JP3884304B2 - Communication control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a communication control method for managing status notifications performed with a gatekeeper in a VoIP (Voice over IP) device connected to an IP (Internet Protocol) network, for example.
[0002]
[Prior art]
The VoIP device is a general term for gateway devices and terminal devices that perform multimedia communication based on ITU-T Recommendation H.323. The gatekeeper manages devices in the IP network. Messages sent between the gatekeeper and the VoIP device are managed based on ITU-T recommendation H.323 and recommendation H.225. As one of the management methods, there is a method of notifying a state (keep alive) from the VoIP device to the gatekeeper.
[0003]
In this method, the VoIP device sends a registration request (Registration ReQuest: RRQ) message to the gatekeeper, and the VoIP device receives a response message from the gatekeeper for this transmission, that is, a registration confirmation (Registration ConFirm: RCF) message. To do. At this time, the VoIP device receives the RCF message and transmits the next RRQ message. The transmission interval is defined by the time to live (hereinafter referred to as TTL) included in the RCF message. The gatekeeper determines the operation of the VoIP device depending on whether or not the RRQ message is notified from the VoIP device within a certain time specified by TTL. When the RRQ is successfully received at the gatekeeper, the gatekeeper continues to register with the source VoIP device that supplies the RRQ.
[0004]
[Problems to be solved by the invention]
By the way, even if the VoIP device normally sends out the RRQ message immediately after the above-mentioned TTL time, the RRQ message may not reach the gatekeeper due to a slight delay occurring in the IP network, for example. The gatekeeper determines that the VoIP device has become unable to communicate due to some failure. As a result, the VoIP device becomes unregistered with respect to the gatekeeper.
[0005]
In order to eliminate the problem due to such delay, the VoIP device transmits the RRQ message after a fixed time shorter than the TTL time after receiving the RCF message. This fixed time is, for example, half of the TTL time.
[0006]
However, one gatekeeper accommodates thousands to tens of thousands of VoIP devices in a general VoIP network. In addition, since the route between the gatekeeper and the VoIP device is different, the network throughput is also different. Therefore, even if the RRQ message is sent from the VoIP device to the gatekeeper in a short fixed time, the IP network resources are occupied, which may promote network congestion and gatekeeper overload.
[0007]
It is an object of the present invention to provide a communication control method capable of solving such a drawback of the prior art and performing stable operation of a VoIP network.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention sends registration information for identifying this device from each of the devices constituting the network to the supply destination of this registration information via the network. The response information supplied in accordance with the registration information is received by each of the devices, and the response information includes the response information included in the response information. In the method of performing communication control with the supply destination, the first step of measuring the required time from sending the registration information to receiving the response signal, and calculating the difference between the time information and the measured required time, and calculating the calculated difference A second step of setting a new sending interval and a third step of sending the next registration information immediately after the elapse of the new sending interval, and responding to the sending of the next registration information as required And repeating the measurement start to the communication control.
[0009]
The communication control method of the present invention measures the required time, reflects the congestion of the network and the load situation of the supply destination that sends the registration information, etc. in the required time, and determines that the required time is all the delay time information. Is calculated as a new transmission interval, the next registration information is transmitted according to the new transmission interval, and the registration information is detected according to the transmission of this registration information. By responding and starting the measurement of the required time and repeating the communication control, it is possible to dynamically follow the situation even if the network situation changes each time, and other messages and packets are lost. Can be suppressed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of a VoIP device according to the present invention will be described in detail with reference to the accompanying drawings.
[0011]
In this embodiment, the communication control method of the present invention is applied to the VoIP device 10. The illustration and description of parts not directly related to the present invention are omitted. In the following description, the signal is indicated by the reference number of the connecting line in which it appears.
[0012]
The VoIP device 10 in FIG. 1 schematically shows a configuration for performing operation management in the device 10. The VoIP device 10 includes an RRQ / RCF detection function unit 12, a timer 14, a transmission interval calculation unit 16, and a system control unit 18. The VoIP device 10 includes a message generation unit that generates a message (not shown), a packetization unit that packetizes data, and a transmission / reception unit that transmits and receives packets. The VoIP device 10 is a device that performs multimedia communication according to ITU-T recommendation H.323.
[0013]
Although not shown, the RRQ / RCF detection function unit 12 is arranged in the data analysis unit. The RRQ / RCF detection function unit 12 detects RRQ / RCF from the data 20 supplied to the data analysis unit, and controls the operation of the timer 14 according to the detection. The RRQ / RCF detection function unit 12 starts the timer 14 by the control signal 22 supplied in the detection of RRQ, and stops the timer 14 by the control signal 22 supplied in the detection of RCF.
[0014]
The timer 14 includes a counter circuit that measures time according to the control signal 22. The timer 14 sets the time measured during this operation as the time required for communication in the network. In this embodiment, the required time reflects the congestion of the network, the load situation of the supply destination to which registration information is transmitted, etc., and all the required time is a delay. The timer 14 outputs the measured required time 24 to the transmission interval calculation unit 16. The timer 14 is reset after this output.
[0015]
The timer 14 sets a new transmission interval 28 obtained by calculation as described later, and measures the time of the set transmission interval. The measurement may be started at the rising edge of the clock signal, for example. The timer 14 notifies the RRQ transmission timing to the system control unit 18 when this transmission interval has elapsed.
[0016]
The transmission interval calculation unit 16 includes a subtraction circuit. The transmission interval calculation unit 16 is supplied with the TTL 26 extracted from the RCF by the data analysis unit and supplied with the required time 24 measured on the other side. The transmission interval calculation unit 16 calculates the difference between the TTL 26 and the required time 24. This difference is a new transmission interval 28 excluding the delay caused by the network. The transmission interval calculation unit 16 outputs a new transmission interval 28 to the timer 14. The timer 14 sets the supplied value.
[0017]
The system control unit 18 uses a CPU (Central Processing Unit). The RRQ transmission timing signal 30 is supplied from the timer 14 to the system control unit 18 in response to the completion of time measurement. The system control unit 18 receives the transmission timing signal 30 and outputs a control signal 32 so as to output an RRQ to a message generation unit (not shown). The VoIP device 10 outputs RRQ in response to this control.
[0018]
Next, a VoIP network system 40 using a plurality of VoIP devices 10 is shown in FIG. The VoIP network system 40 includes VoIP devices 10, 42, 44, 46, telephones 48a, 48b, and a gatekeeper 50 as components. The VoIP devices 42, 44, and 46 include a configuration for performing operation management in the same manner as the VoIP device 10 shown in FIG. The VoIP devices 10, 42, 44, 46 are connected to the IP network 100 via communication lines 10a, 42a, 44a, 46a. The VoIP devices 10 and 42 also connect to a PSTN (Public Switched Telephone Network) 200 via communication lines 10b and 42b, respectively, and also have the role of gateway devices. The VoIP devices 44 and 46 are connected to telephones 48a and 48b via communication lines 44b and 46b, respectively. The VoIP devices 10, 42, 44, 46 output the RRQ to the gatekeeper 50 during registration.
[0019]
The gatekeeper 50 is a device that provides admission control and address translation services to the terminal device or gateway device. The gatekeeper 50 has functions of performing bandwidth control, zone control, call control signaling, call authentication, bandwidth management, and call management in addition to the control described above. The gatekeeper 50 is connected to the IP network 100 via the signal line 52. The gatekeeper 50 outputs an RCF, which is a response signal, to the RRQ supplier in response to the RRQ supplied in registration. The RCF includes a TTL.
[0020]
In this embodiment, VoIP devices 10, 42, 44, and 46 are applied as elements of the VoIP network system 40 as terminal devices called endpoints in multimedia communication defined by ITU-T recommendation H.323. However, an MCU (Multipoint Control Units) may be used. Furthermore, it goes without saying that the present invention can be applied to all terminal devices compatible with ITU-T Recommendation H.323 using a gatekeeper.
[0021]
Next, a communication procedure for continuing communication based on registration in the VoIP network system 40 to which the VoIP device 10 is applied will be described (see FIG. 3). The VoIP device 10 sends a registration request message (hereinafter referred to as RRQ) 60 to the gatekeeper 50 at time t10. The VoIP device 10 detects the transmission of RRQ 60, activates the timer 14, and starts time measurement. Gatekeeper 50 receives RRQ 60 at time t12. The gatekeeper 50 returns a response signal to the VoIP device 10 by sending a registration confirmation message (hereinafter referred to as RCF) 62 at time t14. RCF 62 includes a TTL.
[0022]
The VoIP device 10 at time t16 receives the RCF 62 and detects the RCF. The VoIP device 10 stops measuring the timer 14 in response to this detection. The timer 14 sends the measured required time T0 to the transmission interval calculation unit 16. The transmission interval calculation unit 16 calculates a difference between the extracted TTL 26 and the required time T0, that is, a new transmission interval 28, and sends it to the timer 14. The timer 14 measures time with respect to the transmission interval 28. The timer 14 outputs an RRQ transmission timing signal 30 to the system control unit 18 when the time measurement is completed. The timer 14 resets the measurement. Further, if the timer 14 is operated so as to count down, it is convenient because the count value is 0 at the end of the previous time measurement.
[0023]
The system control unit 18 outputs a control signal 32 corresponding to the timing signal 30. In response to this control, the VoIP device 10 sends the RRQ 64 generated at time t18 to the gatekeeper 50. In response to the RRQ detection, the timer 14 starts measuring time. RRQ 64 is supplied to the gatekeeper 50 at time t20. The time t20 is within the TTL time range shown in FIG. In this way, when the RRQ is supplied and within the time indicated by the TTL, the gatekeeper 50 operates so that the VoIP device 10 determines that it is normal and continues the registration state.
[0024]
At time t22, the gatekeeper 50 transmits the RCF 66 to the VoIP device 10. The VoIP device 10 receives the RCF 66 at time t24, completes the measurement with the timer 14, and obtains the required time T1. RRQ 68 is output to gatekeeper 50 at time t26 after elapse of time corresponding to the difference between TTL and required time T1. The timer 14 again starts measuring the required time T2. RRQ 68 is supplied to the gatekeeper 50 at time t28. At this time, the TTL time is time t30. Therefore, the gatekeeper 50 continues the registration state for the device 10 when the VoIP device 10 is normal.
[0025]
As described above, the transmission time is determined by subtracting the required time from the TTL, assuming that the time required from the transmission of the RRQ to the reception of the RCF reflects the state of network congestion and the load state of the gatekeeper. When this transmission interval becomes a value of 0 or less, it is determined that there is no transmission interval and an RRQ is immediately transmitted. Thus, in order to operate quickly according to the value, the sending interval 28 may be supplied to the system control unit 18 although not shown.
[0026]
As a comparative example, communication control of the VoIP device 10 will be briefly described. In FIG. 3, after receiving the RCF 62 at time t16, the RRQ is transmitted after a TTL time has elapsed. Under this condition, the VoIP device 10 adds the TTL time to the time t16, and at time t32, transmits the RRQ 70 indicated by the broken line to the gatekeeper 50. RRQ 70 reaches the gatekeeper 50 at time t34. However, this arrival time (t34) is greatly deviated from the TTL time range. For this reason, in the VoIP network system 40, there is a possibility that the continuity of communication is lost and packets are lost. The VoIP network system 40 becomes unstable.
[0027]
As another comparative example, there is a method in which the transmission interval is fixed to a time shorter than half the TTL. For example, when the transmission interval is half the TTL, the gatekeeper 50 transmits a registration confirmation message RCF to the VoIP device 10 at time t14. At this time, the RCF 72 indicated by the alternate long and short dash line reaches the VoIP device 10 at time t36 due to a network delay or the like. In this case, the VoIP device 10 sends the RRQ 74 to the gatekeeper 50 at time t38 when half the TTL has elapsed from time t36. The RRQ 74 reaches the gatekeeper 50 at time t40. As shown in FIG. 3, since the time t40 is out of the TTL time range, the continuity of communication is lost in this case, and there is a possibility that the packet may be lost.
[0028]
By the way, when the communication control of the present embodiment is applied, even if the RCF 72 is supplied to the VoIP device 10 with a large delay from the time t36, the VoIP device 10 sets the RRQ as the transmission interval 28 only for (TTL-T0). Is controlled to be sent out. Therefore, the VoIP device 10 can output the RRQ for the RCF 72 at time t18. The RRQ 74 may arrive within the time from time t18 to time t22. A delay equivalent to this delay from the transmission of the RRQ 60 to the gatekeeper 50 from the immediately preceding VoIP device 10 is sufficient. Thus, it is clear that RRQ 74 can be reached within the TTL time range. In this way, by dynamically setting the transmission interval in consideration of the required time and performing communication control, it is possible to maintain communication continuity and prevent packet loss and operate the VoIP network system 40 stably. It becomes like this.
[0029]
By configuring as described above, the delay due to overload in the destination device such as network congestion and gatekeeper is measured, and this delay is taken into account and dynamically subtracted from the TTL time. The transmission interval is changed, communication control is performed so that the next RRQ is output according to the transmission interval, and the RRQ is supplied to the supply destination device within the TTL time. In the supply destination device, it is determined that the status of the supply source device and the communication path is normal at this time, and communication between the devices is continued. Accordingly, it is possible to stably operate a communication system that covers a delay in communication between apparatuses and suppresses packet loss.
[0030]
【The invention's effect】
As described above, according to the communication control method of the present invention, the transmission interval is dynamically changed in consideration of the delay caused by the communication, and communication control is performed so that the next registration information is output according to the transmission interval. The registration information is supplied to the supply destination device within the time information included in the response information, and the communication between the devices is continued. Accordingly, it is possible to stably operate a communication system that covers a delay in communication between apparatuses and suppresses packet loss.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an operation management unit in a VoIP device to which a communication control method of the present invention is applied.
FIG. 2 is a diagram illustrating a connection relationship of a VoIP communication network system to which the VoIP device of FIG. 1 is applied.
3 is a sequential chart illustrating a communication procedure between a VoIP device and a gatekeeper in the VoIP communication network system of FIG.
[Explanation of symbols]
10 VoIP equipment
12 RRQ / RCF detection function
14 timer
16 Transmission interval calculator
18 System controller
40 VoIP network system
50 Gatekeeper

Claims (3)

Registration information for identifying the device is sent from each of the devices constituting the network to the supply destination of the registration information via the network, and response information supplied according to the registration information is sent via the network. A method of performing communication control with the supply destination of the registration information in accordance with time information that is received by each of the devices and includes the response information, which defines a transmission interval from the reception of the response information to the transmission of the registration information The method comprises:
A first step of measuring a time required from sending the registration information to receiving the response signal;
A second step of calculating a difference between the time information and the measured required time, and setting the calculated difference as a new transmission interval;
A third step of sending the next registration information immediately after the elapse of the new sending interval,
A communication control method characterized by starting measurement of the required time in response to sending of the next registration information and repeating communication control. 2. The communication control method according to claim 1, wherein in the third step, when the new transmission interval is a value equal to or smaller than 0, the next registration information is transmitted immediately after reception. 3. The method according to claim 1, wherein the method communicates different types of information including video, audio, and data defined by ITU (International Telecommunication Union) -T (Telecommunication standardization sector) recommendation H.323. A communication control method characterized by being applied to the above.

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