JP4724761B2 - Communication control device and program - Google Patents

Description

  The present invention relates to a technique for measuring communication quality of a communication network and controlling connection of a terminal device to the communication network based on the communication quality.

  An IP telephone service using VoIP communication technology that performs call connection control based on SIP (Session Initiation Protocol) is widely used. In particular, in recent years, wireless IP telephone services using wireless technologies such as wireless LAN are becoming widespread.

  In such a wireless IP telephone service, a terminal device that intends to use the service accesses the wireless access device wirelessly and connects to a SIP server or the like from there. Here, the communication quality of the section related to wireless communication varies depending on the radio wave condition, the number of terminal devices accessing the wireless access device, and the like, and is not stable compared to the wired section.

  However, the user of the terminal device cannot grasp whether or not the communication quality is good until the call connection is actually performed by the terminal device. Therefore, for example, the user of the terminal device first performs an operation to make a call to the other terminal device regardless of the communication quality status. However, depending on the communication quality status, communication may be interrupted or voice may be interrupted during the call. If you do.

  By starting a call regardless of the communication quality in this way, not only does the situation in which the user cannot satisfactorily continue the call occur, but it also adversely affects the communication quality of other users who have been making a good call May affect.

  In addition, although the terminal device used in the wireless IP telephone service generally operates on a battery, the communication quality is poor and communication cannot be performed normally, but by performing the process for call connection many times, The battery may be wasted.

  In addition, there exists patent document 1 as a prior art document relevant to this application.

JP 2007-208930 A

  If it is possible to know whether connection is possible based on communication quality before making a call with the terminal device, it is possible to communicate by means such as mail without performing call connection with the other party when the communication quality is poor. Such inconveniences such as influence on other terminal devices and wasteful consumption of batteries are eliminated. In addition, when a user makes a call, the user can always make a call with the other party with a certain good call quality.

  However, in the prior art, in order to grasp the communication quality, there is only a method such as measuring the time from when the test packet is transmitted from the terminal device to another device until the response is received, and this method is used. If so, the convenience for the user will be greatly reduced. In addition, there is a problem that the battery is consumed by processing only for quality measurement / determination not related to call connection processing.

  By the way, in an IP telephone based on SIP, a terminal device periodically transmits a registration request (REGISTER request) to a call control device (SIP server), thereby continuously maintaining registration information in the call control device. In bad communication quality situations where the connection to the communication network may be frequently lost, sending the registration request at a certain short time interval will cause the call control device to send the location information (IP address, etc.) of the terminal device. It is meaningful in that it can always be grasped and can be connected to both incoming and outgoing calls, but if the communication quality is good, the terminal device is likely to continue to connect to the communication network, and it is a short time interval. There is not much meaning to making a registration request at this point, which causes problems such as wasteful battery consumption and wasteful use of network resources.

  Note that the communication quality of IP networks such as the Internet used for IP telephones is not stable compared to fixed telephone networks. This is a problem that can occur not only with telephone services but also with IP telephone services that connect to IP networks by wire.

  The present invention has been made in view of the above points, and performs connection control of the terminal device according to the communication quality of the communication network without performing communication quality measurement from the terminal device, and is a wasteful transmission transmitted by the terminal device. The purpose is to provide a technique for reducing registration requests.

  In order to solve the above-described problem, the present invention provides a communication control device connected to a terminal device via a communication network, and a plurality of test packets in response to receiving a registration request message from the terminal device. Is transmitted to the terminal device, and for each test packet, a round-trip delay time, which is a time taken from transmitting the test packet to receiving a response packet, is measured, and the round-trip delay time is stored in the communication quality information storage means. The communication quality measuring means to be stored and the normality for determining whether or not the communication quality of the communication network is normal by comparing a plurality of round trip delay times stored in the communication quality information storage means with a predetermined reference value If the communication quality is determined not normal by the normality determination means and the normality determination means, the communication control is performed according to the history of the communication quality measurement result. Connection control for controlling connection so that the terminal device cannot be connected to another terminal device, or the terminal device can be connected to another terminal device for a predetermined period. And a communication control device.

  The history of the communication quality measurement result is a communication quality measurement result immediately before the current communication quality measurement performed by the communication quality measurement unit, and the connection control unit determines normality based on the previous communication quality measurement result. When the result of is not normal, the terminal device and the other terminal device can not be connected, and when the result of the normality determination based on the previous communication quality measurement result is normal, the predetermined time period Connection control may be performed so that the terminal device can be connected to another terminal device.

  Further, in order to make the connection between the terminal device and another terminal device incapable of being connected, the connection control means does not perform registration processing based on the registration request message, and the terminal device and the other device are only connected for the predetermined period. The connection control means may set the valid period of the registration information in the registration process based on the registration request message to the predetermined period so that the terminal apparatus can be connected to the terminal apparatus.

  When the normality determination means determines that the current communication quality is normal, and the normality determination result based on the previous communication quality measurement result is normal, the connection control means The validity period longer than the validity period of the registration information set based on the normality determination based on the communication quality measurement result may be set as the validity period of the registration information in the registration process based on the registration request message.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to perform connection control of a terminal device according to the communication quality of a communication network, without measuring communication quality from a terminal device. Further, when the communication quality is continuously normal, the valid period of the registration information is increased, so that useless registration requests transmitted by the terminal device can be reduced.

1 is a configuration diagram of a system according to an embodiment of the present invention. 2 is a functional configuration diagram of a communication control device 1. FIG. It is a figure which shows an example of the information which the communication quality measurement result storage part 14 stores. It is a sequence diagram for demonstrating the operation example of a system. It is a sequence diagram for demonstrating the operation example of a system. It is a sequence diagram for demonstrating the operation example of a system. It is a figure which shows the meaning of each state. It is a state transition diagram. 3 is a flowchart for explaining the operation of the communication control apparatus 1; 3 is a flowchart for explaining the operation of the communication control apparatus 1;

Embodiments of the present invention will be described below with reference to the drawings.
(System configuration)
FIG. 1 shows a configuration diagram of a system according to an embodiment of the present invention. As shown in FIG. 1, the system according to the present embodiment includes a communication control device 1 and a terminal device 2, which are connected to a communication network 3 such as the Internet. Of course, although not shown in the figure, many other terminal devices to which the terminal device 2 is connected are connected to the communication network 3.

  Although the connection form of the terminal device 2 to the communication network 3 is not particularly limited, in the present embodiment, the terminal device 2 is connected to the communication network 3 wirelessly, and the terminal device 2 is mobile so-called mobile. A terminal is assumed to be supplied with power by a battery.

  The terminal device 2 has a function of performing call connection based on SIP and performing VoIP communication, and a function of receiving an ICMP (Internet Control Message Protocol) echo request and returning an ICMP echo reply. These functions are functions that a terminal device for performing VoIP communication generally has.

  The communication control device 1 is a device having a function of performing call control communication based on SIP and performing connection control for the terminal device 2 based on the communication quality of the communication network between the terminal device 2 and the communication control device 1. FIG. 2 shows a functional configuration diagram of the communication control device 1.

  As illustrated in FIG. 2, the communication control device 1 includes a data communication unit 11, a SIP communication unit 12, a terminal device connection control unit 13, and a communication quality measurement result storage unit 14. The data communication unit 11 is a functional unit that performs data communication via the communication network 3.

  The SIP communication unit 12 is a functional unit that performs call control communication based on SIP, and includes a registration processing unit 15. The registration processing unit 15 is a functional unit that performs registration processing based on SIP, receives a registration request (REGISTER request) from the terminal device 2, and receives binding information (a set of terminal identification information such as name and address information). Processing such as storing in the storage means and returning a response is performed. The SIP communication unit 11 also has an authentication function such as digest authentication.

  The terminal device connection control unit 13 includes a communication quality measurement unit 16 and a connection control unit 17. Based on the instruction from the connection control unit 17, the communication quality measuring unit 16 transmits an ICMP echo request to the terminal device 2, and receives an ICMP echo reply returned from the terminal device 2, so that the ICMP echo request transmission time starts from the ICMP echo request transmission time. It is a functional unit that measures the time until the echo reply reception time (referred to as RTT: Round Trip Time) and stores it in the communication quality measurement result storage unit 14 as a communication quality measurement result. Communication quality measurement based on an instruction from the connection control unit is continuously performed a plurality of times.

  The connection control unit 17 has a function of determining the normality of the communication quality based on the communication quality measurement result and the like, manages the current state, and performs processing corresponding to the state so that the registration processing unit 15 and the communication quality This is a functional unit that controls the measurement unit 16. The connection control unit 17 has state storage means, stores the terminal identification information and the state in the state storage means, reads the state from the state storage means, performs control based on the state, and changes the state If so, the state stored in the state storage means is updated with the changed state.

  FIG. 3 shows an example of information stored in the communication quality measurement result storage unit 14. As illustrated in FIG. 3, the communication quality measurement result storage unit 14 stores terminal identification information, a communication quality measurement time, and a communication quality measurement result in association with each other.

  The communication quality measurement result storage unit 14 does not need to be provided in the communication control device 1 and may be realized as a database server connected to the communication network 3, for example. Further, the information stored in the communication quality measurement result storage unit 14 may be provided to the outside via the communication network 3, or may be accessible from the outside.

  The communication control device 1 is realized by installing a program for realizing the above-described functions in a computer having storage means such as a CPU and a memory. The program can be stored in a storage medium such as a portable memory, and can be installed in the computer from the storage medium.

  For example, the program transmits a plurality of test packets to the terminal device 2 in response to receiving a registration request message from the terminal device 2, and transmits a test packet for each test packet. A communication quality measuring means for measuring a round-trip delay time which is a time taken to receive a response packet, and storing the round-trip delay time in the communication quality information storage means; a plurality of round-trip delays stored in the communication quality information storage means When the communication quality is determined to be not normal by the normality determining means for determining whether the communication quality of the communication network is normal or not by comparing the time with a predetermined reference value In addition, depending on the history of the communication quality measurement result, the terminal device 2 cannot be connected to another terminal device, or a predetermined period Only it is configured as a program for causing the terminal device 2 and the other connection control means for connecting the control to a state capable of a connection between the terminal device function as a.

  The functional unit in the communication control device 1 is not limited to the configuration shown in FIG. Any functional configuration may be used as long as the processing operation for the terminal device 2 described below can be realized.

(System operation)
Hereinafter, an operation example of the system according to the present embodiment will be described with reference to the sequence diagrams shown in FIGS. In each figure, the communication quality measurement result storage unit 14 is shown outside the communication control device 1 for easy understanding of the operation. Further, in each sequence diagram described below, the “state” shown on the right side is a state managed by the communication control apparatus 1 and operation control is performed based on this state. Whether it is used will be described in detail after the description of the sequence diagram. In the process described below, an authentication process using an authentication header is performed, and it is assumed that this authentication process is always successful.

  First, an example of the operation of the system when the normality determination result of communication quality is normal will be described with reference to FIG.

  First, the terminal device 2 transmits an initial (non-retransmit) REGISTER request that does not include an authentication header to the communication control device 1 (step 1). In the communication control device 1, the registration processing unit 15 receives the REGISTER request, and the REGISTER request is passed to the connection control unit 17.

  The connection control unit 17 identifies that the REGISTER request is the first REGISTER request that does not include the authentication header, instructs the registration processing unit 15 to discard the REGISTER request, and communicates with the communication quality measurement unit 16. Is instructed to perform communication quality measurement. Accordingly, the registration processing unit 15 discards the REGISTER request without performing processing such as a response to the REGISTER request.

  The communication quality measuring unit 16 performs communication quality measurement. Specifically, first, the communication quality measurement unit 16 transmits an ICMP echo request a plurality of times to the terminal device 2 that is the transmission source of the REGISTER request (step 2). The number of times the ICMP echo request is transmitted is not limited to a specific value, but is assumed to be transmitted three times in the present embodiment. By performing a plurality of ICMP transmission / receptions and performing a determination using a plurality of RTTs in one communication quality measurement, an appropriate determination can be made without being confused by an instantaneous burst error.

  The terminal device 2 transmits an ICMP echo reply that is a response to the ICMP echo request, and the communication quality measuring unit 16 receives the ICMP echo reply (step 3). In addition, for each ICMP echo request, the communication quality measurement unit 16 calculates a time (RTT) from when the ICMP echo request is transmitted until the ICMP echo reply corresponding to the ICMP echo request is received, RTT, and measurement time. (The time when the last ICMP echo reply was received) and the terminal identification information of the terminal device 2 are associated with each other and stored in the communication quality measurement result storage unit 14 (step 4). The terminal identification information is information included in the REGISTER request, and the communication quality measurement result (RTT) of a specific terminal device can be referred to by using this terminal identification information.

  After that, the terminal device 2 retransmits the REGISTER request without the authentication header (step 5), and the registration processing unit 15 of the communication control device 1 receives the REGISTER request and notifies the connection control unit 17 of it. The connection control unit 17 identifies that the REGISTER request is a REGISTER request related to retransmission without an authentication header, and a plurality of terminal devices 2 stored in the communication quality measurement result storage unit 14 (this embodiment) Then, three RTTs are acquired (step 6).

  Then, the communication quality measurement result storage unit 14 compares a predetermined reference value with each RTT, and determines whether there is at least one RTT smaller than the reference value among the plurality of RTTs. Perform quality normality judgment. In the present embodiment, it is determined that the communication quality is normal when there is at least one RTT smaller than the reference value among a plurality of RTTs.

  In this example, there is at least one RTT smaller than the reference value among a plurality of RTTs, and the connection control unit 17 determines that the communication quality is normal, and returns a 401 response that is a response at this time. The registration processing unit 15 is instructed. The transmission / reception procedure of the REGISTER request and response according to the present embodiment is based on the procedure for performing digest authentication.

  When a 401 response is transmitted from the registration processing unit 15 to the terminal device 2 (step 7), the terminal device 2 transmits a REGISTER request including an authentication header to the communication control device 1 (step 8). In the communication control apparatus 1 that has received the REGISTER request, the communication quality is determined by referring to the RTT in the same manner as described above, and is determined to be normal, and a 200 OK response is returned to the terminal apparatus 2 (step 9, 10). Note that the normality determination process according to step 9 may not be performed.

  Thereafter, for example, if the terminal device 2 makes a call, an INVITE is transmitted from the terminal device 2, and the call connection and disconnection with the counterpart terminal device are performed.

  In the example of FIG. 4, after the validity period of REGISTER has elapsed, a REGISTER request with a new transaction authentication header attached is sent from the terminal device 2 to the communication control device 1 (step 11). In the communication control device 1 that has received the REGISTER request, the connection control unit 17 identifies that the REGISTER request is a REGISTER request including the first authentication header (in a new transaction), and the registration processing unit 15 401 is returned (step 12).

  Further, since the REGISTER request is the first REGISTER request, the connection control unit 17 instructs the communication quality measurement unit 16 to perform communication quality measurement. The communication quality measurement unit 16 performs communication quality measurement in the same manner as steps 2 and 3, and stores a plurality of RTTs as measurement results in the communication quality measurement result storage unit 14 (steps 13 to 15).

  Then, when the communication control device 1 receives the REGISTER request with the authentication header retransmitted from the terminal device 2 (step 16), the connection control unit 17 refers to the communication quality measurement result storage unit 14 to determine the RTT. Obtaining and determining the normality of the communication quality (step 17). Here, it is determined to be normal, and the registration processing unit 15 returns 200 OK to the terminal device 2 based on the instruction from the connection control unit 17 (step 18).

  In the example of FIG. 4, the normality determination result in the immediately previous communication quality measurement result is “normal”, and the normality determination result in the communication quality measurement result in step 15 which is the subsequent communication quality measurement result is also “normal”. It is. As described above, when the normality determination result in the communication quality measurement performed after the communication quality measurement in which the determination result of “normal” is obtained is “normal”, in the present embodiment, an instruction from the connection control unit 17 Based on the above, the registration processing unit 15 in the communication control apparatus 1 sets the previous normality determination to the binding information holding period (expiration time) (next holding period) related to the REGISTER request that triggers the next normality determination. It is increased from the retention period of the binding information related to the REGISTER request (previous retention period). Then, a 200 OK response including the increased retention period is returned to the terminal device 2. Further, the communication quality is measured next, and if the normality determination result is normal, the retention period is increased from the previous retention period.

  That is, if the normality determination result is normal continuously, the retention period is increased from the previous one. However, when the increased holding period reaches a predetermined maximum value, the holding period is set to the maximum value and is not increased thereafter. As an amount to be increased, for example, the next holding period is doubled from the previous holding period. If the normality determination result is not normal in the next normality determination, the initial value is set as the holding period at that time.

  In this way, by increasing the holding period when the normal state continues, it is possible to reduce unnecessary REGISTER request transmission from the terminal device 2, reduce unnecessary use of network resources, and reduce the power consumption of the terminal device 2. Can be reduced.

  The “immediately preceding” communication quality measurement result can be determined by referring to the measurement time stored in the communication quality measurement result storage unit 14. In addition, the normality determination result in the previous communication quality measurement result may be obtained by comparing with the reference value using the previous communication quality measurement result, or the normality determination result of each time together with the measurement time It may be stored in the communication quality measurement result storage unit 14 and read out.

  Next, a first example of a sequence including a case where a normality determination result that is not “normal” is obtained (an example in which a caution / temporary use is possible) will be described with reference to FIG. In the example shown in FIG. 5, it is assumed that the normality determination result immediately before receiving the first REGISTER request is normal.

  In FIG. 5, the communication quality measurement and the normality determination are performed in the same manner as in Step 1 to Step 4 of FIG. In the example of FIG. 5, all three RTTs are larger than the reference value in the normality determination, and “abnormal” is determined in the normality determination (determination related to step 21).

  In the example of FIG. 5, the result of the normality determination performed immediately before the normality determination of this time is normal, and the connection control unit 17 is performed immediately before by referring to the communication quality measurement result storage unit 14. Grasping that the result of normality judgment is normal.

  In the present embodiment, even if there is an abnormality in the current normality determination, if the previous normality determination is normal, the registration processing unit 15 instructs the registration processing unit 15 to set a predetermined period ( For example, processing for enabling the terminal device 2 to communicate with other terminal devices, such as setting a period shorter than the initial value), holding registration information (binding information), and responding to the terminal device 2 Do.

  That is, even after it is determined to be abnormal, the processes of steps 22 to 25 are performed in the same manner as steps 7 and 8 of FIG. The holding period included in the 200 OK response of step 25 is a period shorter than the above-described initial value, for example. Thereafter, for example, INVITE transmission / reception (steps 26 and 27) is obtained and a call is performed. However, in the example of FIG. 5, since the holding period is set short, the REGISTER request is transmitted (processing from step 1) at short time intervals.

  Even if the current determination is abnormal, if it is normal in the previous determination, there is a high possibility that the current abnormality is bursty or temporary. Therefore, by allowing the connection as in this example, convenience for the user is enhanced.

  Next, a second example of a sequence including a case where a normality determination result that is not “normal” is obtained (an example of an error / temporary unusable state) will be described with reference to FIG. In the example illustrated in FIG. 6, it is assumed that the normality determination result immediately before receiving the first REGISTER request is “abnormal”.

  In FIG. 6, communication quality measurement and normality determination are performed in the same manner as in Step 1 to Step 4 of FIG. In the example of FIG. 6, all three RTTs are larger than the reference value in the normality determination, and are determined as abnormal in the normality determination (determination related to step 32).

  In the example of FIG. 6, the result of the normality determination performed immediately before the normality determination of this time is abnormal, and the connection control unit 17 refers to the communication quality measurement result storage unit 14 and is performed immediately before. Grasp that the result of normality judgment is abnormal. In the present embodiment, when the previous normality determination is abnormal and the subsequent normality determination is also abnormal, the registration processing unit 15 is retransmitted from the terminal device 2 according to an instruction from the connection control unit 17. Response processing, registration processing, and authentication processing for the REGISTER request of the same transaction are not performed (ignored) (steps 33 to 36).

  Therefore, even if the communication control device 1 subsequently receives an INVITE request (step 37), normal processing related to the INVITE request is not performed, and a 480 response indicating that the communication is temporarily unavailable is returned (step 38).

  When the communication quality is continuously abnormal, the possibility that the communication quality is improved immediately is low, and thus the connection is not permitted as in this example. This can prevent wasteful power consumption, adverse effects on other terminal devices, and the like.

  After this, in a new transaction, a REGISTER request is sent from the terminal device 2 to the communication control device 1, the communication quality is measured, and the normality determination result is normal, the cautions shown in FIG. Processing in the primary availability state is performed.

(About state transition)
Next, each state in the communication control apparatus 2 will be described. FIG. 7 shows the meaning of each state. FIG. 8 shows a state transition diagram. These states are generated and managed for each terminal device (SIP-URI) and for each transaction.

  When the communication control device 1 receives the first REGISTER request from the terminal device 2, the communication control device 1 changes the state from waiting to checking (step 51 in FIG. 8), and starts communication quality measurement. If the normality determination result using the communication quality measurement result is normal, the state is changed from checking to alive (step 52). When the normality determination in checking is abnormal, if the result is normal in the normality determination before performing the normality determination, the state is changed to zombie (step 53). When the normality determination in checking is abnormal, the state is changed to dead if the result is abnormal even in the normality determination before the normality determination is performed (step 54).

  Further, the communication control device 1 in the alive or zombie state returns the state to wait when it returns a 200 OK response (steps 55 and 56). Further, the communication control device 1 in the dead or checking state times out after a predetermined time has elapsed since becoming dead or checking, and returns to wait (steps 57 and 58).

(About operation of communication control device)
Next, the operation of the communication control apparatus 1 will be described with reference to the flowcharts of FIGS. 9 and 10. The operation shown in FIG. 1 corresponds to the operation of the communication control device 1 extracted from the operation of the sequence described in FIGS. 4 to 6, but FIGS. 9 and 10 clearly show the processing procedure based on the state. Yes. 9 and 10 are performed by the registration processing unit 15, the connection control unit 17, and the communication quality measurement unit 16 shown in FIG. 2, but the functional classification is not limited to this. The communication control device 1 only needs to include means capable of executing the processes of the flowcharts of FIGS.

  In FIG. 9, when the communication control device 1 receives a REGISTER request from the terminal device 2 (step 101), it is determined whether or not the REGISTER request has an authentication header (step 102). If the REGISTER request includes an authentication header, the communication control device 1 determines whether the current state is wait (step 103), and if it is wait, returns a 401 response to the terminal device 2 (step 104). ), The state is set to checking (step 105), and the communication quality normality determination process is performed (step 106). The contents of the communication quality normality determination process will be described later with reference to FIG.

  If the authentication header is not included in step 102, the communication control apparatus 1 determines whether or not the current state is wait (step 107). If it is wait, the process proceeds to step 105.

  If it is wait in step 107, the communication control device 1 determines whether the current state is alive or zombie (step 108), and if it is alive or zombie, returns a 401 response to the terminal device (step 109). Return to the beginning of the flow. If it is neither alive nor zombie in step 107, it returns to the beginning.

  If the status is not wait in step 103, the communication control device 1 determines whether the status is alive (step 110). Here, when the state is alive, it means that the normality determination result of this time is normal, and the communication control device 1 determines whether the previous normality determination result for the terminal device 2 was normal in the next step 111. Determine if. When the previous normality determination result is normal, the communication control device 1 changes the retention period (Expire value) to twice the current value (step 112), and the value is equal to or less than a predetermined maximum value. Whether or not (step 113). If it is less than or equal to the predetermined maximum value, the communication control device 1 returns a 200 OK response to the terminal device 2 (step 114), and changes the state to wait (step 115).

  If the holding period after doubling is not less than or equal to the predetermined maximum value in step 113, the communication control device 1 sets the holding period to the predetermined maximum value (step 116), and the processing after step 114 I do. In step 111, when the previous normality determination result is not normal, the communication control apparatus 1 sets the retention period as an initial value (step 117) and proceeds to step 114.

  If the state is not alive in step 110, the communication control device 1 determines whether or not the state is zombie (step 118). If the state is zombie, the retention period is changed to an initial value and the process proceeds to step 114 (step 119) If not zombie, return to the beginning.

Next, the procedure of normality determination processing will be described with reference to the flowchart of FIG. The communication control device 1 transmits an ICMP echo request a plurality of times to the terminal device 2, receives each ICMP echo reply, calculates an RTT, and stores it in the communication quality measurement result storage unit 14 (step 201).
The communication control device 1 performs communication quality normality determination by determining whether any one of the plurality of RTTs obtained this time has an RTT less than the reference value (step 202). When the result in step 202 is normal, the communication control device 1 changes the state from checking to alive (step 203).

  If the result in step 202 is not normal, the communication control device 1 refers to the previous normality determination result and determines whether it is normal (step 204). If it is normal, the state is changed from checking to zombie (step 205). If not normal, the state is changed from checking to dead (step 206).

  The present invention is not limited to the above-described embodiments, and various modifications and applications are possible within the scope of the claims.

1 communication control device 2 terminal device 3 communication network 11 data communication unit 12 SIP communication unit 13 terminal device connection control unit 14 communication quality measurement result storage unit 15 registration processing unit 16 communication quality measurement unit 17 connection control unit

Claims (7)

A communication control device connected to a terminal device via a communication network,
In response to receiving the registration request message from the terminal device, a plurality of test packets are transmitted to the terminal device, and for each test packet, the time taken from receiving the test packet to receiving the response packet A communication quality measuring means for measuring a certain round-trip delay time and storing the round-trip delay time in a communication quality information storage means;
Normality determination means for determining whether or not the communication quality of the communication network is normal by comparing a plurality of round trip delay times stored in the communication quality information storage means and a predetermined reference value;
When the normality determining means determines that the communication quality is not normal, the communication control device cannot connect the terminal device to another terminal device according to a history of communication quality measurement results. Or connection control means for controlling connection so that the terminal device can be connected to another terminal device only for a predetermined period;
A communication control apparatus comprising: The history of the communication quality measurement result is a communication quality measurement result immediately before the current communication quality measurement made by the communication quality measurement means,
The connection control means, when the result of normality determination based on the previous communication quality measurement result is not normal, makes the connection between the terminal device and another terminal device impossible, and the previous communication quality measurement result The connection control is performed so that the terminal device can be connected to another terminal device only for a predetermined period when the result of normality determination based on the normality is normal. Communication control device.   Making the connection between the terminal device and another terminal device impossible means that the connection control means does not perform a registration process based on the registration request message, 3. The communication according to claim 2, wherein the state in which the connection with the terminal device can be established is that the connection control unit sets the valid period of the registration information in the registration process based on the registration request message to the predetermined period. Control device.   When the normality determination means determines that the current communication quality is normal, and the normality determination result based on the previous communication quality measurement result is normal, the connection control means The valid period of the registration information in the registration process based on the registration request message is a valid period that is longer than the valid period of the registration information set based on the normality determination based on the communication quality measurement result. 4. The communication control device according to 2 or 3.   The normality determination unit determines that the communication quality is normal when at least one of the plurality of round-trip delay times is smaller than the predetermined reference value. The communication control device according to any one of the above.   The communication control apparatus according to any one of claims 1 to 5, wherein the registration request message is a REGISTER request message in SIP. A program for causing a computer to function as a communication control device connected to a terminal device via a communication network,
In response to receiving the registration request message from the terminal device, a plurality of test packets are transmitted to the terminal device, and for each test packet, the time taken from receiving the test packet to receiving the response packet A communication quality measuring means for measuring a certain round-trip delay time and storing the round-trip delay time in a communication quality information storage means;
Normality determination means for determining whether or not the communication quality of the communication network is normal by comparing a plurality of round trip delay times stored in the communication quality information storage means with a predetermined reference value;
When the normality determining means determines that the communication quality is not normal, the communication control device cannot connect the terminal device to another terminal device according to a history of communication quality measurement results. Or connection control means for performing connection control so that the terminal device can be connected to another terminal device only for a predetermined period,
Program to function as.

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