JP2011130177A - Communication control system, and communication control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a communication load in a core network of a mobile communication system during communication between a mobile terminal and the Internet. <P>SOLUTION: A femtocell base station connects communication between a mobile terminal requesting access to an official site and a first server via a core network, by referring to a routing table, and connects the communication between a mobile terminal requesting access to an arbitrary site and a second server via a fixed broadband network, without going via a core network. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication control system and a communication control method for accessing different websites from a mobile terminal using a plurality of networks.

In recent years, with the spread of mobile terminals such as mobile phones, in addition to mobile terminal communication using the core network of the communication control system by mobile terminals, fixed broadband networks via smaller femtocell base stations Communication of mobile terminals using Internet is becoming available.
This femtocell base station is installed in the user's home or office in addition to a large outdoor base station and used in the vicinity of the user, for example, in order to expand radio coverage by a communication company that provides a mobile communication system Is a very small base station.

  For example, in communication from a femtocell base station to the Internet via a fixed broadband network, there are those that use different communication paths and communication channels depending on the contents and the like (see, for example, Patent Document 1 and Patent Document 2).

Moreover, there exist a thing as shown in FIG. 12, FIG. 13 as a communication control system using a femtocell base station.
As shown in FIG. 12, the conventional communication control system includes a fixed broadband network 120, a core network 130 of a mobile communication system, and the Internet 140. The mobile terminal 111 is connected to the Internet 140 via a femtocell base station 112. Are connected to the first server 141 or the second server 142 included.
Here, a site authorized by a mobile communications company that manages the mobile communications system (hereinafter referred to as an official site) is a specific certification authorized in the billing process or user authentication process provided on the core network 130. Accept only user access. It is assumed that a URL (for example, http://www.official.com/) and an IP address (for example, 20.0.2.1) are assigned to this official site.

  On the other hand, a site that is not certified by a mobile communication company (hereinafter referred to as a self-contained site) does not use the above-described billing process or user authentication process provided by the mobile communication company and is not certified in those processes. Also accepts access from users. It is assumed that a URL (for example, http://www.unofficial.com/) and an IP address (for example, 234.2.

The femtocell base station 112 is a base station for performing wireless communication with the mobile terminal 112 in the mobile communication system and connecting the mobile terminal 111 and a website on the Internet 140.
A femtocell gateway (hereinafter referred to as a femtocell GW) (mobile communication network-fixed network gateway) 131 is used when the fixed broadband network 120 is used as an access network to a mobile communication system using femtocells. A device connected to the core network 130 and the fixed broadband network 120 of the mobile communication system, and interconnects both networks.
A GGNS (external IP network gateway) 133 is a device connected to the core network 130 of the mobile communication system and the Internet 140, and interconnects both networks.
The core network 130 of the mobile communication system includes a DNS server 132 having a name resolution function.

Next, the sequence of the communication control system shown in FIG. 12 will be described with reference to FIG.
As shown in FIG. 13, when an Active PDP context request message is transmitted from the mobile terminal 111 to the GGSN 133 in order to request establishment of a communication session required for Internet access and acquisition of setting information, the mobile terminal 111 The IP address of the terminal 111 (for example, 10.1.0.1) is issued and notified to the mobile terminal 111. In addition, a communication session is established for communication of the mobile terminal 111 between the mobile terminal 111 and the GGSN 133 via the femtocell base station 112 and the femtocell GW131.

Here, when access to the official site (http://www.official.com/) is requested from the mobile terminal 111 to the DNS server 132, a communication session assigned to the mobile terminal 111 is used, The DNS server 132 of the mobile communication network notifies the mobile terminal 111 of the IP address (20.2.0.1) of the official site obtained by name resolution.
As a result, the message transmitted from the mobile terminal 111 is transferred to the fixed broadband network 120 via the femtocell base station 112 using the communication session assigned to the mobile terminal 111, and the femtocell GW131. To the core network 130. Further, this message is forwarded via GGSN 133 to a server providing an official site on the Internet 140. Thereby, the mobile terminal 111 is connected to a server that provides the official site, and can access the official site.

On the other hand, when the mobile server 111 requests the DNS server 132 to access a self-contained site (http://www.unofficial.com/), the DNS server 132 obtains the IP of the self-contained site obtained by name resolution. The mobile terminal 111 is notified of the address (234.20.2.133).
Thus, the message transmitted from the mobile terminal 111 is transmitted to the fixed broadband network using the communication session allocated to the mobile terminal 111 via the femtocell base station 112 in the same manner as in the official site. 120 and transferred to the core network 130 via the femtocell GW 131. Further, this message is forwarded to a server providing a self-contained site on the Internet 140 via the GGSN 133. As a result, the mobile terminal 111 is connected to the server that provides the arbitrary site and can access the arbitrary site.

  As described above, according to this communication control system, the message transmitted from the mobile terminal 111 may be an access to the official site or an access to an arbitrary site, the fixed broadband network 120 and the core network 130. To each server in the Internet 140.

JP 2009-21966 A JP 2009-504048 A

  However, there is a problem that the communication load in the core network 30 increases as the file size communicated between the mobile terminal 111 and the Internet 140 increases due to the spread and advancement of the mobile terminal 111.

  The present invention has been made in consideration of such circumstances, and has been made to solve the above-described problems. The object of the present invention is to communicate in a core network of a mobile communication system in communication between a mobile terminal and the Internet. An object of the present invention is to provide a communication control system and a communication control method that reduce a load.

  In order to solve the above problem, a communication control system according to the present invention connects a mobile terminal, a base station connected to the mobile terminal in a communication area, and the base station via a first network. And a second server connected to the base station via a second network different from the first network, the base station including the first server The first interface connected to the first network is associated with the first IP address representing the transmission destination of the message transmitted to the first server, and connected to the second network. A route that associates a second IP address representing a destination of a message transmitted to the second server with respect to the second interface being A first table connected to the first interface based on the routing table when the first IP address includes an IP address representing a transmission destination of a message received from the mobile terminal. When the message is transferred to the first server via the network, and the IP address indicating the destination of the message received from the mobile terminal is included in the second IP address, the routing table The message is forwarded to the second server via a second network connected to the second interface.

  In the communication control system according to the present invention, the base station includes the routing table associating a default route with the second interface as the second IP address, and transmits a message received from the mobile terminal. If the first IP address is not included in the first IP address, the message is sent to the second server via the second network connected to the second interface based on the routing table. It is characterized by transferring to.

  Further, in the communication control system according to the present invention, when the routing table has a plurality of IP addresses representing transmission destinations of messages transmitted to the first server, the number is smaller than the number of the plurality of IP addresses. An IP address group that aggregates the plurality of IP addresses in number is associated with the first interface as the first IP address, and the first IP address included in the IP address group is associated with the first IP address group. The IP address included in the IP address group is determined based on the message received from the base station via the first interface with reference to the information associated with the domain name of the first website provided by the server. A DNS server to be transmitted to the mobile terminal and the IP address group; The base station via the first interface with reference to information associating a plurality of third IP addresses representing each of the plurality of first servers with a plurality of IP addresses included in a group. The destination IP address included in the message received from the IP address group is converted from the IP address included in the IP address group to the third IP address, and the source IP included in the message received from the first server is converted. And a third server for converting an address from the third IP address to an IP address included in the IP address group.

  In order to solve the above problem, a communication control method according to the present invention includes a mobile terminal, a base station connected to the mobile terminal in a communication area, and the base station via a first network. A communication control method in a communication control system comprising: a first server connected to the base station; and a second server connected to the base station via a second network different from the first network, When the base station includes an IP address indicating a transmission destination of a message received from the mobile terminal in the first IP address, the base station is connected to the first interface connected to the first network. A first IP address representing a destination of a message transmitted to one server is associated and connected to the second network A first network connected to the first interface based on a routing table that associates a second IP address representing a transmission destination of a message transmitted to the second server with respect to the second interface; When the IP address indicating the destination of the message received from the mobile terminal is included in the second IP address, the message is transferred to the first server via the routing table. The message is transferred to the second server via a second network connected to the second interface.

  ADVANTAGE OF THE INVENTION According to this invention, the communication load in the core network of a mobile communication system can be reduced in communication between a mobile terminal and the internet.

It is a block diagram which shows an example of a structure of the communication control system which concerns on one Embodiment of this invention. It is a block diagram which shows an example of a structure of the femtocell base station which concerns on one Embodiment of this invention. It is the schematic explaining the system 1 of the communication control system which concerns on one Embodiment of this invention. It is the schematic explaining the system 2 of the communication control system which concerns on one Embodiment of this invention. It is a flowchart for demonstrating an example of the processing flow of IP communication in the system 1 of the communication control system which concerns on one Embodiment of this invention. It is a flowchart for demonstrating an example of the processing flow of IP communication in the system 2 of the communication control system which concerns on one Embodiment of this invention. It is a reference diagram for demonstrating the structure of the data utilized in the system 2 of the communication control system which concerns on one Embodiment of this invention. It is a sequence diagram for demonstrating access to the official site in the system 1 of the communication control system which concerns on one Embodiment of this invention. It is a sequence diagram for demonstrating access to a self-guided site in the system 1 of the communication control system which concerns on one Embodiment of this invention. It is a sequence diagram for demonstrating access to the official site in the system 2 of the communication control system which concerns on one Embodiment of this invention. It is a sequence diagram for demonstrating access to a self-guided site in the system 2 of the communication control system which concerns on one Embodiment of this invention. It is the schematic for demonstrating a prior art example. It is a sequence diagram for demonstrating the flow of a prior art example.

FIG. 1 is a block diagram illustrating an example of a communication control system according to the present embodiment.
As shown in FIG. 1, the communication control system according to this embodiment includes a subscriber network 10, a fixed broadband network 20, a core network 30 in a mobile communication system, and the Internet 40.

  The subscriber network 10 is a subscriber-side network that communicates with the mobile terminal 11 via the femtocell base station 12, and includes, for example, the mobile terminal 11, the femtocell base station 12, and the subscriber network termination. Device 13.

  The mobile terminal 11 is a communication terminal on the subscriber side that performs radio communication with the femtocell base station 12 and is connected to the fixed broadband network 20 via the femtocell base station 12. The mobile terminal 11 can establish a telephone communication by performing wireless communication between terminals via the core network 30. Here, the mobile terminal 11 connected to the Internet 40 via the fixed broadband network 20 using the femtocell base station 12 will be described below.

Further, the mobile terminal 11 requests the femtocell base station 12 for IP communication, so that an IP address (hereinafter referred to as IP address A) necessary for connection to the Internet 40 is a device in the fixed broadband network 20. (For example, a gateway) pays out. Here, the IP address A refers to the IP address of the mobile terminal 11 that can be used on the core network 30, but the present invention is not limited to this, and is an IP address that can be used on both the core network 30 and the Internet 40. Also good.
The mobile terminal 11 stores the IP address A in a storage unit provided therein.

The femtocell base station 12 is a base station that is wirelessly connected to a communication terminal in a very small communication area having a radius of about several tens of meters. For example, communication between the mobile terminal 11 in the communication area and the Internet 40 is performed. Connection is made via the subscriber network termination device 13.
The femtocell base station 12 includes a routing table, and refers to the routing table to access an official site on the Internet 40 based on access from the mobile terminal 11 or on the Internet 40. Determine whether to access an unofficial site (hereinafter referred to as a selfish site). Based on the determination result, the femtocell base station 12 transfers the message to the official site to the subscriber network termination device 13 via the core network 30 or the subscriber network termination via the fixed broadband network 20. The message to the arbitrary site is transferred to the device 13.

  This routing table stores the actual IP addresses (for example, 20.0.2.1, 20.0.2.2,...) Of official sites that can be used on the Internet 40 in the method 1 described below. The first interface 131 (for example, eth1) is associated with the first IP address X1, and the second interface 132 (for example, 0.0.0.0 shown in the figure) is used as the second IP address X2. , Eth0). The actual IP address is an IP address that can be used on the Internet 40.

Also, the routing table, in scheme 2 described below, a group of IP addresses that aggregates multiple IP addresses (hereinafter, referred to as IP address _{X A)} associated with the first interface 131 as a first IP address X1 .
And the aggregated IP address X _A, if the IP address representing a transmission destination of the message to be transmitted to the servers in the Internet 40 are a plurality, in the number smaller than the number of the plurality of IP addresses, this An IP address group that aggregates a plurality of IP addresses.

More specifically, a plurality of IP addresses (hereinafter referred to as IP addresses D) respectively assigned to a plurality of servers included in the Internet 40 (for example, 20.0.2.1, 20.2.0.2). ..)), The aggregated IP address X _A corresponds to each of the plurality of IP addresses (20.2.0.1, 20.0.2.2,...) A plurality of IP addresses (hereinafter referred to as IP addresses C) (for example, 10.2.0.1, 10.2.0.2,...) That can be used on the core network 30 are included. The plurality of IP addresses C (10.2.0.1, 10.2.0.2,...) Are, for example, IP addresses X _A (for example, 10.2.0.1/ 16).

Further, the femtocell base station 12 includes a NAT (Network Address Translation) table, and the IP address A of the mobile terminal 11 that can be used in the core network 30 can be used in the fixed broadband network 20 by referring to the NAT table. The IP address of the mobile terminal 11 (hereinafter referred to as IP address B) is converted.
The NAT table includes the IP address A (10.1.0.1) of the mobile terminal 11 that can be used in the core network 30 and the IP address B (for example, 192) of the mobile terminal 11 that can be used in the fixed broadband network 20. .168.1.11).

  The subscriber network termination device 13 is a home gateway installed on the subscriber side such as a BBR (Broad Band Router), for example, and is connected to an official site and a mobile unit on the Internet 40 via the fixed broadband network 20 and the core network 30. A first interface 131 that connects the terminal 11 and a second interface 132 that connects the mobile terminal 11 and the arbitrary site on the Internet 40 via the fixed broadband network 20 are provided.

  The fixed broadband network 20 is a broadband network provided by a fixed telephone company, for example, and is a network that connects a server that provides a site on the Internet 40 and the subscriber network termination device 13. The fixed broadband network 20 connects the first interface 131 of the subscriber network termination device 13 and the core network 30, and connects the second interface 132 of the subscriber network termination device 13 and the Internet 40.

  The core network 30 is a network provided by, for example, a mobile phone company, and is a network that connects a server that provides a site on the Internet 40 and the subscriber network termination device 13. The core network 30 includes a fixed network gateway 31, a DNS (Domain Name System) server 32, and an external IP network gateway 33.

  In addition, the core network 30 performs, for example, a user authentication process for performing user authentication of a user who accesses the official site and a billing process for a user who accesses the official site.

  This user authentication process refers to, for example, a process for authenticating that the access is from a user (for example, the mobile terminal 11) that can access the official site by the gateway 33 between the external IP networks of the core network 30. Specifically, the external IP network gateway 33 determines whether or not the access is from the mobile terminal 11 registered in advance in the official site server, or the registered mobile terminal 11 It is determined whether or not the access from the mobile terminal 11 is a valid user that can be accepted by the official website. In this determination result, when it is determined that the access is from the mobile terminal 11 that can access the official site, the external IP network gateway 33 authenticates the mobile terminal 11 and receives it from the mobile terminal 11. Forward the message to the server that provides the official website.

  The billing process is, for example, a process in which the external IP network gateway 33 of the core network 30 accepts payment of charges for access from the mobile terminal 11 to a paid official site. Specifically, the external IP network gateway 33 determines whether the access from the mobile terminal 11 is an access from a user who can pay a fee charged to the official site. If it is determined in this determination result that the access from the mobile terminal 11 is an access from a user who can pay a fee charged to the official site, the external IP network gateway 33 Is received, and the message received from the mobile terminal 11 is transferred to the server that provides the official site.

  The fixed network gateway 31 is, for example, a femtocell GW, and is a gateway that connects the subscriber network termination device 13 and the DNS server 32.

The DNS server 32 has a function of referring to information that associates an IP address with a domain name, and resolves the name. For example, a URL (Uniform Resource Locator) of a site on the Internet 40 is used as the domain name. If it is received from the mobile terminal 11, the IP address associated with the URL of this site is transmitted to the mobile terminal 11.
Here, in the case of the method 1 described below, the DNS server 32 uses an actual IP address D (for example, 20.2.0.1) and a domain name (for example, www.official.com) that can be used on the Internet 40. ), And the IP address D is transmitted to the mobile terminal 11 by referring to this information.
On the other hand, in the case of the method 2 described below, the DNS server 32 has an IP address C (for example, 10.2.0.1) and a domain name (for example, www.unofficial.com) that can be used on the core network 30. And the IP address C is transmitted to the mobile terminal 11 by referring to this information.

  The external IP network gateway 33 is, for example, a GGSN (Gateway GPRS Support Node) or the like, and is a gateway that connects a server that provides a site on the Internet 40 and the DNS server 32.

Further, in the method 2 to be described below, the external IP networks gateway 33, the IP address of the core network 30 that is aggregated by the IP address _{X A} C (e.g., 10.2.0.1,10.2 ...) Is provided with a NAT table that associates IP addresses D (for example, 20.0.2.1, 20.0.2....) On the Internet 40.
In method 2, the external IP network gateway 33 refers to the NAT table, converts the destination IP address of the message received from the mobile terminal 11 from the IP address C to the IP address D, and transmits it on the Internet 40. To the server. The external IP network gateway 33 converts the source IP address of the message received from the server on the Internet 40 from the IP address D to the IP address C and forwards it to the mobile terminal 11.

Further, the external IP network gateway 33 uses an IP address (hereinafter referred to as IP address E) (for example, 50.1.0.1) that can be used in the Internet 40 allocated in advance to itself as an internal IP address. Is stored in a storage unit.
When this external IP network gateway 33 receives a message from the mobile terminal 11, it stores the IP address A (10.1.0.1) described therein as the source IP address of the message. A NAT table is created that associates the IP address A that can be used on the Internet 40 with the IP address A that can be used on the core network 30.

More specifically, the external IP network gateway 33 refers to this NAT table in communication between the mobile terminal 11 and the Internet 40, and sets the IP address of the message received from the mobile terminal 11 as the IP address. A is converted into an IP address E and transferred to a server on the Internet 40. The external IP network gateway 33 converts the destination IP address of the message received from the server on the Internet 40 from the IP address E to the IP address A and transfers the IP address A to the mobile terminal 11.
When an IP address A that can be used in both the core network 30 and the Internet 40 is assigned to the mobile terminal 11, the external IP network gateway 33 refers to this NAT table and does not perform conversion. The message can be transferred using the IP address A.

  The Internet 40 includes, for example, a first server 41 that provides an official site on the Internet 40 and a second server 42 that provides an arbitrary site on the Internet 40.

The first server 41 includes a storage unit for storing information on the web page of the official site (for example, IP address, port number, or image data of the web page), and for the mobile terminal 11 that accesses the URL of the official site. To send information on the web page of the official website.
In this official site, for example, a URL (for example, http://www.official.com/) of the website is determined in advance, and this URL can be an IP address (for example, available on the Internet 40). 20.2.0.1) is assigned.

The second server 42 includes a storage unit that stores information on a web page of a self-contained site (for example, an IP address, a port number, or web page image data). To send information about the web page of the site.
For example, the URL of the website (for example, http://www.unofficial.com/) is determined in advance, and this URL may be an IP address (for example, available on the Internet 40). 234.20.2.133).

Next, the configuration of the femtocell base station 12 will be described in more detail with reference to FIG. FIG. 2 is a block diagram illustrating an example of the configuration of the femtocell base station 12.
As shown in FIG. 2, the femtocell base station 12 includes a radio unit 121, a primary storage unit 122, a storage unit 123, a control unit 124, and a communication module 125.

The wireless unit 121 wirelessly communicates with the mobile terminal 11 and receives a message from the mobile terminal 11.
For example, the primary storage unit 122 temporarily stores messages received from the mobile terminal 11.
The storage unit 123 stores a routing table and a NAT table.

  The control unit 124 comprehensively controls the femtocell base station 12 and performs routing of messages received from the mobile terminal 11, for example. The control unit 124 refers to the routing table stored in the storage unit 123 and transfers the message received from the mobile terminal 11 to the first interface 131 or transfers it to the second interface 132. The received message is routed based on the determination result.

  The communication module 125 transmits the message output from the control unit 124 to the subscriber network termination device 13 by IP communication, and based on the routing of the control unit 124, the first interface 131 or the second interface of the subscriber network termination device 13. The message is transferred to the interface 132.

Next, with reference to FIG. 3, system 1 in the communication control system according to the present embodiment will be described.
As shown in FIG. 3, in the scheme 1, the femtocell base station 12 refers to the routing table and performs communication between the mobile terminal 11 that requests access to the official site and the first server 41 in the core network. 30, and the communication between the mobile terminal 11 that requests access to the arbitrary site and the second server 42 is connected via the fixed broadband network 20 without passing through the core network 30. .

  As a result, communication between the mobile terminal 11 and the second server 42 via the fixed broadband network 20 can be established without going through the core network 30 in accessing the arbitrary site. The traffic in the core network 30 can be reduced. Therefore, the communication load in the core network 30 can be reduced.

On the other hand, method 2 different from method 1 will be described with reference to FIG.
As shown in FIG. 4, in Method 2, in addition to the configuration provided in Method 1, in the routing table provided in the femtocell base station 12, the first IP address X1 associated with the first interface 131 is aggregated. The associated IP address X _A (20.2.0.0/16) is associated with the first interface 131.

More specifically, in the scheme 2, the routing table mounted on the femtocell base station 12 associates the forwarding interface with the destination IP address as shown in FIG. For example, this routing table associates the second interface 132 (eth0) that is the forwarding interface with the default route (0.0.0.0 shown in the figure) that is the IP address of the transmission destination. In addition, this routing table associates the first interface 131 (eth1), which is a transfer interface, with the IP address X _A (10.2.0.0/16) in which the destination IP addresses C are aggregated.

  This routing table may be manually stored in the storage unit 123 of the femtocell base station 12 when the femtocell base station 12 is shipped, manufactured, or initially set. Further, at the first activation, the control unit 124 may automatically access the fixed inter-network gateway 31 or the external IP inter-network gateway 33 of the fixed broadband network 20 to acquire this routing table. Further, the femtocell base station 12 can acquire the changed routing table in the same manner even when the routing table is changed.

Further, in the method 2, the IP address that can be used on the Internet 40 to the IP address C included in the aggregated IP address X _A (20.2.0.0/16) in the gateway 33 between the external IP networks. A NAT table for associating D is implemented.
Specifically, the NAT table mounted on the external IP network gateway 33 is, for example, as shown in FIG. 5B, the NATed official site IP address (in this case, the IP address C), The port number of the NATed official site is associated with the actual official site IP address (here, IP address D) and the actual official site port number.

As described above, in the method 2, a plurality of IP addresses C (for example, 10.2.0.1, 10.2.0.2,...) Are less than the number of these plurality of IP addresses C ( For example, one IP address X _A (for example, 10.2.0.1/16) is aggregated, and this aggregated IP address X _A is set in the routing table of the femtocell base station 12. . Thereby, the amount of information held in the routing table can be reduced.
Therefore, traffic of the core network 30 can be reduced while ensuring serviceability (low delay) and operability (update / setting change).

In the schemes 1 and 2, the NAT table mounted on the femtocell base station 12 is an actual transmission source IP address (in this case, a mobile unit) that can be used on the Internet 40 as shown in FIG. The IP address A of the terminal 11, the port number of the actual transmission source that can be used on the Internet 40, and the IP address of the actual transmission destination that can be used on the Internet 40 (here, the IP address of the actual user's site) The destination port number that can be used on the Internet 40, the NAT IP address that can be used on the fixed broadband network 20 (here, IP address B), and the NAT port number that can be used on the fixed broadband network 20 are associated with each other.
The IP address B is issued to the femtocell base station 12 when the subscriber network termination device 13 communicates with the second server 42 via the fixed broadband network 20 when the femtocell base station 12 is activated. It is.

Next, an example of a processing flow in the system 1 of the communication control system according to the present embodiment will be described with reference to FIG. FIG. 6 is a flowchart for explaining an example of a processing flow of IP communication in method 1 of the communication control system according to the present embodiment.
As shown in FIG. 6, when a message requesting the start of IP communication is transmitted from the mobile terminal 11 to the femtocell base station 12, the femtocell base station 12 transmits a device in the core network 30 via the fixed broadband network 20. IP communication is started (step ST1). Thereby, for example, a virtual connection (radio bearer) is established by radio communication between the mobile terminal 11 and devices in the core network 30.

  At this time, the mobile terminal 11 transmits a message requesting acquisition of setting information (for example, IP address) necessary for access to the Internet 40 to the external IP network gateway 33. This external IP network gateway 33 pays out the IP address A that the mobile terminal 11 can use on the Internet 40 and transmits it to the mobile terminal 11.

  Next, a message requesting access destination name resolution from the mobile terminal 11 is transferred to the DNS server 32 via the femtocell base station 12. Then, the DNS server 32 receives this message, performs name resolution of the URL included in the message, and transmits an IP address corresponding to this URL to the mobile terminal 11 (step ST2).

  In other words, in method 1, the DNS server 32 obtains the actual IP address D (for example, 20.0.2.1) assigned to the site of the URL by name resolution, and obtains the gateway between the fixed networks. It is transmitted to the mobile terminal 11 via 31.

Then, the mobile terminal 11 transmits a message requesting access to the IP address D (20.2.0.1) received from the fixed network gateway 31 of the fixed broadband network 20 to the femtocell base station 12.
The femtocell base station 12 refers to the routing table in the storage unit 123 based on the IP address D (20.2.0.1) of the transmission destination included in the received message, and sends it to the first interface 131. The destination IP address D (20.2.0.1) is assigned to the associated first IP address X1 (for example, 20.0.2.1, 20.0.2.2,...). It is determined whether or not an IP address that matches is included (step ST3).

  Here, the destination IP address D (20.2.0.1) is an IP address included in the first IP address X1 associated with the first interface 131 described in the routing table. If they match, the control unit 124 of the femtocell base station 12 sends the mobile terminal 11 to the subscriber network termination device 13 via the first interface 131 associated with the first IP address X1. Is transferred to the core network 30 (step ST4).

The subscriber network termination device 13 sends out the message received from the femtocell base station 12 from the first interface 131 and transfers it to the first server 41 via the core network 30.
Thereby, the mobile terminal 11 performs IP communication with the first server 41 that provides the official site specified by the IP address D (20.2.0.1) (step ST5).

  On the other hand, in step ST3, the transmission destination IP address (for example, 234.20.2.133) is included in the first IP address X1 associated with the first interface 131 described in the routing table. If the IP address does not match, the control unit 124 of the femtocell base station 12 sets the second interface 132 associated with the second IP address X2 (default route) to the subscriber network terminating device 13. Then, the message received from the mobile terminal 11 is transferred to the fixed broadband network 20 (step ST6).

  When the control unit 124 of the femtocell base station 12 transmits a message to the fixed broadband network 20 via the second interface 132 to the subscriber network termination device 13, the NAT stored in the storage unit 123 is stored. With reference to the table, the source IP address included in the message can be used from the IP address A (10.1.0.1) of the mobile terminal 11 in the fixed broadband network 20 to the IP address B (192.168.8.1). .11) (step ST7).

  Then, the femtocell base station 12 sends a message received from the mobile terminal 11 to the subscriber network termination device 13 via the second interface 132 associated with the default route. To be transferred. The fixed network gateway 31 transfers the received message to the external IP network gateway 33, and the external IP network gateway 33 is specified by the IP address (234.20.2.133) included in the message. IP communication with the second server 42 of the self-contained site (step ST8).

Next, an example of a processing flow in the method 2 of the communication control system according to the present embodiment will be described with reference to FIG. FIG. 7 is a flowchart for explaining an example of a processing flow of IP communication in method 2 of the communication control system according to the present embodiment.
In addition, about the process similar to the process shown in FIG. 6, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

As shown in FIG. 7, when the femtocell base station 12 starts IP communication with a device in the core network 30 via the fixed broadband network 20 (step ST1), the mobile terminal 11 requests access destination name resolution. To the DNS server 32 via the femtocell base station 12.
The DNS server 32 receives this message, resolves the name of the URL included in the message, and uses an IP address C (for example, 10.2) that can be used on the core network 30 assigned to the site of the URL. .0.1) is transmitted to the mobile terminal 11 via the gateway 31 between fixed networks.

  Then, when the mobile terminal 11 receives a message requesting access to the IP address C (10.2.0. 1), the femtocell base station 12 transmits the IP address C (10.0.1. ), The routing table in the storage unit 123 is referred to and the IP aggregated to the first IP address X1 (10.2.0.0/16) associated with the first interface 131. It is determined whether the address matches the destination IP address C (10.2.0.1) (step ST3). In other words, the femtocell base station 12 determines whether or not the IP address C (10.2.0.1) is included in the first IP address X1 (10.2.0.0/16). .

  Here, the IP address C (10.2.0.1) of the transmission destination is the first IP address X1 (10.2.0.0/16) associated with the first interface 131 in the routing table. ), The control unit 124 of the femtocell base station 12 makes the first interface associated with the first IP address X1 to the subscriber network terminating device 13. The message received from the mobile terminal 11 is transferred to the core network 30 via 131 (step ST4).

  Then, the subscriber network termination device 13 sends out the message received from the femtocell base station 12 from the first interface 131 and transfers it to the first server 41 via the core network 30.

More specifically, a message transmitted from the first interface 131 of the subscriber network termination device 13 is transferred to the fixed network gateway 31 of the core network 30 via the fixed broadband network 20. This fixed network gateway 31 transfers the received message to the external IP network gateway 33.
Next, the external IP network gateway 33 refers to the NAT table and sets the destination IP address C (10.2.0.1) included in the message transmitted from the mobile terminal 11 to the site of the URL. It is converted into an actual IP address D (for example, 20.0.2.1) assigned to it (step ST9).

  Thereby, the mobile terminal 11 performs IP communication with the first server 41 that provides the official site specified by the rewritten IP address D (20.2.0.1) (step ST5).

  On the other hand, in step ST3, the destination IP address (234.20.2.133) is associated with the first interface 131 described in the routing table in the first IP address X1 (10.2. If the IP address does not match the IP address aggregated to (0.0 / 16), the same processing as Steps 6 to 8 shown in FIG. 6 is performed.

  Next, with reference to FIG. 8, an example of an access sequence to the official site in the method 1 described above will be described with reference to FIG. FIG. 8 is a sequence diagram of access to the official site in Method 1. In the following description, it is assumed that the radio bearer between the mobile terminal 11 and the core network 30 has already been established.

  As shown in FIG. 8, when an Active PDP Context request message is transmitted from the mobile terminal 11 to the femtocell base station 12, the femtocell base station 12 passes between the external IP networks via the subscriber network terminator 13. This message is transferred to the gateway 33 (step ST11). The external IP network gateway 33 allocates an IP address A (for example, 10.1.0.1) that can be used on the Internet 40 to the mobile terminal 11, and Active PDP Context Accept (PDP Address = 10. 1.0.1) message is transmitted to the mobile terminal 11 (step ST12).

  When the mobile terminal 11 receives a message including the IP address A (10.1.0.1) from the external IP network gateway 33, the mobile terminal 11 assigns the IP address A (10.1.0.1) allocated to itself. Is stored in a storage unit provided in its own.

  Here, when the user requests access to the official site specified by the designated URL (for example, http://www.official.com/) via the operation unit of the mobile terminal 11 or the like, The mobile terminal 11 uses the IP address A (10.1.0.1) as the IP address of the transmission source, and an IP address (for example, 10.0.2.10) allocated in advance to the DNS server 32. A DNS (Standard query A www.official.com) message including the destination IP address is transmitted to the femtocell base station 12. The femtocell base station 12 transfers the received message to the DNS server 32 via the subscriber network termination device 13 (step ST13).

  When the DNS server 32 receives a message from the mobile terminal 11, the DNS server 32 executes a name resolution function, and an actual IP address D (corresponding to the URL (http://www.official.com/) of the official site. For example, 20.2.0.1) is obtained and a DNS (Standard query response A 22.0.0.1) message is transmitted via the subscriber network termination device 13 and the femtocell base station 12 to the mobile unit. It transmits to the terminal 11 (step ST14).

  As a result, the mobile terminal 11 uses the IP address A (10.1.0.1) allocated to itself as the transmission source IP address, and the actual IP address D (20.2) whose name is resolved by the DNS server 32. .0.1) as a destination IP address, a TCP [SYN] message is transmitted to the femtocell base station 12 (step ST15).

The femtocell base station 12 refers to the routing table, and the destination IP address (20.2.0.1) included in the received message matches the IP address included in the first IP address X1. Is determined (step ST16). Here, in the routing table, an IP address (20.2.0.1) is described in advance as an IP address included in the first IP address X1.
Accordingly, since the destination IP address (20.2.0.1) matches the IP address included in the first IP address X1, the femtocell base station 12 adds the destination IP address (20 .2.0.1) is described and transmitted from the first interface 131 of the subscriber network terminating device 13 to the first server 41 via the fixed broadband network 20 (step ST17).

The first server 41 transmits a TCP [SYN, ACK] message to the mobile terminal 11 based on the received message (step ST18).
Next, the mobile terminal 11 transmits a TCP [ACK] message to the first server 41 (step ST19) and transmits a GET / HTTP / 1.1 message to the first server 41 (step ST20). ). The first server 41 transmits a TCP message to the mobile terminal 11 (step ST21), and transmits an HTTP 200 OK message to the mobile terminal 11 (step ST22).

  Thereby, the mobile terminal 11 is connected to the official site (IP address: 20.0.2.1) provided by the first server 41 on the Internet 40.

  Next, with reference to FIG. 9, an example of an access sequence to a self-guided site in the scheme 1 will be described. FIG. 9 is a sequence diagram of access to an arbitrary site in Method 1. In the following description, it is assumed that the radio bearer between the mobile terminal 11 and the core network 30 has already been established. Also, detailed description of the same processing as that described in FIG. 8 is omitted.

  As shown in FIG. 9, when the Active PDP Context request message is transmitted from the mobile terminal 11 to the external IP network gateway 33 (step ST31), the Active PDP Context Accept (PDP Address = 10.1.0.1). ) Is transmitted from the external IP network gateway 33 to the mobile terminal 11 (step ST32).

  Here, when the user requests access to an unspecified site specified by a specified URL (for example, http://www.unofficial.com/) via the operation unit of the mobile terminal 11 or the like, The mobile terminal 11 uses the IP address A (10.1.0.1) allocated to itself as the transmission source IP address, and the IP address (10.2.10) allocated in advance to the DNS server 32. ) Is transmitted to the DNS server 32 via the femtocell base station 12 and the subscriber network termination device 13 (step ST33).

  When the DNS server 32 receives the message from the mobile terminal 11, the DNS server 32 executes the name resolution function, and the actual IP address (234) associated with the URL (http://www.unofficial.com/) of the arbitrary site. 20.2.133) and transmits a DNS (Standard query response A 234.2. 2.133) message to the mobile terminal 11 (step ST34).

  As a result, the mobile terminal 11 uses the IP address A (10.1.0.1) allocated to itself as the transmission source IP address, and the actual IP address (234.20. 2. A message of TCP [SYN] including 2.133) as a destination IP address is transmitted to the femtocell base station 12 (step ST35).

The femtocell base station 12 refers to the routing table, and the destination IP address (234.20.2.133) included in the received message matches the IP address included in the first IP address X1. (Step ST36). Here, in the routing table, IP addresses (20.2.0.1, 20.0.2.2,...) Are described in advance as the first IP address X1.
That is, the destination IP address (234.20.2.133) matches the IP address included in the first IP address X1 (20.2.0.1, 20.0.2.2,...). Therefore, the femtocell base station 12 uses the source IP address A (10.1.0.1) (that is, the IP address that can be used in the core network 30) as the source IP address B (192.168.1. .11) (that is, an IP address that can be used in the fixed broadband network 20) (step ST37). This IP address B (192.168.1.11) is an IP address that can be used under the subscriber network termination device 13 included in the fixed broadband network 20.

  Then, the femtocell base station 12 uses the converted IP address B (192.168.1.11) as the transmission source IP address, and the actual IP address (234.20.2. 133) as a destination IP address is transferred from the second interface 132 of the subscriber network terminating device 13 to the second server 42 via the fixed broadband network 20 (step ST38). .

  Based on the received message, the second server 42 transmits a TCP [SYN, ACK] message to the femtocell base station 12 via the fixed broadband network 20 (step ST39). The femtocell base station 12 transfers a TCP [SYN, ACK] message to the mobile terminal 11 (step ST40).

Then, the mobile terminal 11 transmits a TCP [ACK] message to the femtocell base station 12 (step ST41). The femtocell base station 12 transfers the TCP [ACK] message to the second server 42 via the fixed broadband network 20 (step ST42).
In addition, the mobile terminal 11 transmits a GET / HTTP / 1.1 message to the femtocell base station 12 (step ST43). The femtocell base station 12 transfers the GET / HTTP / 1.1 message to the second server 42 via the fixed broadband network 20 (step ST44).

The first server 41 transmits a TCP [SYK, ACK] message to the femtocell base station 12 (step ST45). The femtocell base station 12 transfers a TCP [ACK] message to the mobile terminal 11 (step ST46).
Further, the first server 41 transmits an HTTP 200 OK message to the femtocell base station 12 (step ST47). The femtocell base station 12 transfers the HTTP 200 OK message to the mobile terminal 11 (step ST48).

  As a result, the mobile terminal 11 is connected to a self-contained site (IP address: 234.20.2.133) provided by the second server 42 on the Internet 40.

As described above, in Method 1 in the communication control system according to the present embodiment, the femtocell base station 12 refers to the routing table, and the mobile terminal 11 and the first server 41 request access to the official site. Communication between the mobile terminal 11 and the second server 42 that request access to a self-contained site without using the core network 30. To connect through.
As a result, communication between the mobile terminal 11 and the second server 42 via the fixed broadband network 20 can be established without going through the core network 30 in accessing the arbitrary site. The traffic in the core network 30 can be reduced. Therefore, the communication load in the core network 30 can be reduced.

For access to the official site in the core network 30, communication via the core network 30 can be established.
As a result, communication via the core network 30 can be established for the mobile terminal 11 that needs access to the first server 41 via the core network 30 for user authentication processing and billing processing. it can.

Furthermore, since the number of sites of the arbitrary site is larger than that of the official site, the default route is associated with the second interface 132 for the arbitrary site in the routing table of the femtocell base station 12. .
Thereby, the amount of information held in the routing table of the femtocell base station 12 can be reduced.

  Next, an example of an access sequence to the official site in the method 2 will be described with reference to FIG. FIG. 10 is a sequence diagram of access to the official site in method 2. In the following description, it is assumed that the radio bearer between the mobile terminal 11 and the core network 30 has already been established. Also, the same processes as those described in FIG. 8 are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in FIG. 10, steps ST11 to ST13 are the same as FIG.
In step ST54, when the DNS server 32 receives a DNS (Standard query A www.official.com) message from the mobile terminal 11, the DNS server 32 executes the name resolution function, and the URL (http: // www) of the official site. IP address C (10.2.0.1) associated with .official.com /) is obtained.
Then, the DNS server 32 transmits a DNS (Standard query response A 10.2.0.1) message to the mobile terminal 11 (step ST54).

  As a result, the mobile terminal 11 uses the IP address A (10.1.0.1) allocated to itself as the transmission source IP address, and the IP address C (10.2.0) whose name is resolved by the DNS server 32. .1) as a destination IP address, a TCP [SYN] message is transmitted to the femtocell base station 12 (step ST55).

The femtocell base station 12 refers to the routing table, and the destination IP address C (10.2.0.1) included in the received message is the first IP address X1 (10.2.0. (0/16), it is determined whether or not the IP address is included (step ST56). Here, in the routing table, an aggregated address space called an IP address (10.2.0.0/16) is described in advance as the first IP address X1 (see FIG. 5A).
Accordingly, since the destination IP address C (10.2.0.1) matches the IP address included in the first IP address X1 (10.0.0./16), the femtocell base station 12 Sends a message of TPC [SYN] including the destination IP address C (10.2.0.1) from the first interface 131 of the subscriber network terminating device 13 to the external IP network gateway 33 in the core network 30. (Step ST57).

  This external IP network gateway 33 refers to the NAT table and changes the destination IP address of the received message from IP address C (10.2.0.1) to IP address D (20.2.0.1). The TCP [SYN] message is transferred to the first server 41 of the official site (step ST58). Here, the external IP network gateway 33 refers to the NAT table and changes the source IP address of the received message from IP address A (10.1.0.1) to IP address E (50.1.0. 1). Hereinafter, description of the conversion from the IP address A to the IP address E is omitted.

  Upon receiving this message, the first server 41 transmits a TCP [SYN, ACK] message to the external IP network gateway 33 (step ST59). This external IP network gateway 33 refers to the NAT table and changes the source IP address of the received message from IP address D (20.2.0.1) to IP address C (10.2.0.1). And the TCP [SYN, ACK] message is transferred to the mobile terminal 11 (step ST60).

  Upon receiving this message, the mobile terminal 11 transmits a TCP [ACK] message to the external IP network gateway 33 (step ST61). This external IP network gateway 33 refers to the NAT table and changes the destination IP address of the received message from IP address C (10.2.0.1) to IP address D (20.2.0.1). The TCP [ACK] message is transferred to the first server 41 of the official site (step ST62).

  Next, the mobile terminal 11 transmits a GET / HTTP / 1.1 message to the external IP network gateway 33 (step ST63). This external IP network gateway 33 refers to the NAT table and changes the destination IP address of the received message from IP address C (10.2.0.1) to IP address D (20.2.0.1). The GET / HTTP / 1.1 message is transferred to the first server 41 of the official site (step ST64).

  Upon receipt of this message, the first server 41 transmits a TCP [ACK] message to the external IP network gateway 33 (step ST65). This external IP network gateway 33 refers to the NAT table and changes the source IP address of the received message from IP address D (20.2.0.1) to IP address C (10.2.0.1). The TCP message is transferred to the mobile terminal 11 (step ST66).

  Next, the first server 41 transmits an HTTP 200 OK message to the external IP network gateway 33 (step ST67). This external IP network gateway 33 refers to the NAT table and changes the source IP address of the received message from IP address D (20.2.0.1) to IP address C (10.2.0.1). The HTTP 200 OK message is transferred to the mobile terminal 11 (step ST68).

  Thereby, the mobile terminal 11 is connected to the official site (IP address: 20.0.2.1) provided by the first server 41 on the Internet 40.

Next, FIG. 11 is a sequence diagram showing an example of a sequence of access to an arbitrary site in the method 2.
As shown in FIG. 11, the processing shown here is the same as the processing shown in FIG. 9, and thus the same reference numerals are given and detailed description thereof is omitted.

As described above, in the method 2 in the communication control system according to the present embodiment, in addition to the configuration provided in the method 1, the first associated with the first interface 131 in the routing table provided in the femtocell base station 12 is provided. The IP address X _A (20.2.0.0/16) that has been aggregated is associated with the first interface 131 as the IP address X1.
Further, the NAT that associates the IP address D that can be used on the Internet 40 with the IP address C included in the aggregated IP address X _A (20.2.0.0/16) in the gateway 33 between the external IP networks. Added table implementation. Further, in the mapping set in the DNS server 32, the IP address C is associated with the domain name, and the IP address C is obtained by name resolution.
This reduces the amount of information held in the routing table of the femtocell base station 12, and reduces traffic on the core network 30 while ensuring serviceability (low delay) and operability (update / setting change). Can do.

Even if it is an official site that has fewer sites than a selfish site, there are thousands to tens of thousands of sites. Therefore, for example, every time the IP address of the official site changes, the changed IP address must be transmitted to each femtocell base station 12, and the routing table must be rewritten (updated / changed setting). However, by previously associated with the first interface 131 of the aggregated IP address _{X A} as the first IP address X1, the IP address IP address after the change is included in the aggregated IP address _{X A} In some cases, it is not necessary to rewrite the routing table, and time and labor can be reduced.

Further, when the femtocell base station 12 is developed at a low cost as a device installed in a home, a CPU (Central Processing Unit) with a small memory capacity and a low processing capacity may be mounted. is there. In this case, since the number of IP addresses referenced from the routing table is small, the routing time can be shortened, the control delay can be prevented, and the influence on the operation of the application requiring low delay can be reduced. it can.
That is, the traffic of the core network 30 can be reduced while ensuring serviceability (low delay) and operability (update / setting change).

In addition, since the number of sites on the site is huge compared to the official site, the default route is associated with the second interface 132 for the site on the side of the routing table of the femtocell base station 12. .
Thereby, the amount of information held in the routing table of the femtocell base station 12 can be reduced.

In addition, each structure in the communication control system which concerns on this embodiment is not restricted to the said embodiment, The following structures may be sufficient.
For example, the routing table in the femtocell base station 12 may be configured to have an IP address corresponding to the official site as a default route. In this case, the actual IP address of the arbitrary site is associated with the first interface 131. It may be.
Further, when the official site is associated as the default route, the first interface 131 may be associated with an IP address obtained by collecting a plurality of IP addresses of a plurality of arbitrary sites in the routing table.

  Further, the routing table in the femtocell base station 12 may not be associated with a default route for the first interface 131 and the second interface 132, and may be used for messages transmitted to the Internet 40. All IP addresses representing transmission destinations may be described.

In this case, the femtocell base station 12 refers to the routing table, and the first interface associated with the first interface 131 is based on the destination IP address included in the message received from the mobile terminal 11. It is determined whether or not the IP address X1 of the destination includes an IP address that matches the IP address of the destination, and the second IP address X2 associated with the second interface 132 is It is determined whether an IP address that matches the IP address is included.
When the IP address representing the destination of the message is included in the first IP address X1, the message is sent to the first network via the core network 30 connected to the first interface 131 based on the routing table. Transfer to server 41.
Further, when the IP address representing the message destination is included in the second IP address X2, the second IP address X2 is sent to the second message via the fixed broadband network 20 connected to the second interface 132 based on the routing table. To the server 42.

  In addition, terms used for describing the communication control system according to the present embodiment will be briefly described below.

  A femtocell base station is a device that terminates radio transmitted by a terminal in a mobile communication system. This femtocell is a word indicating that a cell that originally represents a coverage is very small, and a base station configuring the small cell is called a femtocell base station. However, in the definition of the unique terminology, a small-sized base station that makes up this small cell is connected to a fixed broadband network and used in a form that accommodates mobile phone traffic in the mobile communication system via the femtocell GW. The base station is often called a femtocell base station, and here, the term femtocell is used in the sense of a small base station that is connected to the fixed broadband network.

The Activate PDP context request is a message issued to request the mobile terminal to acquire setting information (usually IPv4 address and DNS server information) necessary for Internet access and establish a communication session.
The Activate PDP context accept is a message used to approve an acquisition request and notify the mobile terminal of an IP address and DNS server information.

  NAT refers to a process in the femtocell base station 12 or the external IP network gateway 33 that converts the destination IP address or source IP address of the forwarded message with reference to the NAT table.

  Further, the IP address specifically shown in the above is an arbitrary numerical value for explaining the embodiment, and only the private IP address or the global IP address is specified by the numerical value. is not. For example, an IP address that can be used on the Internet 40 may be a global IP address, and an IP address that is used on the subscriber network 10, the fixed broadband network 20, and the core network 30 may be a private IP. In addition, there may be no distinction between global and private depending on the network.

  DESCRIPTION OF SYMBOLS 10 ... Subscriber network, 11 ... Mobile terminal, 12 ... Femtocell base station, 13 ... Subscriber network termination device, 20 ... Fixed broadband network, 30 ... Core network, 31 ... Gateway between fixed networks, 32 ... DNS, 33 ... Gateway between external IP networks, 40 ... Internet, 41 ... first server, 42 ... second server

Claims (4)

A mobile terminal, a base station connected to the mobile terminal in a communication area, a first server connected to the base station via a first network, and a second different from the first network A communication control system comprising a second server connected to the base station via a network of
The base station
A first IP address representing a transmission destination of a message transmitted to the first server is associated with the first interface connected to the first network, and the second interface is associated with the second network. A routing table associating a second IP address representing a destination of a message transmitted to the second server with respect to the connected second interface;
When the IP address indicating the destination of the message received from the mobile terminal is included in the first IP address, based on the routing table, via the first network connected to the first interface And forwarding the message to the first server,
When the second IP address includes an IP address representing the destination of the message received from the mobile terminal, the second network is connected to the second interface based on the routing table. The communication control system transfers the message to the second server. The base station
The routing table associating a default route with the second interface as the second IP address;
When the IP address indicating the destination of the message received from the mobile terminal is not included in the first IP address, the second network connected to the second interface is connected based on the routing table. The communication control system according to claim 1, wherein the message is transferred to the second server. The routing table is
When there are a plurality of IP addresses representing transmission destinations of messages transmitted to the first server, an IP address group that aggregates the plurality of IP addresses to a number smaller than the number of the plurality of IP addresses is the first address group. 1 as an IP address associated with the first interface,
The base station is referred to via the first interface by referring to information associating each domain name of the first website provided by the first server with a plurality of IP addresses included in the IP address group. A DNS server for transmitting an IP address included in the IP address group to the mobile terminal based on a message received from
With reference to information associating a plurality of third IP addresses representing each of the plurality of first servers with a plurality of IP addresses included in the IP address group, respectively, via the first interface A transmission source included in the message received from the first server while converting the IP address of the transmission destination included in the message received from the base station from the IP address included in the IP address group to the third IP address 3. The communication control system according to claim 1, further comprising: a third server that converts the IP address of the second IP address from the third IP address to an IP address included in the IP address group. A mobile terminal, a base station connected to the mobile terminal in a communication area, a first server connected to the base station via a first network, and a second different from the first network A communication control method in a communication control system comprising a second server connected to the base station via a network of
The base station
When the first IP address includes an IP address representing a destination of a message received from the mobile terminal, the first server is connected to the first interface connected to the first network. A message transmitted to the second server with respect to a second interface connected to the second network while associating a first IP address indicating a destination of a message transmitted to the second network Forward the message to the first server via the first network connected to the first interface based on a routing table that associates a second IP address representing the destination of
When the second IP address includes an IP address representing the destination of the message received from the mobile terminal, the second network is connected to the second interface based on the routing table. The communication control method of transferring the message to the second server.

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