JP2009124367A - Communication apparatus, network selecting method, and network selecting program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To execute switching to the optimum communication means by utilizing characteristics of communication flow when communication quality is degraded. <P>SOLUTION: A communication relaying apparatus 1 detects characteristics of flows with a flow detector 12 responding to a network connection request from a communication terminal 2 and starts communication by selecting the optimum network corresponding to the flow characteristics with a network selector 15 using the flow characteristic database 13 and network characteristic database 14. When a communication quality detector 16 detects that communication quality of the selected network is lower than the requested quality of communication flow, an item of the relevant network of the network characteristic database 14 is updated and the optimum network is newly selected in accordance with the flow characteristics. Here, the communication relaying apparatus 1 switches the network to that selected by the network selector 15 in the stage that the flow detector 12 has detected intermission of flows. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication device, and more particularly to a communication device that switches a plurality of bearers.

  In recent years, with the spread of wireless networks such as mobile phone networks and wireless LANs (Wireless LANs (Local Area Networks)), use cases of connecting to various networks using mobile terminal devices have increased. is doing.

  For example, as a communication system, there are a cellular network, a wireless LAN, a PHS (Personal Handyphone System) connection, Bluetooth (registered trademark), and the like. In addition, as a network to be connected, there are a cellular network, the Internet, a corporate intranet, and a home LAN. In addition, there is a VPN (Virtual Private Network) connection for these.

  When simultaneously connecting to a plurality of networks using IP (Internet Protocol), there are a plurality of routes for reaching the network service that the terminal wants to use. In order to perform communication, a terminal must determine a route (routing) so that a packet is transmitted to an appropriate network.

  JP-A-10-173703 (patent) which switches a port number of TCP (Transmission Control Protocol) / UDP (User Datagram Protocol) and a QoS (Quality of Service) parameter to normally perform path control using a normal IP address. There has been a technique called Policy Routing as shown in Document 1).

  Applying this, as a method of switching routing according to communication contents, a communication application or connection destination information as disclosed in Japanese Patent Application Laid-Open No. 2007-282142 (Patent Document 2) is received in the terminal, and application characteristics A method of selecting an optimum communication means from information in a database and a network characteristic database has been used.

  Further, as an improvement, a method for enabling selection and switching of the optimum communication means in the relay device using a flow characteristic such as a required bandwidth can be considered.

  In addition, bandwidth reservation type QS such as CBR (Constant Bit Rate) in ATM (Asynchronous Transfer Mode), RSVP (Resource reServation Protocol) in IP communication, and DiffServ (Differentiated Services) has been tried. These are performed in such a way that the capacity used by the communication flow is reserved in advance for a relay device such as a router or switch (Switching Hub) on the route, and a packet with a specific flow label is preferentially passed. I came.

  Further, Japanese Patent Laying-Open No. 2005-210347 (Patent Document 3) discloses a related technology of bandwidth reservation type. In this related technology, for the purpose of stabilizing streaming delivery, a method for preferentially allocating a bandwidth to a streaming flow by paying attention to a communication flow is proposed.

JP-A-10-173703 JP 2007-282142 A Japanese Patent Laid-Open No. 2005-210347

  Using the methods shown in Patent Document 1 and Patent Document 2, it is possible to select an optimal communication means at the start of communication, but it is possible to perform reselection when quality degradation occurs during communication. Can not. Here, the quality indicates communication quality.

  In addition, in the method that enables the selection and switching of the optimum communication means in the relay device using the characteristics of the flow such as the requested bandwidth, it is possible to switch when the optimum communication means cannot be selected at the start of communication. However, it does not correspond to the dynamic change of the communication environment.

  In the method of securing QoS by the bandwidth reservation type as shown in Patent Document 3, generally an extra cost is required compared to the best effort type. This is because the bandwidth reservation type QoS secures a fixed bandwidth as in the case of circuit switching regardless of the amount of data that actually flows, and the cost usually increases like a pay-as-you-go bill according to the reserved bandwidth. There are many cases to go. This is effective when strict QoS reservation is required, but measures such as jitter absorption by the buffer are also taken on the application side, and there is a case where QoS reservation up to that point is not required.

  For this reason, with a combination of related technologies, even in a case where strict QoS is not required, only a bearer capable of reserving a bandwidth can be used as an option to ensure a certain level of quality. Here, the bearer indicates a communication service in which a physical communication line and a logical protocol (Protocol) are combined. That is, the bearer can be considered as a physical communication line for performing communication based on a predetermined logical protocol. However, actually, it is not limited to a physical communication line. For example, a logical communication line such as L2TP (Layer 2 Tunneling Protocol) or VLAN (Virtual LAN) logically constructed on a physical communication line may be used.

  The object of the present invention is to provide a simple method only on the terminal side by switching bearers at any time during quality deterioration without increasing costs for strict QoS reservation and adding a complicated system to the network side. It is to provide a communication device, a network selection method, and a network selection program for ensuring quality that can be expected to be effective.

  A communication apparatus according to the present invention includes a flow detection unit that identifies a flow characteristic of communication with a network via a bearer, and a communication quality detection unit that identifies whether the bearer satisfies the required quality of the flow. And a network selection unit that detects a bearer according to network characteristics based on the characteristics of the flow, and switches the bearer to the detected bearer when a break in the flow is detected.

  The network selection method of the present invention includes: (a) identifying a flow characteristic of communication via a bearer with a network; and (b) identifying whether the bearer satisfies the required quality of the flow. And (c) detecting a bearer according to network characteristics based on the characteristics of the flow, and switching the bearer to the detected bearer when a break in the flow is detected.

  The network selection program according to the present invention includes: (a) identifying a flow characteristic of communication with a network via a bearer (Bearer); and (b) identifying whether the bearer satisfies the required quality of the flow. And (c) detecting a bearer according to network characteristics based on the characteristics of the flow and switching the bearer to the detected bearer when a break in the flow is detected. Let

  In a communication system that selects an optimal bearer using flow characteristics, it is possible to reselect and switch the optimal bearer at the time when the condition changes while continuing communication when communication quality deteriorates.

A first embodiment of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a block diagram showing the configuration of the communication relay system according to the first embodiment of the present invention.
The communication relay system according to the first embodiment of the present invention includes a communication relay device 1, a communication terminal device 2, and a network 3.

  The communication relay device 1 is a communication relay device that can connect to one or more (at least one) networks 3 and provide a network service to the communication terminal device 2.

  The communication terminal device 2 is an arbitrary communication terminal. The communication terminal device 2 is connected to the communication relay device 1 by wire or wirelessly. Here, the communication terminal device 2 is a terminal under the communication relay device 1. However, actually, it is not limited to this example. For example, the communication terminal device 2 may be a communication relay device installed in parallel with the communication relay device 1.

  The network 3 is a communication line. As the network 3, for example, various networks such as the Internet, an intranet, a wireless LAN spot, a home LAN, an in-store LAN, a dedicated line, and a telephone communication network are assumed. Here, it is assumed that the network 3 includes a service providing device (a network service providing source) such as a server that provides a network service to the communication terminal device 2 via the communication relay device 1. However, actually, it is not limited to this example.

  Here, the communication relay device 1 includes a communication unit 11, a flow detection unit 12, a flow characteristic database 13, a network characteristic database 14, a network selection unit 15, and a communication quality detection unit 16.

  The communication unit 11 is used for the communication relay device 1 to connect to the network 3. The communication unit 11 is also used for the communication terminal device 2 to connect to the communication relay device 1. That is, the communication unit 11 connects the communication terminal device 2 and the network 3. At this time, as a communication line for the communication relay device 1 to connect to the network 3, for example, a wired LAN, a wireless LAN, a public telephone network, a mobile phone network, PHS (Personal Handy-phone System), IrDA (Infrared Data Association) ), Bluetooth (registered trademark), WiMAX, 3G (third generation mobile phone), bearers such as serial communication, etc. are assumed. These bearers are included in the network 3 when used for connection. That is, bearer switching is synonymous with network 3 switching. Here, the bearer indicates a communication service in which a physical communication line and a logical protocol (Protocol) are combined. That is, the bearer can be considered as a physical communication line for performing communication based on a predetermined logical protocol. However, actually, it is not limited to a physical communication line. For example, a logical communication line such as L2TP (Layer 2 Tunneling Protocol) or VLAN (Virtual LAN) logically constructed on a physical communication line may be used. The protocol used for communication is mainly TCP / IP. A virtual network connection may be performed using a VPN (Virtual Private Network), which can also be regarded as a kind of bearer.

  The flow detection unit 12 identifies characteristics such as the type of flow from the communication content. Here, the type of flow indicates a protocol. That is, the flow characteristic indicates the characteristic of the protocol being used. The flow detection unit 12 can analyze the corresponding protocol by looking at the contents of the packet. Protocols used here include HTTP (Hyper Text Transfer Protocol), FTP (File Transfer Protocol), SMTP (Simple Mail Transfer Protocol), and PPPoE (PPP over Ethernet (registered trademark)). However, actually, it is not limited to these examples. In addition, the flow detection unit 12 detects a flow break.

  The flow characteristic database 13 is a database that stores communication flow characteristics. In addition, the flow characteristic database 13 stores a connection destination address, a port number, a combination of information on the requested speed, and the like. However, actually, it is not limited to these examples. At this time, the flow detection unit 12 identifies the flow characteristic by a method such as searching the flow characteristic database 13 using the connection destination address and the port number as keys.

  The network characteristic database 14 is a database that stores network characteristics. The network characteristic database 14 stores information on the bandwidth, security information, and communication charge of the network 3 to which the communication unit 11 can be connected. However, actually, it is not limited to these examples.

  The network selection unit 15 refers to the flow characteristics obtained from the flow detection unit 12 and searches the flow characteristic database 13 and the network characteristic database 14 to select an optimal network for the flow characteristics. Switch the network 3 to be connected to the selected network. At this time, the network selection unit 15 may instruct the communication unit 11 to switch to the selected network.

  The communication quality detection unit 16 detects deterioration of communication quality. As a method for detecting the deterioration of communication quality, for example, a method for obtaining information in which the communication capacity has changed due to handover from the network 3 connected via the communication unit 11, or the communication quality detection unit 16 itself measures flow throughput. There is a method of determining deterioration of communication quality by performing the above. The communication quality detection unit 16 notifies the network selection unit 15 when the communication quality deterioration is detected. The network selection unit 15 reselects an optimal network when the flow detection unit 12 detects a flow break and notifies the communication unit 11 of the selection. The optimal network here is a network that satisfies the speed required by the flow and is the lowest cost if it is determined with cost priority.

FIG. 2 shows an example of information held in the flow characteristic database 13.
Information representing the characteristics of each communication flow is stored in the flow characteristic database 13. In the example shown in FIG. 2, information on connection source terminal information, communication destination host name / IP address (communication destination identification information), protocol type, average traffic, used network, time stamp indicating the latest communication time, etc. Store. In this example, when the source is the terminal A, the connection destination is “www.foo.com”, and the protocol is HTTPS (Hypertext Transfer Protocol Security), the flow characteristic database 13 is searched by using these as keys. The flow characteristic that the average traffic of the flow is “32 kbps” can be obtained. Even if the HTTP is the same, the flow characteristics vary depending on whether the web page is browsed or used for streaming. When more detailed flow identification is necessary, it can be said that the communication is determined to be the same flow if communication from the same terminal is performed within a certain time by using the information of the transmission source and the time stamp.

FIG. 3 shows an example of information held in the network characteristic database 14.
The network characteristic database 14 stores information related to the communication characteristics of the network 3 to which the communication relay device 1 is connected. In the example shown in FIG. 3, information on the type of network 3, maximum bandwidth, usable bandwidth, security level, and billing system is set. However, in practice, information regarding at least one of the type of network 3, the maximum bandwidth, the available bandwidth, the security level, and the charging system may be set. That is, one or more types of information indicating network characteristics are set in the network characteristics database 14. In this example, since the wireless spot and the intranet are out of the usable area, the usable bandwidth is “0”. The charging system is “8 yen / minute” and “30 yen / minute” for the wireless spot and the cellular, respectively, and “0 yen / minute” because the intranet and the PHS are flat rate systems. Here, if there is a speed request of “32 kbps” from the flow characteristics, when the available bandwidth of the network characteristics database 14 is searched using this as a key, the cellular and the PHS satisfy the request, and the lower cost is the PHS. I know that there is.

FIG. 4 shows an example in which the information held in the network characteristic database 14 is corrected by the communication quality detection unit 16 when quality deteriorates.
In the example shown in FIG. 4, the available PHS bandwidth is changed from “64 kbps” to “32 kbps” due to the handover. Here, the communication quality detection unit 16 that has detected that the available bandwidth has decreased rewrites the PHS available bandwidth from “64 kbps” to “32 kbps”.

With reference to the flowchart shown in FIG. 5, the operation of switching the network 3 by the network selection unit 15 at the time of quality deterioration will be described.
(1) Step S101
The communication quality detection unit 16 monitors the bearer currently in use to determine whether the required flow quality is satisfied.
(2) Step S102
When the monitored bearer deteriorates in quality and does not satisfy the required quality, the communication quality detection unit 16 updates the item of the network characteristic database 14 of the bearer. That is, the communication quality detection unit 16 updates information related to the communication quality of the corresponding bearer stored in the network characteristic database 14. Here, the communication quality detection unit 16 updates information related to the available bandwidth of the corresponding bearer.
(3) Step S103
When the network selection unit 15 receives a notification of quality deterioration from the communication quality detection unit 16, the network selection unit 15 searches for a network to be switched to that satisfies the required quality of the current flow.
(4) Step S104
The network selection unit 15 waits without switching until it reaches the break of the flow.
(5) Step S105
The network selection unit 15 performs switching to the newly selected network when the flow break is reached.

  Here, using HTTP as an example, if a “GET” request is sent from the terminal side and a response is returned, even if the TCP session continues in a multi-session, it is determined that there is a break in the flow. be able to. On the contrary, even if the packet is temporarily interrupted, the flow continues until the end of the response. This is different for each method such as “GET” and “HEAD”, and “GET” has a response header and response body, but in the case of “HEAD”, the contents of the protocol are analyzed. Must.

  As an example of another protocol, FTP is taken as an example. In FTP, communication is performed using two ports, a control connection used for sending and receiving commands and a data connection used for sending and receiving files. For example, as shown in FIG. 6, the data connection is established after the log-in or the designation of the file to be transferred is performed by the control connection. Therefore, by monitoring the control connection, it is possible to know when the data connection flow occurs and ends. At this time, rewriting the address to send only the data connection to another bearer at the same time, or when transferring multiple files, sending the data connection established by each data transfer to a separate bearer It becomes possible.

FIG. 7 is a diagram showing an example of quality deterioration and bearer switching timing of a flow during communication.
In the example shown in FIG. 7, the communication quality detection unit 16 selects the network when the communication quality of the bearer A falls below the required quality and the quality deteriorates while the bearer A that is the initial optimum bearer is selected and used. Notification to the unit 15. The network selection unit 15 refers to the flow characteristics obtained from the flow detection unit 12 and searches for bearer switching candidates based on the flow characteristic database 13 and the network characteristic database 14. Here, bearer B is selected from the search result. In addition, the flow detection unit 12 detects a flow break. The network selection unit 15 reselects the optimum network when the flow is interrupted, and switches to the selected network. Here, the network selection unit 15 switches from bearer A to bearer B.

  According to the present embodiment, it is possible to switch from a bearer with deteriorated communication quality to a bearer with good communication quality without taking an extra cost method such as line duplexing or bandwidth reservation.

Next, a second embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 8 shows the configuration of the second embodiment of the present invention. The configuration of this embodiment is the same as that obtained by adding the address conversion unit 17 to the communication relay device 1 of FIG. 1 showing the configuration of the first embodiment.

  Therefore, in this embodiment, the communication relay device 1 includes the communication unit 11, the flow detection unit 12, the flow characteristic database 13, the network characteristic database 14, the network selection unit 15, the communication quality detection unit 16, and the address. A conversion unit 17 is provided. Here, the communication terminal device 2, the network 3, the communication unit 11, the flow detection unit 12, the flow characteristic database 13, the network characteristic database 14, the network selection unit 15, and the communication quality detection unit 16 are described in the first embodiment. It is the same.

  The address conversion unit 17 rewrites the address and port number of the packet relayed by the communication unit 11 in association with the address and port number used in the communication terminal device 2 and the address and port number used in the network 3. Communication between the communication terminal device 2 and the network 3 is made possible. At this time, the address conversion unit 17 may rewrite the address and the port number in response to an instruction from the network selection unit 15 to the communication unit 11 to switch to the selected network.

  Next, with reference to FIG. 9, the address conversion process in the present embodiment will be described. Here, for each of the four communication terminal apparatuses 2 connected to the communication relay apparatus 1, the communication relay apparatus 1 extracts local addresses (private addresses) A, B, C, and D. The communication relay device 1 has connections to four types of bearers and is given global addresses W, X, Y, and Z, respectively. Each communication terminal device 2 communicates through the communication relay device 1 when performing communication, and the communication relay device 1 rewrites the global address corresponding to the bearer using the local address.

  For example, if the flow characteristics of the communication terminal apparatus 2 to which the local address A is assigned satisfy the PHS network characteristics and PHS is available, the communication relay apparatus 1 sets the local address A to the global address Z. The communication to the external network is established using the bearer PHS.

  If the communication quality deteriorates due to movement or the like in this state, as shown in FIG. 7, the used bearer is in a quality deterioration state that does not satisfy the required flow quality. If 3G, which is another bearer at this point, satisfies the required quality of the flow and is optimal including other conditions such as cost, it is desirable to quickly switch the bearer from PHS to 3G. Here, by using the timing at which the flow is interrupted to change the address rewriting by the address conversion unit 17 from Z to Y, the communication terminal device 2 having the local address A switches the bearer to be used to 3G for communication. It can be performed.

  According to the present embodiment, bearer switching can be performed without interrupting communication by bearer switching on the communication terminal device 2 side by changing the address rewriting destination at the stage where a flow break is detected after quality degradation.

Next, a third embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 10 shows the configuration of the third embodiment of the present invention. The configuration of this embodiment is the same as that obtained by adding the protocol conversion unit 18 to the communication relay device 1 of FIG. 1 showing the configuration of the first embodiment.

  Therefore, in this embodiment, the communication relay device 1 includes the communication unit 11, the flow detection unit 12, the flow characteristic database 13, the network characteristic database 14, the network selection unit 15, the communication quality detection unit 16, and the protocol. A conversion unit 18 is provided. Here, the communication terminal device 2, the network 3, the communication unit 11, the flow detection unit 12, the flow characteristic database 13, the network characteristic database 14, the network selection unit 15, and the communication quality detection unit 16 are described in the first embodiment. It is the same. Note that the communication relay device 1 may further include the address conversion unit 17 described in the second embodiment.

  The protocol converter 18 operates as a proxy, and enables communication between the communication terminal device 2 and the network 3 by rewriting the contents of a protocol used for communication such as HTTP or FTP. The proxy functions as both a terminal and a server, and acts as a server for the terminal and as a terminal for the server.

  Next, referring to FIG. 11, the protocol conversion processing in the present embodiment will be described. This figure shows how the request URL is rewritten in the HTTP proxy.

  The communication terminal device 2 uses the address (A) given by the communication relay device 1 as a source address, the destination address (a) and the port number of the communication relay device 1, and the URL is also the server address in the path portion. A proxy format including (www.foo.com) and a port number (80 in the case of omission) is used. Since the communication relay device 1 functions as an HTTP proxy, the URL in the proxy format is analyzed to obtain the server address and port number, and the URL is rewritten for the server (excluding the address and port number). When the PHS is selected by the network selection unit 15 as the optimal bearer that satisfies the flow characteristics, the communication relay device 1 uses the address (Z in the case of PHS) assigned to the bearer as the transmission source address to the server. On the other hand, by making a request to the transmission destination address (www.foo.com) and the port number (80 in the case of omission) obtained by analyzing the URL earlier, communication by the optimum bearer becomes possible.

  The operation on the side of the communication terminal device 2 is an operation when a general HTTP proxy is used. However, when the communication relay device 1 works as a transparent proxy, the connection destination address and the port number are those of the server, and the URL Can also be in normal form.

  In addition, you may implement each said Example in combination.

  The operation for bearer switching in each of the above embodiments is called a network selection method. A program for causing a processor such as a computer to execute this network selection method is called a network selection program. The network selection program is stored in a storage device or a storage medium (media).

  The present invention can be applied to applications such as a terminal device and a relay device connected to a network, and a communication application program that operates on the device. In addition, an efficient network according to the required quality can be provided to such terminal devices and relay devices.

  As described above, the present invention relates to a communication apparatus and a network protocol stack program used therefor, and more particularly to a bearer switching control method when connecting to a plurality of networks by various communication methods.

  A communication apparatus according to the present invention includes a plurality of bearers, a flow identification unit for identifying a communication flow characteristic, a bearer search unit according to a network characteristic of a bearer that can be used based on a flow characteristic, A communication quality detection unit for identifying whether the required quality is satisfied, and a bearer selection unit that detects a flow break and switches a bearer are provided.

  The bearer selection unit includes an address conversion unit, and is characterized in that the bearer is switched by rewriting the address to the address given to the connection-destination bearer by the address conversion unit.

  The bearer selection unit includes a protocol conversion unit, converts the protocol by the protocol conversion unit, and switches the bearer by connecting to the server using the address assigned to the connection destination bearer as a proxy.

  From another viewpoint, the communication device according to the present invention is implemented as a communication relay device to a terminal or a communication device in which the terminal and the relay device are integrated. This communication device identifies a communication unit that relays a communication flow between a plurality of terminals and a plurality of communication networks, a network characteristic database that holds information such as the speed and communication cost of each network, and a flow such as a connection destination Flow characteristics database that holds information such as information to be transmitted and the communication speed requested by the flow, a communication flow detection unit that identifies the communication flow of packets transmitted and received from each terminal, and the conditions requested by the flow from the flow information and the database A network selection unit that selects an optimal network that satisfies the above condition, and a communication quality detection unit that detects communication quality deterioration due to handover, packet congestion, or the like.

  The network selection unit uses the flow characteristic information such as the requested communication speed obtained by the flow detection unit at the time of starting the communication flow, searches the flow characteristic database, and searches for and connects to the network that satisfies the condition. .

  When the communication quality detection unit detects communication quality deterioration due to handover or packet congestion, the communication quality detection unit changes the characteristic item held in the network characteristic database and sends a notification of quality deterioration to the network selection unit.

  When a flow break is detected by the communication flow detection unit, an optimum network is searched again at that time, and if the quality has deteriorated, the network is switched to a network that satisfies the required conditions.

  The network selection program according to the present invention includes: a process for detecting a communication flow from communication contents; a flow characteristic database process for storing flow characteristics; a network characteristic database process for storing bearer characteristics; The communication quality detection process for identifying whether the condition is satisfied and the process for selecting a bearer for switching a bearer by detecting a flow break are performed.

  The bearer selection process is characterized in that an address conversion process is performed and the bearer is switched by rewriting the address to the address assigned to the connection-destination bearer.

  The bearer selection process is characterized by performing a protocol conversion process and switching a bearer by connecting to a server using an address assigned to the connection-target bearer as a proxy.

  The network selection method according to the present invention refers to a network characteristic database that detects characteristics of a communication flow from communication contents and stores bearer characteristics when relaying communication flows between a plurality of terminals and a plurality of networks. When the bearer does not satisfy the required flow quality, the flow is detected and the bearer is switched.

  The network selection method according to the present invention is characterized in that the bearer is switched by rewriting the address of the packet in the communication flow from the terminal to the address given to the bearer to which the packet is to be transmitted.

  The network selection method according to the present invention is characterized in that it operates as a proxy and switches bearers by using an address assigned to the bearer as a source address.

FIG. 1 is a block diagram showing the configuration of a communication system according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating an example of data stored in the flow characteristic database 13. FIG. 3 is a diagram illustrating an example of data stored in the network characteristic database 14. FIG. 4 is a diagram showing an example of data change in the network characteristic database 14 at the time of quality degradation. FIG. 5 is a diagram showing a flow of bearer switching at the time of quality degradation. FIG. 6 is a diagram illustrating an example of command transmission / reception in FTP. FIG. 7 is a diagram illustrating bearer switching timing at the time of quality degradation. FIG. 8 is a block diagram showing a configuration of a communication system according to the second exemplary embodiment of the present invention. FIG. 9 is a diagram showing a state of address conversion according to the second embodiment of the present invention. FIG. 10 is a block diagram showing a configuration of a communication system according to the third exemplary embodiment of the present invention. FIG. 11 is a diagram showing a state of protocol conversion in the HTTP proxy.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Communication relay apparatus 11 ... Communication part 12 ... Flow detection part 13 ... Flow characteristic database 14 ... Network characteristic database 15 ... Network selection part 16 ... Communication quality detection part 17 ... Address conversion part 18 ... Protocol conversion part 2 ... Communication terminal device 3 ... Network

Claims (15)

A flow detector for identifying a flow characteristic of communication with a network via a bearer;
A communication quality detection unit for identifying whether the bearer satisfies the required quality of the flow;
A communication apparatus comprising: a network selection unit that detects a bearer according to network characteristics based on the characteristics of the flow, and switches the bearer to the detected bearer when a break in the flow is detected. The communication device according to claim 1,
A communication apparatus further comprising: an address conversion unit that rewrites a connection destination address to an address given to the detected bearer when the bearer is switched to the detected bearer. The communication device according to claim 1 or 2,
When switching the bearer to the detected bearer, a protocol conversion unit that operates as a proxy, converts a protocol, and connects to the network using an address assigned to the detected bearer is further provided. Communication device. The communication device according to any one of claims 1 to 3,
The connection source terminal information, the communication destination identification information, the protocol type, the average communication amount, the network used, and the time stamp indicating the latest communication time are retained, and the connection source terminal is identified when identifying the characteristics of the flow. A communication apparatus further comprising: a flow characteristic database that provides information regarding the characteristics of the flow to the flow detection unit using the information, the communication destination identification information, and the protocol type as a key. The communication device according to any one of claims 1 to 4,
Information on at least one of connectable network type, maximum bandwidth, usable bandwidth, security level, and billing system is retained, and the communication quality detection unit retains the information when the flow quality deteriorates. A communication apparatus further comprising a network characteristic database in which information stored therein is corrected. (A) identifying a flow characteristic of communication with a network via a bearer;
(B) identifying whether the bearer meets the required quality of the flow;
(C) detecting a bearer according to network characteristics based on the characteristics of the flow, and switching the bearer to the detected bearer when a break in the flow is detected. The network selection method according to claim 6, comprising:
(D) A network selection method further comprising a step of rewriting a connection destination address to an address given to the detected bearer when the bearer is switched to the detected bearer. The network selection method according to claim 6 or 7,
(E) when switching the bearer to the detected bearer, the step of acting as a proxy, converting a protocol, and connecting to the network using an address assigned to the detected bearer; Includes network selection method. A network selection method according to any one of claims 6 to 8, comprising:
The step (a) includes:
(A1) holding information related to connection source terminal information, communication destination identification information, protocol type, average traffic, network used, and time stamp indicating the latest communication time;
(A2) including a step of providing information on the characteristics of the flow using the connection source terminal information, the communication destination identification information, and the protocol type as a key when identifying the characteristics of the flow. A network selection method according to any one of claims 6 to 9,
The step (c) includes:
(C1) holding information relating to at least one of a connectable network type, a maximum bandwidth, an available bandwidth, a security level, and a charging system;
(C2) modifying the held information when the flow quality deteriorates;
Including network selection method. (A) identifying a flow characteristic of communication with a network via a bearer;
(B) identifying whether the bearer meets the required quality of the flow;
(C) detecting a bearer according to network characteristics based on the characteristics of the flow, and causing the computer to execute a step of switching the bearer to the detected bearer when the flow break is detected. Network selection program. The network selection program according to claim 11,
(D) A network selection program for causing a computer to further execute a step of rewriting a connection destination address to an address given to the detected bearer when the bearer is switched to the detected bearer. The network selection program according to claim 11 or 12,
(E) when switching the bearer to the detected bearer, acting as a proxy, converting the protocol and connecting to the network using the address given to the detected bearer; A network selection program to be executed by a computer. A network selection program according to any one of claims 11 to 13,
The step (a) includes:
(A1) holding information related to connection source terminal information, communication destination identification information, protocol type, average traffic, network used, and time stamp indicating the latest communication time;
(A2) a step of providing information on the characteristics of the flow using the connection source terminal information, the communication destination identification information, and the protocol type as keys when identifying the characteristics of the flow. A network selection program according to any one of claims 11 to 14,
The step (c) includes:
(C1) holding information relating to at least one of a connectable network type, a maximum bandwidth, an available bandwidth, a security level, and a charging system;
(C2) modifying the held information when the flow quality deteriorates;
Including network selection program.

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