Network identifier sharing method, and mobile router

[0095] (Embodiment 1)

[0096] FIG. 1 is a diagram showing the configuration of a mobile network system according to Embodiment 1 of the present invention.

[0097] In Figure 1, the mobile network 2 is composed of mobile routers (MR) 4-1, 4-2 and terminals 5-1, 5-2. In addition, an external network (for example, the Internet) 1 is connected to a home agent 7 that manages the location of the mobile network, access routers (AR) 3-1 to 3-4 that make connections to the mobile network, and an external terminal 6.

[0098] In addition, in this embodiment, there are two mobile routers, but it is not limited to this. In addition, the access routers 3-1 to 3-4 have wireless or wired interfaces such as cellular and wireless LAN that can be connected to the mobile router, and the internal link connected to the mobile router can be either wired or wireless.

[0099] Next, the structure of the mobile router of the present invention will be explained with reference to the drawings.

[0100] FIG. 2 is a diagram showing the structure of the mobile router 4 according to this embodiment.

[0101] In FIG. 2, the internal network interface 401 performs physical layer processing and data link layer processing in communication with terminals connected to the mobile network 2 and other mobile routers. The external network interface 403 performs physical layer processing and data link layer processing for connecting with an access router, a base station, an access point, etc., which are a connection point of the external network 1. The packet transmission/reception/relay processing unit 402 performs relay or reception processing of packets received from the internal network interface 401 and the external network interface 403. In addition, the packet transmission/reception/relay processing unit 402 performs processing of IP and higher layers (TCP, UDP, ICMP) when the mobile router itself transmits the packet.

[0102] The network identifier setting unit 411 has a user interface, and sets the prefix of the link to which the internal network interface 401 is connected according to an instruction from the user.

[0103] The mobility management unit 404 registers with the home agent 7 as a mobile router, and the location information storage unit 408 stores location information managed by the mobility management unit 404.

[0104] The network identifier notification transmission unit 405 transmits a network identifier notification message (hereinafter, referred to as "RA message"), and the network identifier notification reception unit 406 receives a network identifier notification message (RA message) transmitted from other neighboring routers.

[0105]The RA message uses the Router Advertisement Message (Router Advertisement Message) specified by RFC2461 in this embodiment. In addition, the RA message is characterized in that the network identifier selection index field described later is defined in the prefix selection of the router advertisement message.

[0106] Fig. 12 is a diagram showing the format of the RA message of the present invention.

[0107] In FIG. 12, the source address 130 and the destination address 131 respectively describe the link-local address of the mobile router of the source and the multicast address to all nodes in the link.

[0108] The valid time field 132 in the prefix selection 135 records the time when the address generated using the prefix 134 is valid, and the prefix field 134 records the network identifier. In addition, in the network identifier selection index field 133, an index for selecting a network identifier shared by the mobile network from a plurality of network identifiers is described. In this embodiment, as the network identifier selection index, the time that has passed since the network identifier was registered to the home agent (hereinafter referred to as "registration time") is used.

[0109] The above is the description of the RA message.

[0110] When the network identifier notification receiving unit 406 receives the prefix 134 as the network identifier information from the RA message, the received prefix 134 is registered in the network identifier storage unit 409. In addition, when the network identifier notification receiving unit 406 has not received the RA message for a certain period of time, the corresponding registration stored in the network identifier storage unit 409 is deleted.

[0111] The network identifier selection unit 407 selects the network identifier registered in the home agent 7 as the prefix of the internal link from the network identifiers recorded in the network identifier storage unit 409.

[0112] Here, the data structure of the network identifier storage unit 409 will be explained using FIG. 8.

[0113] In FIG. 8, the network identifier 91, the registered mark 92, the selection index 93, the registrant mark 94, and the selection mark 95 are registered as a set. In the network identifier field 91, the user's unique network identifier (prefix) set by the network identifier setting unit 411 or the network identifier advertised by other mobile routers through the RA message is recorded.

[0114] In the registered flag 92, if the location of the corresponding network identifier 91 is registered in the home agent 7, it is recorded as "1" ("Yes"), and if it is not registered, it is recorded as "0" ("No"). In addition, the network identifier 91 registered in the home agent 7 is overwritten every time the location is registered, so there is only one.

[0115] In the selection index 93, when the corresponding network identifier 91 is a unique network identifier registered by itself, the time elapsed after the location is registered to the home agent 7 is recorded. In addition, when it is the network identifier of another mobile router, the registration time included in the RA message is recorded. In this embodiment, the value of the selection index 93 is increased by one count at a time according to a timer not shown in the figure as time elapses.

[0116] In the registrant flag 94, when the corresponding network identifier 91 is a network identifier registered by itself, it is recorded as "1" ("Yes"), and when it is a network identifier notified by another mobile router, it is recorded as " 0'("No").

[0117] The selection flag 95 is recorded as "1" when it corresponds to the network identifier selected by the network identifier selection unit 407, and is recorded as "0" in other cases.

[0118] The above is the description of the data structure of the network identifier storage unit 409.

[0119] The announcement information storage unit 410 stores information used by the network identifier announcement receiving unit 406 to manage the arrival information of RA messages.

[0120] FIG. 7 shows the data structure of the announcement information storage unit 410.

[0121] In FIG. 7, the source mobile router address 81, the network identifier 82, and the effective time 83 are recorded as a set. In the mobile router address 81, the address of the mobile router that is the source of the RA message is recorded. This address is a link local address in IPv6.

[0122] In the network identifier 82, the prefix (network identifier) ​​set in the prefix 134 of the RA message is recorded.

[0123] In the valid time 83, the elapsed time from the last reception of the RA message is recorded. The valid time 83 is counted down by one at a time by a timer not shown in the figure as time elapses.

[0124] The above is the description of the data structure of the announcement information storage unit 410.

[0125] For the mobile router constructed in this way, the action and effect will be described below.

[0126] 4 is a flowchart for explaining the operation when the mobile network formed by the mobile router 4 is connected to the access router 3 of the external network 1 for the first time. In addition, in this embodiment, it is assumed that the network prefix has been set in the mobile router by the network identifier setting unit 411.

[0127] First, the packet transmission/reception/relay processing unit 402 receives a router advertisement message from the access router 3 via the external network interface 403 (step S11).

[0128] Next, the packet transmission and reception/relay processing unit 402 obtains a care-of address (hereinafter referred to as "CoA") using the advertised network prefix, and notifies it to the mobility management unit 404 (step S12). The mobility management unit 404 accepts the notification, records the newly acquired CoA in the location information storage unit 408, and requests the packet sending and receiving/relay processing unit 402 to set the assigned local address (HomeAddress: HoA) and the already-assigned local address (HomeAddress: HoA) as internal The prefix (MNP) and CoA set for the network identifier of the link are registered in the home agent 7.

[0129] Next, the packet transmission and reception/relay processing unit 402 accepts these requests, generates a location registration (Binding Update: BU) message setting the newly acquired CoA, HoA, and prefix (MNP), and sends it to the home via the external network interface 403 Agent 7 (step S13).

[0130] Next, when the packet transmission/reception/relay processing unit 402 receives a location registration response (Binding Acknowledgement) message from the home agent 7, it notifies the mobility management unit 404. After receiving the message, the mobility management unit 404 determines that the registration with the home agent 7 is completed, and records in the network identifier storage unit 409 that the prefix of the internal link has been registered in the home agent 7 (step S14). That is, the mobility management unit 404 records the prefix set on itself in the network identifier 91 in the network identifier storage unit 409, and sets the registration completed flag 92 to "1" and the selection index to "0". , The registrant flag 94 is set to '1'. At this time, "1" is not set in the selection flag 95.

[0131] Next, the network identifier notification sending unit 405 uses the network identifier registered in the home agent 7 as the RA message included in the prefix selection, and announces it in the mobile network 2 via the internal network interface 401 (step S15).

[0132] As described above, when the mobile router 4 is connected to the visitor router, it registers its own location information and its own prefix (network identification information) in the home agent 7.

[0133] Next, the actions and functions of the mobile router when it receives RA messages from other routers on the internal link are described.

[0134] Fig. 5 is a flowchart showing the network identifier registration process in the mobile router.

[0135] First, when the packet transmission/reception processing unit 402 receives an RA message from another mobile router via the internal network interface 401 (step S21), it notifies the network identifier notification receiving unit 406 of the transmission source described in the RA message Address 130, valid time 132, network identifier selection index 133, and prefix 134.

[0136] After receiving the information, the network identifier notification receiving unit 406 records the transmission source address 130 in the transmission source mobile router address 81 of the notification information storage unit 410, the prefix 134 in the network identifier 82, and the effective time 83. Effective time 132. In addition, at the same time, the network identifier notification receiving unit 406 newly additionally registers the notified prefix 134 in the network identifier storage unit 409. That is, the network identifier notification receiving unit 406 records the prefix 134 in the network identifier 91, records the registration time of the network identifier selection index 133 in the selection index 93, and sets "0" in the registrant flag 94. Then, the network identifier notification receiving unit 406 notifies the network identifier selection unit 407 that a new network prefix is ​​registered (step S22).

[0137] Next, the network identifier selection unit 407 reads the information of the network identifier storage unit 409, and compares the selection index 93 corresponding to the newly added network identifier with the selection index 93 corresponding to the network identifier set in the registered flag 92 (step S23 ). Then, when the newly registered selection index is greater than the selection index 93 set in the registration completed flag 92, the network identifier 91 is set to "1" in the registration completed flag 92 of the newly registered place, and "1" is also set in the selection flag 95. '. In addition, the registration completed flag 92 updates the registration flag 92 corresponding to the set network identifier to "0", and the selection flag 95 is also set to "0" (step S24).

[0138] Next, the mobility management unit 404 accepts the replacement of the selection mark 95 recorded in the network identifier storage unit 409, and instructs the packet transmission and reception/relay processing unit 402 so that the new selection mark 95 replaces the set network identifier. The prefix update of 91 is registered in the home agent 7. The packet sending/receiving/relay processing unit 402 accepts the instruction, generates a location registration message describing the new prefix of the mobile network, and sends it to the home agent 7 via the external network interface 403 (step S25).

[0139] Next, the network identifier notification transmitting unit 405 generates an RA message in which "0" is described in the network identifier selection index 133 of the prefix selection 135 in order to notify itself that the previously notified prefix is ​​invalid. Then, the network identifier notification sending unit 405 gives an instruction so that the RA message is sent to the packet sending/receiving/relay processing unit 402. After receiving the message, the packet transmission and reception/relay processing unit 402 adds an IPv6 header 136 and a router advertisement 137 to the prefix selection 135, and performs multicast transmission via the internal network interface 401 (step S26).

[0140] On the other hand, in step S23, when the newly registered selection index is smaller than the selection index 93 set in the registration completed flag 92, the network identifier 91 is set to "0" in the registration completed flag 92 of the new registration location, and the selection flag 95 is selected. "0" is also set in (step S27), and the process ends.

[0141] In addition, in step S21, when the RA message is not received, the network identifier announcement receiving unit 406 confirms whether the effective information 83 recorded in the announcement information storage unit 410 is "0" (step S28).

[0142]If the valid time is not '0', return to step S21, and if it is '0', the network identifier notification receiving unit 406 deletes the entry registered by the corresponding prefix from the network identifier storage unit 409 (step S29) . Then, transfer to step S23 to confirm whether it is necessary to update the registration of the prefix of the internal link to the home agent. The subsequent processing is the same as described above.

[0143] As described above, when the mobile router receives an RA message from another mobile router connected to the internal link, it will give priority to the prefix with a long registration time to the home agent 7 as the selected prefix. Therefore, it is possible to prevent the communication of the terminal in the mobile network that stably maintains a longer communication time than other terminals from being interrupted after being registered with the home agent 7.

[0144] Next, the operation and function of the mobile router periodically sending RA messages to the internal link will be described.

[0145] Fig. 6 is a flowchart showing a network identifier notification transmission process in a mobile router.

[0146] The network identifier notification sending unit 405 determines whether or not a network identifier in which the registered flag 92 and the registrant flag 94 recorded in the network identifier storage unit 409 are both "1" ("Yes") is registered (step S31). When there is a corresponding registration, the network identifier notification sending unit 405 sets the registered network identifier in the prefix 134, and sets the registered selection index 93 in the network identifier selection index 133. In addition, the network identifier notification transmitting unit 405 generates an RA message in which a predetermined initial time is set in the valid time 132 (step S32). Then, the network identifier notification sending unit 405 instructs the packet sending/receiving/relay processing unit 402 to send the RA message.

[0147] The packet transmission/reception/relay processing unit 402 accepts the instruction, adds the IPv6 header 136 and the router advertisement 137, and performs multicast transmission to the internal link via the internal network interface 401 (step S33). Then, when a certain period of time has elapsed (step S34), the process returns to step S31, and the above-mentioned processing is repeated.

[0148] Next, the structure and operation of the home agent 7 of this embodiment will be described.

[0149] FIG. 3 is a diagram showing the structure of the home agent 7.

[0150] The local network interface 701 is connected to a local network to perform physical layer processing and data link layer processing. The packet transmission and reception/relay processing unit 702 performs packet transmission and reception and packet relay processing to the mobile network, and the mobility management unit 703 manages the location of the mobile router in the mobile network.

[0151] The location information storage unit 704 is used to store location information managed by the mobility management unit 703, and represents the data structure recorded in FIG. 10.

[0152] In FIG. 10, HoA111, CoA112, and lifetime 113 are recorded as a set. HoA111 and CoA112 respectively record the HoA (Home Address) and CoA (Care of Address) of the mobile router that has completed the location registration process. In addition, the valid time of the location registration information is recorded in the lifetime 113. In addition, the life 113 is counted down as time passes by a timer not shown. Furthermore, as a result of the count down, when it becomes "0", the mobility management unit 703 deletes the registration.

[0153] The network identifier storage unit 705 records in order to manage the network identifier of the mobile network, and shows the data structure recorded in FIGS. 11A and 11B.

[0154] In FIG. 11A, the network identifier 121 and the mobile router 122 are recorded as a set. The network identifier 121 and the mobile router 122 respectively record the network identifier included in the location registration message received from the mobile router and the HoA of the source mobile router.

[0155] The operation of the home agent 7 configured as above will be described below.

[0156] FIG. 15 is a flowchart showing the operation of the home agent 7 registering the location registration information of the mobile router and transferring packets to the mobile router.

[0157] First, when the packet transmission and reception/relay processing unit 702 receives a location registration message via the local network interface 701, it notifies the mobility management unit 703 (step S1501). The mobility management unit 703 extracts HoA, CoA, and lifetime from the location registration message, registers them in the location information storage unit 704, and also extracts the network identifier and registers it in the network identifier storage unit 705 (step S1502).

[0158] Then, when the packet transmission and reception/relay processing unit 702 captures the packet transmitted to the node on the local network (step S1503), it queries the mobility management unit 703 for the destination address of the captured packet in the network identifier. Whether the mobile router is registered (step S1504). The mobility management unit 703 retrieves the HoA of the mobile router from the network identifier storage unit 705 based on the network identifier. When the corresponding mobile router is registered, the mobility management unit 703 retrieves the CoA recorded by the location information storage unit 704 from the HoA (step S1505).

[0159] Then, the mobility management unit 703 responds to the obtained CoA to the packet transmission/reception/relay processing unit 702. The packet transmission and reception/relay processing unit 702 receives the response, seals the received packet, and transfers the CoA to the mobile router as the address (step S1506).

[0160] In addition, when multiple mobile routers have registered the same network identifier, the mobility management unit 703 selects any one to respond to the packet transmission/reception/relay processing unit 702.

[0161] Next, as shown in FIG. 1, in the mobile network system having the mobile router and home agent of the present embodiment described above, the network identifier when a plurality of mobile routers are connected to the same link of the mobile network will be explained using the drawings. Shared processing.

[0162] Fig. 14 is a sequence diagram showing a method of sharing a network identifier according to the present invention.

[0163] First, mobile routers (MR) 4-1 and 4-2 use MNP2 and MNP3 as prefixes of network identifiers, respectively, and set them according to the conventional method (step S101).

[0164] Next, when the mobile network 2 moves, and the mobile routers (MR) 4-1 and 4-2 are respectively connected to the address router 3, the mobile routers (MR) 4-1 and 4-2 respectively obtain the care-of addresses CoA MR4-1 and CoA_MR4 -2 (Step S102).

[0165] Next, the mobile routers (MR) 4-1 and 4-2 respectively register MNP2 and MNP3 in the home agent 7 (step S103). 10 and 11A show the data content of the location information storage unit 704 and the network identifier storage unit 705 at this time. Thus, similar to the conventional example shown in FIG. 17, the packet addressed to the terminal 5-2 with the address generated by MNP3 is transferred to the mobile router 4-2 based on the information registered in the network identifier storage unit 705, and is generated by MNP2 The packet addressed to the terminal 5-1 of the address is transferred to the mobile router 4-1.

[0166] Next, the mobile routers 4-1 and 4-2 notify the mobile network 2 of the RA message that the network identifiers MNP2 and MNP3 registered in the home agent 7 are included in the prefix selection to the mobile network 2 (step S111). 8 and 9A respectively show the data content of the network identifier storage unit 409 of the mobile routers 4-1 and 4-2 at this time.

[0167] Since it is an example where the mobile routers 4-1 and 4-2 register the prefix in the home agent 7 at different times, the registration time recorded in the selection index 93 is '100' in FIG. 8 and is in FIG. 9A '50'.

[0168] Next, when mobile routers 4-1 and 4-2 receive mutual RA messages, they compare the network identifier selection index 133 with the selection index 93 recorded in its own network identifier storage unit 409, and determine the prefix (network identifier) ​​to be shared. ) (Step S112). In the example of FIG. 14, the value of the selection index 93 is greater than the network identifier selection index 133 of the mobile router 4-1, and therefore the mobile router 4-2 that has received the RA message of the mobile router 4-1 selects MNP2.

[0169] FIG. 9B shows the data content of the network identifier storage unit 409 of the mobile router 4-2 at this time.

[0170] In Fig. 9B, the selection marker 95 of MNP2 is '1', but at this moment the home agent 7 is still registered with MNP3. Therefore, the registration completed marker 92 is '1' ("Yes") in MNP3, and in MNP2 The middle is '0' ("No").

[0171] At this time, the mobile router (MR) 4-2 that has shared a prefix different from the prefix registered in the home agent by itself transmits a location registration message containing MNP2 to the home agent 7 (step S113). The home agent accepts the message and updates the location registration. At this time, as shown in FIG. 9C, the mobile router 4-2 changes the registration completed flag 92 of its own network identifier storage unit 409 to "1".

[0172] In addition, FIG. 11B shows the data content of the network identifier storage unit 705 of the home agent 7. In FIG. 11B, the network identifiers 121 of the mobile routers of both registered parties become prefix MNP2.

[0173] In addition, the mobile router 4-2 indicates that the MNP3 included in the transmitted RA message is invalid, that is, transmits an RA message with the effective time 132 set to "0" (step S114). In addition, mobile router 4-2 notifies MNP2 as a new prefix as an RA message. The terminal 5-2 accepts the message and regenerates the address using MNP2 (step S115).

[0174] Next, the mobile routers (MR) 4-1, 4-2 are all registered with the prefix MNP2, so when the home agent 7 receives the packet sent to the terminal 5-2 in the mobile network 2 (step S116), it seals the packet , Select any one of the mobile routers (MR) 4-1 and 4-2 to transmit (step S117). The mobile router (MR) 4-1 that has received it releases the seal of the received packet, and then transfers it to the destination terminal 5-2 (step S118).

[0175] In addition, if the mobile router 4-2 does not receive the RA message periodically sent from the mobile router 4-1 for a certain period of time, it is considered to be separated from the mobile network 2 and a location registration message including MNP3 is sent to the home agent 7. The home agent 7 accepts the message, thereby updating the location registration of the mobile router 4-2.

[0176] FIG. 16 is a flowchart showing the process of setting location registration in the home agent 7 again by the mobile router 4-2 of the present invention at this time.

[0177] First, the network identifier selection unit 407 of the mobile router 4-2 confirms whether the network identifier notification receiving unit 406 has received an RA message from a neighboring mobile router (step S1601). When the network identifier notification receiving unit 406 receives it, the network identifier selection unit 407 performs the update processing of the network identifier information shown in step S22 to step S26 in FIG. 5 (step S1602).

[0178]On the other hand, when the network identifier notification receiving unit 406 has not received the RA message, the network identifier selection unit 407 confirms whether a predetermined time has passed since the RA message was received last time (step S1603). Then, if the predetermined time has not elapsed, the network identifier selection unit 407 returns to the process of step S1601. On the other hand, when the predetermined time has elapsed, the network identifier selection unit 407 determines that it has separated from the mobile network 2 to which it belongs, and the network identifier selection unit 407 uses the network identifier initially set on itself as its own The network identifier of the connected internal link is selected. Then, the network identifier selection unit 407 performs update registration of the prefix of the home agent 7 in the same manner as steps S24 and S25 shown in FIG. 5 (step S1604).

[0179] Next, the network identifier notification sending unit 405 multicasts and sends the RA message notifying that the previous prefix is ​​invalid (step S1605).

[0180] In addition, the prefix selection field 135 is used in this embodiment, but it is not limited to this, as long as it can notify the prefix to be shared and the network identifier selection index used to select the prefix and the effective time, even if it is other extensions of the RA message It doesn't matter.

[0181] In addition, in the present embodiment, the case where the mobile routers 4-1 and 4-2 of the two mobile routers 4-1 and 4-2 are not registered to the home agent 7 are sequentially connected to the visitor router, but it is not limited to this, and other routers are connected with the terminal. In the case of a mobile network that has been registered in the home agent, the network identifier sharing process can also be implemented.

[0182] According to the present invention as described above, a plurality of mobile routers initially set with different prefixes in internal links can share a network identifier. Therefore, the robustness and load distribution generated by multiple mobile routers can be realized.

[0183] In addition, this embodiment uses the time since the prefix is ​​registered to the home agent as the selection index used when selecting the network identifier, but it is not limited to this, and the number of terminals under the mobile router and information related to it can also be used. As a selection indicator.

[0184] The following describes a case where information equivalent to the number of terminals is used as the selection index.

[0185] For example, the mobile router 4 can obtain information corresponding to the number of terminals under its own by using a neighbor cache having a data structure as shown in FIG. 13.

[0186] In FIG. 13, the IP address 141 records the IP address of the terminal, the MAC address 142 records the MAC address of the terminal, and the interface 143 records the interface of the link end connected to the terminal, where the internal network interface IF_in is recorded.

[0187] When the mobile router 4 receives a packet from the terminal 5, the registration of the terminal is added to the neighbor cache, so the actual number of terminals is not necessarily reflected. However, the so-called continuous communication terminal being registered means that it is more suitable as a selection index for the network identifier than the actual number of terminals used.

[0188] Therefore, the mobile router only needs to set the number of terminals registered in the neighbor cache in the network identifier selection index 133 of the RA message and send it.

[0189] In addition, the mobile router records the number of terminals in the selection index 93 of the network identifier storage unit 409.

[0190] As a result, as a selection index, the mobile router can use the number of terminals recorded in the neighbor cache.

[0191] In addition, when the number of terminals is used as a selection index, the number of terminals whose addresses are generated from the prefix of the unshared network identifier can be made smaller than the number of terminals whose addresses are generated from the shared header. Therefore, the number of terminals whose communication is interrupted can be reduced. Suppress to small. As a result, it is possible to further smoothly share prefixes.