JP5387574B2 - Communication terminal - Google Patents

Description

  The present invention relates to a communication terminal having a communication function, a connection method using the same, and a program.

  In recent years, a location registration gateway connected to a communication terminal can register the address of the communication terminal and the address of the location registration gateway to realize mobile communication with the communication terminal as a mobile node. it can. As a method generally used for that purpose, Reference 1 (“Proxy Mobile IPv6 draft-ietf-netlmn-proxy6-18.txt”, May 30, 2008, http://tools.ietf.org/html/draft-ietf There is PMIPv6 (Proxy Mobile IPv6) described in -netlmm-proxymip6-18).

  FIG. 1 is a diagram illustrating an example of a general mobile communication system to which PMIPv6 is applied.

  The mobile communication system to which PMIPv6 shown in FIG. 1 is applied includes a mobility management server 100, location registration gateways 200a and 200b, a mobile node 300, a communication node 400, a network 500, and access networks 600a and 600b. Is done.

  Here, the location registration gateway 200a and the location registration gateway 200b have the same configuration. When attention is paid to the function as the location registration gateway, the location registration gateway 200a is described as the location registration gateway 200 because there is no difference between the two. On the other hand, when it is necessary to distinguish between the two, they are described as a location registration gateway 200a and a location registration gateway 200b, respectively. The same applies to the access networks 600a and 600b.

  The communication node 400 is not an essential component of PMIPv6, but is shown as a node that communicates with the mobile node 300.

  The mobility management server 100 and the location registration gateway 200 are connected via a network 500.

  The location registration gateway 200 and the mobile node 300 are connected via an access network 600.

  The mobility management server 100 is referred to as “Local Mobility Anchor (LMA)” in Document 1. The mobility management server 100 includes a Home Network Prefix (HNP) corresponding to a network prefix portion of an address (Home Address (HoA)) used for communication, which is notified from the location registration gateway 200, and the location registration gateway 200. And a correspondence relationship with the address (hereinafter referred to as Proxy Care-of Address (Proxy-CoA)). With this held correspondence, the data packet sent from the communication node 400 to the HoA is tunneled with the address of the mobility management server 100 and the Proxy-CoA as endpoints and transferred to the location registration gateway 200. . On the other hand, it has a function of decapsulating the data packet from the mobile node 300 transferred from the location registration gateway 200 through the tunnel with the proxy-CoA and the address of the mobility management server 100 as endpoints and transferring it to the communication node 400.

  The location registration gateway 200 is referred to as “Mobile Access Gateway (MAG)” in Document 1. The location registration gateway 200 receives the Router Solicitation (RS) transmitted from the mobile node 300 after the mobile node 300 is connected to the access network 600. In response to the reception, it has a function of registering the correspondence between HNP and Proxy-CoA in the mobility management server 100 by proxy binding update (PBU). Thereafter, when Proxy Binding Acknowledgment (PBA), which is a PBU response, is received from the mobility management server 100, Router Advertisement (RA) is transmitted to the mobile node 300. Here, RS and RA are protocols defined in Document 2 (RFC4861, “Neighbor Discovery for IP version 6 (IPv6)”, September 2007, http://www.ietf.org/rfc/rfc4861), respectively. RS is a signal that is transmitted when a node equipped with Internet Protocol version 6 (IPv6) requests an RA. The RA also provides information necessary for automatically generating an IPv6 address to an IPv6 node and a router to be used as a gateway when transmitting packet data to a network outside the connected link (that is, the RA transmission source). Router advertisement message for advertising information on the router.

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

  The mobile node 300 is a communication terminal equipped with IPv6 (without a special function related to movement such as a movement management protocol). Since it is a terminal (node) that is assumed to move between access networks 600, it is referred to as a “mobile node”, but a mobile node in PMIPv6 has the same configuration as a normal IPv6 node.

  In Mobile IPv6 (MIPv6) described in Reference 3 (RFC3775, “Mobility Support in IPv6”, June 2004, http://www.ietf.org/rfc/rfc3775), the location registration gateway 200 uses PBU in PMIPv6. The mobile node 300 itself performs the location registration process to be performed (the signal transmitted at this time 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 characterizing 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 of the communication node 400 is the same as that of the mobile node 300. Although the communication node 400 is connected to the network 500 in FIG. 1, it 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 access network 600. A wireless technology is basically applied to the access network 600 (becomes a wireless network). In addition, the access network 600, that is, the location registration gateway 200 and the mobile node 300 is a layer 2 link, and is basically configured without a router. 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.

  The operation of PMIPv6 will be described below.

  FIG. 2 is a sequence diagram for explaining the operation of PMIPv6 in the mobile communication system shown in FIG.

  First, in step a1, the mobile node 300 connects to the access network 600a where the location registration gateway 200a is arranged. At this time, authentication processing of the mobile node 300 is performed depending on the mobile communication system, but since it is not directly related to the present invention, a detailed description is omitted here.

  Next, the mobile node 300 that has detected the connection to the access network 600a transmits an RS in 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 (indicating PBU) to the mobility management server 100 using RS reception as a trigger in step a3. This 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, if the mobility management server 100 is requested to allocate an HNP, “0” is set in the HNP.

  Next, when the mobility management server 100 receives the location registration request signal, the correspondence between the HNP and the Proxy-CoA included in the received location registration request signal is recorded. When “0” is set in the HNP, after the HNP is dynamically allocated by using the identification information of the mobile node 300, the correspondence between the HNP and the Proxy-CoA is recorded. 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 (indicating PBA) storing a code indicating the processing result in step a4. This location registration response signal includes identification information of the HNP and 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 (considering the case of successful registration here), and sets the HNP. The stored RA is transmitted to the mobile node 300 in 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, as with a general IPv6 node. Also, set the default gateway.

  As a result, the mobile node 300 and the communication node 400 can communicate with each other in step a6. Specifically, the data packet sent from the mobile node 300 is transferred to the mobility management server 100 by tunneling at the location registration gateway 200a, and is transferred to the communication node 400 after the tunnel is removed by the mobility management server 100. The On the other hand, the data packet transmitted from the communication node 400 is routed to the mobility management server 100 and then transferred from the mobility management server 100 to the location registration gateway 200a by tunneling, and the tunnel is removed at the location registration gateway 200a. Thereafter, the extracted packet is transferred to the mobile node 300.

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

  Next, an operation when the mobile node 300 moves between access networks 600a and 600b that support PMIPv6 will be described.

  FIG. 3 is a sequence diagram for explaining an operation when mobile node 300 moves between access networks 600a and 600b in the mobile communication system shown in FIG.

  First, consider the situation where the mobile node 300 is connected to the access network 600a to which the location registration gateway 200a is connected in the procedure described using the sequence diagram shown in FIG. At this time (step b1), the mobile node 300 and the communication node 400 are in a state where they can communicate via a tunnel between the location registration gateway 200a and the mobility management server 100. As a general IPv6 node operation, the mobile node 300 records (holds) information on a gateway (router) as a default gateway in a default gateway list. This recorded information is identification information given to the gateway in order to identify the gateway as the default gateway. At this time, the location registration gateway 200a is recorded in the default gateway list as a default gateway.

  Thereafter, in order to move to the access network 600b, the mobile node 300 disconnects the connection with the access network 600a in 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. However, the problem to be solved by the present invention is as follows. Since it is not important for explanation, it is omitted here.

  The subsequent processing from step b3 (step in which the mobile node connects to the access network) to step b7 (step in which the mobile node receives the RA) is the same as the processing from step a1 to step a5 described using FIG. Since there is, explanation is omitted.

  When the processing of step b7 is completed, the default gateway information registered in the default gateway list of the mobile node 300 is the location registration gateway 200a, the location registration gateway 200b, and the location registration gateway 200b by receiving RA from the location registration gateway 200b. It becomes two. As described above, even when the RA is received from the new router (location registration gateway 200b), the information of the source router (location registration gateway 200a) remains in the mobile node 300 without being overwritten by the new information.

  This operation is not dependent 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” in Document 2 describes that an IPv6 node should hold information on at least two default gateways. This is to increase the choice of default gateway and improve fault tolerance. This operation works well when the IPv6 node does not move, but causes a problem when the IPv6 node moves like the mobile node 300. This will be described later.

  The mobile node 300 tries to transmit a data packet to the communication node 400 in 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 gateway. In this selection algorithm, various conditions are conceivable, and elements depending on the implementation are also conceivable. Therefore, there is a case where the location registration gateway 200a of the movement source is selected as the default gateway. In this case, prior to data packet transmission, Neighbor Solicitation (NS) for confirming the arrival of the packet to the default gateway is transmitted in step b9. The NS link local address and link layer address of the NS 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 target location registration gateway 200a.

  The mobile node 300 determines in step b10 that the NS has not arrived at the destination based on the fact that the Neighbor Advertisement (NA) serving as the NS response has not been responded and a predetermined time has elapsed (timed out).

  At this point, the location registration gateway 200a information is finally deleted from the list of default gateways held by the mobile node 300.

  Thus, 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 can finally transmit a data packet to the communication node 400 in step b11. It becomes.

  This timeout time depends on the implementation, but in Reference 2, the default value is 1000 [msec]. The measurement using WindowsXp is about 2000 [msec].

  Japanese Patent Laid-Open No. 2003-274436 discloses a technique for changing a router (gateway) to be accessed to a router that has received a router notification from an original router in a mobile node having the MIPv6 (Mobile IPv6) protocol. .

  As described above, a situation occurs in which a data packet cannot be transmitted from the mobile node 300 to the communication node 400 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 described in Document 1 proposes that the link layer address and the link local address of all location registration gateways be the same value. However, in this configuration, a shared link model is applied to the access network (a model in which a plurality of terminals are connected on the same link), and a mobile node having a MIPv6 function or a node that does not use a mobile communication service based on PMIPv6 (that is, There is a problem in the situation where nodes that communicate using addresses depending on the access network) coexist. First, in a mobile node having the MIPv6 function, there is a possibility that a movement detection algorithm does not operate normally. In that case, the terminal will continue to use the address (CoA) that was used for the movement source, and the router (location registration gateway) connected after the movement will move as a packet sent from an address other than that belonging to its own network. The result is that the packet sent by the node is discarded. Even for a node that does not use the PMIPv6 mobile communication service, it cannot be detected that communication with the default gateway of the movement source has become impossible, and the address used for the movement source will continue to be used. As a result, as in the case of the MIPv6 terminal, the packet transmitted by the terminal 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 this case, as described above, there is a problem with the solution of making the link layer address and the link local address of all location registration gateways the same. Arise. In addition to the problems described above, if the administrator of the mobility management server or location registration gateway is different, it is possible that not all link layer addresses and link local addresses may be the same for administrative reasons. .

  Moreover, in the technique described in the patent publication 2003-274436, the mobile node provided with MIPv6 is used, and the mobile node provided with general IPv6 is not used.

  That is, the problem to be solved by the present invention is that when the mobile node moves through the access network, a communication interruption time of about several seconds occurs when the mobile node sends a packet. This is because not only the location registration gateway at the destination but also the location registration gateway at the source remains as a candidate for the default gateway, and the mobile node selects the source location registration gateway as the default gateway. Because there is.

  The object of the present invention is made in view of such a problem, and the object of the present invention is not to make the link layer address and the link local address of all location registration gateways 200 the same, and the mobile node 300 further. Therefore, after the mobile node 300 moves to a new access network, communication disconnection can be avoided by appropriately selecting the destination location registration gateway 200 as a default gateway. It is to provide a communication terminal, a connection method, and a program.

In order to achieve the above object, the present invention provides:
A communication terminal that does not have a mobility management protocol for managing mobility,
A list for recording identification information given to the gateway for identifying the gateway connected to the communication terminal via the network is retained, and the communication terminal is included in the list as a gateway to which packet data is first transmitted. A packet processing unit for selecting the first gateway to which the recorded identification information is attached;
A movement determination unit that determines whether the communication terminal has moved from the first network to a second network other than the first network;
When the movement determination unit determines that the communication terminal has moved, the packet processing unit does not select the first gateway as a gateway that transmits the packet data first.

Also, a connection method for connecting a gateway connected to a network and a communication terminal that does not have a mobility management protocol for managing movement, via the network,
Maintaining a list for recording identification information given to the gateway for identifying the gateway;
Selecting a first gateway to which identification information recorded in the list is assigned as a gateway to which the communication terminal first transmits packet data;
Determining whether the communication terminal has moved from a first network to a second network other than the first network;
And a step of avoiding selecting the first gateway as a gateway for transmitting the packet data first when it is determined that the communication terminal has moved.

Also, a program that is executed by a communication terminal that does not have a mobility management protocol for managing mobility,
A procedure for maintaining a list for recording identification information given to the gateway for identifying the gateway connected to the communication terminal via the network;
A procedure for selecting the first gateway to which the identification information recorded in the list is assigned as a gateway to which the communication terminal first transmits packet data;
A procedure for determining whether the communication terminal has moved from the first network to a second network other than the first network;
When it is determined that the communication terminal has moved, a procedure for avoiding selecting the first gateway as a gateway that transmits the packet data first is executed.

  As described above, in the present invention, a list for recording identification information given to a gateway connected to a communication terminal that does not have a mobility management protocol for managing movement and a gateway connected via the network is recorded. And when it is determined that the communication terminal has moved from the first network to a second network other than the first network, the communication terminal is recorded in the list as a gateway that transmits the packet data first. Since the first gateway to which the identification information is given is not selected, communication disconnection when the mobile node moves and connects to a new access network without requiring any change to the IP stack of the mobile node Can be avoided.

It is a figure which shows an example of the general mobile communication system to which PMIPv6 is applied.

It is a sequence diagram for demonstrating the operation | movement of PMIPv6 in the mobile communication system shown in FIG.

FIG. 2 is a sequence diagram for explaining an operation when a mobile node moves between access networks in the mobile communication system shown in FIG. 1.

It is a figure which shows one Embodiment of this invention.

It is a figure which shows 1st Embodiment of the mobile node shown in FIG.

6 is a flowchart for explaining the operation of the mobile node shown in FIG. 5.

FIG. 5 is a sequence diagram for explaining an operation when the mobile node shown in FIG. 4 moves between access networks.

It is a figure which shows 2nd Embodiment of the mobile node shown in FIG.

9 is a flowchart for explaining the operation of the mobile node shown in FIG. 8.

The best mode for carrying out the present invention will be described in detail with reference to the drawings.
(First embodiment)
(Description of configuration)
FIG. 4 is a diagram showing an embodiment of the present invention.

  As shown in FIG. 4, the present embodiment includes a mobility management server 100, location registration gateways 200a and 200b, a communication node 400, a mobile node 700, a network 500, and access networks 600a and 600b.

  Here, the location registration gateway 200a and the location registration gateway 200b have the same configuration. When attention is paid to the function as the location registration gateway, the location registration gateway 200a is described as the location registration gateway 200 because there is no difference between the two. On the other hand, when it is necessary to distinguish between the two, they are described as a location registration gateway 200a and a location registration gateway 200b, respectively. The same applies to the access networks 600a and 600b.

  The communication node 400 is not an essential component of PMIPv6, but is described as a node that communicates with the mobile node 700.

  The mobility management server 100 and the location registration gateway 200 are connected via a network 500.

  The location registration gateway 200 and the mobile node 700 are connected via an access network 600.

  In FIG. 4, components having the same names and symbols as those of the components shown in FIG. 1 have the same functions as those of the components having the same names and symbols as shown in FIG. 1. That is, except for the mobile node 700, the configuration is the same as that of a general PMIP mobile communication system. A detailed description of the same configuration as that of a general PMIP mobile communication system is omitted here.

  The mobile node 700 is a communication terminal that has IPv6 in PMIPv6 and does not have a special function related to movement such as a movement management protocol for managing movement of the mobile node 700.

  FIG. 5 is a diagram showing a first embodiment of the mobile node 700 shown in FIG.

  The mobile node 700 according to the first embodiment of the present invention includes a packet transmission / reception unit 710, a signal detection unit 720, a movement determination unit 721, an information storage unit 722, a signal generation unit 723, as shown in FIG. , And a packet processing unit 730.

  The packet transmission / reception unit 710 has a function of receiving a packet that has arrived at the mobile node 700 and outputting the received packet to the packet processing unit 730 via the signal detection unit 720. Further, it has a function of receiving a packet output from the packet processing unit 730 and transmitting it to the access network 600.

  The signal detection unit 720 checks the packet output from the packet transmission / reception unit 710 and determines whether the packet is an RA. If the packet is RA, the packet is output to the movement determination unit 721.

  Here, for determining whether or not it is RA, for example, when the NextHeader field of the IPv6 header of the received packet is “2” and the first byte (ICMPv6 Type field) of the payload portion of the packet is 134. RA can be determined. However, the determination may be performed by other methods.

  The signal detection unit 720 also has a function of outputting the packet as it is to the packet processing unit 730 regardless of whether the packet is RA or not.

  After receiving the RA (new RA) output from the signal detection unit 720, the movement determination unit 721 reads the last recorded RA (old RA) from the information storage unit 722. The information included in the new RA and the information included in the old RA are compared to determine whether the mobile node 700 has moved. For comparison between the information included in the new RA and the information included in the old RA, for example, the network prefix information, the link layer address of the RA transmission source node, and the link local address of the RA transmission source node can be used. . However, the determination may be made using only a part of the information elements described above or using other information. Furthermore, if information that serves as a hint for determining movement other than RA (the connected network has changed) can be used, the movement may be determined using information other than information included in the RA.

  The movement determination unit 721 has a function of recording information on the new RA in the information storage unit 722 when it is determined that the mobile node 700 has moved. At this time, all RA information may be recorded, or the minimum necessary information may be recorded in order to save the storage capacity. The necessary minimum is, for example, network prefix information, a link layer address of the RA transmission source node, a link of the RA transmission source node, and a link local address.

  In addition, when movement is detected as a result of movement determination, the movement determination unit 721 outputs a trigger (signal) indicating that movement has occurred to the signal generation unit 723 along with information on the old RA read from the information storage unit 722. It has a function.

  In the example described above, the movement determination unit 721 performs movement determination using the RA output from the signal detection unit 720. When it is possible to determine that the movement is detected by detecting disconnection from the access network 600, a trigger indicating that the movement has occurred is output to the signal generation unit 723 together with the old RA information read from the information storage unit 722 at that time. You can also However, in this case, since there is no entry in the default gateway list, if a session is established between the mobile node 700 and the communication node 400, there is a high possibility that this will end.

  The signal generator 723 is triggered by the fact that a trigger indicating that the mobile node 700 has moved is input from the movement determination unit 721. Based on the old RA information input from the movement determination unit 721, the signal generator 723 Is provided with a function of generating an old RA with “0” set to “0” and outputting the generated RA to the packet processing unit 730. Here, in generating the old RA, necessary information is acquired from the movement determination unit 721, but may be read from the information storage unit 722. The Router Lifetime is a parameter included in the RA and indicating the expiration date of the router (location registration gateway 200). The mobile node 700 that has received the RA whose parameter is “0” invalidates the RA received in the past from the router (location registration gateway 200).

  The signal generation unit 723 outputs the RA in which the Router Lifetime field is set to “0” to the packet processing unit 730, so that “0” is set to the Router Lifetime from the source location registration gateway 200 to the packet processing unit 730. It is possible to make it appear as if the received RA has been received.

  The information storage unit 722 has a function of recording the RA information input from the movement determination unit 721. The RA information recorded in the information storage unit 722 is read from the movement determination unit 721 as necessary. However, it may be read from the signal generation unit 723 as described above. In this case, even when new RA information is recorded from the movement determination unit 721, at least one previously recorded RA information is retained.

  The packet processing unit 730 has a function of processing various protocols belonging to the IP layer and the transport layer that is an upper layer thereof. Thus, the packet output from the packet transmission / reception unit 710 via the signal detection unit 720 is processed, and the packet generated by the operation according to the application and various protocols of the IP layer is output to the packet transmission / reception unit 710. The packet processing unit 730 also has a function of generating an address and assigning an address to a network interface using the input RA as part of the IP layer processing. Furthermore, it has the above-described default gateway list, and also has a function of adding, deleting, and updating entries in the default gateway list.

  The packet transmitting / receiving unit 710 and the packet processing unit 730 are functions that also include a general mobile node 300 or a communication node 400.

  The packet transmitting / receiving unit 710 is generally implemented by, for example, a network interface card (NIC) such as a wireless LAN card and software (driver) that operates the network interface card (NIC).

  The packet processing unit 730 is basically implemented by software as a part of the OS.

  On the other hand, the signal detection unit 720, the movement determination unit 721, the information storage unit 722, and the signal generation unit 723 are all characteristic elements of the present invention, and can be realized as software (driver) that operates the NIC. For the information storage unit 722, a memory provided in a node equipped with a NIC can be used, or a memory provided in the NIC itself can be used. As the memory, a semiconductor memory is suitable, but it can also be implemented with a hard disk or other storage device (medium).

  The elements that characterize the present invention are implemented by the NIC and the software that operates the NIC. On the other hand, the packet processing unit 730 that is a part of the OS and is difficult to change is not modified. The present invention can be easily applied to a notebook computer or the like. For example, if the function of the present invention is added to a wireless LAN card and its driver and is mounted on a notebook PC, the mobile node 700 of the present invention is obtained.

The form shown above is merely an example, and other methods may be used.
(Description of operation)
Next, the operation of the mobile node 700 shown in FIG. 5 will be described.

  FIG. 6 is a flowchart for explaining the operation of mobile node 700 shown in FIG.

  First, in step c1, the packet transmitting / receiving unit 710 receives a packet from the access network 600.

  Next, in step c2, it is determined whether or not the received packet is RA (router advertisement) by the action of the signal detection unit 720. If it is determined to be RA, the process proceeds to 'Yes' to execute step c3. On the other hand, if it is determined that it is not RA, the process proceeds to 'No' to end the process.

  Here, regardless of whether or not RA is determined, the packet received by the packet transmitting / receiving unit 710 is output to the packet processing unit 730. The packet output from the packet processing unit 730 is sent to the access network 600 via the packet transmission / reception unit 710. These processes other than RA are not described in the flowchart shown in FIG. 6 because they are not related to the operation of the present invention.

  In step c3, it is determined whether or not the mobile node 700 has moved due to the action of the movement determination unit 721. If it is determined that it has moved, the process proceeds to 'Yes' and step c4 is executed. If it is determined that it has not moved, the process proceeds to 'No' to end the process. In order to determine whether it has moved, as described above, the result of comparing the information included in the new RA with the information included in the old RA is used.

  In step c4, information included in the RA is recorded in the information storage unit 722.

  Next, in step c5, an RA including the same information as the source RA and having the Router Lifetime “0” is generated from the RA information received by the source by the operation of the signal generation unit 723, and this is generated as a packet. Processing to be output to the processing unit 730 is performed.

  Then, the packet processing unit 730 invalidates the information of the location registration gateway 200 (first gateway) arranged in the access network 600 (first network) of the movement source. That is, it avoids selecting the location registration gateway 200 registered in the default gateway list as the default gateway.

  By the above operation, when the mobile node 700 moves to a new access network 600 (second network), the location registration gateway 200 (first network) arranged in the source access network 600 (first network). Information on the mobile node 300 of the gateway) can be deleted from the default gateway list. In addition, information of the mobile node 300 of the location registration gateway 200 (second gateway) arranged in the destination access network 600 (second network) is added (recorded) to the default gateway list.

  Next, an operation sequence when the mobile node 700 of the present invention moves from the access network 600a to the access network 600b will be described.

  FIG. 7 is a sequence diagram for explaining the operation when the mobile node 700 shown in FIG. 4 moves from the access network 600a (first network) to the access network 600b (second network).

  Steps d1 to d7 shown in FIG. 7 are the same as steps b1 to b7 described with reference to FIG. 3 showing the sequence when the mobile node 300 shown in FIG. 1 moves. However, at the time of step d1, not only the mobile node 700 holds the information of the location registration gateway 200a as a default gateway list, but also the RA information transmitted by the location registration gateway 200a is recorded in the information storage unit 722. Is different.

  In step d8, the process described using the flowchart shown in FIG. 6 is executed. As a result, the information on the location registration gateway 200a connected to the source is deleted from the default gateway list of the mobile node 700, and information on the location registration gateway 200b is newly added. In addition, information on the RA transmitted by the location registration gateway 200b is recorded in the information storage unit 722.

  Next, in step d9, consider the case where the mobile node 700 tries to transmit a data packet. In this case, NS is transmitted prior to data transmission in step d10. As described above, since only the information of the location registration gateway 200b is held in the default gateway list, the NS is always transmitted to the location registration gateway 200b. This NS is processed by the location registration gateway 200b, and Neighbor Advertisement (NA) is returned to NS based on the general IPv6 specification in step d11.

  Finally, the mobile node 700 that has received the NA has confirmed the reachability to the location registration gateway 200b. In step d12, the mobile node 700 transmits data to the communication node 400 via the location registration gateway 200b and the mobility management server 100. Packets can be transmitted.

  Note that RS and RA are exchanged in steps d4 and d7, respectively, and the reachability of the packet between the mobile node 700 and the location registration gateway 200b has already been confirmed, so the steps d10 and d11 are omitted. Sometimes it is done.

As described above, in the first embodiment, when the mobile node 700 moves to the new access network 600, the movement determination unit 721 performs movement determination using the RA detected by the signal detection unit 720, and From the RA information received at the source by the signal generation unit 723, an RA pretending to be transmitted by the source location registration gateway 200 with the Router Lifetime set to “0” is generated, and this is generated in the packet processing unit 730. By configuring so as to output, it is possible to delete the entry of the movement source location registration gateway 200 held in the default gateway list at the time of movement. As a result, the mobile node 700 always uses the destination location registration gateway 200 as the default gateway, so that the communication interruption described in the problem does not occur and the data packet can be transmitted immediately.
(Second Embodiment)
(Description of configuration)
Next, a second embodiment of the present invention will be described.

  FIG. 8 shows a second embodiment of mobile node 700 shown in FIG. In the second embodiment, only the mobile node 700 of the first embodiment is different, and other elements are the same as those of the first embodiment. Here, in order to distinguish from the first embodiment, the mobile node 700b is assumed.

  As shown in FIG. 8, the mobile node 700b according to the second embodiment of the present invention includes a packet transmission / reception unit 710, a signal detection unit 720, a movement determination unit 721, an information storage unit 722, and a router information deletion unit. 724 and a packet processing unit 730. Elements having the same names and symbols as those of the mobile node 700 in the first embodiment shown in FIG. 5 have the same functions as the components of the mobile node 700 in the first embodiment shown in FIG.

  As described above, the difference between the mobile node 700 of the first embodiment and the mobile node 700b of the second embodiment is that the mobile node 700b replaces the signal generation unit 723 of the mobile node 700 with router information. The deletion unit 724 is provided.

  The router information deletion unit 724 receives the RA indicating that the mobile node 700 has moved from the movement determination unit 721, and receives the RA received from the access network 600 of the movement source input from the movement determination unit 721. Based on this information, the function of specifying and deleting the information of the location registration gateway 200 arranged in the access network 600 of the movement source from the default gateway list held by the packet processing unit 730 is provided. As information for specifying the location registration gateway 200, for example, a link address can be used.

  The router information deletion unit 724 may acquire the RA (old RA) information received by the access network 600 of the movement source from the information storage unit 722. Further, instead of receiving a trigger indicating movement from the movement determination unit 721, the router information deletion unit 724 may periodically access the movement determination unit 721 and read the determination that the movement has occurred.

  In the above-described example, the movement determination unit 721 has exemplified the case where the movement determination is performed using the RA output from the signal detection unit 720. As another method, when it can be determined that the movement is detected by detecting the disconnection from the access network 600, a trigger indicating that the movement has occurred is generated together with the old RA information read from the information storage unit 722 at that time. It can also be output to the router information deletion unit 724. However, in this case, since there is no entry in the default gateway list, if a session is established between the mobile node 700 and the communication node 400, there is a high possibility that this will end.

  In carrying out the second embodiment, it is necessary to assume that the packet processing unit 730 exposes an interface for operating routing information including default gateway information to the outside, such as an upper application. . In currently popular OSs (Unix OSs such as Windows Xp, Windows Vista, and Linux), the interface is disclosed. Therefore, it is possible to implement the present invention according to the second embodiment almost without limitation.

  When implementing the second embodiment, the packet transmission / reception unit 710 is realized by a NIC such as a wireless LAN card, and the signal detection unit 720, the movement determination unit 721, and the information storage unit 722 are connected to the NIC. It can be realized as software (driver) to be operated. For the information storage unit 722, a memory provided in a node equipped with a NIC can be used, or a memory provided in the NIC itself can be used. The router information deletion unit 724 can be realized as application software. When realized by application software, it is not necessary to modify the OS including the packet processing unit 730 as in the first embodiment.

The form shown above is merely an example, and other methods may be used.
(Description of operation)
Next, the operation of the mobile node 700b shown in FIG. 8 will be described.

  FIG. 9 is a flowchart for explaining the operation of the mobile node 700b shown in FIG.

  Since the processing from step e1 to step e4 is the same as the processing from step c1 to step c4 described with reference to the flowchart of FIG. 6 showing the operation of the first embodiment, description thereof will be omitted.

  In step e5, when a trigger indicating movement determination is generated by the action of the movement determination unit 721, the router information deletion unit 724 accesses the routing information using the interface disclosed by the packet processing unit 730, and the packet processing unit 730 The entry of the location registration gateway 200 arranged in the source access network 600 is deleted from the held default gateway list. For identifying the location registration gateway 200, the information on the old RA acquired from the movement determination unit 721 or the information storage unit 722 is used.

  The sequence when the mobile node 700b in the second embodiment moves from the access network 200a to the access network 200b is the same as the sequence in the first embodiment shown in FIG.

  As described above, in the present embodiment, when the mobile node 700b moves to the new access network 600, the movement determination unit 721 uses the RA detected by the signal detection unit 720 to make a movement determination. The router information deletion unit 724 operates to delete the information of the location registration gateway 200 of the movement source from the default gateway list held by the packet processing unit 730 using the RA information received at the movement source. As a result, the mobile node 700b always uses the destination location registration gateway 200 as a default gateway (avoids using the original location registration gateway 200 as a default gateway). It becomes possible to transmit.

  Note that the processing of the mobile nodes 700 and 700b may be performed by a logic circuit manufactured according to the purpose. Further, as described above, the program (software) describing the processing contents as a procedure is recorded on a recording medium readable by the mobile nodes 700 and 700b, and the program recorded on the recording medium is read by the mobile nodes 700 and 700b. It may be executed. The recording medium readable by the mobile nodes 700 and 700b is a removable recording medium that can be attached to and detached from the mobile nodes 700 and 700b, a memory such as a ROM and a RAM, and an HDD built in the mobile nodes 700 and 700b. Etc. The program recorded on the recording medium is read by a CPU (not shown) in the mobile nodes 700 and 700b, and the same processing as described above is performed under the control of the CPU. Here, the mobile nodes 700 and 700b operate as a computer that executes a program read from a recording medium on which the program is recorded.

  As described above, when the mobile node 700 receives an RA after newly connecting to the access network 600, signal detection is performed in the middle of being output to the IP stack (block having a function of processing the IP layer) of the mobile node 700. The RA reception is detected (acquired) by the action of the unit 720, the information set in the acquired RA by the movement determination unit 721, and the information of the RA received by the access network 600 of the movement source recorded in the information storage unit 722 , Thereby detecting that the mobile node 700 has moved. The movement determination unit 721 records the RA information acquired here in the information storage unit 722. When the movement determination unit 721 determines that the mobile node 700 has moved, the signal generation unit 723 generates the movement source RA using the information set in the movement source RA. However, the Router Lifetime field is set to “0”. The RA with the generated Router Lifetime “0” is output to the IP stack.

  As a result, the information on the location registration gateway 200 of the movement source recorded in the default gateway list of the mobile node 700 is regarded as the expiration of the valid time and is deleted. Therefore, the mobile node 700 can always transmit a data packet to the destination location registration gateway 200.

  As described above, the IP stack is not changed, but this is very important in applying the method of the present invention.

  One of the reasons is that the processing of the IP layer and the transport layer is usually implemented as a part of the operation system (OS), and it is difficult for anyone other than the vendor of the OS developer to make changes. Also, the fact that no additional function is required in the IP stack of the terminal (mobile node 700) is a major reason for applying PMIP, along with the reason that it is difficult to change to the IP stack for the above reason. This is because it is not appropriate to include a special function for operation in a specific system in an IP stack of a general-purpose terminal such as a notebook PC.

  As described above, the following effects can be obtained by the present invention.

  The first effect is that communication disconnection when the mobile node moves and connects to a new access network can be avoided without requiring any change to the IP stack of the mobile node.

  The reason is that when a communication node detects movement, it is configured to send an RA that looks like an RA sent by the location registration gateway of the move source and that has an Router Lifetime field of “0” to the IP stack. This is because the information of the location registration gateway of the movement source can be deleted from the default gateway list held by the mobile node.

  The second effect is similar to that in the case where the destination location registration gateway sends the same processing, that is, the RA pretending to be the RA sent by the source location registration gateway and the Router Lifetime is “0”. Thus, the bandwidth of the access network can be saved.

  The reason is that RA is generated in the mobile node and output to the IP stack, so that the access network bandwidth is not consumed. Further, in order for the location registration gateway to transmit the above-described RA, information exchange between the location registration gateways is required, but there is also an advantage that no additional function is required for the location registration gateway.

  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, it can be said that the present invention can be applied to mobile communication systems formulated by those standardization organizations and is effective.

  Although the present invention has been described with reference to the embodiments, 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 claims the priority on the basis of Japanese application Japanese Patent Application No. 2008-188504 for which it applied on July 22, 2008, and takes in those the indications of all here.

Claims (15)

A communication terminal that does not have a mobility management protocol for managing mobility,
A list for recording identification information given to the gateway for identifying the gateway connected to the communication terminal via the network is retained, and the communication terminal is included in the list as a gateway to which packet data is first transmitted. A packet processing unit for selecting the first gateway to which the recorded identification information is attached;
A movement determination unit that determines whether the communication terminal has moved from the first network to a second network other than the first network;
The packet processing unit is a communication terminal that does not select the first gateway as a gateway that transmits the packet data first when the movement determination unit determines that the communication terminal has moved. The communication terminal according to claim 1,
An information storage unit for recording a router advertisement message including identification information of the first gateway;
The movement determination unit compares a router advertisement message including identification information of the first gateway with a router advertisement message transmitted from a second gateway connected to the second network, and compares the first advertisement with the router advertisement message. When the router advertisement message including the gateway identification information is different from the router advertisement message transmitted from the second gateway, it is determined that the communication terminal has moved,
The information storage unit records a router advertisement message transmitted from the second gateway when the movement determination unit determines that the communication terminal has moved. The communication terminal according to claim 2,
The packet processing unit, when the movement determination unit determines that the communication terminal has moved, deletes the identification information of the first gateway recorded in the list from the list. Terminal. The communication terminal according to claim 3,
The packet processing unit, when the movement determination unit determines that the communication terminal has moved, identification information given to the second gateway included in the router advertisement message transmitted from the second gateway Is recorded in the list. The communication terminal according to claim 3,
When the movement determination unit determines that the communication terminal has moved, a router advertisement message in which the parameter indicating the expiration date of the gateway included in the router advertisement message including the identification information of the first gateway indicates invalidity A signal generation unit that generates and outputs to the packet processing unit,
When the router advertisement message indicating that the parameter is invalid is output from the signal generation unit, the packet processing unit deletes the identification information of the first gateway recorded in the list from the list. A characteristic communication terminal. A connection method for connecting a gateway connected to a network and a communication terminal not equipped with a movement management protocol for managing movement through the network,
Maintaining a list for recording identification information given to the gateway for identifying the gateway;
Selecting a first gateway to which identification information recorded in the list is assigned as a gateway to which the communication terminal first transmits packet data;
Determining whether the communication terminal has moved from a first network to a second network other than the first network;
And a step of avoiding selecting the first gateway as a gateway that transmits the packet data first when it is determined that the communication terminal has moved. The connection method according to claim 6, wherein
Recording a router advertisement message including identification information of the first gateway;
Comparing a router advertisement message including identification information of the first gateway with a router advertisement message transmitted from a second gateway connected to the second network;
Determining that the communication terminal has moved when the router advertisement message including the identification information of the first gateway is different from the router advertisement message transmitted from the second gateway;
And a step of recording a router advertisement message transmitted from the second gateway when it is determined that the communication terminal has moved. The connection method according to claim 7,
When it is determined that the communication terminal has moved, the connection method includes a step of deleting the identification information of the first gateway recorded in the list from the list. The connection method according to claim 8,
When it is determined that the communication terminal has moved, the method includes a step of recording in the list the identification information given to the second gateway included in the router advertisement message transmitted from the second gateway. Connection method. The connection method according to claim 8,
If it is determined that the communication terminal has moved, generating a router advertisement message in which a parameter indicating an expiration date of the gateway included in the router advertisement message including the identification information of the first gateway indicates invalidity;
And deleting the identification information of the first gateway recorded in the list from the list based on the generated advertisement message. For communication terminals that do not have a mobility management protocol for managing mobility,
A procedure for maintaining a list for recording identification information given to the gateway for identifying the gateway connected to the communication terminal via the network;
A procedure for selecting the first gateway to which the identification information recorded in the list is assigned as a gateway to which the communication terminal first transmits packet data;
A procedure for determining whether the communication terminal has moved from the first network to a second network other than the first network;
A program for executing a procedure for avoiding selecting the first gateway as a gateway for transmitting the packet data first when it is determined that the communication terminal has moved. The program according to claim 11,
Recording a router advertisement message including identification information of the first gateway;
Comparing the router advertisement message including the identification information of the first gateway with the router advertisement message transmitted from the second gateway connected to the second network;
A procedure for determining that the communication terminal has moved when a router advertisement message including identification information of the first gateway is different from a router advertisement message transmitted from the second gateway;
When determining that the communication terminal has moved, a program for executing a procedure for recording a router advertisement message transmitted from the second gateway. The program according to claim 12,
When it is determined that the communication terminal has moved, a program for executing a procedure for deleting the identification information of the first gateway recorded in the list from the list. The program according to claim 13, wherein
When it is determined that the communication terminal has moved, a procedure for recording the identification information given to the second gateway included in the router advertisement message transmitted from the second gateway in the list is executed. A featured program. The program according to claim 13, wherein
If it is determined that the communication terminal has moved, a procedure for generating a router advertisement message in which the parameter indicating the expiration date of the gateway included in the router advertisement message including the identification information of the first gateway indicates invalidity;
And a program for deleting the identification information of the first gateway recorded in the list from the list based on the generated advertisement message.

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