JP5167317B2 - Session control apparatus, session control method and program thereof - Google Patents

Description

  The present invention relates to a traffic control technique in the case of performing a plurality of types of communication services via an IP (Internet Protocol) network or the like, and in particular, congestion control of a C-plane (call control signal plane) that performs signaling such as connection control, The present invention relates to a traffic control technique that takes into account both the usage status of resources of a U-plane (user information transfer plane) that transfers data. The session between the caller and the callee establishes a session using a connection request (SIP INVITE request or the like) and starts providing a service. This communication service establishes a session between a caller and a callee using a connection request (SIP INVITE request or the like), and starts providing the service.

  Conventionally, there are technologies for providing various communication services such as a telephone communication service via an IP network. There are the following techniques as congestion control techniques in such communication services. For example, Patent Document 1 discloses a technique for controlling the number of connections in a connection request based on the call density, which is the number of calls per unit time of each connection control device, in a telephone communication system using an IP network. ing. In addition, if any connection control device in the IP network performs over-regulation to prevent congestion, the connection request processing capability of the entire IP network may be reduced. In order to solve such a problem, there is a technique described in Patent Document 2.

  This patent document 2 discloses a technique for allocating the total number of calls (hereinafter referred to as the total number of calls) that can be processed by the ground of the call where the congestion occurs (hereinafter referred to as the total number of connections) to each connection control apparatus on the transmission side. Is disclosed. A call exceeding the number of calls allocated to each connection control device on the caller side (allocated call count) is regarded as a restricted encounter. The restriction encounter means that connection processing based on the connection request is not performed. According to such a technique, since the total number of calls is distributed to each connection control device on the transmission side according to the processing capability of the connection control device that has detected congestion in the network, the connection control device that has detected congestion in the network The congestion that has occurred can be calmed down while effectively utilizing the processing capacity of the connection request. That is, it is possible to suppress a decrease in the processing capacity of the connection request of the entire network due to congestion.

  Furthermore, as a bandwidth control method for an IP network, Non-Patent Document 1 describes RACS (which secures communication quality by securing the bandwidth (requested bandwidth) requested by each connection request in available resources (available bandwidth). Resource and Admission Control Subsystem) is disclosed. According to such a technique, it is possible to ensure communication quality in various communication services using the IP network.

  Here, in the IP network, the bandwidth required for calls (connection requests) in various communication services including a telephone communication service (for example, a videophone service, a video-on-demand service, or a voice or video distribution service) is the communication bandwidth. Different for each service. Therefore, when various communication services are provided in the IP network, in order to ensure the communication quality, in addition to call density control (see Patent Document 1) and total amount distribution (see Patent Document 2), bandwidth management control is performed. (See Non-Patent Document 1).

  For example, in an IP network, a method as shown in FIG. 2 is conceivable as a method for performing the above-described call density control and total amount distribution (hereinafter collectively referred to as absolute amount control) and bandwidth management control. This method establishes a session only for a connection request that communicates both the call density control and the bandwidth management control, and starts providing a service.

  First, in response to a connection request directed to a session control device (connection control device) where congestion has occurred, the traffic distribution calculation device determines the call density (number of calls per unit time ( The threshold value of the number of connection requests)) is notified. Then, the call density control unit of each session control device determines whether or not to make a regulation encounter using this call density threshold. For example, as shown in FIG. 1, when call density control is performed based on a call density threshold of 5 calls per second, up to 5 calls can be communicated in the first-come-first-served basis added to 1 second for multiple connection requests. All connection requests added after 6 calls are regulated. That is, even if a new connection request is received, the call number density control unit receives the connection request if the call number density threshold is not exceeded. Then, the received connection request is output to the bandwidth management control unit. On the other hand, even if a call connection density control unit receives a new connection request, if the call number density threshold is exceeded, the call number density control unit regards this connection request as a restriction encounter and does not output to the bandwidth management control unit. Next, the bandwidth management control unit determines whether or not the requested bandwidth of the connection request output from the call number density control unit is within the usable bandwidth. The bandwidth management control unit communicates when the requested bandwidth of the connection request is within the usable bandwidth, but does not communicate when the requested bandwidth exceeds the usable bandwidth, that is, it encounters a regulation encounter. As described above, even when the newly accepted connection request does not meet the regulation due to the call density, the session control device requests the new connection request when the requested bandwidth of the connection request exceeds the usable bandwidth. Suppose you encounter a regulation.

Japanese Patent No. 2749659 Patent 3715604 Specification

ETSI / TISPAN ES 282 003, [online], [Search March 30, 2010], Internet, <URL: http: //www.etsi.org/deliver/etsi#es/282000#282099/282003/02.00 .00 # 60 / es # 282003v020000p.pdf>

  However, when the session control apparatus subject to call restriction performs call density control and bandwidth management control in response to connection requests for various communication services in the IP network, as shown in FIG. A connection request that did not become a regulation encounter in the control by call density control becomes a regulation encounter in bandwidth management control, and the call density is wasted, and a new connection request occurs after that. Even if the usable bandwidth remains, if the call density is used wastefully and there is no unused call density, there is a problem that the usable bandwidth may not be effectively utilized. This will be described using a specific example.

  For example, when the call density is 5 calls / 1 second, the call density control unit in FIG. 2 accepts a new connection request on a first-come-first-served basis per second, and when the number of calls exceeds 5 calls, Suppose you encounter a regulation. For example, when the total available bandwidth is 80 Mbps, the bandwidth management control unit regulates this connection request when the total of the already used bandwidth and the requested bandwidth of the new connection request exceeds 80 Mbps. Let's say an encounter. Here, the call density control unit accepts connection requests indicated by reference numerals 901 to 906 in the order of arrival. In the example of this figure, 901, 902, ..., 905, 906 are accepted in this order. Further, it is assumed that the connection request bandwidth shown by reference numerals 901, 903, 904, and 906 is 10 Mbps, and the connection request bandwidth shown by reference numerals 902 and 905 is 30 Mbps. The call density control unit outputs the connection request to the bandwidth management control unit because the call density is within 5 calls / second until the connection request indicated by reference numeral 905. When this connection request is output to the bandwidth management controller, the call density is increased. However, when the connection request indicated by reference numeral 906 is received next to the connection request indicated by reference numeral 905, if this connection request is received, the call density exceeds 5 calls / 1 second. Makes this connection request a regulatory encounter. Here, when the connection requests indicated by reference numerals 901 to 904 are communicated, the usable bandwidth remains only 80 Mbps-60 Mbps = 20 Mbps. Therefore, the bandwidth management control unit regards the connection request (requested bandwidth = 30 Mbps) indicated by reference numeral 905 as a restriction encounter. By performing such restrictions, calls (connection requests) are concentrated on a predetermined session control device in the IP network, and communication is performed within the usable bandwidth while suppressing congestion, ensuring communication quality. it can.

  However, in such a method, there is a possibility that the available bandwidth in the IP network is not always effectively used. In other words, in the above example, both the connection request indicated by reference numeral 905 (request bandwidth = 30 Mbps) and the connection request indicated by reference numeral 906 (request bandwidth = 10 Mbps) are subject to regulatory encounters. The available bandwidth (20 Mbps) is not effectively used. In other words, even if the connection request indicated by reference numeral 905 becomes a regulation encounter in the bandwidth management control unit, the value of the call number density is increased when it is output from the call density control unit to the bandwidth management control unit. Therefore, the connection request indicated by reference numeral 906 received next is a restriction encounter. Therefore, with the method described above, the connection request indicated by reference numeral 906 cannot be communicated. For this reason, among the available bandwidths managed by this session control device, the connection request (10 Mbps) indicated by reference numeral 906 cannot be communicated even though there is a remaining available bandwidth (for 20 Mbps), The available bandwidth cannot be used effectively. As described above, when the session control apparatus accepts connection requests of various required bandwidths in the IP network, the value of the call density is unnecessarily increased, and the usable bandwidth may not be effectively used.

  Accordingly, the present invention solves the above-described problems, and performs session control in the IP network that provides various communication services, suppresses the occurrence of congestion, and effectively utilizes the connection request processing capacity and available bandwidth of the entire IP network. For the purpose.

In order to solve the above-described problems, the session control system of the present invention (1) performs a session based on a connection request transmitted from a terminal or another session control device on a C-plane (call control plane) of an IP network. The session control device to be established, and (2) the call density that is the number of calls per unit time that are used when the session control device encounters a restriction request for a connection request according to the processing capacity of the IP network session control device. And (3) bandwidth management for monitoring the usable bandwidth of the U-plane (user information transfer plane) of the IP network connected to the session control device and assigned to the session control device. And a control device. When the remaining resource amount allocated to the session control apparatus is equal to or less than a predetermined threshold, the session control apparatus notifies the traffic distribution calculation apparatus of the occurrence of congestion in the session control apparatus. Further, when the session control device receives a connection request restriction instruction for the congestion session control device, which is a session control device in which congestion occurs, including the calculated call density threshold value from the traffic distribution calculation device, Process. That is, the session control unit, the measurement of the call number density of the congestion session controller, done by performing communication with the counted number of calls per unit time, and the threshold of the call number density contained in the restriction instruction, the congestion Compare the call density to the session controller. Then, when the measured call density exceeds the threshold value, the session control device executes a restriction encounter for the received connection request. On the other hand, when the measured call density does not exceed the threshold value, the bandwidth management control device connected to the session control device is inquired whether the requested bandwidth indicated in the received connection request can be secured. When the session control device receives a response from the bandwidth management control device indicating that the requested bandwidth can be secured, the session control device executes connection processing based on the received connection request and increases the count value of the call density. . On the other hand, when the session control device does not receive a response indicating that the requested bandwidth can be secured from the bandwidth management control device, it does not instruct connection processing based on the received connection request and increases the count value of the call density. I won't let you.

  Conventionally, a C-plane session control device of an IP network regulates a connection request when the call density does not exceed a predetermined threshold but the requested bandwidth of the connection request exceeds the usable bandwidth. At this time, since the call number density remains increased, the call number density is used by a connection request that is not actually used (a session could not be established). At this time, even if there is a surplus in the usable bandwidth, even if the usable bandwidth remains due to the useless call density, the newly generated connection request cannot use the call density. There was a fear. However, the session control apparatus of the present invention increases the value of the call number density when the call number density is within a predetermined threshold and the requested bandwidth of the connection request is within the usable bandwidth. That is, even if the call density is within a predetermined threshold, the session control device does not increase the call density when the requested bandwidth of the connection request exceeds the usable bandwidth. Therefore, the session control apparatus can avoid that the call density is wasted due to call density control and the usable bandwidth is not wasted. As a result, even when various communication services are provided in the IP network, it is possible to reduce the congestion that has occurred and to effectively utilize the connection request processing capacity of the entire IP network and the usable bandwidth of the IP network.

  The present invention also provides a program for causing a session control device, which is a computer, to execute a session control method. According to such a program, a session control method can be executed by a general computer.

  According to the present invention, when the IP network provides various communication services, session control is performed by effectively utilizing the connection request processing capacity of the entire IP network and the usable bandwidth of the IP network, and calming the generated congestion. be able to.

It is the figure which showed the example of call density control. It is the figure which showed notionally the session control method used as a comparative example. It is the figure which showed the structural example of the session control system of this Embodiment. It is the figure which showed the example of a structure of the session control apparatus of the session control system of FIG. 3, a traffic allocation calculation apparatus, and a bandwidth management control apparatus. It is the figure which showed the process sequence of the session control apparatus of FIG. It is the figure which showed the modification of the process sequence of the session control apparatus of FIG.

  Hereinafter, modes (embodiments) for carrying out the present invention will be described. First, a configuration example of the session control system (system) according to the present embodiment will be described with reference to FIG. The system includes an IP network, and provides various communication services by connecting terminals (for example, PC (Personal Computer), etc.) 50 of the IP network via the session control device 10. . The communication service here is, for example, a voice or video distribution service such as a videophone service or a video on demand service. This system includes a session control device 10 (10A, 10B, 10C) that performs session control when connecting terminals 50 of an IP network, and each of the session control devices when congestion occurs in any one of the session control devices 10. 10 includes a traffic distribution calculation device 20 that instructs call restriction using call density. In the following description, the call density is the number of calls per unit time (number of connection requests).

  In the following description, a network in which the session control device 10 is installed is called a C-plane (call control signal plane), and data transmission / reception between terminals 50 is performed by a data transfer device (for example, a router). The network is called a U-plane (user information transfer plane). The C-plane and U-plane may be physically different networks, or may be physically the same network, and both may be logically different networks.

  This system includes a bandwidth management control device 30 (30A, 30B, 30C) that monitors the usable bandwidth of the U-plane. The bandwidth management control device 30 is connected to the session control device 10 and returns whether or not the requested bandwidth for the connection request can be secured in the available bandwidth monitored by the session control device 10 in response to an inquiry from the session control device 10. When the session control device 10 uses SIP (Session Initiation Protocol) for session control, this connection request is an INVITE signal or the like. In the following description, the congestion session control device is the session control device 10 in which congestion has occurred, and the call restriction session control device is the congestion session control device based on an instruction from the traffic distribution calculation device 20. It is assumed that the session control apparatus 10 that performs call restriction on the call is shown.

  Here, an outline of the operation of the system will be briefly described. When the session control apparatus 10 receives a new connection request from the terminal 50, the session control apparatus 10 establishes a session up to the target connection destination of the connection request. Here, for example, when connection requests to be processed in the session control apparatus 10A of FIG. 3 increase and resources are compressed and congestion occurs, the session control apparatus 10A notifies the traffic distribution calculation apparatus 20 of the occurrence of congestion. Next, the traffic distribution calculation device 20 calculates the total number of calls that can be processed by the session control device 10A (congestion generation session control device). Based on the total number of calls and the traffic status of the session control devices 10B and 10C, the call density used by the session control devices 10B and 10C (call control session control device) in the IP network to regulate connection requests The threshold value is calculated, and the call control density threshold value is notified to the session control apparatuses 10B and 10C. Then, the session control devices 10B and 10C regulate the connection request to the session control device 10A using the notified threshold value of the call density.

  Specifically, when the session control devices 10B and 10C receive a new connection request to the session control device 10A, the session control devices 10B and 10C determine whether or not the counted call density exceeds the call density threshold. To do. Here, if the counted call density value does not exceed the call density threshold value, the session control devices 10B and 10C use the requested bandwidth of this connection request to the bandwidth management control devices 30B and 30C. Queries whether it can be secured within the possible bandwidth. Next, when the session control device 10 confirms that the request request bandwidth can be secured, the session control device 10 communicates the connection request and increases the value of the call count density. Then, this connection request is transferred to the next session control apparatus 10A and connected between the connection destination terminals 50 to establish a session between the caller and the callee. On the other hand, if the requested bandwidth of the connection request cannot be secured within the usable bandwidth, this connection request is regarded as a regulation encounter and the value of the call density is not increased. When the call density exceeds the call density threshold, the session control apparatuses 10B and 10C make this connection request a restriction encounter.

  In this way, when a call control session control device accepts a new connection request, when the call density value is equal to or smaller than a predetermined threshold and the usable bandwidth can be secured, Increase the value. Therefore, the call control session control device increases the value of the call number density even for a connection request for which the usable bandwidth cannot actually be secured, so that the requested bandwidth for the next new connection request can be used. Even if it is below, it is possible to avoid the occurrence of regulations. According to such a system, it is possible to perform session control that effectively uses the available bandwidth without reducing the congestion generated by the IP network and using the call density unnecessarily.

  Next, the configuration of the session control device 10, the traffic allocation calculation device 20, and the bandwidth management control device 30 will be described with reference to FIG. In the following description, the input / output unit of each device includes an input / output interface and a communication interface. The processing unit is realized by a program execution process by a CPU (Central Processing Unit) included in each device, a dedicated circuit, or the like. Further, the storage unit includes a storage medium such as a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), and a flash memory. When each device is realized by program execution processing, a program for realizing the function of each device is stored in the storage unit of each device.

  The session control device 10 includes an input / output unit 11, a processing unit 12, and a storage unit 13. The input / output unit 11 controls input / output of data with other devices such as the traffic distribution calculation device 20 and the other session control device 10. The processing unit 12 controls the entire session control apparatus 10. The storage unit 13 stores a threshold value or the like when the session control apparatus 10 makes a restriction encounter using the call density.

  The processing unit 12 includes a resource monitoring unit 121, a call restriction requesting unit 122, a connection request processing unit 123, and a call density control unit 124.

  The resource monitoring unit 121 monitors whether the remaining resource amount to be monitored by the session control apparatus 10 is equal to or less than a predetermined threshold. That is, the resource monitoring unit 121 monitors whether or not connection requests to be processed in the session control apparatus 10 are increased and the resources are compressed and are in a congestion state. Here, the resource refers to, for example, the contract resource (the number of contracted lines) of the specific subscriber to be monitored by the session control apparatus 10 or the CPU usage rate of the session control apparatus 10.

  When it is detected that the remaining resource amount is equal to or less than a predetermined threshold, the call restriction request unit 122 notifies the traffic distribution calculation device 20 of the occurrence of congestion in its own session control device 10.

  The connection request processing unit 123 receives connection requests from the terminal 50 or other session control devices 10 via the input / output unit 11 in the order in which the connection requests are received. Then, data transmission / reception for session establishment is performed with another session control apparatus 10 or the connection destination terminal 50 of the connection request.

  The call density control unit 124 measures the call density to the congestion session control device, and uses the call density threshold included in the call restriction instruction received from the traffic distribution calculation device 20 to make a connection request. Call regulation (regulation encounter). That is, when the call density control unit 124 receives a connection request restriction instruction (call restriction) for the congestion session control device, the call number density control unit 124 calls the connection request to the congestion session control device from its own session control device 10. It is determined whether the number density exceeds this threshold value. Here, the call density control unit 124 sends the connection request to the connection request processing unit 123 via the input / output unit 11 when the call density of the connection request to the congestion session control device exceeds the threshold. Directing regulatory encounters. On the other hand, when the call density of the connection request to the congestion session control device is equal to or less than the threshold, the call density control unit 124 sends the requested bandwidth indicated by the connection request to the bandwidth management control device 30 via the input / output unit 11. Inquire whether or not can be secured. When the call density control unit 124 receives a response from the bandwidth management control device 30 that the requested bandwidth can be secured, the call number control unit 124 notifies the connection request processing unit 123 that the connection based on the connection request is permitted. Send. Then, the call density value recorded in the storage unit 13 is increased. On the other hand, when a response indicating that the requested bandwidth cannot be secured is received from the bandwidth management control device 30, the connection request is regarded as a regulation encounter. That is, the call density control unit 124 does not allow the connection request processing unit 123 to perform connection processing based on the connection request.

  The storage unit 13 stores a call density threshold value and a call density value communicated by the session control device 10 to be referred to when the call density control unit 124 performs call restriction using the call density. Remember.

  When receiving the notification of congestion detection from the congestion session control device, the traffic distribution calculation device 20 is based on the specific subscriber contract resource included in the congestion occurrence notification of the congestion session control device and the processing capability of each session control device 10. Then, each session control apparatus 10 calculates a call density threshold used for call restriction. The traffic distribution calculation device 20 includes an input / output unit 21, a processing unit 22, and a storage unit 23. The input / output unit 21 controls input / output of data with other devices such as the other session control device 10. The processing unit 22 controls the traffic distribution calculation apparatus 20 as a whole. The storage unit 23 stores information indicating the connection request processing capability of each session control device 10 for each identification information (address information or the like) of each session control device 10. Note that the processing capacity of this connection request is collected from each session control device 10 by the traffic distribution calculation device 20.

  The processing unit 22 includes an allocated call value determination unit 221 and a control instruction unit 222. When the distributed call value determination unit 221 receives a notification of occurrence of congestion from the congestion session control device via the input / output unit 21, the total number of calls that can be processed by the congestion session control device stored in the storage unit 23, Based on the processing capability of the connection request in the session control device 10, a threshold value for the call density to be distributed to each session control device 10 (call restriction session control device) is calculated. The calculation of the call density threshold here uses, for example, the techniques described in Patent Documents 1 and 2. That is, the session control apparatus 10 having a relatively large number of calls that can be processed per unit time increases the threshold value of the call number density. On the other hand, the session control apparatus 10 having a relatively small number of calls that can be processed per unit time lowers the threshold value of the call number density.

  The control instruction unit 222 transmits, via the input / output unit 21, a connection request restriction instruction including a call density threshold specific to the session control device 10 to each session control device 10.

  In response to the inquiry from the session control device 10, the bandwidth management control device 30 returns whether or not the requested bandwidth of the connection request can be secured in the usable bandwidth of the U-plane. The bandwidth management control device 30 includes an input / output unit 31, a processing unit 32, and a storage unit (not shown). The input / output unit 31 transmits and receives various data to and from the session control device 10 and a U-plane transfer device (not shown). The processing unit 32 controls the entire bandwidth management control device 30. The storage unit (not shown) of the bandwidth management control device 30 stores, for example, a usable bandwidth of the U-plane.

  The processing unit 32 includes a bandwidth management control unit 321, an available bandwidth monitoring unit 322, and a bandwidth reservation unit 323.

  The bandwidth management control unit 321 compares the requested bandwidth of the connection request indicated in the inquiry received from the session control device 10 with the usable bandwidth of the U-plane. Then, the bandwidth management control unit 321 (1) notifies the session control device 10 that the requested bandwidth for the connection request cannot be secured when the requested bandwidth exceeds the usable bandwidth of the U-plane. On the other hand, the bandwidth management control unit 321 instructs the bandwidth reservation unit 323 to reserve the requested bandwidth for the U-plane transfer device when the requested bandwidth is equal to or less than the usable bandwidth. Then, the bandwidth management control unit 321 transmits a response indicating that the requested bandwidth can be secured to the session control device 10 that is the transmission source of the inquiry.

  The usable bandwidth monitoring unit 322 monitors the usable bandwidth of the U-plane. Based on the reservation instruction from the bandwidth management control unit 321, the bandwidth reservation unit 323 transmits a reservation signal for the requested bandwidth to the U-plane transfer device.

Note that the interface for the inquiry of the usable bandwidth and the transmission / reception of the response between the bandwidth management control unit 321 of the bandwidth management control device 30 and the call density control unit 124 of the session control device 10 are, for example, DIAMETER-Gq 'I / F (interface) is used. For this DIAMETER-Gq'I / F, Draft ETSI TS 183 017 V3.0.0 (Resource and Admission Control DIAMETER protocol for session based policy set-up information
It is described in exchange between the Application Function (AF) and the Service Policy Decision Function (SPDF); Protocol specification).

  Next, with reference to FIG. 4, the processing procedure of the session control device 10 (10B, 10C) serving as a call restriction session control device and the bandwidth management control device 30 will be described using FIG. Here, when the traffic distribution calculation device 20 in FIG. 4 receives a notification of the occurrence of congestion from the congestion session control device, it calculates a threshold value of the call density used in each call restriction session control device. Then, a connection request restriction instruction including the call density density threshold is transmitted to the call restriction session control apparatus.

  Thereafter, the call density control unit 124 of the session control device 10 which is a call control session control device substitutes “0” for the value of the parameter a (the number of calls communicated per unit time), and measures the elapsed time. If the unit time has not yet elapsed (Yes in S102), the connection request processing unit 123 determines whether or not a new connection request has been received (S103). On the other hand, if the unit time has already passed (No in S102), the process returns to S101. That is, the call density controller 124 returns the value of the parameter a to “0” and starts measuring elapsed time again. When the call density control unit 124 determines in S103 that a new connection request has been received (Yes in S103), the value of parameter b (threshold for call density) ≧ value of parameter a (per unit time) If it is the number of calls that have been communicated (Yes in S104), the process proceeds to S105. That is, when the call number density of the connection request to the congestion session control device is equal to or less than the call number density threshold value notified from the traffic distribution calculation device 20, the call number density control unit 124 passes the bandwidth via the input / output unit 11. The management controller 30 is inquired whether the requested bandwidth indicated in the connection request can be secured. Then, the bandwidth management control unit 321 of the bandwidth management control device 30 substitutes the value of the requested bandwidth of the received connection request for the parameter c, and the usable bandwidth monitored by the usable bandwidth monitoring unit 322 for the parameter d. Is substituted (S105). On the other hand, when No in S103, the process returns to S102. After S105, when the value of the parameter c is equal to or smaller than the value of the parameter d (Yes in S106), that is, when the requested bandwidth of the connection request is equal to or smaller than the usable bandwidth, the bandwidth management control unit 321 secures the requested bandwidth. A response indicating that it is possible is transmitted to the session control apparatus 10 that is the transmission source of the inquiry. In addition, the bandwidth management control unit 321 instructs the bandwidth reservation unit 323 to reserve the requested bandwidth of the connection request to the U-plane transfer device. Then, the bandwidth management control unit 321 substitutes a value obtained by subtracting the value of the parameter c from the value of the parameter d as a new value of the parameter d (S107). That is, a required bandwidth indicated by the connection request is subtracted from the available bandwidth to obtain a new usable bandwidth. Further, the call density control unit 124 of the session control apparatus 10 that has received the response increases the value of the parameter a by one (S108). Then, the process returns to S102.

  In S104, the call density control unit 124 of the session control apparatus 10 determines that the value of the parameter a (the number of calls communicated per unit time) exceeds the value of the parameter b (the call density density threshold). Session control (No in S104) and when the bandwidth management control unit 321 of the bandwidth management control device 30 determines in S106 that the requested bandwidth of the connection request exceeds the usable bandwidth (No in S106). The connection request processing unit 123 of the device 10 sets the received connection request as a regulation encounter (S109).

  When the connection request processing unit 123 of the session control device 10 receives a response from the bandwidth management control device 30 indicating that the requested bandwidth of the connection request can be secured, the connection request processing unit 123 sends the connection request via the input / output unit 11. The connection request is transmitted to the next session control device 10 on the route to the connection destination. And the session control apparatus 10 which received this connection request also performs the process after S103 mentioned above. A session for providing a communication service is established between the terminals 50 in the IP network by executing such processing by each session control device 10 on the route to the connection destination terminal 50 of the connection request.

  As described above, the session control device 10 (call-restricting session control device) determines the call density when the call density does not exceed a predetermined threshold and the connection request bandwidth is within the usable bandwidth. The value of the parameter a used for the measurement is increased. The call density is regulated using the value of parameter a. Therefore, according to such a session control device 10, it is possible to perform session control that suppresses the occurrence of congestion in the IP network and effectively utilizes the available bandwidth. In general, congestion of the session control apparatus 10 often occurs due to concentration of the number of calls rather than a shortage of usable bandwidth. Therefore, the session control apparatus 10 first determines whether or not the regulation encounter should be performed by determining whether or not the regulation encounter should be performed using the call density threshold before the determination of the usable bandwidth. Can be quickly determined.

  In the above-described embodiment, it has been described that the bandwidth management control device 30 performs bandwidth management control after the session control device 10 performs call density control. However, the bandwidth management control device 30 performs bandwidth management control. After performing the above, the session control apparatus 10 may perform call density control. The processing procedure at this time is as shown in FIG.

  The processing in S201 to S203 in FIG. 6 is the same as that in S101 to S103 described above, and will be described from S204. When the answer is YES in S203, the call density control unit 124 of the session control device 10 can secure the requested bandwidth indicated in the connection request to the bandwidth management control device 30 via the input / output unit 11 as in S105. Inquire whether or not. Then, the bandwidth management control unit 321 of the bandwidth management control device 30 substitutes the value of the requested bandwidth of the received connection request for the parameter c, and the usable bandwidth monitored by the usable bandwidth monitoring unit 322 for the parameter d. Is substituted (S204). Here, when the value of the parameter c is equal to or smaller than the value of the parameter d (Yes in S205), that is, when the requested bandwidth of the connection request is equal to or smaller than the usable bandwidth, the bandwidth management control unit 321 is indicated in the connection request. It responds to the session control device 10 that the requested bandwidth can be secured. Then, the call number density control unit 124 of the session control apparatus 10 determines whether or not the value of the parameter b (call number density threshold) ≧ the value of the parameter a (the number of calls communicated per unit time) (S206). Here, if the value of parameter b (threshold of call density) ≧ value of parameter a (number of calls communicated per unit time) (Yes in S206), that is, the connection request to the congestion session control device When the call density is equal to or less than the call density threshold, the process proceeds to S207. Since the processes in S207 and 208 are the same as those in S107 and 108, description thereof is omitted.

  In S205, when the bandwidth management control unit 321 determines that the requested bandwidth of the connection request exceeds the usable bandwidth (No in S205), the call density control unit 124 determines the value of the parameter a (unit: When it is determined that the number of calls communicated per time) exceeds the value of parameter b (call density threshold) (No in S206), the connection request processing unit 123 sets the received connection request as a restriction encounter. (S209).

  Also with such a session control apparatus 10, it is possible to perform session control that effectively uses the available bandwidth without reducing the congestion of the IP network and using the call density unnecessarily.

10 (10A, 10B, 10C) Session control device 11, 21, 31 Input / output unit 20 Traffic allocation calculation device 12, 22, 32 Processing unit 13, 23 Storage unit 30 Band management control device 50 Terminal 121 Resource monitoring unit 122 Calling Restriction request unit 123 Connection request processing unit 124 Call density control unit 221 Allocation call value determination unit 222 Control instruction unit 321 Band management control unit 322 Usable band monitoring unit 323 Band reservation unit

Claims (3)

(1) a session control device that establishes a session on the C-plane (call control plane) of the IP network based on a connection request transmitted from a terminal or another session control device; and (2) session control of the IP network. (3) a traffic distribution calculation device for calculating a threshold value of call density, which is the number of communicated calls per unit time used when a restriction encounter for the connection request is made in the session control device according to the processing capacity of the device; The session control in a session control system comprising: a bandwidth management control device connected to the session control device and monitoring a usable bandwidth of a U-plane (user information transfer plane) of the IP network assigned to the session control device A device,
A connection request processing unit that accepts the connection requests from the terminal or other session control device in the order in which the connection requests are received, and executes restriction encounters for the accepted connection requests based on instructions from a call density control unit; ,
A resource monitoring unit that determines whether the remaining resource amount of the session control device is equal to or less than a predetermined threshold;
A call restriction requesting unit for notifying the traffic allocation calculating device of the occurrence of congestion in its own session control device when the resource monitoring unit determines that the remaining resource amount is equal to or less than a predetermined threshold; ,
The call density from the session control device to the congestion session control device that is the session control device in which the congestion has occurred when receiving a connection request restriction instruction including the call density threshold from the traffic distribution calculation device The call density is determined by comparing the call density density threshold included in the restriction instruction with the measured call density to determine whether or not the received connection request is restricted. A control unit,
The call density control unit
The call density is measured by counting the number of connected calls per unit time,
If the measured call density exceeds the threshold, the connection request processing unit is instructed to encounter a restriction on the received connection request,
When the measured call density does not exceed the threshold, the bandwidth management control device connected to the session control device is inquired whether the requested bandwidth indicated in the connection request can be secured,
When a response indicating that the requested bandwidth can be secured is received from the bandwidth management control device, the connection request processing unit is instructed to perform connection processing based on the received connection request, and the call density density count value is set. Increase ,
When the response indicating that the requested bandwidth can be secured is not received from the bandwidth management control device, the connection request processing unit is not instructed to perform connection processing based on the received connection request, and the call density A session control apparatus characterized by not increasing a count value . (1) a session control device that establishes a session on the C-plane (call control plane) of the IP network based on a connection request transmitted from a terminal or another session control device; and (2) session control of the IP network. (3) a traffic distribution calculation device for calculating a threshold value of call density, which is the number of communicated calls per unit time used when a restriction encounter for the connection request is made in the session control device according to the processing capacity of the device; The session control in a session control system comprising: a bandwidth management control device connected to the session control device and monitoring a usable bandwidth of a U-plane (user information transfer plane) of the IP network assigned to the session control device The device
When the residual resource amount allocated to the session control device is below a predetermined threshold,
Performing the step of notifying the traffic allocation calculation device of the occurrence of congestion in its own session control device;
When receiving from the traffic distribution calculation device a connection request restriction instruction to the congestion session control device, which is the session control device in which the congestion has occurred, including the calculated call density threshold, the session control device the measurement of the call number density to a session control device which congestion occurs congested session controller, done by performing a count of the number of calls that the communication per unit time, the number of calls included in the restriction instruction Comparing the density threshold with the call density to the congestion session controller;
If the measured call density exceeds the threshold, perform a regulatory encounter for the received connection request;
If the measured call density does not exceed the threshold, the bandwidth management control device connected to the session control device is inquired whether the requested bandwidth indicated in the received connection request can be secured, and When a response indicating that the requested bandwidth can be secured is received from the bandwidth management control device, connection processing based on the received connection request is executed, the count value of the call density is increased, and the bandwidth management control device The session control is characterized in that, when a response indicating that the requested bandwidth can be secured is not received, connection processing based on the received connection request is not instructed and the count value of the call density is not increased. Method.   The program for making the session control apparatus which is a computer perform the session control method of Claim 2.

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