JP4806364B2 - Router switching method and router device - Google Patents

Description

The present invention relates to a router switching method and a router device.

  In recent years, in a communication system using IP (Internet Protocol), a case where a certain local network is connected to another network such as the Internet via a plurality of router devices is increasing. In such a case, even though a terminal connected to the local network is communicating with an external device (such as an information distribution server) via a default router device, the communication is When cut due to factors such as a decrease in electric field strength, the following processing is performed. That is, the router device is switched to another router device, and communication between the two devices is continued without disconnecting the session between the terminal and the external device.

For example, a conventional router device broadcasts a routing stop message to all nodes (other router devices and terminals) in the local network when it is predicted that the routing function cannot be executed. As a factor of the prediction, for example, when the connection of the router device to the external link is overloaded, the electric field strength is reduced during the wireless connection with the external link, or the like. Then, in the other router device of the broadcast distribution destination, when the routing stop message is received, the routing function can be executed when the own routing function can be executed or after a predetermined time. Broadcast messages to all nodes (other routers and terminals) in the local network. In this way, switching between router devices is realized at high speed. Such switching is realized on the following system.
That is, this is a system in which a plurality of router devices (those that can be externally linked) are managed by the same management server (home agent) and the same network prefix is advertised to the local network (see, for example, Patent Document 1). ). However, for example, there are cellular interfaces such as third-generation mobile communication and wireless LAN interfaces as external connection interfaces, and router devices having respective interfaces are accommodated in management servers under the management of different communication entities. It is also assumed that there may be cases. In such a case, it is considered that the domains under the management of the telecommunications carrier are different, and the network prefix for the local network assigned to each router device also takes a different value (network prefix value of a different domain). It is done.
This system will be described with reference to FIG. The terminal 30 communicates with the external terminal 20 via the router device 10a and the management server 18. For example, when it becomes difficult for the router device 10a to maintain the link connection with the base station device 16, the communication flow during communication between the terminal 30 and the external terminal 20 is transferred from the router device 10a to the router device. Switch to route to 10b. At this time, the router device 10 a performs location registration (Binding registration) with the management server 18, and the router device 10 b performs location registration with the management server 19.

  Next, another conventional switching method (for example, Non-Patent Document 1) will be described with reference to FIG. In this case, at the time of switching between router devices, for example, the switching source router device 10a notifies the switching destination router device 10b of the address of the management server 18 in which the router device 10a is accommodated. The router device 10b having received the notification transmits a binding update to the management server 18 in which the router device 10a is accommodated. The management server 18 describes the network prefix advertised by the router device 10a in the response message for binding confirmation and transmits it to the router device 10b. The router device 10b extracts the network prefix advertised by the router device 10a from the received response message. Then, the router device 10b advertises to the local network 1. In this way, each of the router device 10a and the router device 10b shares a network prefix, and the router device 10b advertises the same network prefix as the router device 10a. Thereby, the communication flow relayed via the management server 18 and the router device 10a is switched and relayed via the management server 18 and the router device 10b. Further, the terminal 30 continues to use the address according to the network prefix of the router device 10a after the switching of the router device, and maintains a session with the external terminal 20.

Japanese Patent Application No. 2004-116404 J.Ryu N Choi, “Failover for Multiple Mobile Routers in a Mobile Network”, [online], Internet-Draft, July 8, 2005, Internet <URL: http://www.ietf.org/internet-drafts/draft -ryu-nemo-mr-failover-00.txt>

However, in the method described in Patent Document 1, since the router device 10a and the router device 10b advertise different network prefixes in the local network, the session with the external terminal 20 is disconnected when the router device is switched. The This is because the router device 10a indicated in the next hop of the network prefix advertised to the router device 10a loses the relay function, and the terminal 30 cannot perform packet transmission in the communication flow so far.
Further, since the packet transmitted from the external terminal 20 is addressed to the address generated from the network prefix advertised by the router device 10a, the session between the terminal 30 and the external terminal 20 is disconnected. This is because the packet transmitted from the external terminal 20 passes through the management server 18 even after the switching of the router device, but after the communication between the router device 10a and the base station device 16 is disconnected. This is because the management server 18 cannot transfer the packet to the terminal 30.

  Further, in the method described in Non-Patent Document 1, when the terminal 30 establishes a new session after switching the router device, the address according to the network prefix advertised by the router device 10a is still used. It will be. Originally, the network prefix of the router device 10a shared by the router device 10b is managed and owned by a telecommunications carrier different from that to which the router device 10b belongs, and is newly established after switching the router device. On the other hand, the network prefix managed and owned by the communication carrier to which the router device 10b belongs should be used. However, for the above reason, when the terminal establishes a new session, the terminal cannot use an address conforming to an appropriate network prefix originally advertised by the router device 10b.

  As described above, in the methods such as Patent Document 1 and Non-Patent Document 1, when a terminal establishes a new session, the terminal uses an address conforming to an appropriate network prefix originally advertised by the router device 10b. Can not.

  In view of the above, an object of the present invention is to solve the above-described problems and to appropriately switch the communication flow between the counterpart device and the mobile terminal.

In order to achieve the above object, a router switching method according to the present invention relays communication between a mobile terminal in a network and a counterpart device via the mobile terminal and an external network, and connects to the external network. A router switching method in a system including a plurality of router devices managed by a plurality of external management devices, wherein another router device as a switching destination of the router device being relayed is A step of acquiring a first prefix in the network assigned to the router device being relayed, and the external management device managing the router device being relayed including the acquired first prefix The step of registering the binding via the external network and the priority of the acquired first prefix assigned to the own device; The first prefix having the respective priorities is set to be lower than the second prefix or at least one of setting the priority of the second prefix higher than the first prefix. And transmitting a router advertisement including the second prefix on the network. After the communication with the counterpart device is completed, the mobile terminal uses the transmitted second prefix having a high priority, and manages the other router device and the router device. Starting communication with the counterpart device via
Thereby, after the communication with the counterpart device is completed, a communication path using a prefix with a high priority can be secured.

  In order to achieve the above object, a router device according to the present invention is assigned to a relaying router device that relays communication between a mobile terminal in a network and a partner device via an external network. An acquisition unit that acquires a prefix in a network, and a registration unit that causes an external management device that manages a relaying router device to register a binding including the acquired first prefix via the external network; The priority of the acquired first prefix is set lower than the second prefix assigned to the own apparatus, or the priority of the second prefix is set from the first prefix. A router that includes a setting unit that performs at least one of the higher settings and the first and second prefixes having the respective priorities. Comprising a transmitter for transmitting over the Ttowaku, the.

  In order to achieve the above object, a mobile terminal according to the present invention receives and manages a router advertisement including a first prefix having a low priority and a second prefix having a high priority. After the communication via the router device between the mobile terminal in the network and the partner device is completed, the second prefix having a high priority is used to start communication with the partner device. A communication unit that uses the first prefix having a low priority while continuing communication with the counterpart device, and continues communication with the counterpart device.

  According to the present invention, it is possible to appropriately switch router devices.

FIG. 1 is a block diagram showing a configuration example of the entire system including a router device according to an embodiment of the present invention.
In FIG. 1, a terminal (mobile terminal) 30 is configured to be connectable to a local network (network) 1, and the terminal 30 can be wirelessly connected to an external link destination base station apparatus 16 via a router apparatus 10 a. It is configured. The terminal 30 is, for example, a personal computer, a PDA, a mobile phone, a game machine, or the like.
The base station device 16 is connected to an external terminal (partner device) 20 via an access network (external network) 2 such as the Internet network and a backbone network (external network) 4. Note that a management server (external management device) 18 is connected to the access network 2.
In addition, a router device 10b is also connected to the local network 1, and the terminal 30 is configured to be connectable to the base station device 17 wirelessly via the router device 10b. The base station device 17 is connected to an external terminal 20 via an access network (external network) 3 such as a mobile phone network and a backbone network 4. A management server (external management device) 19 is connected to the access network 3.
In FIG. 1, one terminal 30 and two router apparatuses 10a and 10b are shown, but the number of these is not limited to this. Further, although the external terminal 20 is described as being connected to the backbone network 4, the external terminal 20 may be connected to the access networks 2 and 3.

For example, when the router device 10a is connected to the base station device 16 and the address of the router device 10a is given by the base station device 16, the router device 10a notifies the management server 18 of the address. At the time of this notification, the router device 10a also notifies the management server 18 of the network prefix to be advertised (broadcast) to the local network 1. After this notification, the management server 18 captures the packet from the external terminal 20 (addressed to the terminal 30) and tunnels it to the router device 10a. The router apparatus 10 a forwarded by tunneling removes the tunnel header from the packet and forwards the inner packet to the terminal 30.
Note that the packet transmitted from the terminal 30 to the external terminal 20 is tunnel-transferred to the management server 18 under the management of the router device 10a, for example. The management server 18 that has received the tunnel transfer removes the tunnel header from the packet and transfers the inner packet to the external terminal 20.
Also, for example, when the router device 10b is connected to the base station device 17 and the address of the router device 10b is given by the base station device 17, the router device 10b uses the address as in the case of the router device 10a. The management server 19 is notified. At the time of this notification, the router device 10b also notifies the management server 19 of the network prefix to be advertised (broadcast) to the local network 1. With this notification, the management server 19 then captures the packet from the external terminal 20 (addressed to the terminal 30) or tunnels it to the router device 10b. The router device 10b that has been tunneled removes the tunnel header from the packet and transfers the inner packet to the terminal 30.
Note that the packet transmitted from the terminal 30 to the external terminal 20 is tunnel-transferred to the management server 19 under the management of the router device 10b, for example. The management server 19 that has received the tunnel transfer removes the tunnel header from the packet and transfers the inner packet to the external terminal 20.

[Switching between router devices]
Next, the switching process between the router devices 10a and 10b will be outlined. Here, when the terminal 30 is communicating with the external terminal 20 via the router device 10a, the communication state between the router device 10a and the base station device 16 (hereinafter referred to as the external link state) is deteriorated. Assuming the above case, processing 1, processing 2, and processing 3 to be described later will be sequentially described. In the present embodiment, the external link means connection with a node (base station apparatus) outside the local network.
In this case, first, the relaying router device 10a that has detected the deterioration of the external link state determines whether there is a communication flow in which the session should be continued. As a result, when there is a communication flow, the router device 10a requests another router device 10b in the local network 1 to take over the relay of the communication flow by the terminal 30, and starts router switching (processing) 1: processing in which the router device 10b acquires a prefix assigned to the router device 10a).

  Subsequently, in order to switch the router device, the router device 10a or the router device 10b (one of them) transmits a binding update to the management server 18 regarding the location information of the router device 10b. Binding refers to a set of a home address, a care-of address, and a network prefix advertised in the local network, which will be described later. (Process 2: Processing for registering the binding including the prefix assigned to the router device 10a in the management server 18).

Next, after the registration of the location information is completed, the router device 10b sets the priority of the network prefix (first prefix) advertised by the router device 10a to “low” and the network device advertised by the router device 10b. The priority of the fix (second prefix) is set to “high”, and these two network prefixes are advertised to the local network 1. In the present embodiment, the case where the priorities of both network prefixes are set will be described. However, the priority of either one of the network prefixes may be set.
The terminal 30 uses a network prefix having a priority of “low” with respect to a communication flow that avoids session disconnection by switching the router device. The terminal 30 uses a network prefix having a “high” priority for a newly established session. The router device 10b uses a prefix list 900 to be described later, and gives priority to two network prefixes and advertises them in the local network (Process 3: Router advertisement including a network prefix to which the router device 10b has priority). Process to send).

Hereinafter, the processing 1, processing 2, and processing 3 will be described in detail.
First, processing 1 will be described in detail with reference to FIGS. 2A to 2C. Here, the three processing methods shown in FIGS. 2A to 2C will be described step by step.
In FIG. 2A, in S51, the router device 10a detects the deterioration of the radio wave condition. That is, the router device 10a determines that it is difficult to maintain the connection with the base station device 16 due to the deterioration of the external link state.

In S <b> 40, the router device 10 a issues a disconnection notification toward the local network 1. Specifically, the router device 10 a transmits a disconnection notification message for notifying the disconnection of communication with the base station device 16 to the local network 1. For example, the disconnection notification message is realized by describing an estimated time until the connection with the base station apparatus 16 is disconnected in a router lifetime field of a router advertisement (RA) message defined in RFC 2461. Can do. The router advertisement refers to advertising information such as a global address prefix (including router lifetime, valid lifetime, and preferred lifetime). The router lifetime indicates a time during which the router that has transmitted the RA can be used as a default.
Furthermore, in S40, the router device 10a transmits a disconnection notification (including an inquiry about the presence / absence of communication) to the router device 10b and the terminal 30 in communication because the external link status of the router device 10a has deteriorated.

  In S41, the terminal 30 issues a switching request as a response to the disconnection notification. Specifically, the terminal 30 transmits a switching request message to the router device 10a. The switching request message is a message for requesting switching of the router device. S41 will be described in detail. The terminal 30 detects the presence / absence of a communication flow with the router device 10a as the next hop from the state of a socket generated for communication by the installed application. As a result of the detection, if a communication flow exists, the terminal 30 transmits a switching request message to the router device 10a.

In S42, upon receiving the transmission, the router device 10a makes a switching request. Specifically, the router device 10a transmits a switching request message (including the network prefix of the local network 1 and the address of the router device 10a) to the router device 10b.
In order to add the binding update list of the router device 10a to the router device 10b, the binding update list held by the router device 10a is included in one of the disconnection notification message (see S40) or the switch request message (see S42). (Details will be described later).
In S52, the router device 10b that has received the switch request message from the router device 10a performs link connection to the outside (this is referred to as external link connection; the same applies hereinafter).

  As described above, when switching from the router device 10a to the router device 10b is started, the switching is performed only when there is a communication flow relayed by the router device 10a. In this case, it is not necessary to switch the router device which is originally unnecessary. For this reason, it is possible to reduce resource consumption in the router device and reduce battery consumption of the router device. Note that the router apparatus 10a sends the final switching request message (see S42), so that the conventional switching method of the router apparatus need not be changed as much as possible.

  When the disconnection notification message includes a binding update list (see FIG. 9) to be described later and the switching request message (see S42) does not include the binding update list to be described later (see FIG. 9), switching of the router device may be started. If possible, both the switching request messages (see S41 and S42) may have the same format and description, or may be different.

Next, the processing method shown in FIG. 2B will be described in detail. Since the processes of S40, S51, and S52 are the same as those in FIG. 2A, only the process of S43 will be described.
In S43, the terminal 30 issues a switching request to the router device 10b in addition to the router device 10a. Specifically, after detecting the presence or absence of the communication flow, the terminal 30 broadcasts a switching request message (including the network prefix of the local network 1 and the address of the router device 10a) also on the local network 1 (or multicast). )
If it carries out as mentioned above, reliable flow detection can be implemented because the terminal 30 detects the presence or absence of a communication flow. Furthermore, since the terminal 30 distributes the switching request message (see S43) to the router device 10b, for example, by broadcast, it is possible to quickly start the switching processing of the router device.
Since the terminal 30 does not hold the binding update list (see FIG. 9) of the router device 10a, the binding update list held by the router device 10a is included in the disconnection notification message (see S40) (described later).

Next, the processing method shown in FIG. 2C will be described. Since the processes of S40, S51, and S52 are the same as those in FIG. 2A, only the process of S44 will be described.
In S44, the router device 10a detects the communication flow, and sends a switching request message (including the network prefix of the local network 1 and the address of the router device 10a) to the router device 10b. When detecting the communication flow, the router device 10a records the time of the packet to be relayed and detects a communication flow by detecting a TCP (Transmission Control Protocol) SYN packet or a reset packet. Examples of the transmission method include broadcast and multicast.
Since the router device 10b adds the binding update list (see FIG. 9) of the router device 10a, the binding held by the router device 10a in one of the disconnection notification message (see S40) or the switch request message (see S44). Include an update list (see below).

  In S41 to S44 (see FIGS. 2A to 2C), when the terminal 30 or the router device 10a transmits a switching request, the router device 10b extracts the address of the router device 10a and the network prefix from the switching request. And stored in the network prefix list 900 described later.

Next, the process 2 will be described in detail with reference to FIGS. 3A to 3D. Here, the four processing methods shown in FIGS. 3A to 3D will be described step by step.
In FIG. 3A, after the router device 10b completes the external link connection (S52), in S61, the router device 10b requests the router device 10a to send a binding (BU) update (hereinafter referred to as a BU transmission request). Do. The BU transmission request is performed using a message, and this message (also referred to as a request message) includes an address given by external link connection (hereinafter referred to as a care-of address of the router device 10b). In the present embodiment, the care-of address means an address used in the subnet visited by the router device 10b. Since the router device 10b immediately transfers the packet transferred from the mobility management server 18 to the terminal 30 after the external link is connected, first, in the disconnection notification message (see S40) or the switch request message (see S42). The binding update list (see FIG. 9) of the included router device 10a is extracted from each message. Then, the router device 10b adds the extracted binding update list (see the first row 804 in FIG. 9) of the router device 10a to its own binding update list (see the second row 805 in FIG. 9). After updating the binding update list, a BU transmission request message is transmitted.

  In S62, the router apparatus 10a that has received the request message transmits a binding update (including the management server 18 address, the care-of address of the router apparatus 10b, and the network prefix advertised by the router apparatus 10a (hereinafter “Prefix1”)). . Specifically, the router device 10a extracts the care-of address of the router device 10b from the request message. Then, the router device 10a describes the extracted care-of address in the care-of address option of the update message and transmits it to the management server 18. The update message is a binding update message, and includes a network prefix advertised to the local network 1 by the router device 10a. The management server 18 that has received the update message may transmit a banding response (binding update completion message) after completing the update of the binding cache (registering the care-of address of the router device 10b in the binding cache). In this case, when the router device 10a receives the binding response transmitted from the management server 18, the router device 10a may transmit to the router device 10b that the binding is completed.

Thereafter, the external link of the router device 10a is disconnected (see the broken line in FIG. 3A), and the terminal 30 communicates with the router device 10b (S65). The router device 10b communicates with the management server 18 (S66). Furthermore, the management server 18 communicates with the external device 20 (S67).
Specifically, when the terminal 30 transmits a packet addressed to the external terminal 20, the router device 10b captures the packet (see S65). Then, the router device 10b tunnels the packet to the management server 18 (see S66). The tunnel transfer destination management server 18 extracts the tunnel packet from the packet and transfers it to the external terminal 20 (see S67).
On the other hand, when the external terminal 20 transmits a packet addressed to the terminal 30, the management server 18 captures the packet (see S67). Then, the management server 18 tunnels the packet to the router device 10b (see S66). The tunnel transfer destination router 10b extracts the tunnel packet from the packet and transfers it to the terminal 30 (see S65).

[Processing of communication flow of router device]
Here, processing of the communication flow of the router device 10b in the case of FIG. 3A will be described.
When the transmission source address of the communication flow from the terminal 30 to the external terminal 20 is an address generated using Prefix 1 advertised by the router device 10a, the router device 10b uses the network prefix in the binding update list 800 described later. It is determined that the flow is via the management server 18. At this time, the router device 10b performs transmission by tunneling to the management server 18, and adds a header (transmission destination address = address of the management server 18, transmission source address = care-of address of the router device 10b) and transmits the result.
On the other hand, when the transmission source address of the communication flow is an address generated using Prefix 2 advertised by the router device 10b, the router device 10b uses the network prefix in the binding update list 800 as a flow via the management server 19. Judge that there is. At that time, since the router device 10b performs tunnel transfer to the management server 18, the router device 10b adds a header (transmission destination address = address of the management server 19 and transmission source address = care-of address of the router device 10b), Send.

Next, the processing method shown in FIG. 3B will be described. Note that the processing of S52 is the same as in the case of FIG. 3A, so other processing will be described.
In S71, the router device 10b requests binding update. Specifically, the router device 10 b transmits an update message for requesting binding update to the management server 19. The update message includes the care-of address given by the external link connection.
In S72, the management server 19 that has received the update message sends a binding response. Specifically, the management server 19 performs a binding response in response to the update message, and transmits the response message to the router device 10b.
In S73, the router device 10b receiving the response message makes a BU transmission request to the router device 10a. Specifically, the router device 10b transmits a BU transmission request message to the router device 10a. This message (also referred to as a request message) includes the home address of the router device 10b assigned to the management server 19. In the present embodiment, the home address means an address that the terminal 30 continues to use for communication with the external terminal 20.

In S74, the router device 10a that has received the BU transmission request transmits a ping request packet addressed to the home address of the router device 10b, and the management server 18 captures the packet.
In S75, the management server 18 transfers the ping request packet to the home address of the router device 10b. Since the management server 19 captures the ping request packet as a proxy for the router device 10b, the management server 19 completes address resolution and captures the ping packet. Specifically, when completing the address resolution, the management server 19 first receives a neighbor solicitation message with the home address of the router device 10b as the destination address. The management server 19 transmits a neighbor advertisement message to receive a ping packet as a proxy for the router device 10b. However, since the router device 10b may exist on the same link, the neighbor advertisement message is transmitted with a delay. In RFC 2461, a delay of 1 second is provided. This completes address resolution.
In S76, the management server 19 transfers the ping request packet to the router device 10b.
In S77, the router device 10b that has received the ping request packet transmits a ping response packet corresponding to the ping request packet, and the management server 19 captures the packet.
In S78, the management server 19 transmits the ping response packet, and the management server 18 captures the packet.
In S79, the management server 18 that has received the ping response packet transfers the ping response packet to the router device 10a.

  In S80, the router device 10a that has received the ping response packet transmits a binding update (including the address of the management server 18, the home address of the router device 10b, and the network prefix “Prefix1”). Specifically, the router device 10a receives the BU transmission request and extracts the home address of the router device 10b from the request message. Then, the router device 10a describes the extracted home address in the care-of address option of the update message and transmits it to the management server 18. The update message is a binding update message, and includes a network prefix advertised to the local network 1 by the router device 10a. The management server 18 that has received the update message may transmit a banding response after completing the update of the binding cache. In this case, when the router device 10a receives the binding response transmitted from the management server 18, the router device 10a may transmit to the router device 10b that the binding is completed.

Thereafter, the external link of the router device 10a is disconnected (see the broken line in FIG. 3B), and the terminal 30 communicates with the router device 10a (S84). The router device 10b communicates with the management server 19 (S83). The management server 19 communicates with the management server 18 (S82). Furthermore, the management server 18 communicates with the external device 20 (S81).
Specifically, when the terminal 30 transmits a packet addressed to the external terminal 20, the router device 10b captures the packet (see S84). Then, the router device 10b generates a tunnel packet addressed to the management server 18 based on the packet and forwards the tunnel packet to the management server 19 (see S83). The management server 19 at the tunnel transfer destination extracts the tunnel packet and transfers it to the management server 18 (see S82). Further, the management server 18 extracts the transferred tunnel packet and transfers it to the external terminal 20 (S81). reference).
On the other hand, when the external terminal 20 transmits a packet addressed to the terminal 30, the management server 18 captures the packet (see S81). When the management server 18 tunnels the packet to the home address of the router device 10b, the management server 19 captures the tunnel packet (see S82) and forwards the tunnel packet to the router device 10b (see S83). . The router device 10b extracts the tunnel packet and transfers it to the terminal 30 (see S84).

[Processing of communication flow of router device]
Here, the processing of the communication flow of the router device 10b in the case of FIG. 3B will be described (the same applies to the processing of FIG. 3A).
When the transmission source address of the communication flow transmitted from the terminal 30 to the external terminal 20 is an address generated using Prefix 1 advertised by the router device 10a, the router device 10b transmits the network prefix in the binding update list 800 described later. Therefore, it is determined that the flow is via the management server 18. At that time, since the router device 10 b first performs tunnel transfer from the management server 19 to the management server 18, the header (transmission destination address = address of the management server 18, transmission source address = route of the router device 10 b assigned to the management server 19). Home address) is added. Next, in order to perform tunnel transfer from the router device 10b to the management server 19, the router device 10b further adds a header (transmission destination address = address of the management server 19, transmission source address = router device 10b) to the packet to which the header is added. ) And send it.

  On the other hand, when the transmission source address of the communication flow is an address generated using Prefix 2 advertised by the router device 10b, the router device 10b passes the management server 19 from the network prefix in the binding update list 800 described later. It is determined that the flow is. At that time, since the router device 10b performs tunnel transfer to the management server 18, the router device 10b adds a header (transmission destination address = address of the management server 19, transmission source address = care-of address of the router device 10b) and transmits To do.

Next, the processing method shown in FIG. 3C will be described. Note that the processing of S52 is the same as in the case of FIG. 2A, so other processing will be described.
In S91, the router device 10a makes a BU transmission request. Specifically, the router device 10a transmits a request message for a BU transmission request to the router device 10b following the router device switching request. The request message includes the following information. That is, the security policy for the router device 10a to establish a security association with the management server 18, information on the current security association, the address of the management server 18, and the home address of the router device 10a.

In the present embodiment, since communication between nodes uses IPv6 (Internet Protocol Version 6), security between nodes is ensured according to regulations of IPsec (Security Architecture for Internet Protocol). Therefore, when the router device 10b transmits a BU update message instead of the router device 10a, a security policy and a security association are required.
The security policy defines which packet is used for communication using IPsec. The security association means exchanging and sharing parameter information (encryption method, encryption key, etc.) for performing communication using IPsec between nodes to secure a safe communication path.

  Although FIG. 3C shows a case where the BU transmission request in S91 is made after S52, the order may be reversed.

  In S92, the router device 10b requests binding update. Specifically, the router device 10b receives the BU transmission request in S91 and confirms whether the external link connection (see S52) is completed. If it is not completed as a result of the confirmation, the router device 10b waits until it is completed. On the other hand, when the external link connection is completed, the router device 10b transmits an update message for requesting a binding update to the management server 18 based on the content requested for BU transmission. This update message is configured based on the information extracted from the request message requested for BU transmission, and includes the care-of address of the router device 10b.

In addition, when transmitting the update message, the router device 10b confirms the communication method by IPsec from the contents of the security policy. Therefore, the router device 10b creates a packet for performing communication by IPsec from the security association corresponding to the security policy.
Parameter information (information such as an encryption method and an encryption key) used in the security policy and the security association is based on information extracted from the request message requested to be transmitted by BU.

The management server 18 requested to update the binding in S92 makes a binding response. Specifically, the management server 18 registers the home address of the router device 10b in the binding cache, and transmits a response message for notifying that the registration is completed to the router device 10a. The router device 10b receives the response message from the management server 18. The binding update list may be updated again after receiving the binding response message.
Thereafter, the external link of the router device 10a is disconnected (see the broken line in FIG. 3C), and the packet addressed to the external terminal 20 transmitted from the terminal 30 is captured by the router device 10b (see S94), and then the management server 18 (See S95). The tunnel transfer destination management server 18 extracts the tunneled packet and transfers it to the external terminal 20 (see S96).
On the other hand, the packet addressed to the terminal 30 transmitted from the external terminal 20 is captured by the management server 18 (see S96) and then tunneled to the router device 10b (see S95). The tunnel transfer destination router apparatus 10b extracts the tunnel packet transferred through the tunnel and transfers it to the terminal 30 (see S94).

Next, the processing method shown in FIG. 3D will be described. Note that the processing of S52 is the same as in the case of FIG. 2A, so other processing will be described.
In S111, the router device 10b requests binding update. Specifically, the router device 10 b transmits an update message for requesting binding update to the management server 19. The update message includes the care-of address given by the external link connection in S52.
In S112, the management server 19 requested to update the binding makes a binding response to the router device 10b in response to the request. Thereby, the router device 10b receives the response message of the binding response from the management server 19.

In S113, the router device 10b receives the binding response and performs router advertisement. Specifically, the router device 10b sends a router advertisement message including a managed network prefix to the local network 1.
In S114, the router device 10a receives the router advertisement message from the router device 10b, and requests the router device 10b to update the binding. Specifically, an address corresponding to the network prefix under the management of the router device 10b is generated and assigned to the internal interface of the router device 10a. Then, the router device 10a uses the assigned address as a care-of address and includes it in the update message for requesting the binding update, and transmits the update message to the management server 18.

In S115, the router device 10b captures the update message from the router device 10a and tunnels it to the management server 19.
In S116, the management server 19 extracts the tunnel packet transferred by the tunnel from the router device 10b. The management server 19 includes the extracted tunnel packet in the update message and transfers the update message to the management server 18.
In S117, the management server 18 sends a binding response to the management server 19. Specifically, the management server 18 receives the update message from the management server 19 and registers an address corresponding to the network prefix under the management of the router device 10b in the binding cache. Then, the management server 18 transmits a response message for notifying that the registration is completed to the router device 10a.
In S118, receiving the transmission from the management server 18, the management server 19 captures the response message and tunnels it to the router device 10b.
In S119, the router device 10a extracts the tunnel packet transferred through the tunnel, and transfers it to the router device 10a. Thereby, the router apparatus 10a receives the response message, and the registration is completed.

  Thereafter, the external link of the router device 10a is disconnected (see the broken line in FIG. 3D), and the packet addressed to the terminal 30 transmitted from the external terminal 20 is captured by the management server 18 (see S120), and then the router device 10a. And is captured by the management server 19 (see S121). Then, the management server 19 tunnels the packet to the router device 10b (see S122). The router device 10b forwards the tunneled tunnel packet to the router device 10a (see S123), and the router device 10a extracts the tunnel packet and forwards it to the terminal 30 (see S124).

  On the other hand, the packet addressed to the external terminal 20 transmitted from the terminal 30 is captured by the router device 10a (see S124). Thereafter, the router device 10a generates a tunnel packet addressed to the management server 18 and transmits it to the router device 10b, and the router device 10b captures the tunnel packet (see S123). Then, the router device 10b tunnels the tunnel packet to the management server 19 (see S122). The management server 19 extracts the tunnel packet transferred by the tunnel and transmits it to the management server 18, and the management server 18 captures the tunnel packet (see S121). Then, the management server 18 extracts the tunnel packet and transfers it to the external terminal 20 (see S120).

Next, processing 3 will be described with reference to FIG.
In S201, the router device 10b performs a router advertisement. Specifically, the router device 10 b sends a router advertisement message to be transmitted (for example, broadcast) on the local network 1 to the local network 1. The router advertisement message here includes a network prefix under management of the router device 10a (which has been acquired in advance by the router device 10b) and a network prefix under management of the router device 10b.
Further, the router device 10b gives priority to the two network prefixes when sending the router advertisement message. In the present embodiment, a priority of “low” is given to the network prefix under the management of the router device 10a, and a priority of “high” is given to the network prefix under the management of the router device 10b. Is granted. That is, the router device 10b sets the priority of the network prefix under its management higher than the network prefix under the management of another router device 10a.

Here, an example of the prefix information option 500 included in the router advertisement message is shown in FIG.
In this example, the prefix information option 500 includes a network preference field (prf) 501 and a prefix field (prefix) 502. The preference field 501 holds the priority of the network prefix, and the prefix field 502 holds the value of the network prefix. The prefix field 502 also includes information related to the network prefix such as the valid time and the network prefix length.
The prefix information option 500 is given for each network prefix.

Returning to FIG. 4, in S <b> 202, the router device 10 b sends a stop notification to the local network 1 to stop the relay processing for the network prefix of the router device 10 a. Thereby, the terminal 30 receives the stop notification and changes the next hop (default router) for the network prefix (the router device 10a) indicated in the stop notification to the router device 10b.
However, even in such a case, when the terminal 30 starts a new session, it corresponds to the network prefix to which the priority of “high” is given, that is, the network prefix under the management of the router device 10b. An address is used, and an address corresponding to the network prefix of the router device 10a is not used.

Therefore, when the terminal device 30 has a communication flow at the time of switching to the router device 10b, that is, at the time of switching the router device, the following relay processing is performed. That is, when the terminal 30 transmits a packet addressed to the external terminal 20, the router device 10b captures the packet (see S203). Then, the router device 10b tunnels the packet to the management server 18 or the management server 19 (see S204). Thereafter, the management server 18 extracts the tunnel packet transferred by the tunnel and transfers it to the external terminal 20 (see S205).
On the other hand, when the external terminal 20 transmits a packet addressed to the terminal 30, the packet is relayed in the order from the external device 20 to the management server 18, the router device 10b, and the terminal 30 (see S205, S204, and S203).

On the other hand, when the terminal 30 starts a new session in S53, the end point of the communication flow is an address corresponding to the network prefix under the management of the router device 10b.
That is, when the terminal 30 transmits a packet addressed to the external terminal 20, the router device 10b captures the packet (see S206). Then, the router device 10b tunnels the packet to the management server 19 (see S207). Thereafter, the management server 19 extracts the tunneled packet that has been forwarded to the external terminal 20 (see S208).
On the other hand, when the external terminal 20 transmits a packet addressed to the terminal 30, the packet is relayed in the order from the external device 20 to the management server 19, the router device 10b, and the terminal 30 (see S208, S207, and S206).

[Configuration example of router device]
Next, a configuration example of the router device 10a will be described with reference to FIG. The configuration of the router device 10b is the same as the configuration of the router device 10a.
In FIG. 6, the router device 10 a includes an external communication interface 21, an internal communication interface 22, an L3 processing unit 23, and an upper layer processing unit 24. Furthermore, the router device 10a includes a switching processing unit (also referred to as an acquisition unit, a registration unit, or a setting unit) 25, a prefix control unit (transmission unit) 26, a communication flow detection unit 27, and a movement management unit 28.
The external communication interface 21 is an interface for connecting to the base station apparatuses 16 and 17 outside the local network 1. The internal communication interface 22 is an interface for connecting to the local network 1. The L3 processing unit 23 performs processing at the network layer.

The upper layer processing unit 24 performs processing in a layer higher than the network layer. The upper layer processing unit 24 is necessary when the router device 10a performs relay at layer 4 or higher or when an application is operated, but is not required when relay at layer 3 or lower is performed.
In the present embodiment, the router device 10a performs relaying at layer 3, and therefore, the upper layer processing unit 24 will be described as unnecessary. The router device 10a may perform relay in a layer other than layer 3. Other functions of each part of the router device 10a will be described later.
The switching processing unit (acquisition unit) 25 is a first in the network 1 assigned to the relaying router device that relays communication between the terminal 30 in the network 1 and the external terminal 20 via the external network. Get the prefix of. Also, the switching processing unit (registration unit) 25 causes the management server that manages the relaying router device to register the binding including the first prefix via the external network. Further, the switching processing unit (setting unit) 25 sets the priority of the first prefix lower than the second prefix assigned to the own apparatus, or the priority of the second prefix. Is set higher than the first prefix.

[Processing example of router device]
Next, a processing example of the router device 10a will be outlined. The router device 10b performs the same processing as the router device 10a.
In the router device 10a, when the L3 processing unit 23 receives a packet via the external communication interface 21, the following processing is performed. That is, when the packet is addressed to the router device 10 a, the L3 processing unit 23 processes the packet or transfers it to the switching processing unit 25, the movement management unit 28, and the upper layer processing unit 24.
On the other hand, when the packet is not addressed to the router device 10a, the L3 processing unit 23 transfers the packet to the external communication interface 21 or the internal communication interface 22 according to the destination of the packet. For example, when the packet is addressed to the terminal 30 on the local network 1, the L3 processing unit 23 sends the packet to the local network 1 via the internal communication interface 22. Note that when the L3 processing unit 23 receives a packet via the internal communication interface 22, the same processing as when a packet is received via the external communication interface 21 is performed.

  The mobility management unit 28 performs control based on, for example, Mobile IP / NEMO (Network Mobility) defined in IETF. Specifically, when the address (care-of address) given to the external communication interface 21 is changed, the movement management unit 28 receives a notification to that effect from the L3 processing unit 23 and performs the following processing. That is, the mobility management unit 28 includes the set of the home address of the router device 10a and the changed care-of address in the update message. Then, the movement management unit 28 transmits the update message to the management server 18.

In the present embodiment, the L3 processing unit 23 manages the network prefix assigned to the communication link connected to the internal communication interface 22. This network prefix is included in the update message. The management server 18 manages a set of the home address of the router device 10a and the care-of address.
By doing so, the packet addressed to the network prefix, that is, the packet on the local network 1 to which the internal communication interface 22 is connected (addressed to the terminal 30) passes through the router 10a via the management server 18. And transferred to the local network 1. From the above, it is possible to realize movement transparency of the network (clarity of the packet relay route).

  The network prefix may be statically assigned by the router device 10a or may be dynamically set. In the case of this dynamic setting, the network prefix is assigned by a management server installed on the network or a DHCP server (not shown) according to a request from the router device 10a (known technique).

[Processing example of switching source router]
Next, a processing example of the switching source router device 10a will be described based on FIGS. 7A to 7C, FIGS. 8 and 9. FIG.
First, it demonstrates based on FIG. 7A. The processing example in FIG. 7A corresponds to the series of processing in FIGS. 2A, 3A, and 4.
In S170, the switching processing unit 25 of the router device 10a starts router switching (corresponding to S51 in FIG. 2A). Specifically, the switching processing unit 25 monitors the communication state of the external communication interface 21, and determines the start of switching of the router device when detecting the deterioration of the communication state. Note that the cause of detecting the deterioration of the communication state includes, for example, link disconnection, an increase in bit error rate, and a decrease in received electric field strength.
In S171, the switching processing unit 25 notifies disconnection (corresponding to S40 in FIG. 2A). Specifically, the switching processing unit 25 sends a disconnection notification message (see S40 in FIG. 2A) to the local network 1 via the L3 processing unit 23 and the internal communication interface 22.

In S <b> 172, the switching processing unit 25 determines whether there is a switching request from the terminal 30. Specifically, the switching processing unit 25 determines whether a switching request message (see S41 in FIG. 2A) from the terminal 30 has been received.
For example, if the switching request message is not received even after a predetermined time has elapsed, it is determined that there is no switching request from the terminal 30 (No in S172), and the prefix control unit 26 transmits a router advertisement. (S180). Specifically, the prefix control unit 26 sets the router lifetime value to “0” (router lifetime = 0), and sends a router advertisement message having the value to the local network 1. It is not necessary to explicitly disconnect the external link.

  On the other hand, when the switching request message is received, when it is determined that there is a switching request from the terminal 30 (Yes in S172), the switching processing unit 25 issues a switching request to the router device 10b (S42 in FIG. 2A). Equivalent). Specifically, the switching processing unit 25 transmits a switching request message (see S42 in FIG. 2A) to be sent to the switching destination router device 10b via the L3 processing unit 23 and the internal communication interface 22. The switching request message may be newly generated, or may be based on the switching request message received from the terminal 30.

Note that the disconnection notification message or the switch request message of the present embodiment includes a binding update list held by the router device 10a. This binding update list includes an address of the management server 18, a home address of the router device 10a, and a network prefix advertised by the router device 10a.
When the router device 10b receives the disconnection notification message or the switching request message, the router device 10b extracts the banding update list of the router device 10a from each message. Then, the banding update list of the router device 10a, that is, the address of the management server 18, the home address of the router device 10a, and the network prefix advertised by the router device 10a are added to the binding update list held by itself. This additional example is shown in FIG.

In this example, the binding update list 800 includes a management server address 801, a home address 802, and a network prefix 803.
The first line 804 of the binding update list 800 includes the banding update list of the router apparatus 10a, and the second line 805 includes the banding update list of the router apparatus 10b. The first line 804 is an added list. That is, in the first line 804, the address of the management server 18, the home address of the router device 10a, and the value of Prefix1 are associated and added (this is the binding update held by the router device 10a). List contents).

In S174, the switching processing unit 25 receives a request for BU transmission (corresponding to S61 in FIG. 3A). Specifically, the switching processing unit 25 receives a request message (see S61 in FIG. 3A) from the router device 10b via the internal communication interface 22 and the L3 processing unit 23.
In S175, the movement management unit 28 requests binding update (corresponding to S62 in FIG. 3A). Specifically, the switching processing unit 25 extracts the care-of address of the router device 10b requested from the router device 10b from the received request message. Then, the switching processing unit 25 notifies the movement management unit 28 of the care-of address.
Upon receiving the notification, the movement management unit 28 includes the new care-of address in the update message (see S62 in FIG. 3A), and the update message is sent to the management server via the L3 processing unit 23 and the external communication interface 21. 18 to send.

Here, a configuration example of the care-of address option 600 including the new care-of address is described.

As shown in FIG. In this example, an Care-of Address field (Alternate Care-of Address) 60
1 holds the care-of address of the router device 10b.

When the movement management unit 28 of the router apparatus receives a binding response from the management server 18, the movement message is received from the management server 18 via the external communication interface 21 and the L3 processing unit 23.
Then, the switching processing unit 25 transmits a BU completion message. Specifically, the switching processing unit 25 sends a BU completion message indicating that the new care-of address has been registered in the management server 18 to the router device 10b via the L3 processing unit 23 and the external communication interface 21. Send.

  Thereafter, the router device 10b transmits a router advertisement message including the prefix of the router device 10a (the value of Prefix 1 in FIG. 9) (corresponding to S201 in FIG. 4), and sends a stop notification message to the local network 1 at a predetermined timing. (Corresponding to S202 in FIG. 4).

  In response to the transmission, in S178 in FIG. 7A, the switching processing unit 25 receives a stop notification from the router device 10b (corresponding to S202 in FIG. 4). Specifically, the switching processing unit 25 receives a stop notification message via the internal communication interface 22 and the L3 processing unit 23. In this case, if the external link is connected, the switching processing unit 25 disconnects the external link (S179). This completes the switching process of the router device 10a.

In FIG. 7A, the case of the process corresponding to the series of processes of FIGS. 2A, 3A, and 4 has been described. However, when the process of FIG. 2B is applied instead of FIG. Different from 2A.
That is, the process of S173 in FIG. 7A is omitted. In the case of FIG. 2B, since the terminal 30 also transmits the switching request message to the router device 10b (see S43 in FIG. 2B), the router device 10a does not need to transmit the switching request message to the router device 10b. . The switching request message transmitted from the terminal 30 includes the network prefix managed by the prefix control unit 26 and advertised to the local network 1, and the address of the router device 10a.

When the process of FIG. 2C is applied instead of FIG. 2A, the following points are different from those of FIG. 2A (see FIG. 7A).
That is, the switching processing unit 25 proceeds to S173 when it is confirmed that there is a relay flow having the terminal 30 as a termination point instead of the switching request (Yes in S172 of FIG. 7A). That is, in S172, the flow detection unit 27 of the router device 10a confirms whether there is a communication flow having the terminal 30 as a termination point.

When the process of FIG. 3B is applied instead of FIG. 3A, the following points are different from those of FIG. 3A (see FIG. 7A).
That is, after receiving the request for BU transmission (corresponding to S174 in FIG. 7A), the switching processing unit 25
The switching processing unit 25 notifies the L3 processing unit 23 to transmit a ping request packet. Receiving the notification, the L3 processing unit 23 transmits a ping request packet to the home address of the router device 10b via the external communication interface 21. Thereafter, the L3 processing unit 23 receives the ping response packet via the external communication interface 21 and notifies the switching processing unit 25 of a message indicating that the ping response packet has been received.

Next, a description will be given based on FIG. 7B. The processing example in FIG. 7B corresponds to the series of processing in FIG. 2B, FIG. 3C, and FIG. In addition, about the process same as FIG. 7A, the code | symbol (code | symbol included) same as it is attached | subjected and duplication description is abbreviate | omitted. Therefore, the process of S172A will be described below.
In S172A, the switching processing unit 25 of the router device 10a requests BU transmission (corresponding to S91 in FIG. 3C). Specifically, the switching processing unit 25 receives a switching request message from the terminal 30 via the internal communication interface 22 and the L3 processing unit 23. Then, in response to the switching request message, the switching processing unit 25 transmits a BU transmission request message to the router device 10b via the L3 processing unit 23 and the internal communication interface 22, and the processes after S178 are performed.
The request message includes the following contents as described above. That is, the security policy between the router device 10a and the management server 18, information on the current security association, the address of the management server 18, and the home address of the router device 10a.

Next, a description will be given based on FIG. 7C. The processing example in FIG. 7C corresponds to the series of processing in FIG. 2A, FIG. 3D, and FIG. In addition, about the process same as FIG. 7A, the code | symbol (code | symbol included) same as it is attached | subjected and duplication description is abbreviate | omitted. Therefore, in the following, the process of S172B will be mainly described.
In S172B, the switching processing unit 25 of the router device 10a receives an RA (Router Advertisement) indicating a router advertisement (corresponding to S113 in FIG. 3D), and proceeds to S175. Specifically, in S172B, the switching processing unit 25 receives the switching request message from the terminal 30 and receives the router advertisement message (RA) via the internal communication interface 22 and the L3 processing unit 23.
In S175, the switching processing unit 25 requests a binding update (corresponding to S114 in FIG. 3D). Specifically, the switching processing unit 25 generates and assigns an address corresponding to the network prefix under the management of the router device 10b. Then, the switching processing unit 25 includes the address as a care-of address in the update message, and transmits the update message to the management server 18 via the L3 processing unit 23 and the external communication interface 21.

[Processing example of the switching destination router]
Next, a processing example of the switching destination router apparatus 10b will be described with reference to FIGS. 10A to 10C and FIG.
First, it demonstrates based on FIG. 10A. Note that the processing example in FIG. 10A corresponds to the series of processing in FIGS. 2A, 3A, and 4.
In FIG. 10A, in S130, the switching processing unit 25 of the router device 10b receives a switching request (corresponding to S42 in FIG. 2A). Specifically, the switching processing unit 25 receives a switching request message from the router device 10 a via the internal communication interface 22 and the L3 processing unit 23. Thereafter, the switching processing unit 25 extracts the address and network prefix of the source router device 10a from the switching request message. Then, the switching processing unit 25 transfers the extracted address (for example, MR 10a) of the router device 10a and the network prefix (for example, Prefix 1) to the prefix control unit 26. Upon receiving this transfer, the prefix control unit 26 manages them in a prefix list. An example of this management is shown in FIG.

The prefix list 900 shown in FIG. 11 includes a network prefix column 901 that describes a network prefix value, a communication interface column 902 that describes a communication interface to which a network prefix is assigned, and the address of the management entity of the network prefix. And an address field 903 that describes the priority given when the network prefix is advertised.
In the network prefix column 901, Prefix 1 (the network prefix of the router device 10a) notified by the switching request in S130 is described. In the communication interface column 902, an internal IF1 (communication interface provided in the router device 10b) indicating the internal communication interface 22 is described. Further, the address field 903 describes the address MR10a of the router device 10a. In the priority column 904, “low” indicating that the priority is low is described.

  Here, the disconnection notification message or the switch request message of the present embodiment includes a binding update list held by the first router device (10a or 10b). The second router device (10b or 10a) extracts the binding update list of the first router device from any of the above messages. Then, the second router device adds the extracted binding update list, that is, the address of the management server, the home address, and the network prefix to the binding update list held by itself. This additional example is as shown in FIG. In the binding update list of FIG. 9, the binding update list of the router device 10a is added to the first line 804.

  Returning to FIG. 10A, in S131, the L3 processing unit 23 connects to an external link (base station device 17) by the external communication interface 21 (corresponding to S52 in FIG. 2A). With this connection, the L3 processing unit 23 is connected to the external link, and acquires or generates an address (care-of address) for the external communication interface 21 (from). Then, the L3 processing unit 23 notifies the movement management unit 28 of the care-of address and causes the switching processing unit 25 to control it. The movement management unit 28 appropriately registers the care-of address in the management server 18.

In S132, the switching control unit 25 requests BU transmission (corresponding to S61 in FIG. 3A).
Specifically, the switching control unit 25 acquires the notified care-of address from the movement management unit 28 and writes it in a BU transmission request message. The switching control unit 25 transmits a BU transmission request message to the switching request source router device 10a received in S130. In the case of the process of FIG. 3B, in S132, the switching control unit 25 transmits the BU transmission request message with its own home address. Only this point is different from the case of FIG. 3A. Thereby, in the router apparatus 10a, the process which makes the management server 18 register the address of the router apparatus 10b is performed.

In S134, the prefix control unit 26 performs router advertisement (corresponding to S201 in FIG. 4). Specifically, after the switching processing unit 25 receives the BU completion message, the prefix control unit 26 determines that the router advertisement message (internal communication interface) is based on the prefix list 900 (see FIG. 11) constructed previously. (Including the network prefix related to 22) is sent to the local network 1 via the L3 processing unit 23 and the internal communication interface 22. At this time, two network prefixes are sent: a network prefix under the management of the router device 10a (Prefix 1 in FIG. 11) and a network prefix under its own management (Prefix 2 in FIG. 11). .
When performing the router advertisement, the prefix control unit 26 sets the priority of the network prefix of “Prefix 1” to “low” and sets the priority of the network prefix of “Prefix 2” to “high”. .

  In S135, the prefix control unit 26 transmits a stop notification to the local network 1 with the transmission source address as the router device 10a (corresponding to S202 in FIG. 4). In this case, the prefix control unit 26 sets the following information in the stop notification message in response to an instruction from the switching processing unit 25. That is, the transmission source address of the router device 10a (MR 10a of the address 903 in FIG. 11), the network prefix “Prefix1” corresponding to the address (see the network prefix 901 in FIG. 11), and the router lifetime of “0” Value.

Next, a description will be given based on FIG. 10B. The processing example in FIG. 10B corresponds to the series of processing in FIG. 2B, FIG. 3C, and FIG. In addition, about the process same as FIG. 10A, the code | symbol (code | symbol included) same as it is attached | subjected and duplication description is abbreviate | omitted. Therefore, hereinafter, the processing of S131A and S131B will be described.
In S131A, the switching control unit 25 of the router device 10b receives a request for BU transmission (corresponding to S91 in FIG. 3C). In this case, the BU transmission request message includes the following information. That is, it is information relating to a security policy for establishing a security association between the router device 10a and the management server 18, and the current security association. Furthermore, it is the address of the management server 18 and the home address of the router device 10a.
In S131B, the movement management unit 28 requests binding update (corresponding to S92 in FIG. 3C). Specifically, the mobility management unit 28 uses IPsec to transmit a binding update update message to the management server 18 based on the content of the request message requested for BU transmission in S131A.

Next, a description will be given based on FIG. 10C. The processing example in FIG. 10C corresponds to the series of processing in FIGS. 2A, 3D, and 4. In addition, about the process same as FIG. 10A, the code | symbol (code | symbol included) same as it is attached | subjected and duplication description is abbreviate | omitted. Therefore, in the following, the process of S131C will be described.
In S131C, the prefix control unit 26 performs router advertisement (corresponding to S113 in FIG. 3D). Specifically, the prefix control unit 26 transmits a router advertisement message in the local network 1. Thereby, thereafter, the prefix control unit 26 performs tunnel transfer of the binding update update message from the router device 10a to the router device 10b.

  In the present embodiment, the case where the two router devices 10a and 10b (see FIGS. 7A to 7C and FIGS. 10A to 10C) operate independently has been described. Those operations may be performed.

[Example of terminal configuration]
Next, a configuration example of the terminal 30 will be described with reference to FIG.
In FIG. 12, the terminal 30 includes a communication interface 31, an L3 processing unit 32, and an upper layer processing unit 33. Furthermore, the terminal 30 includes a communication flow detection unit 34, a switching processing unit (also referred to as a management unit, a communication unit, or a transmission unit) 35, and a prefix determination unit 36.
The communication interface 31 is an interface for connecting to the local network 1, and the L3 processing unit 32 performs network layer processing. The upper layer processing unit 33 performs processing higher than the network layer.
The communication flow detector 34 detects the presence or absence of a communication flow. The switching processing unit 35 performs a switching process of the router device. Specifically, the switching processing unit (management unit) 35 receives and manages a router advertisement including a first prefix with a low priority and a second prefix with a high priority. In addition, after the communication with the external terminal 20 is completed, the switching processing unit (communication unit) 35 uses the second prefix to start communication with the external terminal 20 and the external terminal 20. While the communication with is continued, the first prefix is used and the communication with the external terminal 20 is continued. Further, when a communication flow is detected by the communication flow detection unit 34, the switching processing unit (transmission unit) 35 transmits information (switching request) indicating that the router device being relayed is changed to another router device (switch request). Send in.
The prefix determination unit 36 identifies the priority of the network prefix.

[Example of terminal processing]
Next, a processing example of the terminal 30 will be described with reference to FIG. Here, regarding the processing related to the switching processing of the router device, processing until a session is newly started will be described.
In S150, the switching processing unit 35 of the terminal 30 performs a disconnection notification reception process (see S40 in FIGS. 2A to 2C). Specifically, the switching processing unit 35 receives and manages the disconnection notification message from the router device 10a via the communication interface 31 and the L3 processing unit 32.

In S151, the communication flow detection unit 34 detects whether or not there is a flow that relays the disconnection notification transmission source. Specifically, the communication flow detection unit 34 detects whether or not there is a communication flow with the disconnection notification message source, that is, the router device 10a as the next hop.
If the communication flow does not exist (No in S151), the process ends. On the other hand, if it exists (Yes in S151), the process proceeds to S152, and the switching processing unit 35 issues a switching request (in FIG. 2A). S41, corresponding to S43 in FIG. 2B). In the case of S152, the switching processing unit 35 transmits a switching request message to the router device 10a that is the transmission source of the disconnection notification message. Thereby, the switching process from the router apparatus 10a to the router apparatus 10b is started.

  In S153, the L3 processing unit 32 receives the router advertisement (see S201 in FIG. 4). Specifically, the L3 processing unit 32 receives the router advertisement message transmitted from the router device 10b. Thereafter, the L3 processing unit 32 extracts a network prefix (see Prefix 502 in FIG. 5) from the prefix information option 500 (see FIG. 5) in the router advertisement message. Then, the L3 processing unit 32 assigns each prefix and its priority (to the router device 10b) to a prefix table (not shown) that holds information related to packet transmission / reception control and routing control. 10C (see S134).

In S154, the L3 processing unit 32 receives a stop notification (see S135 in FIGS. 10A to 10C) (see S202 in FIG. 4). Specifically, the L3 processing unit 32 receives a stop notification message from the router device 10b. This stop notification message includes the source address of the router device 10a and the router lifetime of “0”. As a result, the L3 processing unit 32 deletes the entry for relaying with the router device 10a as the next hop from the routing table (not shown).
In S155, the L3 processing unit 32 uses the low-priority (that is, “low” priority) prefix and performs flow transmission to the switching destination router (router device 10b) (see S203 in FIG. 4). At this time, the next hop of the network prefix under the management of the router device 10a is changed to the router device 10b. For this reason, the terminal 30 starts without being aware of the communication via the router device 10b (that is, means that the same processing as the communication so far is performed).

Thereafter, when the communication flow detection unit 34 detects a new session (Yes in S156: see S51 in FIG. 4), the process proceeds to S157. Of the ongoing sessions, those that use the address corresponding to the network prefix under the management of the router 10a as the transmission source address will continue to be used until the session ends. Is done.
In S157, the L3 processing unit 32 performs flow transmission to the switching destination router (router device 10b) using a prefix with a low priority (that is, a priority of “high”) (see S206 in FIG. 4). In this case, the L3 processing unit 32 uses an address corresponding to the network prefix under the management of the router device 10b.

  After that, the L3 processing unit 32 of the terminal 30 determines that a network prefix with a low priority is completed according to the priority of the network prefix determined by the prefix determination unit 36 based on the policy. Do not use, but use an address that conforms to a high-priority network prefix for new sessions. As a result, when all the sessions continued during the router switching process are completed, there is no terminal 30 using the network prefix managed by the router device 10a, that is, the network prefix set to the low priority. The local network 1 can be efficiently migrated to an appropriate network prefix. When a session to be newly started is detected in a state where there is no flow to be relayed, the prefix advertised by the router device 10b is only the prefix of the own device. Therefore, the terminal 30 transmits the flow to the router device 10b using the prefix advertised by the router device 10b.

As described above, according to the present embodiment, the router device 10b acquires the network prefix assigned to the router device 10a, and causes the management server 18 to register the binding update including the network prefix. Then, the router device 10b sets the priority of the prefix to “low” and sets the priority of the network prefix of the own device to “high”. Further, the router device 10b transmits a router advertisement including the network prefix having each priority on the local network 1. Thereby, for example, when there is a new session, the terminal 30 uses the network prefix having the priority of “high” and transmits the flow to the router device 10b. On the other hand, for example, when the communication flow is continuing, the terminal 30 uses a network prefix having a priority of “low” and transmits the flow to the router device 10b.
Therefore, it is possible to secure a communication path using network prefixes having different priorities according to the communication status. Thus, communication using an appropriate network prefix can be realized.
Also, unlike the conventional method, after the presence or absence of a communication flow is determined, switching of the router device is performed as necessary. Therefore, for example, the battery consumption of the router device itself can be reduced.

  The present invention is useful for switching between router devices in a local network where a plurality of router devices having a function of connecting to an external link exist. In addition, when disconnection from an external link network is expected, this is suitable for a case where a router apparatus is quickly switched while suppressing packet loss.

It is a figure which shows the structural example of the whole system containing the router apparatus which concerns on embodiment of this invention. It is a figure which shows the 1st process example of the process 1 among the switching processes between router apparatuses. It is a figure which shows the 2nd process example of the process 1 among the switching processes between router apparatuses. It is a figure which shows the 3rd processing example of the process 1 among the switching processes between router apparatuses. It is a figure which shows the 1st process example of the process 2 among the switching processes between router apparatuses. It is a figure which shows the 2nd processing example of the process 2 among the switching processes between router apparatuses. It is a figure which shows the 3rd process example of the process 2 among the switching processes between router apparatuses. It is a figure which shows the 4th process example of the process 2 among the switching processes between router apparatuses. It is a figure which shows the process example of the process 3 among the switching processes between router apparatuses. It is a figure which shows an example of a prefix information option. It is a figure which shows the structural example of a router apparatus. It is a figure which shows the 1st process example of the router apparatus of the switching origin. It is a figure which shows the 2nd process example of the router apparatus of the switching origin. It is a figure which shows the 3rd processing example of the router apparatus of the switching origin. 5 is a diagram illustrating a configuration example of a care-of address option 600. FIG. It is a figure which shows an example of a binding update list. It is a figure which shows the 1st process example of the router apparatus of a switching destination. It is a figure which shows the 2nd process example of the router apparatus of a switching destination. It is a figure which shows the 3rd processing example of the switching destination router apparatus. It is a figure which shows an example of a prefix list. It is a figure which shows the structural example of a terminal. It is a figure which shows the process example of a terminal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Local network 2, 3 Access network 4 Backbone network 10 Router apparatus 16, 17 Base station apparatus 18, 19 Management server 20 External terminal 21 External communication interface 22 Internal communication interface 23 L3 process part 24 Upper layer process part 25 Switching process part 26 Prefix control unit 27 Communication flow detection unit 30 Terminal 31 Communication interface 32 L3 processing unit 33 Upper layer processing unit 34 Communication flow detection unit 35 Switching processing unit

Claims (7)

A plurality of router devices managed by a plurality of external management devices that relay communication between the mobile terminal in the network and the counterpart device via the mobile terminal and the external network, and are connected to the external network; A router switching method in a system configured to include:
Another router device that is the switching destination of the relaying router device is:
Obtaining a first prefix in the network assigned to the relaying router device;
Registering a binding including the acquired first prefix via the external network with an external management device that manages the router device that is relaying;
The priority of the acquired first prefix is set lower than the second prefix assigned to the device, or the priority of the second prefix is set higher than the first prefix. Performing a router advertisement on the network that includes the first and second prefixes having respective priorities, and performing at least one of the following:
The mobile terminal
After the communication with the counterpart device is completed, the second prefix with the high priority transmitted is used, and the other router device and the external management device that manages the router device are used to Starting communication with a counterpart device,
Router switching method. The mobile terminal
While the communication with the counterpart device continues, the first prefix advertised by the router with a low priority is used, and the other router device and the first prefix are registered. Further comprising the step of continuing communication with the counterpart device via an external management device,
The router switching method according to claim 1. The mobile terminal
Before the step of starting communication with the counterpart device, further comprising the step of receiving information indicating a change from the router device being relayed to the other router device,
The router switching method according to claim 1. Before the step of obtaining the first prefix by the another router device,
The relaying router device inquires of the network whether or not there is communication with the counterpart device;
The mobile terminal in the network that has received the inquiry further responds to the presence or absence of the communication,
The router switching method according to claim 1.   The router switching method according to claim 4, wherein the response includes the first prefix acquired by the another router device. The other router device is:
Further comprising the step of stopping the advertisement of the first prefix upon completion of communication with the counterpart device from the mobile terminal on the network.
The router switching method according to claim 1. An acquisition unit that acquires a prefix in the network assigned to a router device in relay that relays communication between a mobile terminal in the network and a counterpart device via an external network;
A registration unit that registers the binding including the acquired first prefix via the external network with respect to the external management device that manages the router device that is relaying;
The priority of the acquired first prefix is set lower than the second prefix assigned to the own apparatus, or the priority of the second prefix is higher than the first prefix. A setting unit that performs at least one of the settings;
A transmission unit for transmitting a router advertisement including the first and second prefixes having respective priorities on the network;
Router equipment including

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