JP2008172521A - Communication apparatus and communication system - Google Patents

Abstract

To obtain a mobile router that realizes efficient TCP communication.
The present invention manages a connection in a network involving movement, and transmits TCP data transmitted / received between a mobile node connected to the mobile node and a correspondent node connected via a base station and a home agent. A communication device for relaying, when a communication band used by a mobile node is determined based on a wireless communication state with a wireless base station, and when TCP data is received from the mobile node, information on the determined communication band The inter-MN communication control unit (12) that returns the included delivery confirmation and the inter-MN communication control unit (12) transmit the TCP data received from the mobile node to the home agent, and the TCP data received from the home agent A communication control unit between TCP proxies (13) that transmits to the destination node via the communication control unit between MN (12) It was decided.
[Selection] Figure 2

Description

  The present invention relates to IP (Internet Protocol) packet communication, and more particularly, to a communication apparatus and a communication system that realizes efficiency of TCP (Transmission Control Protocol) communication in a mobile IP network mobility system (Mobile IP Network Mobility System). Is.

  A TCP extended function is added to the TCP layer of the mobile terminal, and a function for notifying the mobility management information to the IP mobility function is added to the IP layer, while the opposite apparatus communicating with the mobile terminal has the same function. By doing so, there is a technique for suppressing TCP congestion control associated with handover (for example, Patent Document 1 below).

  In the technology described in Patent Document 1 below, a dedicated protocol control function is implemented in the mobile terminal and the opposing communication device, and the TCP communication is improved when the mobile terminal communicates with the opposing communication device in which the dedicated protocol function is implemented. ing.

  In addition, the cellular mobile terminal recognizes the optimum window size from the communication band at the handover destination before executing the handover between the radio base stations, and continues the communication with the optimum window size immediately after the handover is completed. Technology exists (for example, Patent Document 2 below).

In the technology described in Patent Document 2 below, when it is known in advance that the bandwidth will decrease after the handover is completed, the occurrence of TCP layer congestion due to a decrease in the radio bandwidth is suppressed by reducing the window size immediately after the handover. ing. In the cellular system, packet synchronization associated with handover is guaranteed, so no packet loss occurs. Therefore, this technology does not aim to avoid congestion control triggered by packet loss due to handover (control to reduce the window size), but to suppress congestion control due to communication bandwidth fluctuations associated with handover. Yes.
JP 2005-57397 A JP 2004-153321 A

  In a MobileIP Network Mobility (MobileIP NEMO) system consisting of a mobile router and a home agent, the mobile node connected to the mobile router is not aware that it is connected to the mobile IP (MobileIP) network. Thus, temporary packet loss and delay associated with mobile router handover is determined as network congestion.

  For this reason, every time a mobile router handover occurs, the mobile node TCP determines that congestion has occurred, and the TCP congestion window size is unnecessarily lowered, so that efficient TCP communication cannot be realized. It was.

  In the technique described in Patent Document 1, the mobile terminal recognizes the occurrence of handover, and improves the efficiency by executing different processes depending on whether the handover is in progress or not. The opposite terminal (communication partner terminal) must also implement the same function. That is, efficient communication cannot be performed with a normal terminal that does not have a special function. Also, it cannot be applied when accessing an Internet website.

  In addition, for example, in a system configuration in which the TCP proxy function is only implemented in the mobile router and the home agent, the TCP proxy function cannot recognize the communication state or handover state of the mobile router, so communication between TCP proxies can be optimized. Can not.

  In addition, there is a problem that TCP communication cannot be optimized before and after handover because communication other than TCP affects the TCP connection bandwidth even if only the communication bandwidth of the TCP connection is optimized in the wireless communication link. .

  Further, the TCP connection can continue to be established even when no packet is flowing. Therefore, there is a problem that when a large number of mobile nodes are connected under a device such as a mobile router and a large number of TCP connections are established, if a communication band is allocated equally to the TCP connections, a wasteful communication band increases. there were.

  The present invention has been made in view of the above, and when a mobile router executes a handover, the connected mobile node determines that congestion has occurred in the network and reduces communication efficiency. It is an object of the present invention to obtain a communication device and a communication system that can prevent TCP and realize efficient TCP communication.

  In order to solve the above-described problems and achieve the object, the present invention manages connections in a network involving movement, and is connected to a mobile terminal device connected to itself via a base station and a mobile network management device. A communication device that relays protocol data with a delivery confirmation transmitted / received to / from a fixed terminal device, and determines a communication band to be used by the mobile terminal device based on a wireless communication state with a wireless base station, A communication control means for returning a delivery confirmation including information of the determined communication band when protocol data with a delivery confirmation is received from the mobile terminal apparatus; and with a delivery confirmation received from the mobile terminal apparatus by the communication control means. Protocol data with transmission confirmation transmitted to the mobile network management device and received from the mobile network management device Characterized in that it and a data relay means for transmitting to the destination terminal via said communication control means.

  According to the present invention, when TCP data is received from the mobile node, a pseudo delivery confirmation is immediately returned, so that when the mobile router performs a handover, the mobile node connected to the mobile router is connected to the network. It is possible to prevent the TCP congestion window size from being erroneously determined that congestion has occurred, that is, to reduce the communication efficiency.

  Embodiments of a communication apparatus and a communication system according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment FIG. 1 is a diagram showing a configuration example of a communication system including a communication apparatus according to the present invention.

  The communication system includes a mobile router 1, a mobile router 1, a home agent 2 that manages a home address of each node connected to the network managed by the mobile router 1, and a connection relationship between the nodes by the mobile router 1. Mobile node 3 that connects to the managed network, a correspondent node 4 that is an opposite node that communicates with the mobile node 3, an access router 5, and a wireless base that communicates with the mobile router 1 A station 6 and a mobile unit 7 on which the mobile router 1 is mounted.

  Further, this communication system is basically configured by MobileIP NEMO (Mobile IP Network Mobility). When the mobile router 1 moves by switching the radio base station 6, the home agent 2 moves the mobile router 1. Is detected, and a mobile IP tunnel is set to a new care-of address and captured. Therefore, communication between the mobile node 3 connected to the network managed by the mobile router 1 and the correspondent node 4 disposed on the ground is continued regardless of the movement of the mobile router 1.

  FIG. 2 is a diagram illustrating an internal configuration example of the mobile router. This mobile router 1 includes a TCP proxy function unit 10 including a TCP connection management unit 11, an inter-MN (Mobile Node) communication control unit 12, an inter-TCP proxy communication control unit 13, and a radio link management unit 14, and a bandwidth control unit 15. And an NM (Network Mobility) function unit 16, a wireless interface unit 17, and an IP processing unit 18.

  FIG. 3 is a diagram illustrating an internal configuration example of the home agent. The home agent 2 includes a TCP connection management unit 21, a CN (Correspond Node) communication control unit 22, and a TCP proxy function unit 20 including a TCP proxy communication control unit 23, a bandwidth control unit 25, an NM (Network Mobility ) The functional unit 26 and the IP processing unit 28.

  Hereinafter, the operation of each part constituting the mobile router 1 and the home agent 2 will be briefly described.

  In the mobile router 1 illustrated in FIG. 2, the TCP connection management unit 11 performs communication bandwidth and connection state during communication (the mobile router performs normal communication based on information received from the radio link management unit 14 and the NM function unit 16. Middle or handover). In addition, information including the communication bandwidth of the mobile router is notified to the inter-MN communication control unit 12 and the TCP proxy communication control unit 13.

  The inter-MN communication control unit 12 that operates as a communication control unit adjusts the TCP window size for the mobile node 3 based on the information received from the TCP connection management unit 11 and controls the communication band used by the mobile node 3. To do. When TCP data is received from the mobile node 3, a data delivery confirmation (ACK: ACKnowledgement) for the received data is transmitted in a pseudo manner.

  The TCP proxy communication control unit 13 that operates as a data relay unit and a communication state notification unit transmits and receives TCP data to and from the TCP proxy communication control unit 23 of the home agent 2 via the mobile IP network mobility. The communication protocol between TCP proxies communicates with TCP in a normal communication state, and communicates with a communication protocol dedicated to handover only when the mobile router is performing handover. In addition, information received from the TCP connection management unit 11 is used to manage bandwidth control for each TCP connection and retransmission control between TCP proxies (between the mobile router 1 and the home agent 2). Further, the TCP proxy communication control unit 23 of the home agent 2 is notified of the operation state of the mobile router and the state of the wireless link by a dedicated message.

  The radio link management unit 14 always manages the radio interface unit 17 and has a function of determining that network switching is approaching from information such as the radio status, the physical position of the mobile router, and the moving speed. The TCP connection management unit 11 is notified that the handover is approaching. Further, the communicable bandwidth information is held from the communication state of the wireless link, and the information is notified to the TCP connection management unit 11.

  The bandwidth control unit 15 performs bandwidth control of traffic other than the TCP connection. Specifically, in order to preferentially allocate a bandwidth to the TCP proxy function unit 10, the bandwidth of the data flow other than the TCP connection is controlled. In addition, data flows other than the TCP proxy are identified and internal priority control is performed.

  The NM function unit 16 has a function of notifying the TCP connection management unit 11 of completion of location registration of the mobile IP, in addition to the control function of the normal mobile IP network mobility.

  The wireless interface 17 is an interface for performing wireless connection with the wireless base station 6 and notifies the wireless link management unit 14 of the state of the wireless link (reception radio wave intensity, data retransmission rate in wireless section, communicable bandwidth, etc.). To do.

  In the home agent shown in FIG. 3, the TCP connection management unit 21 operates based on the information received from the TCP proxy communication control unit 13 of the mobile router 1 and the information received from the NM function unit 26 ( Under normal operation, during handover, during communication bandwidth, etc.), the bandwidth control for each TCP connection and the retransmission control between TCP proxies are managed. In addition, information including the communication band of the mobile router is notified to the inter-CN communication control unit 22 and the TCP proxy communication control unit 23.

  The inter-CN communication control unit 22 that operates as a communication control unit adjusts the TCP window size for the correspondent node 4 based on the information received from the TCP connection manager 21, and uses the communication band used by the correspondent node 4. To control. When TCP data is received from the correspondent node 4, a data delivery confirmation (ACK) for the received data is transmitted in a pseudo manner.

  The TCP proxy communication control unit 23 that performs operations as a data relay unit and a communication state acquisition unit transmits and receives TCP data to and from the TCP proxy communication control unit 13 of the mobile router 1 via the mobile IP network mobility. The communication protocol between the TCP proxies communicates with TCP in a normal communication state, and communicates with a communication protocol dedicated to handover (TCP-like protocol) only during the handover of the mobile router. In addition, by receiving a dedicated message from the TCP proxy inter-proxy communication control unit 13 of the mobile router 1, the operating state of the mobile router 1 and the state of the wireless link are grasped, and the grasped contents are notified to the TCP connection management unit 21. In addition, information received from the TCP connection management unit 21 is used to manage bandwidth control for each TCP connection and retransmission control between TCP proxies (between the mobile router 1 and the home agent 2).

  The bandwidth control function unit 25 performs bandwidth control of traffic other than the TCP connection. Specifically, the bandwidth of the data flow other than the TCP connection is controlled in order to preferentially allocate the bandwidth to the TCP proxy function unit 20. In addition, data flows other than the TCP proxy are identified and internal priority control is performed.

  The NM function unit 26 has a function of notifying the TCP connection management unit 21 of the completion of mobile IP location registration, in addition to the normal mobile IP network mobility home agent function.

  FIG. 4 is a diagram illustrating the division points of the TCP connection in the communication system according to the present embodiment.

  As shown in FIG. 4, in the communication system of the present embodiment, TCP connections are made between the mobile node 3 and the mobile router 1 (section 30), between the home agent 2 and the correspondent node 4 (section 31), The mobile router 1 and the home agent 2 are divided into three sections (section 32), and the TCP proxy function (TCP proxy function units 10 and 20) is implemented in the mobile router 1 and the home agent 2, respectively, and the TCP connection is divided. is doing.

  Further, movement management is performed between the mobile router 1 and the home agent 2 by mobile IP tunneling (33).

  Further, it seems logically that a TCP connection is established between the end-to-end mobile node 3 and the correspondent node 4. However, in actuality, the TCP proxy function notifies the mobile node and the correspondent node of the window size optimized for each TCP connection to improve the efficiency of TCP communication.

  Next, basic operations of the mobile router 1 and the home agent 2 will be described with reference to FIGS. 5, 6-1 and 6-2. FIGS. 5, 6-1 and 6-2 are sequence diagrams illustrating an example of basic operations in the communication system according to the present embodiment. Note that the access router 5 and the radio base station 6 constituting the communication system (see FIG. 1) of the present embodiment are the same as those of the conventional apparatus. Therefore, for convenience of explanation, in FIGS. 5, 6-1, and 6-2, the sequence of parts related to these devices is omitted.

  Here, the operation of adjusting the TCP window between the devices performing communication (between the mobile node and the opposite node) and performing congestion control will be briefly described. Normally, when a mobile node and a correspondent node perform TCP communication on a communication system that supports mobile IP network mobility, the TCP window size gradually increases with the start of communication, and is a result of adjustment on the transmission side and the reception side. It stabilizes at. Further, when packet loss or the like occurs in the network, it is determined that the network is congested, and the size of the congestion window is reduced, resulting in a reduction in communication bandwidth.

  Next, each part of the mobile router 1 and the home agent 2 in the “TCP window size adjustment operation” and the “TCP data transmission / reception operation between the mobile node 3 and the correspondent node 4” shown in the sequences S10 and S11 of FIG. Will be described.

  As shown in the sequence S10, the wireless link (wireless communication line) in which the wireless link management unit 14 is notified from the wireless interface (wireless IF) 17 while the mobile router 1 is communicating (connected to the wireless base station). Information on the status of the network is monitored, and the result (wireless link status) is notified to the TCP connection management unit 11. Here, the wireless link state refers to a state such as a received radio wave intensity, a data retransmission rate in a wireless section, a communicable band, and the like. The TCP connection management unit 11 recognizes the operation state and communication band of the mobile router based on the wireless link state notified from the wireless link management unit 14 and the location registration state acquired from the NM function unit 16. Further, the wireless communication state (MR state) between the mobile router 1 and the wireless base station is notified to the inter-MN communication control unit 12 and the TCP proxy communication control unit 13. The TCP proxy communication control unit 13 notified of the MR state notifies the MR state to the TCP proxy communication control unit 23 of the home agent 2. The MR status is notified using a dedicated message.

  The TCP proxy communication control unit 23 of the home agent 2 notifies the TCP connection management unit 21 of the notified MR state (wireless communication state between the mobile router 1 and the wireless base station). The TCP connection management unit 21 recognizes the operation state and the communication band of the mobile router based on the notified MR state and the MIP (MobileIP) location registration state notified from the MN function unit 26, and determines the MR state as CN. The communication control unit 22 and the TCP proxy communication control unit 23 are notified. Then, based on the MR state information acquired in the above procedure, the inter-MN communication control unit 12 of the mobile router 1 and the inter-CN communication control unit 22 of the home agent 2 are connected to the mobile node (MN) 3 and the correspondent node (CN). ) Adjust the size of the TCP window to 4 (the sequence S10).

  Further, as shown in the sequence S11, when the TCP data is transmitted from the mobile node 3, the inter-MN communication control unit 12 receives the TCP data. The inter-MN communication control unit 12 that has received the TCP data immediately returns an ACK (pseudo ACK). That is, a pseudo ACK is returned even if an ACK for the TCP data is not obtained from the TCP data destination node (here, the correspondent node 4). At the time of returning the pseudo ACK, the TCP window size at that time is notified to the mobile node 3. Further, the inter-MN communication control unit 12 transmits the received TCP data to the NM function unit 16 via the TCP inter-proxy communication control unit 13. The NM function unit 16 encapsulates the received TCP data, and the encapsulated TCP data is transmitted to the home agent 2 via the wireless interface unit 17 using a mobile IP tunnel (MIP Tunnel). At this time, the TCP inter-proxy communication control unit 13 buffers the received TCP data until a delivery confirmation is received from the home agent 2.

  In the home agent 2 that has received the encapsulated TCP data, the NM function unit 26 performs decapsulation, and the inter-TCP proxy communication control unit 23 receives the TCP data. Also, the TCP inter-proxy communication control unit 23 that has received the TCP data transmits a delivery confirmation (TCP inter-proxy ACK) to the inter-TCP proxy communication control unit 13 of the mobile router 1. The TCP inter-proxy communication control unit 23 transmits the TCP data to the correspondent node 4 via the inter-CN communication control unit 22, and the correspondent node 3 that has received the TCP data returns an ACK. The ACK transmitted from the correspond pond node 4 is terminated at the inter-correspond node communication control unit 22. When TCP data is transmitted from the correspondent node 4 to the mobile node 3, that is, when TCP data is transmitted from the inter-CN communication control unit 22 to the inter-MN communication control unit 12, the same operation is performed in the opposite direction. Flow (Sequence S11). In FIG. 5, TCP data is transmitted from the correspondent node 4 after the TCP data transmission from the mobile node 3 is completed, but these processes are executed in parallel.

  Next, the operation of each part of the mobile router 1 and the home agent 2 when the mobile router 1 shown in the sequences S20 to S24 of FIGS. 6-1 and 6-2 executes a handover will be described.

  First, as shown in the sequence S20, the TCP window size is also adjusted when a handover is executed. Specifically, in the mobile router 1, during communication (during connection with the radio base station), the radio link management unit 14 monitors information on the status of the radio link notified from the radio interface 17, and the result (wireless Link status) is notified to the TCP connection management unit 11. The TCP connection management unit 11 recognizes the operation state and communication band of the mobile router based on the wireless link state notified from the wireless link management unit 14 and the location registration state acquired from the NM function unit 16. Further, the wireless communication state (MR state) between the mobile router 1 and the wireless base station is notified to the inter-MN communication control unit 12 and the TCP proxy communication control unit 13. At this point, the mobile router 1 recognizes the handover state. The TCP inter-proxy communication control unit 13 notified of the MR state notifies the MR state to the inter-TCP proxy communication control unit 23 of the home agent 2. The notification of the MR state is performed using a dedicated message.

  The inter-TCP proxy communication control unit 23 of the home agent 2 notifies the TCP connection management unit 21 of the notified MR state. The TCP connection management unit 21 recognizes the operating state and communication band of the mobile router based on the notified MR state and the MIP location registration state notified from the MN function unit 26, and controls the MR state to the inter-CN communication control. To the communication control unit 23 and the TCP proxy communication control unit 23. Then, based on the MR state information acquired in the above procedure, the inter-MN communication control unit 12 of the mobile router 1 and the inter-CN communication control unit 22 of the home agent 2 set the TCP window to the mobile node 3 and the correspondent node 4. The size is adjusted (Sequence S20).

  After the sequence S20 is executed and the size of the TCP window is adjusted, when TCP data is transmitted from the mobile node 3, the inter-MN communication control unit 12 receives the TCP data. The inter-MN communication control unit 12 that has received the TCP data immediately returns an ACK (pseudo ACK). That is, a pseudo ACK is returned even if an ACK for the TCP data is not obtained from the TCP data destination node (here, the correspondent node 4). Further, the inter-MN communication control unit 12 transmits the received TCP data to the NM function unit 16 via the TCP inter-proxy communication control unit 13. The NM function unit 16 encapsulates the received TCP data and transmits the encapsulated TCP data to the wireless interface unit 17. However, since the handover process is being executed, the wireless link is disconnected halfway and data does not flow.

  At this time, even if the delivery confirmation from the TCP proxy communication control unit 23 of the home agent 2 does not arrive, the TCP inter-proxy communication control unit 13 receives the TCP data from the mobile node 3 without determining that congestion has occurred. continue. The inter-MN communication control unit 12 controls the bandwidth by notifying the mobile node 3 of the result of adjusting the TCP window size using the pseudo ACK. Bandwidth control (adjustment of the TCP window size) is performed based on the empty state of the buffer of the TCP proxy communication control unit 13. Similarly, the TCP data from the home agent 2, that is, the correspondent node 4 does not arrive, and each part of the home agent 2 performs the same operation as each part of the mobile router 1 (the sequence S21).

  Thereafter, the handover process is continued, and when the mobile router 1 and the handover destination radio base station are connected as shown in sequence S22 of FIG. 6-2, information on the radio link status notified from the radio interface 17 is obtained. The monitored wireless link management unit 14 notifies the TCP connection management unit 11 to that effect (that the wireless link connection has been detected). Further, the NM function unit 16 executes a conventional mobile IP network mobility control function, and performs location registration with the home agent using a new care-of address (transmits a MIP Binding Update to the NM function unit 26 of the home agent 2). . Thereafter, upon receiving a location registration completion message (MIP Binding ACK) from the NM function unit 26 of the home agent 2, the NM function unit 16 notifies the TCP connection management unit 11 of the location registration state.

  The TCP connection management unit 11 recognizes the operation state and communication band of the mobile router based on the wireless link state notified from the wireless link management unit 14 and the location registration state notified from the NM function unit 16. Further, the wireless communication state (MR state) between the mobile router 1 and the wireless base station is notified to the inter-MN communication control unit 12 and the TCP proxy communication control unit 13. The TCP inter-proxy communication control unit 13 notified of the MR state notifies the MR state to the inter-TCP proxy communication control unit 23 of the home agent 2. The notification of the MR state is performed using a dedicated message.

  The inter-TCP proxy communication control unit 23 of the home agent 2 notifies the TCP connection management unit 21 of the notified MR state. The TCP connection management unit 21 recognizes the operating state and communication band of the mobile router based on the notified MR state and the MIP location registration state notified from the MN function unit 26, and controls the MR state to the inter-CN communication control. To the communication control unit 23 and the TCP proxy communication control unit 23. Then, based on the MR state information acquired in the above procedure, the inter-MN communication control unit 12 of the mobile router 1 and the inter-CN communication control unit 22 of the home agent 2 set the TCP window to the mobile node 3 and the correspondent node 4. The size is adjusted (Sequence S22).

  Immediately after the sequence S22 is executed and the normal communication state is returned from the handover state, the TCP proxy inter-proxy control unit 13 of the mobile router 1 has not received the delivery confirmation from the opposite side as shown in the sequence S23. Start resending. If the TCP data to be retransmitted is set with a flag indicating that it is retransmitted data (set flag), whether the receiving side has received the retransmitted TCP data, that is, when the same TCP data is received multiple times It is possible to determine whether the transmission side has been intentionally retransmitted or whether the same data has been received a plurality of times due to the occurrence of an abnormality in the communication path. The inter-TCP proxy communication control unit 23 of the home agent 2 that has received the retransmitted data discards the data that has already been received, and transmits only the delivery confirmation to the opposing inter-TCP proxy communication control unit 13. The TCP data buffered on the home agent 2 side (TCP proxy communication control unit 23) during the handover is also transmitted to the opposite side (Sequence S23). In FIG. 6B, the data retransmission from the home agent 2 is performed after the data retransmission from the mobile router 1 is completed, but these processes are executed in parallel.

  When the process of sequence S23 described above is executed and the data retransmission process is completed, a normal data transmission flow (sequence S24) is executed. Note that the processing shown in the sequence S24 is the same as the above-described sequence S11 in FIG.

  Next, the bandwidth control operation of the data flow other than TCP and TCP will be described with reference to FIG.

  As shown in FIG. 7, communication other than TCP communication flows through the mobile router 1. As for TCP communication, the TCP proxy function unit 20 manages all TCP connections for each TCP connection, and adjusts traffic according to the communication band of the wireless interface.

  On the other hand, for data flows other than TCP, the bandwidth controller 15 allocates the bandwidth of the wireless interface so that traffic exceeding the allocated bandwidth does not compress the TCP data flow (congestion occurs in TCP communication). (Do not control).

  Further, the bandwidth control unit 15 has a function of preferentially flowing a flow designated by a transmission source IP address, a transmission destination IP address, and a transmission port in addition to a function of band-limiting all flows other than TCP. ). This control is performed based on information obtained in cooperation with the application of the mobile node 3 connected to the mobile router 1 or information set in advance in the mobile router 1.

  Next, control for preferentially allocating a bandwidth to a specific TCP connection when a plurality of TCP connections are established will be described with reference to FIG.

  This function is implemented in the TCP proxy function unit of both the home agent 2 and the mobile router 1, and specifically, the inter-CN communication control unit 22 of the home agent 2 and the inter-MN communication control unit 12 of the mobile router 1. Realized by operation.

  Here, the operation will be described taking the case of the mobile router 1 as an example. When the TCP connection is established, in the initial state, the TCP connection management unit 11 assigns a communication band defined for the established TCP connection. The communication band to be assigned is a value obtained by excluding communication bands other than TCP from the total communication band of the wireless interface. The inter-MN communication control unit 12 constantly monitors all TCP connections managed by the TCP connection management unit 11. As shown in FIG. 8, the range to be monitored is a period from the current time to a time that goes back to a certain time, and this period is designated by the TCP connection management unit 11 as a window size for monitoring.

  The window size for monitoring is determined based on the number of TCP connections and the communication bandwidth of the mobile router, and is updated according to the monitoring result of these situations (number of connections and communication bandwidth).

  Specifically, the monitoring result in the inter-MN communication control unit 12 is passed to the TCP connection management unit 11, and the TCP connection management unit 11 lowers the priority of the TCP connection in which no packet flows in the window. Set and set a high priority for the TCP connection through which the packet is flowing. The monitoring result is provided with hysteresis, and control is performed so that the priority state (setting of “high” and “low”) does not fluctuate frequently. Then, since the TCP connection whose priority is set low by the TCP connection management unit 11 does not flow while the connection is established, the communication band is lowered to the minimum level. Finally, the available communication bandwidth (unassigned communication bandwidth) obtained by this operation is assigned to another TCP connection (a TCP connection with a high priority), and the efficiency of communication bandwidth utilization as a whole system Realize.

  Further, when a packet transmission / reception is observed by subsequent monitoring for a TCP connection once set with a low priority, the TCP connection management unit 11 increases the TCP window size to secure a communication band, and performs other communication. Lower the window size for medium TCP connections.

  The same applies to the control when the home agent 2 preferentially allocates a bandwidth to a specific TCP connection. In other words, the TCP connection management unit 11 executes the bandwidth control operation using the monitoring result by the inter-CN communication control unit 22.

  Communication between TCP proxies (mobile router and TCP proxy function part of home agent) communicates in the same operation as TCP when mobile router 1 is in a normal operation state, but wireless communication is the sum of TCP communication and communication other than TCP. Adjustment is made so as not to exceed the bandwidth, and control is performed so that TCP congestion does not occur. That is, control is performed so as to avoid execution of processing for reducing the TCP window size by congestion control between end-to-end devices that perform TCP communication.

  As described above, in the present embodiment, the home agent grasps the communication state of the mobile router, and the mobile router and the home agent receive the TCP data received from the mobile node connected to the mobile router and its opposite node. By sending a pseudo delivery confirmation (pseudo ACK) to the mobile router, the mobile router performs bandwidth control so that the process of reducing the TCP window size due to congestion control is not executed between nodes during handover execution. It was. As a result, when the mobile router executes a handover, it is possible to prevent the mobile node from determining that congestion has occurred in the network and reducing the communication efficiency.

  In addition, since the bandwidth control is performed separately for the data flow other than TCP and the TCP data flow, when the data flow other than TCP increases, the TCP data flow is compressed and the TCP congestion control operates. This can be suppressed, and TCP communication can be stabilized.

  In addition, since the TCP connection data flow is constantly monitored and the TCP connection bandwidth with no data flowing is dynamically allocated to the current connection, the communication bandwidth of the mobile router connected wirelessly Can be used more efficiently.

  In the communication system according to the present embodiment, the operation has been described as a configuration in which the TCP proxy function unit is added to the mobile router and the home agent. However, the configuration is not limited to this configuration. For example, as illustrated in FIG. The TCP proxy devices 8 and 9 corresponding to the TCP proxy function units of the mobile router and the home agent may be provided outside the mobile router 1a and the home agent 2a. Even in the case of such a configuration, the same effect can be obtained by the same control sequence as in the case of the configuration of FIG. 1 described above.

  In the description of the present embodiment, TCP is used as a protocol to be used in the communication system. However, the protocol is not limited to TCP, and any protocol that performs communication while confirming delivery and controls the bandwidth is the same. It is possible to obtain the effect.

  As described above, the communication device according to the present invention is useful as a communication device constituting the mobile IP network mobility system.

It is a figure which shows the structural example of the communication system containing the communication apparatus concerning this invention. It is a figure which shows the internal structural example of a mobile router. It is a figure which shows the internal structural example of a home agent. It is a figure which shows the division | segmentation point of the TCP connection in a communication system. It is the sequence diagram which showed an example of the basic operation | movement in a communication system. It is the sequence diagram which showed an example of the basic operation | movement in a communication system. It is the sequence diagram which showed an example of the basic operation | movement in a communication system. It is a figure for demonstrating the bandwidth control operation | movement of a data flow. It is a figure for demonstrating the control which allocates the bandwidth in a TCP connection preferentially. It is a figure which shows the other structural example of the communication system containing the communication apparatus concerning this invention.

Explanation of symbols

1 Mobile Router 2 Home Agent 3 Mobile Node
4 Correspond Node
DESCRIPTION OF SYMBOLS 5 Access router 6 Wireless base station 7 Mobile body 8, 9 TCP proxy apparatus 10, 20 TCP proxy function part 11, 21 TCP connection management part 12 MN (Mobile Node) communication control part 13, 23 TCP proxy communication control part 14 Radio link management unit 15, 25 Band control unit 16, 26 NM function unit 17 Wireless interface unit 18, 28 IP processing unit 22 CN (Correspond Node) communication control unit 23 TCP proxy communication control unit

Claims (19)

Manages connections in networks that involve movement, and relays protocol data with delivery confirmation sent and received between mobile terminal devices connected to itself and fixed terminal devices connected via base stations and mobile network management devices A communication device,
When a communication band used by the mobile terminal apparatus is determined based on a wireless communication state with a radio base station, and protocol data with a delivery confirmation is received from the mobile terminal apparatus, information on the determined communication band is A communication control means for returning the included delivery confirmation;
The communication control means transmits the protocol data with delivery confirmation received from the mobile terminal apparatus to the mobile network management apparatus, and the protocol data with delivery confirmation received from the mobile network management apparatus is sent to the destination via the communication control means. Data relay means for transmitting to the terminal device;
A communication apparatus comprising:   The communication apparatus according to claim 1, wherein when the data relay unit cannot receive a delivery confirmation as a response to the protocol data with a delivery confirmation transmitted to the mobile network management apparatus, the data relay unit retransmits the data.   The communication control means transmits the protocol data with delivery confirmation received from the mobile network management device via the data relay means to the destination communication terminal, and then received the delivery confirmation as a response to the protocol data with delivery confirmation. The communication apparatus according to claim 1 or 2, wherein the delivery confirmation is terminated in some cases.   4. The communication apparatus according to claim 2, wherein, when retransmitting the protocol data with delivery confirmation, the data relay unit sets a retransmission flag and retransmits the corresponding data. further,
A communication status notifying means for notifying the mobile network management device of the wireless communication status so that the mobile network management device can allocate a communication band to the fixed terminal device based on the wireless communication status;
The communication apparatus according to any one of claims 1 to 4, further comprising:   The communication apparatus according to claim 5, wherein the communication state notification unit notifies a wireless communication state using a dedicated message.   7. The data relay unit performs an operation as a proxy for a protocol with delivery confirmation, and stops the congestion control operation of the protocol with a delivery confirmation during movement of the IP layer. The communication apparatus according to one. further,
Acknowledgment that determines the communication band to be allocated to each protocol connection with acknowledgment based on the status of the protocol data with acknowledgment to and from each protocol connection with acknowledgment to all connected mobile terminals Protocol connection management means with
The communication apparatus according to any one of claims 1 to 7, further comprising:   The protocol connection management unit with delivery confirmation reduces the communication band assigned to the protocol connection with delivery confirmation for which transmission / reception of protocol data with delivery confirmation has not been performed within a predetermined period, The communication apparatus according to claim 8, wherein the communication apparatus is assigned to a protocol connection with delivery confirmation in which transmission / reception of protocol data with delivery confirmation is performed. further,
Bandwidth control means for allocating a communication bandwidth to a connection other than the protocol with delivery confirmation based on the protocol connection with delivery confirmation with the mobile terminal device;
The communication apparatus according to any one of claims 1 to 9, further comprising: Manages networks with movement and relays protocol data with delivery confirmation sent and received between wireless base stations and mobile terminal devices connected via mobile router devices in the network and fixed terminal devices connected to itself A communication device for
Communication state acquisition means for acquiring information on a wireless communication state between the mobile router device and the wireless base station;
When the communication band used by the fixed terminal apparatus is determined based on the information acquired by the communication state acquisition means, and the protocol data with delivery confirmation is received from the fixed terminal apparatus, the information of the determined communication band is included. A communication control means for sending back a delivery confirmation;
The communication control means transmits the protocol data with delivery confirmation received from the fixed terminal device to the mobile router device, and the destination data terminal device with the delivery confirmation protocol data received from the mobile router device via the communication control means Data relay means for transmitting to,
A communication apparatus comprising:   12. The communication apparatus according to claim 11, wherein when the data relay unit cannot receive a delivery confirmation as a response to the protocol data with a delivery confirmation transmitted to the mobile router apparatus, the data relay unit retransmits the data.   The communication control means transmits the protocol data with delivery confirmation received from the mobile router device to the destination terminal device, and thereafter terminates the delivery confirmation when the delivery confirmation for the data is received. The communication apparatus according to claim 11 or 12.   14. The communication apparatus according to claim 12, wherein, when retransmitting protocol data with delivery confirmation, the data relay unit sets a retransmission flag and retransmits the corresponding data.   15. The data relay unit performs an operation as a proxy for a protocol with delivery confirmation, and stops the congestion control operation of the protocol with a delivery confirmation during movement of the IP layer. The communication apparatus as described in any one. further,
Acknowledgment that determines the communication band to be allocated to each protocol connection with acknowledgment based on the status of the protocol data with acknowledgment to and from each protocol connection with acknowledgment to all connected fixed terminal devices Protocol connection management means with
The communication apparatus according to claim 11, further comprising:   The protocol connection management unit with delivery confirmation reduces the communication band assigned to the protocol connection with delivery confirmation for which transmission / reception of protocol data with delivery confirmation has not been performed within a predetermined period, The communication apparatus according to claim 16, wherein the communication apparatus is assigned to a protocol connection with delivery confirmation in which transmission / reception of protocol data with delivery confirmation is performed. further,
Bandwidth control means for allocating a communication bandwidth to a connection other than a protocol with a delivery confirmation based on a protocol connection with a delivery confirmation with a fixed terminal device;
The communication apparatus according to claim 11, further comprising: A mobile router device having a function as a communication device according to any one of claims 1 to 10,
A mobile network management device having a function as a communication device according to any one of claims 11 to 18,
A communication system comprising:

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