   b  and a demand that the service charge be compensated for the user  10242 C are selected and displayed. The threshold values for executing measures are inputted ( 10212 ) as conditions for executing the selected measures in  10243   a-c ,  10244   a-c  and  10245   a-c . The SA evaluation policy is set for each service or service group defined in the service quality evaluation model. Therefore, the steps  10211 - 10212  are carried out repeatedly ( 10213 ) until the evaluation policies for all services have been set. The inputted SA evaluation policies are stored on the SA evaluation policy table  10351  held in the service quality management model storage block  103 , to finish the SA evaluation policy inputting process. 
   The steps described up to now constitute the process carried out when a contract is made. The acceptance of the inputted conditions by the provider A means the arrival at the service level agreement. From this time on, the provider A has the duty to supply services to the user in accordance with the contents of the agreement. The procedure for managing the services supplied to the user in this system will now be described. 
   The service condition monitoring block  104  in the service management system  302  transmits service evaluation items and a range of measurement value evaluation levels to the network management module  106  in the network management system  303 , and gives instructions to carry out a network monitoring operation ( 10104 ). The counting of the time is then done so as to determine the quality evaluation intervals, by using a time counter. After the time counter (not shown) is cleared, the counting of the time during which services are supplied starts being done ( 10105 ). 
   The network management module  106  starts monitoring the network in accordance with the service evaluation items and evaluation level received from the service condition monitoring block  104 . The network management module  106  determines evaluation levels to which the measurement data concerning different service evaluation items belong respectively. Every time the transition of the level is detected, the transition of the level is issued as a notification of event. The events may be notified periodically at predetermined time intervals. An event notified includes service evaluation items, and, an evaluation level and a time stamp at the notification time. The service condition monitoring block  104  is adapted to monitor ( 10106 ) the condition of the network on the basis of an event notified by the network management module  106 . The details of the procedure of this monitoring operation will be described with reference to FIG.  8 . 
   The service condition monitoring block  104  receives ( 10401 ) a level transition notifying event from the network management module  106 . An after-transition evaluation level is identified ( 10402 ) on the basis of the received event, and the event added ( 10403 ) to a level transition hysteresis table held in the service quality management model storage block  103 . The level transition hysteresis table  10411  shown in  FIG. 18  has a customer&#39;s contract number  10302 , a service evaluation item  10303  (for example, “speech delay”), an evaluation level  10412  (for example, “level  2 ”) notified by an event  1 , and a time stamp  10413  of the event  1 . Second and later hysteresis data with respect to the same customer&#39;s contract number are stored ( 10414 - 10417 ) continuously by the same format. The network monitoring operation continues to be carried out while services are supplied. 
   The service quality calculation and evaluation block  105  monitors ( 10107 ) the service supply time counted by the counter, as to whether or not the service supply time exceeds the time specified by the quality evaluation interval. When the service supply time exceeds the quality evaluation interval, the service availability is calculated ( 10108 ) for every service defined in the quality evaluation model, on the basis of the contents of what are held in the level transition hysteresis table  10411 . The details of the procedure of the process will be described later. 
   The service quality calculation and evaluation block  105  evaluates the service quality ( 10109 ) on the basis of the calculated service availability and SA evaluation policy held on the SA evaluation policy table  10351 . The details of the procedure of the process will be described. 
   The steps  10105 - 10109  of  FIG. 5  are carried out repeatedly while the services continue to be supplied, and the measurement, calculation and evaluation of the service quality based on the service level agreement are thereby carried out ( 10110 ). 
   The detailed procedure for calculating the service availability will be described with reference to FIG.  9 . First, whether the service availability per evaluation interval is calculated or the service availability accumulated from the service supply starting time is calculated with reference to service  1  calculation conditions  10334  on the service configuration table  10331 , is determined ( 10501 ). A case where the calculations are made for every interval is now taken as an example, and a description of such a case will be given. The service quality calculation and evaluation block  105  takes out ( 10502 ) the contained data during the time corresponding to the quality evaluation interval actually measured, from the level transition hysteresis data  10411  held in the service condition monitoring block  104 . A service quality evaluation model corresponding to the relative service is obtained with reference to the service quality evaluation model defining table  10301 , and the service availability is calculated ( 10503 ). The service availability is determined by the following equation.
 
 SA =Σ(time during which a service level is held×degrading coefficient)÷evaluation interval  (1) 
 
   When there are plural service evaluation items, this equation is applied to all of the evaluation items, and a product of the calculated service availability is determined, the product being used as a value of the availability of the relative service. The service availability determining method is not limited to this method. The lowest value of service availability among the values of service availability concerning all service evaluation items may be used as a value of availability of the relative service, or a value of service availability may be determined by carrying out a weighting operation with respect to each service evaluation item. 
   The information is then retrieved ( 10511 ) from the SA evaluation policy table corresponding to the service, and the calculated value of the service availability and a measures execution threshold value are compared ( 10512 ) with each other concerning the quality evaluation item for which the degree of satisfaction restoring measures are set. When the value of the service availability is lower than the measures execution threshold value, the measures are executed ( 10513 ). 
   For example, when “the service availability calculated concerning SA1-int is lower than 0.95”, instructions to demand that a trouble ticket be issued are given to the trouble management system  312 . When “the service availability calculated concerning SA1-all is lower than 0.7”, instructions to demand that the service charge be compensated for the customer are given to the billing system  313 . Concerning all the values of calculated service availability, the steps  10511 - 10513  are carried out repeatedly ( 10514 ). The service quality calculation and evaluation block  105  may clarify the results of calculation of the service availability concerning a specific customer in accordance with a request made by an external management system. 
   According to the above-described service management system, the degree of satisfaction in conformity with the circumstances of each user concerning the service quality can be determined quantitatively by employing a single index, which is called service availability, on the basis of a service quality evaluation model determined by the user. 
   The provider can check by this system the quality of the system at any time during an operation thereof, and execute when the quality of the system lowers suitable measures at a suitable time so as to restore the degree of the user&#39;s satisfaction. This enables the provider to maintain the degree of the user&#39;s satisfaction at a level not lower than a predetermined level at all times, and the competitive power of the provider to be improved. 
   According to this system, the provider becomes able to set service charge proportional to the service quality. Namely, the provider can set the service charge high by promising that high-quality services will be supplied. Conversely, the service quality may be lowered by reducing the service charge. Employing such a service charge system has the following advantages. When a user sets the measures execution threshold value to a level near zero, the service quality lowers but the user can receive the supply of services at a correspondingly low price. On the other hand, when the user sets the measures execution threshold value to a level near one, the user can always receive high-quality services, and, even when the service quality should lower, compensation is given correspondingly. However, the service charge becomes correspondingly high. 
   A second embodiment of the present invention will now be described. 
     FIG. 4  shows the construction of a system of a provider C supplying private line services having plural service classes, and that of a system of a user D utilizing the services among plural positions thereof. 
   A system  401  of the provider C is formed of a provider&#39;s service network  305  adapted to supply private line services, a management data transfer network  304  adapted to give and take management information by using a protocol, such as a SNMP between itself and a network unit, a network management system  303  adapted to monitor and control the condition of the network, a service management system  302  adapted to monitor the condition of the services received by the user, in cooperation with the network management system  303 , and a service ordering system  402  adapted to manage the reception of orders for private line services. The system of the user D is formed of a head office system  403  and a branch office system  404 . An access node  406  provided in a provider&#39;s service network  305  and a multiplexer  405  provided on the systems  403 ,  404  are respectively connected together. The user D can therefore utilize services simultaneously by using various types of business terminals network-connected to the multiplexer  405 . 
   In the same manner as in the first embodiment, the user makes a service level agreement with the service provider, i.e., defines a service quality evaluation model (group) and a SA evaluation policy. This operation is carried out by utilizing the service quality evaluation model (group) input screen  10551  shown, for example, in  FIG. 12 , which displays input fields for a customer&#39;s contract number  10222 , a name  10232  of a service group, the kinds  10552 ,  10557 ,  10560  of services, weighting coefficients  10553 ,  10558 ,  10562  for these services, service classes  10554 ,  10559 ,  10563 , service evaluation items of a usable band width  10555 , a transfer delay  10560  and an abandonment rate  10564  of cell, and degrading coefficients  10556 ,  10560 ,  10565  thereof. The user inputs information in all of these input fields. The weighting coefficients  10553 ,  10558 ,  10562  represent a relative order of precedence when there are plural kinds of services in the service group, and set so that the sum of all of the weighting coefficients becomes one. 
   In this embodiment, plural applications (EDI service, TV meeting service and e-mail) can be utilized at once on a common access line, and these services shall form one service group. When the user sets the weighting coefficients  10553 ,  10558 ,  10562  in accordance with the degree of importance of the applications in such a case, the service quality of the service group as a whole can be evaluated. 
   When a service group having net work resources in common is defined ( 10505 ) in the service availability calculation flow shown in  FIG. 9 , the service availability of the group as a whole is determined ( 10506 ) in accordance with the following equation.
 
 SA =Σ( SA  calculated for every kind of service×weighting coefficient) ( SA : Service Availability)  (2) 
 
   Owing to the service availability thus calculated, the user can determine, for example, what point in time the service contract number should be increased or decreased, by comparing the service availability of each single kind of service with each other, or with reference to the service availability of a group on which more important business requirement, i.e. more important kind of service for the above-mentioned business is reflected. 
   When the provider anticipates that a service quality-deteriorated condition will continue for a certain period of time, by utilizing the results of the summarization of service availability of the same kind of services, the service management system  302  can demand a temporary inhibition of the reception of orders for the same services from the service ordering system  402 . 
   Owing to the present invention described above, a service management system for obtaining a single index representing the degree of user&#39;s satisfaction in which the user&#39;s individual circumstances are taken into consideration, and determining the user&#39;s satisfaction on the basis of the index can be attained. 
   Also, a service management system giving other existing system instructions to execute suitable measures corresponding to the degree of the user&#39;s satisfaction can be attained.