WO2010038701A1

WO2010038701A1 - Communication processing device and communication processing method

Info

Publication number: WO2010038701A1
Application number: PCT/JP2009/066782
Authority: WO
Inventors: 潤粟野; 康博水越
Original assignee: 日本電気株式会社
Priority date: 2008-10-03
Filing date: 2009-09-28
Publication date: 2010-04-08

Abstract

A communication processing device comprises a storage unit (725) and a control unit (752). The storage unit (725) stores information relating to a communication terminal wherein information relating to whether a router advertisement is transmitted or not to the communication terminal at a connection destination is recorded corresponding to the communication terminal. When transmitting the router advertisement to the communication terminal to be connected, the control unit (752) investigates whether the router advertisement is to be transmitted for the first time or not to the communication terminal on the basis of the information relating to the terminal device. When the transmission is the first time, the control unit (752) sets information for giving higher priority of selecting the device as a communication destination to the router advertisement; when the transmission is not the first time, the control unit (752) sets information for giving priority lower than the priority to be given when the transmission is the first time, to the router advertisement.

Description

Communication processing apparatus and communication processing method

The present invention relates to a communication processing device and a communication processing method for maintaining communication of a communication terminal when a connection destination network changes as the communication terminal moves.

As a method for realizing mobile communication by registering the address of the mobile node and the address of its own device by the location registration gateway, "Proxy Mobile IPv6", http://tools.ietf.org/html/draft-ietf -PMIPv6 (Proxy Mobile IPv6) disclosed in netlmm-proxymip6-18 (hereinafter referred to as non-patent document 1) is known.

A mobile communication system to which PMIPv6 is applied will be briefly described. FIG. 2 is a sequence diagram showing an example of an operation procedure of the mobile communication system when a mobile node connects to an access network in the mobile communication system shown in FIG. 1.

The mobile communication system to which PMIPv6 is applied has a mobility management server 100 and

location registration gateways

200a and 200b as shown in FIG. A mobile node 300 is connected to this mobile communication system. The mobile node 300 is a terminal operated by a user of the mobile communication system. Although the communication node 400 is not an essential component for the description of PMIPv6, it is shown in the figure as a communication destination node of the mobile node 300. Each of the mobile node and the communication node is a kind of communication terminal.

Note that the location registration gateway 200a and the location registration gateway 200b have the same configuration, and there is no difference between them when attention is paid to the function as the location registration gateway. Therefore, in the following description, the contents common to the two

location registration gateways

200a and 200b will be described as “location registration gateway 200”. Gateway 200a ”and“ Location registration gateway 200b ”are described. The same applies to the access network 600a and the access network 600b.

The mobility management server 100 and the location registration gateway 200 are connected via a network 500. On the other hand, the location registration gateway 200 and the mobile node 300 are connected via the access network 600. Each configuration will be described below.

The mobility management server 100 corresponds to what is referred to as “Local Mobility Anchor (LMA)” in Non-Patent Document 1. The mobility management server 100 allocates the Home Network Prefix (HNP) corresponding to the network prefix portion of the address (HomeAddress: HoA) used for communication, which is notified from the location registration gateway 200, to the location registration gateway 200. The correspondence relationship with the address (Proxy Care-of Address: Proxy-CoA) is held.

The mobility management server 100 tunnels the data packet sent from the communication node 400 to the HoA of the mobile node 300 with the own device address and Proxy-CoA as endpoints, and registers the location of the data packet. Transfer to the gateway 200. On the contrary, the data packet addressed to the communication node 400 is decapsulated from the mobile node 300 and transferred to the communication node 400, which is transferred through the tunnels with the proxy-CoA of the location registration gateway 200 and the address of the own device as endpoints. To do.

The location registration gateway 200 corresponds to what is referred to as Mobile Access Gateway (MAG) in Non-Patent Document 1. The location registration gateway 200 receives a router solicitation (Router Solicitation: RS) transmitted from the mobile node 300 after the mobile node 300 is connected to the access network 600, and then uses HNP and Proxy by Proxy Binding Update (PBU). -CoA correspondence is registered in the mobility management server 100. After that, when a proxy binding acknowledgment (PBA) that is a PBU response is received from the mobility management server 100, a router advertisement (Router Advertisement: RA) is transmitted to the mobile node 300.

Here, each of RS and RA is defined in RFC4861 ("Neighbor Discovery for IP version 6 (IPv6)" http://www.ietf.org/rfc/rfc4861: hereinafter referred to as Non-Patent Document 2) Protocol. The RS is a signal transmitted when a node equipped with Internet Protocol version 6 (IPv6) requests an RA. The RA is a router to be used as a gateway when transmitting packet data to a network outside the connected link, that is, information necessary for automatically generating an IPv6 address for an IPv6 node (that is, a router that is an RA transmission source). Advertise information.

Here, the trigger of PBU transmission is RS reception, but PBU may be transmitted by different triggers.

The mobile node 300 is a terminal equipped with IPv6. Although it is called a mobile node because it is a node that is assumed to move between access networks 600, a mobile node in PMIPv6 has the same configuration as a normal IPv6 node. In MobileIPv6 (MIPv6) described in RFC 3775 ("Mobility Support in IPv6" http://www.ietf.org/rfc/rfc3775: hereinafter referred to as non-patent document 3), the location registration gateway 200 uses PBU in PMIPv6. The mobile node 300 itself performs the location registration process to be performed. At this time, a signal transmitted to the mobility management server 100 is referred to as “Binding Update (BU)”. For this reason, the mobile node 300 needs a function for performing MIPv6 operations such as location registration in addition to a general IPv6 function.

On the other hand, in PMIPv6, the mobile node 300 only needs to have a function as a general IPv6 node. This is the largest difference between PMIPv6 and MIPv6, and is an element that characterizes PMIPv6. Therefore, it is important not to require functions higher than general IPv6 nodes as much as possible in the IP layer of the mobile node 300 in order to reduce the significance of applying PMIPv6.

The communication node 400 is a node that communicates with the mobile node 300 as described above, and assumes a general IPv6 node. Therefore, the configuration is the same as that of the mobile node 300. In FIG. 1, the communication node 400 is connected to the network 500, but may be connected to the access network 600 under the location registration gateway 200 like the mobile node 300.

The network 500 is a network in which the mobility management server 100 and the location registration gateway 200 are connected. Note that the network 500 is generally a network managed by an operator who provides a mobile communication service.

The access network 600 is a network to which the mobile node 300 is connected, and the location registration gateway 200 is also arranged in the network. A wireless technology is basically applied to the access network 600. In addition, this access network, that is, between the location registration gateway 200 and the mobile node 300 is a layer 2 link, and basically has a configuration in which no router exists. However, there may be a router. In this case, the location registration gateway 200 and the mobile node 300 may be logically viewed as 1 hop by a technique such as tunneling.

Next, the operation of PMIPv6 will be described. FIG. 2 is a sequence diagram showing an operation procedure of the mobile communication system when the mobile node is connected to the access network in the mobile communication system shown in FIG.

First, the mobile node 300 connects to the access network 600a where the location registration gateway 200a is arranged (step a1). At that time, authentication processing of the mobile node 300 is performed depending on the mobile communication system, but the authentication processing is not directly related to the present invention, and thus detailed description thereof is omitted.

Next, the mobile node 300 that has detected the connection to the access network 600a transmits the RS to the location registration gateway 200a (step a2). This is a normal IPv6 node operation.

The location registration gateway 200a that has received the RS transmits a location registration request signal (corresponding to the PBU) to the mobility management server 100 using RS reception as a trigger (step a3). The location registration request signal includes the identification information of the mobile node 300, the HNP corresponding to the network prefix portion of the HoA that is the IP address used when the mobile node 300 communicates, and the Proxy- assigned to the location registration gateway 200a itself. CoA information and the like are included. Here, the HNP needs to be a prefix routed to the mobility management server 100. At this time, when the HNP allocation request is issued to the mobility management server 100, 0 is set in the HNP.

Next, when the location management request signal is received from the location registration gateway 200a, the mobility management server 100 records the correspondence between the HNP stored in the signal and the Proxy-CoA. When 0 is set in the HNP, the mobility management server 100 records the correspondence between the HNP and the Proxy-CoA after dynamically assigning the HNP using the identification information of the mobile node 300 or the like. At the same time, preparation is made to transfer a packet addressed to the HNP to the location registration gateway 200a by tunneling with the address of the mobility management server 100 and Proxy-CoA as endpoints. Thereafter, the mobility management server 100 responds to the location registration gateway 200a with a location registration response signal (corresponding to the PBA) storing a code indicating the processing result (step a4). This location registration response signal includes HNP, identification information of the mobile node 300, and the like.

Next, when the location registration gateway 200a receives the location registration response signal, the location registration gateway 200a confirms that a code indicating successful registration is set in the location registration response signal (here, it is assumed that the registration is successful), and the HNP Is stored in the mobile node 300 (step a5).

Next, when the mobile node 300 receives the RA in which the HNP is set, the mobile node 300 generates a HoA from the HNP as necessary, like a general IPv6 node. Also, set the default gateway.

As a result of such an operation, the mobile node 300 and the communication node 400 become communicable (step a6). Specifically, the data packet transmitted from the mobile node 300 is transferred to the mobility management server 100 by tunneling at the location registration gateway 200a, and transferred to the communication node 400 after the tunnel is removed. On the other hand, the data packet sent from the communication node 400 is routed to the mobility management server 100, transferred to the location registration gateway 200a by tunneling, and taken out after the tunnel is removed by the location registration gateway 200a. The packet is forwarded to the mobile node 300.

The procedure described above is the basic operation when the mobile node 300 is connected to a network that supports PMIPv6.

Next, the operation when the mobile node 300 moves between access networks 600 that support PMIPv6 will be described. FIG. 3 is a sequence diagram showing an operation procedure of the mobile communication system when the mobile node moves in the mobile communication system shown in FIG.

First, the mobile node 300 is connected to the access network 600a under the location registration gateway 200a by the procedure described with reference to FIG. At this time, the mobile node 300 and the communication node 400 can communicate via the tunnel between the location registration gateway 200a and the mobility management server 100 (step b1). The mobile node 300 retains information on a router as a default gateway in the default gateway list as a general IPv6 node operation. At this time, the location registration gateway 200a is recorded as the default gateway. A list of default gateways is shown in Figure 3 ().

Thereafter, the mobile node 300 disconnects from the access network 600a as it moves to the access network 600b (step b2). Originally, the location registration gateway 200a transmits a signal for canceling the registration of the HNP and Proxy-CoA for the mobile node 300 to the mobility management server 100, which is important for explaining the problem of the present invention. Therefore, detailed description thereof is omitted. Further, the subsequent steps b3 (the step in which the mobile node connects to the access network) to b7 (the step in which the mobile node receives the RA) are the same as the steps a1 to a5 in FIG. Is omitted.

When the operation of step b7 is completed, the default gateway information registered in the mobile node 300 is two, that is, the location registration gateway 200a and the location registration gateway 200b, when RA is received from the location registration gateway 200b. Thus, even when RA is received from a new router (location registration gateway 200b), new information is not overwritten on the information of the source router (location registration gateway 200a), and the source router Information remains in the mobile node 300.

This operation does not depend on a specific OS or implementation, but is in accordance with the specifications of the IPv6 node. Specifically, “5.3. Garbage Collection and Timeout Requirements” of RFC4861 (Non-Patent Document 2) indicates that an IPv6 node should hold information on at least two default routers. This is to increase default router selection and fault tolerance.

However, the operation of leaving the information of the source router in the mobile node 300 works well when the IPv6 node does not move, but causes a problem when the mobile node 300 moves. This problem will be described in detail.

The mobile node 300 tries to transmit a data packet to the communication node 400 in step b8 shown in FIG. 3 (step b8). At this time, the mobile node 300 selects either the location registration gateway 200a or the location registration gateway 200b as a default router. In this selection algorithm, various conditions are conceivable and elements depending on the implementation are conceivable. In any case, the source location registration gateway 200a may be selected as a default gateway. In this case, prior to transmission of the data packet, Neighbor Solicitation (NS) for confirming the arrival of the packet to the default gateway is transmitted from the mobile node 300 to the location registration gateway 200a (step b9). NS's Link local address and Link layer address are those of the source location registration gateway 200a. However, since the mobile node 300 has already moved to the access network 600b, the NS does not reach the location registration gateway 200a serving as a transmission destination for achieving the purpose.

The mobile node 300 determines that the NS has not arrived at the destination due to the elapse of a predetermined time (timeout) without receiving the Neighbor Advertisement (NA) as a response to the NS (step b10). At this point, the location registration gateway 200a information is finally deleted from the list of default gateways held by the mobile node 300.

As described above, after waiting for the NA response to time out and the information of the location registration gateway 200a being deleted from the default gateway list of the mobile node 300, the mobile node 300 selects the location registration gateway 200b as the default router. Finally, the data packet can be transmitted to the communication node 400 (step b11).

The above-mentioned timeout time depends on the implementation, but in RFC4861, the default value is 1000 [msec]. The measurement using WindowsXp was about 2000 [msec].

Therefore, a situation occurs in which a data packet cannot be transmitted from the mobile node 300 for several seconds. This is a problem because it leads to service disruption. In particular, it becomes a big problem in applications that are strongly affected by communication interruption such as voice communication.

In order to deal with this problem, the PMIPv6 base specification (Non-Patent Document 1) proposes that the link layer address and the link local address of all location registration gateways be the same value. However, this configuration applies a shared link model (a model in which multiple terminals are connected on the same link) to the access network, and a node that does not use a mobile communication service based on PMIPv6 or a mobile node having MIPv6 function (ie, In a situation where nodes that communicate using addresses depending on the access network) coexist, there are the following problems.

First, there is a possibility that the movement detection algorithm does not operate normally on a terminal having the MIPv6 function. In this case, the terminal continues to use the address (CoA) used before the movement, and the router (location registration gateway) to which the terminal has connected after the movement is from a node other than the address belonging to its own network. As a packet to be received, the packet received from the terminal is discarded. Also, a node that does not use the PMIPv6 mobile communication service cannot detect that communication with the default gateway before moving cannot be detected, and similarly continues to use the address used before moving. As a result, as in the case of the MIPv6 terminal, the packet transmitted by the node at the destination router (location registration gateway) is discarded.

The PMIPv6 base specification does not support the Shared link model, but only the Point-to-Pointlink model in which only the location registration gateway 200 and the mobile node 300 exist on the link. However, there is a strong demand to support the Shared link model in the future. In that case, as described above, there is a problem in the solution in which the Linklayer address and the Link local address of all the location registration gateways are the same. In addition to the problems described above, if the administrator of the mobility management server or the location registration gateway is different, it is considered that there may be cases where all the Linklayer address and Link local address cannot be made the same for management reasons.

As described above, when the mobile node moves on the access network, not only the destination location registration gateway but also the source location registration gateway remains as a default gateway candidate. In some cases, the source location registration gateway is selected. In this case, there may be a problem that a communication interruption time of about several seconds occurs when the mobile node sends a packet.

An example of an object of the present invention is to provide a communication processing apparatus and a communication processing method that can avoid a communication disconnection when a connection destination access network changes as a communication terminal moves.

A communication processing apparatus according to an aspect of the present invention is connected to a storage unit that stores communication terminal information in which information indicating whether or not a router advertisement has been transmitted to a connection destination communication terminal is recorded corresponding to the communication terminal. When sending a router advertisement to a communication terminal, check the communication terminal information to see if it is the first time to send a router advertisement to the communication terminal. And a control unit that sets information for increasing in the router advertisement, and sets information for lowering the priority in the router advertisement if it is not the first time.

The communication processing method according to one aspect of the present invention is a communication processing method by a communication processing device, and when transmitting a router advertisement to a connected communication terminal, whether or not the router advertisement is transmitted to the communication terminal. For the first time to send a router advertisement to the communication terminal by referring to the communication terminal information recorded in correspondence with the communication terminal, to increase the priority of selecting the own device as the communication destination Information is set in the router advertisement, and if it is not the first time, information for lowering the priority than in the first case is set in the router advertisement.

FIG. 1 is a diagram illustrating an example of a mobile communication system to which PMIPv6 is applied. FIG. 2 is a sequence diagram showing an operation procedure of the mobile communication system when the mobile node is connected to the access network in the mobile communication system shown in FIG. FIG. 3 is a sequence diagram showing an operation procedure of the mobile communication system when the mobile node moves in the mobile communication system shown in FIG. FIG. 4 is a block diagram illustrating a configuration example of the mobile communication system according to the present embodiment. FIG. 5 is a block diagram illustrating a configuration example of the location registration gateway according to the present embodiment. FIG. 6 is a table showing information about mobile nodes recorded in the storage unit shown in FIG. FIG. 7 is a flowchart showing a processing procedure when the location registration gateway of this embodiment receives an RS. FIG. 8 is a flowchart showing a processing procedure when the location registration gateway of this embodiment receives a location registration response. FIG. 9 is a flowchart showing a processing procedure when the location registration gateway of this embodiment periodically transmits an RA to a mobile node. FIG. 10 is a flowchart showing a processing procedure for determining the RA priority and transmitting the RA in the location registration gateway of the present embodiment. FIG. 11 is a sequence diagram showing an operation procedure when the location registration gateway of this embodiment is applied to a mobile communication system. FIG. 12 is a diagram showing the transition of entries recorded in the default gateway list of the mobile node in the operation procedure of FIG.

The configuration of the mobile communication system of this embodiment will be described. FIG. 4 is a block diagram illustrating a configuration example of the mobile communication system according to the present embodiment.

As shown in FIG. 4, the mobile communication system of this embodiment includes a mobility management server 100 and

location registration gateways

700a and 700b. A mobile node 300 is connected to this mobile communication system. The communication node 400 is not an essential component for PMIPv6 in the present embodiment, but is listed as a node that communicates with the mobile node 300.

It should be noted that the location registration gateway 700a and the location registration gateway 700b have the same configuration, and there is no difference between them when attention is paid to the function as the location registration gateway. Therefore, in the following description, the contents common to the two

location registration gateways

700a and 700b will be described as “location registration gateway 700”, and when it is necessary to distinguish the two, the “location registration gateway 700a” will be described. And “Location registration gateway 700b”. The same applies to the access network 600a and the access network 600b shown in FIG.

The mobility management server 100 and the location registration gateway 700 are connected via the network 500. On the other hand, the location registration gateway 700 and the mobile node 300 are connected via the access network 600.

In addition, the same code | symbol is attached | subjected about the structure similar to the structure of the mobile communication system shown in FIG. 1, and the detailed description is abbreviate | omitted. In the present embodiment, the configuration excluding the location registration gateway 700 is the same configuration as the PMIP mobile communication system described in FIG.

Next, the configuration of the location registration gateway 700 of this embodiment will be described in detail. FIG. 5 is a block diagram illustrating a configuration example of the location registration gateway according to the present embodiment.

As illustrated in FIG. 5, the location registration gateway 700 includes a storage unit 725, a communication unit 751, and a control unit 752. The communication unit 751 includes a packet transmission / reception unit 710 and a packet transmission / reception unit 711. The control unit 752 includes router request detection means 720, priority determination means 721, periodic trigger generation means 722, router advertisement generation means 723, disconnection determination means 724, and location registration gateway function implementation means 730.

Packet transmission / reception means 710 connects to the network 500 and transmits / receives packets to / from the communication partner via the network 500. The packet transmission / reception means 710 mainly exchanges packets with the mobility management server 100. Packets exchanged with the mobility management server 100 include a data packet and a signal packet for PMIP operation. The data packet includes a data packet sent from the communication node 400 to the mobile node 300 and a data packet sent from the mobile node 300 to the communication node 400 on the contrary.

On the other hand, the signal packet is a location registration request signal (PBU) or a location registration response signal (PBA). The location registration request signal is sent from the location registration gateway 700 to the mobility management server 100. The location registration response signal is sent from the mobility management server 100 to the location registration gateway 700 as a response to the location registration request signal.

Packet transmission / reception means 711 connects to the access network 600 and transmits / receives packets to / from the communication partner via the access network 600. The packet transmitting / receiving unit 711 mainly exchanges packets with the mobile node 300. Packets exchanged with the mobile node 300 include a data packet and a control packet used by a general IP terminal. The data packet includes a data packet sent from the communication node 400 to the mobile node 300 and a data packet sent from the mobile node 300 to the communication node 400 on the contrary. On the other hand, the control packet is RS or RA.

The router solicitation detection unit 720 confirms whether the packet received by the packet transmission / reception unit 711 is an RS, and if the packet is an RS, the router request detection unit 720 positions a notification including information indicating that the RS has been received together with information included in the RS. Output to the registered gateway function realization means 730. Further, the router request detection means 720 records information included in the RS in the storage unit 725.

The information included in the RS is, for example, Link Layer Address, Link local address of the mobile node 300, or the like. FIG. 6 is a table showing information on mobile nodes recorded in the storage unit of the location registration gateway. This table is referred to as a mobile node information table. Information such as Link Layer Address, Link local address, and the like of the mobile node 300 is recorded in the storage unit 725 in the form of a mobile node information table shown in FIG.

As shown in FIG. 6, in the mobile node information table, the identifier of the mobile node 300, the link layer address, the link local address, the HNP, and the RA transmission status of the mobile node 300 are recorded. Here, the RA transmission status is information indicating whether or not an RA has already been transmitted to the mobile node 300 which is a node connected for communication. If the RA transmission status is “0”, it means “not transmitted”, and if it is “1”, it means “transmitted”. However, the RA transmission status recording method is not limited to this case.

As an identifier of the mobile node 300, for example, NAI (Network Access Identifier) can be used. However, the NAI is not included in the RS. Even if the NAI is not included in the RS, there are several methods for associating the mobile node with the RS, and since it is not directly related to the present invention, a detailed description thereof will be omitted. explain.

When the mobile node 300 is connected to the access network 600, access authentication is generally performed by the location registration gateway 700. At this time, depending on the system, the location registration gateway 700 can acquire the above-described LinkLayer Address and NAI, and can know the correspondence between them. Other than this method, the location registration gateway 700 may hold the correspondence between the two in advance, or a server (not shown) may be arranged in the network 500 and the correspondence between the two may be recorded on the server. Good.

In any case, the location registration gateway 700 acquires the above-mentioned NAI based on the information included in the RS, and records it in the storage unit 725 together with the information included in the RS. When the NAI cannot be acquired, Linklayer address or Link local address may be used as the identifier of the mobile node 300. Further, identifiers other than those listed here may be used as identifiers.

The periodic trigger generation means 722 sets the mobile node on the mobile node information table recorded in the storage unit 725 as the RA transmission target, and the RA transmission that triggers the transmission of the RA and the identifier of the mobile node recorded in the table. RA transmission trigger information, which is information including the trigger, is sequentially output to the priority determination means 721. The periodic trigger generation means 722 periodically generates an RA transmission trigger for each mobile node, but this interval may be set in advance by an operator or other device. Other devices may be able to set this interval. For example, the RA transmission interval may be set from the outside.

Note that this RA transmission interval is the same time between a plurality of location registration gateways 200 constituting the communication system. Furthermore, this interval is preferably set to a short time such as 60 seconds.

When receiving the RA transmission trigger information from the location registration gateway function realizing unit 730 or the periodic trigger generating unit 722, the priority determining unit 721 stores information on the mobile node 300 corresponding to the identifier included in the received RA transmission trigger information. Read from 725. Then, the information on the RA transmission status in the mobile node information table and the identifier of the mobile node 300 are read, and it is determined whether or not it is the first time to transmit an RA to the target mobile node 300. Otherwise, it is decided to lower the priority. Further, priority information including information on the priority determined here and the identifier of the mobile node 300 is output to the router advertisement generation means 723. In a system in which RA transmitted as an RS response is guaranteed to be processed prior to periodic transmission of RA, the priority is lowered when the timing of RA transmission is periodic transmission. You may decide.

When the router advertisement generation unit 723 receives the priority information from the priority determination unit 721, the router advertisement generation unit 723 refers to the storage unit 725, reads the mobile node information that matches the identifier of the mobile node included in the priority information, and An RA corresponding to the priority included in the information is generated. At that time, the router advertisement generation means 723 sets a value corresponding to the priority of the received priority information in the RA's Preferences (DefaultPouter Preferences) field (2-bit length field). Specifically, “00” is set in binary notation when the priority is high, and “10” is set in binary notation when the priority is low.

The router advertisement generation unit 723 generates the above RA, then outputs the generated RA to the packet transmission / reception unit 711 and records information indicating that the RA has been transmitted in the mobile node information table of the storage unit 725. The RA input to the packet transmitting / receiving unit 711 is transmitted to the mobile node 300 via the access network 600.

The disconnection detecting means 724 detects that the mobile node 300 is disconnected from the access network 600 when the mobile node 300 is disconnected from the access network 600, and stores information on the mobile node 300 in the mobile node information table of the storage unit 725. Delete from. In general, the wireless interface is provided with a mechanism for detecting disconnection (LinkDown). There are various detection mechanisms depending on the type of the wireless interface, and the detection method itself is not directly related to the features of the present invention. For this reason, a general method may be used as the cutting detection method, and detailed description thereof is omitted.

The disconnection determination unit 724 uses information that can identify the mobile node 300 in order to identify information on the mobile node 300 that is to be deleted in the mobile node information table in the storage unit 725. For example, the Linklayer address of the mobile node 300 can be used. However, the information used as the identifier may be different depending on the disconnection detection method and the applied system. For example, as described above, after acquiring the NAI from the Linklayer address, the NAI may be used as the identifier. When the identifier of the point-to-point link established individually between the location registration gateway 700 and the mobile node 300 can be used, information for identifying the link may be used as the mobile node identifier instead of the Linklayer address.

As described above, the storage unit 725 records the mobile node information table shown in FIG. Information in the mobile node information table is recorded, updated, or deleted by the router request detection means 720, router advertisement generation means 723, disconnection detection means 724, and location registration gateway function realization means 730. In addition, information on the mobile node is read from the mobile node information table by the priority determination unit 721, the periodic trigger generation unit 722, and the router advertisement generation unit 723.

The location registration gateway function realization means 730 has a function required as a general location registration gateway, that is, a MAG described in Non-Patent Document 1. Specifically, it has a function of executing the following operation. The location registration gateway function realization means 730 sends a location registration request signal to the mobility management server 100 in response to reception of the RS, thereby managing the correspondence between the HNP of the mobile node 300 and the Proxy-CoA of the location registration gateway 700. A registration request is sent to the server 100 and a location registration response signal as a response is received from the mobility management server 100. Then, when a location registration response signal is received from the mobility management server 100, priority is given to the RA transmission trigger information that is information including the identifier of the mobile node and the RA transmission trigger that triggers the transmission of RA to the mobile node. It outputs to the degree determination means 721.

Also, the location registration gateway function realization means 730 of the present embodiment records information such as HNP set in the location registration response signal in the storage unit 725. Further, when a code indicating successful registration is set in the location registration response signal, the location registration gateway function realization means 730 transfers the packet received from the mobile node 300 to the mobility management server 100 by tunneling. On the contrary, after decapsulating the packet addressed to the HNP tunneled from the mobility management server 100, the packet is transferred to the mobile node 300.

In addition, although reception of RS was a trigger for transmitting a location registration request signal, in a system in which the location registration gateway can detect that mobile node 300 is connected to access network 600, mobile node 300 accesses instead of receiving RS. A location registration request signal may be transmitted upon connection to the network 600.

The packet transmission / reception means 710 and the packet transmission / reception means 711 described above include, for example, a network interface card (NIC) such as a LAN card and driver software that operates the network interface card (NIC). As the access network 600, a wireless link is usually used. At this time, the packet transmission / reception means 711 described above may be a wireless interface, the wireless base station is installed outside the location registration gateway 700, and the wireless base station and the packet transmission / reception means 711 are connected by wire. There may be. Either case is applicable to the present invention.

The router request detection means 720, priority determination means 721, periodic trigger generation means 722, router advertisement generation means 723, disconnection determination means 724, and location registration gateway function realization means 730 have a CPU (Central Processing Unit) software program. By executing this, the location registration gateway device is virtually configured. However, a part or all of them may be configured by hardware of a dedicated circuit that executes a target function. The specific configuration of the storage unit 725 is a device capable of recording information, such as a semiconductor memory or a hard disk drive.

When the mobile node 300 receives the RA from the location registration gateway 700, the mobile node 300 registers a gateway that is a packet transfer request destination in a storage unit (not shown). The registered gateway list corresponds to the default gateway list. In this embodiment, the gateway and its priority information are registered in the default gateway. When the mobile node 300 sends a packet to the outside, the mobile node 300 refers to the default gateway list and selects a gateway set with a high priority as a transfer request destination.

Note that the above-described configuration of the location registration gateway 700 is an example for carrying out the present invention, and may be another configuration.

Next, the operation procedure of the location registration gateway 700 of this embodiment will be described. 7 to 10 are flowcharts showing the operation procedure of the location registration gateway of this embodiment.

First, the processing procedure when the location registration gateway 700 receives an RS from the mobile node 300 connected to the access network 600 will be described with reference to the flowchart of FIG.

When the location registration gateway 700 receives a packet via the access network 600 and the packet transmission / reception means 710, the router request detection means 720 determines whether or not the received packet is an RS (step c1). If the received packet is not an RS, the process ends. On the other hand, when the received packet is an RS, information included in the RS is recorded in the storage unit 725 together with the identifier of the mobile node that is the transmission source of the RS (step c2). At this time, the contents and format of the information recorded in the storage unit 725 are as described above.

Subsequently, the router solicitation detection means 720 outputs a notification including information indicating that the RS has been received together with information included in the RS to the location registration gateway function realization means 730 (step c3). This notification triggers the transmission of the location registration request. When the location registration gateway function realization unit 730 receives the notification, the location registration gateway function realization unit 730 transmits a location registration request signal to the mobility management server 100 via the packet transmission / reception unit 710 and the network 500 (step c4).

In this way, the location registration gateway 700 executes processing from reception of the RS to transmission of the location registration request signal.

Next, a processing procedure from when the location registration gateway 700 receives a location registration response signal from the mobility management server 100 until it transmits an RA to the mobile node 300 will be described with reference to the flowchart of FIG.

When the packet transmission / reception unit 710 receives the location registration response signal from the mobility management server 100, the location registration gateway function realization unit 730 processes the location registration response signal according to the specifications disclosed in Non-Patent Document 1 (step d1). ). At that time, the location registration gateway function realization means 730 generates an RA transmission trigger and records the mobile node identifier and HNP set in the location registration response signal in the storage unit 725. When the location registration gateway function realization means 730 generates an RA transmission trigger, the location registration gateway 700 executes a router advertisement transmission process that is a process for transmitting a router advertisement (step d2), and selects an RA corresponding to the result. Transmit to mobile node 300. Details of the router advertisement transmission process will be described later.

Next, a processing procedure when the location registration gateway 700 periodically transmits an RA to the mobile node 300 will be described with reference to the flowchart of FIG.

Periodic trigger generation means 722 periodically generates an RA transmission trigger (step e1). When the periodic trigger generation means 722 generates an RA transmission trigger, the location registration gateway 700 executes a router advertisement transmission process (step e2), and transmits an RA corresponding to the result to the mobile node 300. Details of the router advertisement transmission process will be described later.

Next, the procedure of the router advertisement transmission process will be described with reference to the flowchart of FIG. The process described here is a process corresponding to step d2 shown in FIG. 8 and step e2 shown in FIG.

Upon receiving the RA transmission trigger information from the location registration gateway function realizing unit 730 or the periodic trigger generating unit 722, the priority determination unit 721 stores the storage unit 725 for the mobile node 300 corresponding to the identifier included in the received RA transmission trigger information. The RA transmission status of the mobile node information table is read (step f1).

Note that in a system in which an RA transmitted as an RS response is guaranteed to be processed prior to periodic RA transmission, the storage unit 725 is searched when the RA transmission trigger is periodic transmission. Instead, the determination process in the next step f2 may be skipped and the process may proceed to step f3.

The priority determination means 721 checks the RA transmission status read in step f1, and determines whether or not an RA has already been transmitted to the target mobile node 300 (step f2). If the RA has already been transmitted to the mobile node 300, the router advertisement generation means 723 sets a value indicating the priority “low” in the variable indicating the priority in the RA (step f3). On the other hand, when it is the first RA transmission, the router advertisement generation unit 723 sets a value indicating priority “high” in a variable indicating priority in RA (step f4). Subsequently, the router advertisement generation unit 723 transmits the RA generated as described above to the mobile node 300 (step f5).

In the RA preference (default gateway preference) field of the transmitted RA, an appropriate value is set according to the value of the variable indicating the priority set in step f3 or step f4. The preference field is a 2-bit field. Specifically, when the priority is “high”, the binary notation is set to “00”, and when the priority is “low”, the binary notation is used. '10' is set in the field.

When the router advertisement generation means 723 transmits the RA addressed to the mobile node 300, the router advertisement generation means 723 accesses the mobile node information table registered in the storage unit 725 and updates the RA transmission status of the mobile node 300 (step f6). That is, information that the RA has already been transmitted for the entry of the mobile node 300 is recorded.

Next, the overall operation procedure of the mobile communication system in this embodiment will be described. FIG. 11 is a sequence diagram showing an operation procedure when the location registration gateway of the present embodiment is applied to a mobile communication system. Here, it is assumed that the mobile node 300 moves to the access network 600b under the location registration gateway 700b after connecting to the access network 600a under the location registration gateway 700a shown in FIG.

The mobile node 300 connects to the access network 600a under the location registration gateway 700a (step g1). Thereafter, when the mobile node 300 detects connection to the network, it transmits the RS to the location registration gateway 700a (step g2). When receiving the RS from the mobile node 300, the location registration gateway 700a transmits a location registration request signal to the mobility management server 100 according to the procedure of the flowchart shown in FIG. 7 (step g3).

Subsequently, when the location registration gateway 700a receives a location registration response signal from the mobility management server 100 (step g4), the location registration gateway 700a executes processing in accordance with the procedures of the flowcharts shown in FIGS. Here, it is assumed that the mobile node information table recorded in the storage unit 725 is as shown in FIG. 6 and the identifier of the mobile node 300 is “MN_ID_1”. In this case, since the item of the RA transmission state of this entry is “0”, it can be seen that the mobile node 300 has not yet transmitted the RA. As a result, the RA in which the preference field is set to “00” (priority “high”) is transmitted to the mobile node 300 by the location registration gateway 700a (step g5). At this time, the location registration gateway 700 a updates the RA transmission status of the mobile node 300 in the mobile node information table to “1”, that is, “RA transmission completed”.

At this time, the information of the location registration gateway 700a is recorded in the default gateway list of the mobile node 300, and the priority thereof is 'high'. A list of default gateways is shown in FIG. The list records gateways and their priorities.

After the mobile node 300 receives the RA, the mobile node 300 and the communication node 400 can communicate via a tunnel between the location registration gateway 700a and the mobility management server 100 (step g6).

Next, the case where it is time to periodically transmit RA will be described.

When the periodic trigger generation means 722 generates an RA transmission trigger, the location registration gateway 700a transmits the RA to the mobile node 300 according to the procedure of the flowcharts shown in FIGS. 9 and 10 (step g7). At that time, the location registration gateway 700a refers to the mobile node information table shown in FIG. 6. However, since the entry of 'MN_ID_1' is set to '1' (sent) in step g5, the preference field is The RA set to “10” (priority “low”) is transmitted to the mobile node 300.

At this time, the information of the location registration gateway 700a is recorded in the default gateway list of the mobile node 300, and its priority is updated to 'low'.

Next, a case where the mobile node 300 transmits the RS again will be described. The process from the mobile node 300 transmitting the RS to the location registration gateway 700a in Step g8 shown in FIG. 11 to Step g10 is executed similarly to Step g2 to Step g4.

When the location registration gateway 700a receives the location registration response signal from the mobility management server 100 in step g10, the location registration gateway 700a executes processing in accordance with the procedures of the flowcharts shown in FIGS. 8 and 10 (step g11). At this time, the location registration gateway 700a refers to the mobile node information table recorded in the storage unit 725. Since the entry of 'MN_ID_1' is set to '1' (sent) in step g5, the preference field Is set to “10” (priority “low”), and the RA is transmitted to the mobile node 300.

Here, the priority of the entry in the default gateway list of the mobile node 300 is not changed.

Next, the case where the mobile node 300 is disconnected from the access network 600a (step g12) and connected to the access network 600b (step g13) will be described.

The mobile node 300 transmits the RS to the location registration gateway 700b after connecting to the access network 600b under the location registration gateway 700b in step g13 (step g14). When receiving the RS from the mobile node 300, the location registration gateway 700b transmits a location registration request signal to the mobility management server 100 according to the procedure of the flowchart shown in FIG. 7 (step g15).

Subsequently, when the location registration gateway 700b receives the location registration response signal from the mobility management server 100 (step g16), the location registration gateway 700b executes processing in accordance with the procedures of the flowcharts shown in FIGS. At this time, the location registration gateway 700 b refers to the mobile node information table recorded in the storage unit 725. As described in step g5, the mobile node information table is referenced based on the identifier “MN_ID_1” of the mobile node 300, and the RA transmission status item of the corresponding entry is confirmed. As a result, when the location registration gateway 700b recognizes that the RA transmission status column is “0” (not transmitted), the location registration gateway 700b sets the RA in which the preference field is set to “00” (priority “high”) to the mobile node 300. (Step g17). At this time, the location registration gateway 700b updates the RA transmission status of the mobile node 300 in the mobile node information table to “1”, that is, “RA transmission completed”.

After the mobile node 300 receives the RA from the location registration gateway 700b, the mobile node 300 and the communication node 400 can communicate via the tunnel between the location registration gateway 700b and the mobility management server 100 (step g18).

At this point, two information of the location registration gateway 700b and the location registration gateway 700a are recorded in the default gateway list of the mobile node 300. However, since the priority of the location registration gateway 700b is high and the priority of the location registration gateway 700a is low, the mobile node 300 designates the location registration gateway 700b having a high priority as the default gateway when transmitting data. Choose as. Therefore, it is possible to prevent the problem of communication interruption at the time of data transmission described with reference to FIG.

Next, the state of the entry in the default gateway list of the mobile node 300 and the transition of the entry that the mobile node 300 selects as the default date way when the process is executed according to the sequence procedure shown in FIG. 11 will be described.

FIG. 12 is a diagram showing the transition of entries recorded in the default gateway list of the mobile node in the operation procedure of FIG.

In FIG. 12, 'entry # 1' and 'entry # 2' indicate entries set in the default gateway list of the mobile node 300. 'Default gateway' indicates whether the entry selected by the mobile node 300 as the default gateway is the entry # 1 or the entry # 2 of the two entries described above. The horizontal axis of FIG. 12 is time.

When the mobile node 300 receives the RA from the location registration gateway 700a at time t1 in step g5 of FIG. 11, it creates entry # 1 (location registration gateway 700a) in the default gateway list. At this time, the priority of the entry is 'high'. At this stage, since there is only one entry, the default gateway selected when the mobile node 300 sends the packet to the outside is the location registration gateway 700a of entry # 1.

When the mobile node 300 receives the RA triggered by the periodic trigger from the location registration gateway 700a at time t2 in step g7 in FIG. 11, the priority of the entry # 1 in the default gateway list is updated from “high” to “low”. . The expiration time of the entry is also updated. Although the priority is 'low' but there is still only one entry, the mobile node 300 uses the location registration gateway 700a of entry # 1 as the default gateway.

The mobile node 300 receives the RA from the location registration gateway 700a at time t3 as a response to the RS in step g11 of FIG. Since the priority set in the received RA is 'low', entry # 1 of the default gateway list of the mobile node 300 remains 'low'. However, the expiration time of this entry is updated. It is still the location registration gateway 700a of entry # 1 that the mobile node 300 uses as the default gateway.

After the mobile node 300 has moved from the access network 600a to the access network 600b in step g12 and step g13 in FIG. 11, the mobile node 300 receives RA as a response to the RS from the location registration gateway 700b at time t4 in step g17.

Since the RA received at time t4 is sent from the location registration gateway 700b, the mobile node 300 adds entry # 2 to the default gateway list. The priority of this entry # 2 is “high”. At this time, the location registration gateway that the mobile node 300 selects as the default gateway is changed to the location registration gateway 700b of entry # 2.

Entry # 1 expires at time t5 in FIG. As a result, entry # 1 is deleted from the default gateway list, and only entry # 2 remains. Accordingly, the mobile node 300 remains the location registration gateway 700b as the default router.

In this embodiment, when the mobile node moves into the communication area of the new access network, the destination location registration gateway performs the location registration process for the mobile node and then transmits the RA to the mobile node. It is determined whether or not it is the first time that the RA is transmitted to the node. If it is the first time, the preference field in the RA is set to '00' (priority 'high'). If not, the field is set to '10' ( Set to low priority). In this way, even if information on a plurality of location registration gateways is recorded in the default gateway list of the mobile node, the priority of the location registration gateway at the destination is set high. Therefore, when the mobile node transmits a data packet, the destination location registration gateway is always selected as the default gateway, and the packet can be appropriately transmitted to the destination location registration gateway. In this embodiment, it is possible to prevent a communication disconnection from occurring when the mobile node moves and connects to a new access network without requiring a large change in the configuration of the mobile node.

As described above, this embodiment does not significantly change the mobile node, and this is a very important factor. One of the reasons for applying PMIP to a mobile communication system is that no change is required for IP terminals in which PMIP is widely used. The IP layer and transport layer processes are usually implemented as part of the Operation System (OS), and it is difficult for anyone other than the vendor of the OS developer to make changes. Therefore, PMIP is a protocol that enables mobile communication services to be provided to general IP terminals by providing the network side with mobility management capability rather than an unspecified number of mobile nodes. Therefore, in solving the problem related to PMIP, as described above, it is important that the change to the mobile node is not required as much as possible.

Also, in this embodiment, it is not necessary to make the link layer address and link local address of all location registration gateways the same, and further, no change to the IP layer processing unit of the mobile node is required. In this embodiment, after the mobile node has moved to a new access network, communication disconnection can be avoided by appropriately selecting the destination location registration gateway as the default gateway.

In this embodiment, the communication processing apparatus that executes the communication processing method of the present invention has been described as a location registration gateway.

The mobile communication system of the present invention can be applied to a mobile communication system to which PMIPv6 is applied. PMIPv6 is adopted as a mobility management technology in various standardization organizations such as 3GPP, 3GPP2, and WiMAX Forum. Therefore, the present invention can be applied to mobile communication systems formulated by those standardization organizations. In particular, the present invention is suitable when it is difficult to add a special function to the mobile node, such as when the mobile node is an open terminal such as a notebook PC.

As an example of the effect of the present invention, communication disconnection can be prevented when the communication terminal moves and connects to a new access network without requiring a large change in the configuration of the communication terminal.

The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

This application incorporates all the contents of Japanese Patent Application No. 2008-258755 filed on October 3, 2008, and claims priority based on this Japanese application.

DESCRIPTION OF SYMBOLS 100 Mobile management server 300 Mobile node 400 Communication node 500

Network

600a,

600b Access network

700a, 700b Location registration gateway 710 Packet transmission / reception means 711 Packet transmission / reception means 720 Router request detection means 721 Priority determination means 722 Periodic trigger generation means 723 Router advertisement generation Means 724 Disconnection determination means 725 Storage unit 730 Location registration gateway function realization means 751 Communication unit 752 Control unit

Claims

A storage unit that stores communication terminal information in which information indicating whether or not a router advertisement has been transmitted to the communication terminal of the connection destination is recorded corresponding to the communication terminal;
When transmitting the router advertisement to a connected communication terminal, the communication terminal information is checked to determine whether or not it is the first time to transmit a router advertisement to the communication terminal. A control unit for setting information for increasing the priority to be selected in the router advertisement, and setting information for lowering the priority in the router advertisement than when it is the first time if it is not the first time;
A communication processing apparatus.
The controller is
If the trigger for transmitting the router advertisement to the communication terminal is not a router request transmitted from the communication terminal, information for lowering the priority than the first case is sent to the router advertisement. The communication processing device according to claim 1, wherein
The controller is
The communication processing device according to claim 1, wherein after transmitting the router advertisement to the communication terminal, the router advertisement transmission status for the communication terminal is updated in the communication terminal information.
A communication processing method by a communication processing device,
When sending a router advertisement to the connected communication terminal, refer to the communication terminal information recorded in correspondence with the communication terminal information whether or not the router advertisement was sent to the communication terminal,
When it is the first time to send a router advertisement to the communication terminal, the router advertisement is set with information for increasing the priority for selecting the own device as a communication destination. A communication processing method of setting information for lowering the priority in the router advertisement.
If the trigger for transmitting the router advertisement to the communication terminal is not a router request transmitted from the communication terminal, information for lowering the priority than the first case is sent to the router advertisement. The communication processing method according to claim 4, wherein
The communication processing method according to claim 4 or 5, wherein after transmitting the router advertisement to the communication terminal, the router advertisement transmission status for the communication terminal is updated in the communication terminal information.