JP2008199091A - Communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform an end-to-end communication in a communication system wherein a plurality of communication networks different in communication protocols are connected to each other. <P>SOLUTION: The communication system 100 comprises a first communication network N1 based upon IPv6 and a second communication network N2 based upon IEEE802.15.4. When transmitting data transmitted from equipment 21 to equipment 10, a gateway 3 sets as a transmission source address an IPv6 address allocated to the equipment 21 (obtained by adding a MAC address of the equipment 21 to a dummy prefix allocated to the second communication network N2) to make the equipment 21 transparent as equipment in the first communication network N1 to the equipment 10. An AMS 1 manages address information on equipment participating in the second communication network N2 and the equipment 21 can transmit neighborhood packets by unicasting to the AMS1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication system in which a plurality of communication networks having different communication protocols are connected to each other.

  In recent years, with the development of network communication technology, a communication system in which a plurality of communication networks with different communication protocols are connected to each other has been constructed, and various technologies related to such a communication system have been proposed (for example, patent documents). 1).

  FIG. 15 shows a first communication network N1 defined based on IPv6 (Internet Protocol version 6) and a ZigBee (registered trademark) network defined based on IEEE (Institute of Electrical and Electronic Engineers) 802.15.4. The structure of the communication system with which the 2nd communication network N2 was mutually connected is shown. The devices 201 to 205 in the second communication network N2 conform to the IEEE802.15.4 standard. The second communication network N2 connects devices in the network and has a function of forwarding packet data. Thereby, packet data can be transmitted and received between the devices 201 to 205.

Between the first communication network N1 and the second communication network N2, a gateway 300 that connects the two networks to each other is provided. In order for the device 101 in the first communication network N1 to obtain the address information of the device 201 in the second communication network N2, the device 101 accesses the gateway 300, and the gateway 300 uses the ZigBee protocol from the device 201. It is necessary to virtually access the collected data, or the gateway 300 understands the packet data of the first communication network N1 up to the upper application layer and then converts it into the ZigBee protocol. Further, in order for the device 201 to access the device 101, it is necessary to separately develop a similar gateway.
Japanese Patent Laid-Open No. 2005-268888

  However, the above-described conventional communication system has a problem in that development efficiency is poor because it is necessary to develop an application gateway for each communication protocol. Further, because communication is terminated at the gateway due to a difference in communication protocol, there is a problem that end-to-end communication is difficult and end-to-end security cannot be ensured.

  An object of the present invention is to enable end-to-end communication in a communication system in which a plurality of communication networks having different communication protocols are connected to each other without developing an application gateway for each communication protocol. .

In order to solve the above problem, the invention described in claim 1 connects a first communication network defined based on an Internet protocol and a second communication network having a communication protocol different from that of the first communication network. In a communication system
A first device in the first communication network;
A second device in the second communication network;
A management device for managing communication between the first communication network and the second communication network,
The second communication network is a network in which a data transmission amount is limited as compared with the first communication network, and communication with lower power consumption than the first communication network is possible.
The management device
The IP address of the first device in the first communication network and the address in the second communication network are stored in association with each other, and the IP address of the second device in the first communication network and the second communication network Having an address assignment table storing addresses in association with each other;
The IP address of the second device in the first communication network is a dummy prefix preset in the second communication network so that the second device is recognized as a device in the first communication network. An address of the second device in the second communication network is added,
When transmitting the data transmitted from the second device to the first device, the IP address of the second device in the first communication network as a source address based on the address information stored in the address assignment table The IP address of the first device in the first communication network is set as the destination address.

  According to a second aspect of the present invention, in the communication system according to the first aspect, when the management device transmits data transmitted from the first device to the second device, the data is transmitted from a header portion of the data. Using the pseudo header excluding the original address and the destination address, based on the address information stored in the address assignment table, as the source address of the data in the second communication network as the source address of the data, as the destination address An address of the second device in the second communication network is set.

According to a third aspect of the present invention, in the communication system according to the first or second aspect, the second device obtains an IP address of the first device in the first communication network and an address in the second communication network. It has an address assignment table that associates and holds for a predetermined time,
When starting communication with the first device, if the address information of the first device is not held in the address assignment table in the second device, the address information is inquired of the management device. .

According to a fourth aspect of the present invention, in the communication system according to the third aspect, the address assignment table of the second device further includes an address in the first communication network of another device in the second communication network. An IP address and an address in the second communication network are associated with each other and held for a predetermined time,
The second device is
When starting communication with another device in the second communication network, if the address information of the other device is not held in the address allocation table, the address information is inquired of the management device. To do.

  According to a fifth aspect of the present invention, in the communication system according to the third or fourth aspect, when the second device transmits data to the first device, a source address and a header address of the data Using the pseudo header excluding the destination address, based on the address information stored in the address assignment table in the second device, the address in the second communication network of the second device as the source address, and the address as the destination address An address of the first device in the second communication network is set.

A sixth aspect of the present invention is the communication system according to any one of the first to fifth aspects, wherein the management device includes:
When data is transmitted from the first device to the second device, or when data is transmitted from the second device to the first device, the address assignment table in the management device includes If the address information of the two devices is not registered, the transmission target data is discarded.

  According to a seventh aspect of the present invention, in the communication system according to any one of the first to sixth aspects, the second communication network is a wireless communication network.

  According to the present invention, since the first device in the first communication network recognizes the second device in the second communication network as a device in the same network, it is possible to develop an application gateway for each communication protocol. , End-to-end communication is possible.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In this embodiment, devices in a communication network that have a limited frame size and feature low power consumption, such as a communication network defined based on IEEE802.15.4 (IEEE802.15.4 network), are defined based on IPv6. A technology capable of end-to-end communication with devices in a communication network (IPv6 network) will be described.

  In order to realize this end-to-end communication, in the present embodiment, the IEEE 802.15.4 network is configured so that the devices in the IEEE 802.15.4 network can be seen transparently as devices in the IPv6 network. It is assumed that an IP address using a dummy prefix is assigned to the internal device.

  In an IPv6 network, many basic functions such as neighbor discovery and router detection are realized by communication using multicast. On the other hand, in the IEEE 802.15.4 network, it is difficult to use broadcast or multicast from the viewpoint of power and bandwidth. Further, in IPv6, the IP address is 128 bits, and when the source address and the destination address are combined, it becomes 256 bits. The size of the IP address portion is 32 octets, and the ratio to the 102 octets, which is the payload size of the ZigBee network layer defined in IEEE802.15.4, is very large.

  Therefore, in this embodiment, an AMS (Address Management Server) that manages address information of each device participating in the communication network is prepared in order to realize basic functions such as neighbor search by unicast in the IEEE 802.15.4 network. . Further, a pseudo header obtained by removing the IP address portion from the IPv6 header is used, and instead, an IEEE 802.15.4 16-bit address that is much smaller than the IP address is set. In order to realize this, a 16-bit address in the IEEE 802.15.4 network and a 128-bit address in the IPv6 network are assigned to each of the above devices, and both addresses are managed in combination in AMS. That is, even without using an IP address, an IP address can be derived from a 16-bit source address and destination address used in the MAC (Media Access Control) layer of IEEE802.15.4.

Hereinafter, specific means for realizing the above functions will be described in detail.
First, the configuration in the present embodiment will be described.

  FIG. 1 shows a schematic configuration of a communication system 100 according to an embodiment of the present invention. The communication system 100 includes a first communication network N1 defined based on IPv6 and a second communication network N2 defined based on IEEE802.15.4. Both communication networks are connected via a gateway 3. The

  A device 10 such as a PC (Personal Computer) capable of IPv6 communication is connected to the first communication network N1, and a device 21 that is a wireless communication terminal conforming to the IEEE 802.15.4 standard is connected to the second communication network N2. ~ 25 are connected. Each device in the second communication network N2 has a function of forwarding packet data. Thereby, packet data can be transmitted and received between the devices 21 to 25. The number of devices in the first communication network N1 and the number of devices in the second communication network N2 are not limited.

  The second communication network N2 is provided with an AMS 1 that manages address information of each device that participates in the second communication network N2, and a PAN (Personal Area Network) coordinator 2. The AMS 1, the PAN coordinator 2, and the gateway 3 function as a management device that manages communication between the first communication network N1 and the second communication network N2.

  FIG. 2 shows a main part configuration of the AMS 1. As shown in FIG. 2, the AMS 1 includes a communication unit 4, a control unit 5, and a storage unit 6.

  The communication unit 4 performs control for communicating with each device (devices 21 to 25, PAN coordinator 2) and the gateway 3 in the second communication network N2 connected to the AMS1.

  The control unit 5 is configured by a CPU (Central Processing Unit) or the like, and controls the operation of each unit of the AMS 1 according to a control program stored in the storage unit 6.

  Specifically, the control unit 5 uses an address assignment table 61 stored in the storage unit 6 to be described later in response to an inquiry from the devices 21 to 25 in the second communication network N2 or an inquiry about address information from the gateway 3. Thus, processing for providing address information of the devices participating in the second communication network N2 is performed. When the address information inquired is not registered in the address allocation table 61, the control unit 5 requests the PAN coordinator 2 to allocate the address of the corresponding device, and the device acquired from the PAN coordinator 2 The address information is registered in the address assignment table 61.

  The storage unit 6 stores a control program executed by the control unit 5 and data necessary for executing the program. The storage unit 6 includes an address assignment table 61 that stores address information of each device that has participated in the second communication network N2 as data necessary when the control unit 5 executes the control program.

  FIG. 3 shows the data structure of the address assignment table 61. As shown in FIG. 3, the address allocation table 61 stores “IPv6 address”, “MAC address”, “within IEEE 802.15.4”, and “Life Time” in association with each device. The “IPv6 address item” and the “MAC address” item indicate an IPv6 address (128 bits) and a MAC address (16 bits) assigned to the corresponding device, respectively. The item “in IEEE802.15.4” indicates whether or not the corresponding device is a device in the second communication network N2, and if it is a device in the second communication network N2, “TRUE”, other communication network ( If it is a device of the first communication network N1), “FALSE” is set. The “Life Time” item indicates a time (sec: second) in which the corresponding address is held in the AMS 1.

  The IPv6 address of the device in the second communication network N2, that is, the device in which “TRUE” is set in the “in IEEE802.15.4” item, is the device in the first communication network N1 as the device in the first communication network N1. It is an address using a dummy prefix so that it can be seen transparently from the device 10 (as recognized by the device 10). In the first communication network N1, packet data addressed to the dummy prefix is delivered to devices in the second communication network N2 via the gateway 3. In order to realize this function, one second communication network N2 is treated as one subnet, and one gateway 3 is required as shown in FIG. The dummy prefix is recognized as a prefix assigned to the subnet in the devices in the second communication network N2, and each device is assigned a global address with a 16-bit MAC address added to the prefix.

  The MAC address of the device 10 in the first communication network N1, that is, the device in which “FALSE” in the “IEEE802.15.4” item of the address assignment table 61 is set is assigned by the AMS1 and assigned by the PAN coordinator 2. 16-bit address.

  The devices in the first communication network N1 and the devices in the second communication network N2 have different prefixes, meaning that they exist in different subnets. Normally, when transmitting to a different subnet, the MAC address of the router is designated as the destination MAC address regardless of the destination IPv6 address. In this embodiment, the gateway 3 is directed to which IPv6 address the received frame is addressed to. A different 16-bit MAC address is assigned to each IPv6 address so that it can be identified. Therefore, the gateway 3 must be able to receive frames addressed to a plurality of MAC addresses.

  The “Life Time” item is a value (Permanent) indicating that it is a static device if it is a device in the second communication network N2, and is defined in advance if it is a device in the first communication network N1. A finite value (for example, 3600 sec) is set. The value of Life Time set for the device in the first communication network N1 indicates the remaining time that the address can be used, and is subtracted as time passes after registration. When the value of Life Time becomes 0, the entry of the corresponding device is deleted after a lapse of a certain time (for example, 30 seconds). In other words, the delay from when the Life Time value becomes 0 until the entry is actually deleted serves as a hard timer.

  In FIG. 1, the PAN coordinator 2 assigns a 16-bit MAC address to the device in response to a request from the device in the second communication network N2, and notifies the assigned MAC address to the device. In response to a request from the AMS 1, the PAN coordinator 2 assigns a 16-bit MAC address to the device 10 of the first communication network N1 that has accessed the second communication network N2, and notifies the AMS 1 of the assigned address.

  FIG. 4 shows a main part configuration of the gateway 3. As shown in FIG. 4, the gateway 3 includes a communication unit 11 connected to the first communication network N1, a control unit 12, a communication unit 13 connected to the second communication network N2, and a storage unit 14. Composed.

  The communication unit 11 performs control for communicating with devices in the first communication network N1. The communication unit 13 performs control for communicating with devices in the second communication network N2.

  The control unit 12 is configured by a CPU or the like, and controls the operation of each unit of the gateway 3 according to a control program for interconnecting the first communication network N1 and the second communication network N2, which is stored in the storage unit 14. .

  The storage unit 14 stores a control program executed by the control unit 12 and data necessary for executing the program.

  The storage unit 14 includes an address allocation table 141 that stores address information of each device that has participated in the second communication network N2 as data necessary when the control unit 12 executes the control program. FIG. 5 shows the data structure of the address assignment table 141. The address allocation table 141 stores the address information notified from the AMS 1 and, as shown in FIG. 5, the items “IPv6 address”, “MAC address”, and “Life Time” are associated with each device. Remember. The “IPv6 address” item and the “MAC address” item indicate the IPv6 address (128 bit) and the MAC address (16 bit) of the corresponding device, respectively, and the Life Time item indicates the time for which the corresponding address is held in the gateway 3 ( sec: seconds).

  If the Life Time value notified from the AMS 1 is a finite remaining time, the remaining time is set in the “Life Time” item of the address allocation table 141, and the Life Time value notified from the AMS 1 is Permanent In the “Life Time” item, a predetermined specific finite value (for example, 86400 sec) is set. This specific finite value indicates the period during which packet data may continue to be transmitted from other nodes even if the device disappears without going through the registration deletion procedure. Has been. The Life Time value set in the “Life Time” item of the address assignment table 141 is subtracted with the time after registration, and when the Life Time value becomes 0, the entry of the corresponding device in the address assignment table 141 is deleted.

  FIG. 6 shows a main part configuration of the device 21 in the second communication network N2. Since the devices 22 to 25 have the same configuration as the device 21, a description thereof is omitted here. As illustrated in FIG. 6, the device 21 includes a communication unit 15, a control unit 16, and a storage unit 17.

  The communication unit 15 performs control for communicating with other devices (AMS1, PAN coordinator 2, gateway 3, devices 22 to 25) connected to the device 21.

  The control unit 16 is configured by a CPU or the like, and controls the operation of each unit of the device 21 according to a control program stored in the storage unit 17. For example, when transmitting data to another device, the control unit 16 performs processing for inquiring of the AMS 1 if the MAC address of the other device is not registered in an address assignment table 171 described later.

  The storage unit 17 stores a control program executed by the control unit 16 and data necessary for executing the program. The storage unit 17 includes an address assignment table 171 that stores address information of other devices that have communicated with the device 21 as data necessary when the control unit 16 executes the control program. FIG. 7 shows the data structure of the address assignment table 171. Since the data configuration of the address allocation table 171 is the same as that of the address allocation table 141 shown in FIG. 5, the description thereof is omitted here.

Next, the operation in this embodiment will be described.
In the following description, it is assumed that the device in the second communication network N2 is the device 21 unless otherwise specified.

  First, with reference to the flowchart of FIG. 8, an address registration process that is executed when a device in the second communication network N2 is activated will be described.

  When the device 21 is activated (step S1; YES), information on the device 21 is registered in the PAN coordinator 2 (step S2). Next, the 16-bit MAC address is notified to the device 21 by the PAN coordinator 2 (step S3). In step S3, the address of AMS1 is notified to the device 21 as necessary.

  Next, the device 21 transmits a MAC address registration request message notified in step S3 to the AMS1, and the MAC address is registered in the address assignment table 61 of the AMS1 (step S4). When the MAC address of the device 21 is registered in the address assignment table 61 of the AMS1, a registration completion notification is transmitted to the device 21 by the AMS1 (step S5), and this address registration process ends. In step S5, network information (a prefix assigned to the second communication network N2, an address of the gateway 3, etc.) is also notified simultaneously with the registration completion notification.

  If a well-known address is used as the address of AMS1, notification of the address of AMS1 is not necessary in step S3. Similarly, when a known address is used as the address of the gateway 3, the address notification of the gateway 3 is unnecessary in step S5.

  Next, with reference to the flowchart of FIG. 9, the process at the time of access from the device 10 in the first communication network N1 to the device 21 in the second communication network N2 will be described.

  When packet data is transmitted from the device 10 to the device 21, the packet data reaches the gateway 3 by route control in the first communication network N1 (step S101). When the packet data reaches the gateway 3, the gateway 3 searches the address assignment table 141 for the address information of the device 21 based on the IPv6 address of the packet data in the address assignment table 141. It is determined whether it is registered (step S102).

  If it is determined in step S102 that the address information of the device 21 is registered in the gateway 3 (step S102; YES), the process proceeds to step S107 described later. If it is determined in step S102 that the address information of the device 21 is not registered in the gateway 3 (step S102; NO), the AMS1 is inquired about the address information of the device 21 (step S103).

  When receiving an inquiry from the gateway 3, the AMS 1 searches the address assignment table 61 for the address information of the device 21 to determine whether the address information of the device 21 is registered. Then, the presence or absence of registration of the address information of the device 21 is notified to the gateway 3 by the AMS 1 (step S104).

  When the gateway 3 is notified that the address information of the device 21 is registered in the AMS 1 (step S105; YES), the gateway 3 acquires the address information of the device 21, and the address information is stored in the address assignment table 141. The process is held for a predetermined time, and the process proceeds to step S107. Here, the time for which the gateway 3 holds the address information of the device 21 (Life Time) is notified by the AMS 1.

  When the gateway 3 is notified that the address information of the device 21 is not registered in the AMS 1 (step S105; NO), the gateway 3 transmits an ICMPv6 (Internet Control Message Protocol version 6) error message to the device 10, The packet data transmitted from the device 10 is discarded (step S106), and this process ends.

  In step S107, in the address assignment table 141 of the gateway 3, an IEEE 802.15.4 address assigned to the device 10 based on the source IPv6 address of the packet data transmitted from the device 10 (hereinafter simply referred to as “MAC address”). ) And the MAC address assigned to the device 10 is registered in the address assignment table 141.

  If it is determined in step S107 that the MAC address assigned to the device 10 is registered in the address assignment table 141 of the gateway 3 (step S107; YES), the process proceeds to step S113 described later. If it is determined in step S107 that the MAC address assigned to the device 10 is not registered (step S107; NO), a message requesting assignment of the MAC address for the device 10 is transmitted to the AMS 1 (step S108). ).

  Upon receiving the address assignment request, the AMS 1 determines whether or not the MAC address of the device 10 is registered in the address assignment table 61 (step S109). If it is determined in step S109 that the MAC address of the device 10 is not registered in the address assignment table 61 (step S109; NO), a message requesting assignment of the address is transmitted to the PAN coordinator 2 (step S109). S110). Upon receiving the address assignment request, the PAN coordinator 2 assigns a 16-bit MAC address to the device 10, and notifies the AMS 1 of the address (step S111). The address is held in the address assignment table 61 of the AMS 1 for a certain time.

  When it is determined in step S109 that the MAC address of the device 10 is registered in the address assignment table 61 of AMS1 (step S109; YES), or when the address is notified from the PAN coordinator 2 to AMS1 in step S111 The address is notified from the AMS 1 to the gateway 3 (step S112). The address is held in the address assignment table 141 of the gateway 3 for a predetermined time. Here, the AMS 1 notifies the time for holding the address (Life Time).

  After step S112 or 107, the gateway 3 creates a frame having the MAC address of the device 21 as the destination address and the MAC address assigned to the device 10 as the source address, and the IPv6 transmitted from the device 10 in this frame. Packet data is stored and transmitted to the device 21 based on the destination address (step S113).

  As the header of the packet data stored in step S113, a pseudo header obtained by removing the IP address portion from the IPv6 header is used. FIG. 10A shows the configuration of the IPv6 header, and FIG. 10B shows the configuration of the pseudo header. As shown in FIG. 10A, the IPv6 header includes a version, a traffic class, a flow label, a payload length, a next header, a hop limit, a source address, and a destination address. Since both of the IP address parts (source address and destination address) are 128 bits, 128 × 2 = 256 bits can be saved per packet data by using the pseudo header shown in FIG.

  Various formats can be adopted as the frame used in step S113. FIG. 11 shows an example of a frame format that can be used in step S113. FIG. 11A shows a case where there is no Fragment (when data included in the payload portion (Payload) is not divided packet data), and FIGS. 11B and 11C show a payload portion (Payload). 1 indicates the format of the first Fragment (1st Fragment), the intermediate Fragment, or the final Fragment (intermediate Fragment / Last Fragment), respectively. In FIG. 11, the Fragment Flag indicates whether or not the data included in the payload part (Payload) is divided packet data, the Payload Type indicates the data type included in the payload part, and the ID is the original Indicates an identifier of packet data (used to determine whether or not they are part of the same packet data), and Fragment # indicates the order of fragmented frames.

  After step S113, the device 21 determines whether or not the address information of the device 10 is registered in the address assignment table 171 based on the MAC address assigned to the device 10 that is the transmission source device (step S114). ).

  If it is determined in step S114 that the address information of the device 10 is registered in the address assignment table 171 (step S114; YES), this process ends. If it is determined in step S114 that the address information of the device 10 is not registered in the address assignment table 171 (step S114; NO), the device 21 inquires of the IPv6 address corresponding to the MAC address of the device 10 from the AMS1. Is performed (step S115).

  In response to the inquiry, the AMS 1 searches the address allocation table 61 for an IPv6 address corresponding to the MAC address of the device 10, notifies the device 21 of the IPv6 address (step S116), and ends the process. In the device 21 that has received the notification of the IPv6 address of the device 10, the IPv6 address and the MAC address of the device 10 are associated with each other and registered in the address assignment table 171 and held for a certain period of time. The holding time is notified by AMS1.

  When a 16-bit address range for dynamic allocation is given to AMS1, 16-bit allocation can be performed by AMS1 from the address range to the device 10 in the first communication network N1. In this case, the processing of steps S110 and S111 can be omitted.

  Further, the destination device information inquiry from the gateway 3 to the AMS 1 (step S103) and the address assignment request to the transmission source device (step S108) may be carried on the same message. The notification (steps S104 and S112) from the AMS 1 to respond to the inquiry and the request may be put on the same message.

  Further, immediately after the 16-bit MAC address assigned to the device 10 as the transmission source device is notified to the AMS 1 in step S111, the combination of the IPv6 address and the MAC address of the device 10 is set ahead of the gateway 3 and the destination device. You may make it notify to the apparatus 21 which is. The packet for this notification is called unsolicited neighbor advertisement. This unsolicited neighborhood advertisement is preferably highly reliable. For example, the reliability of the notification frame can be increased by encrypting the notification frame using the IEEE 802.15.4 function.

  Next, with reference to the flowchart of FIG. 12, the process at the time of access from the device 21 in the second communication network N2 to the device 10 in the first communication network N1 will be described. In the following, it is assumed that the device 21 has already acquired an address.

  When the device 21 starts communication toward the device 10, the MAC address assigned to the device 10 as the destination device is registered in the address assignment table 171 by searching the address assignment table 171 of the device 21. It is determined whether or not there is (step S201). If it is determined in step S201 that the MAC address assigned to the device 10 is registered (step S201; YES), the process proceeds to step S207 described later.

  If it is determined in step S201 that the MAC address assigned to the device 10 is not registered (step S201; NO), an address resolution inquiry is made to the AMS1 (step S202). The packet for inquiry in step S202 is called a neighbor search packet. In step S202, since the device 21 transmits a neighbor search packet to a specific device (AMS1), unicast can be used.

  In response to the inquiry, the AMS 1 searches the address assignment table 61 of the AMS 1 to determine whether or not the MAC address of the device 10 is registered in the address assignment table 61 (step S203).

  If it is determined in step S203 that the MAC address assigned to the device 10 is not registered (step S203; NO), a message requesting assignment of the MAC address to the device 10 is transmitted from the AMS1 to the PAN coordinator 2. (Step S204). In the PAN coordinator 2, a 16-bit MAC address is assigned to the device 10, and the assigned address is notified to the AMS 1 (step S205). In the AMS 1, the address is held in the address assignment table 61 for a certain period of time.

  When it is determined in step S203 that the MAC address assigned to the device 10 is registered (step S203; YES), or when the address is notified in step S205, the address is notified from the AMS 1 to the device 21. (Step S206). The notification message in step S206 is referred to as a neighborhood advertisement. In the device 21, the notified MAC address of the device 10 is held in the address assignment table 171 for a certain period of time. The holding time (Life Time) is notified by the AMS 1.

  When the device 21 acquires the 16-bit MAC address assigned to the device 10, a frame having the MAC address assigned to the device 10 as the destination address and the MAC address of the device 21 as the source address is created. IPv6 packet data is stored and transmitted to the device 10 (step S207). At this time, the pseudo header shown in FIG. 10B is used as the IPv6 header of the stored packet data.

  The data transmitted from the device 21 reaches the gateway 3 by route control in the second communication network N2. In the gateway 3, by searching the address assignment table 141 based on the MAC address of the data, the address information of the device 10 that is the destination device and the device 21 that is the transmission source device is registered in the address assignment table 141. It is determined whether or not there is (step S208).

  When it is determined in step S208 that the address information of the device 10 and the device 21 is registered (step S208; YES), the process proceeds to step S211 described later. If it is determined in step S208 that the address information of the device 10 and the device 21 is not registered (step S208; NO), an address information inquiry is made to the AMS 1 (step S209).

  In response to the inquiry, the AMS 1 searches the address assignment table 61 and notifies the gateway 3 of the address information of the devices 10 and 21 (step S210). If the address information of the device 10 is not registered in the address assignment table 61 due to elapse of the holding time in the address assignment table 61, the processes of steps S204 and S205 are performed.

  When the registration of the address information of the device 10 and the device 21 is confirmed in the gateway 3, the IPv6 address of the device 10 is used as the destination address, and the IPv6 address of the device 21 is used as the transmission source address (the device in the dummy prefix of the second communication network N2). IPv6 packet data having a MAC address of 21) is created and transmitted to the device 10 based on the destination address (step S211), and this process ends. This packet data reaches the device 10 by route control of the first communication network N1. Note that if the gateway 3 cannot confirm the presence of the device 21 that is the transmission source device, the packet data is discarded.

  When a 16-bit address range for dynamic allocation is given to AMS1, 16-bit allocation can be performed by AMS1 from the address range to the device 10 in the first communication network N1. In this case, the processing of steps S204 and S205 can be omitted.

  Further, before performing the process of step S206, the AMS 1 may notify the gateway 3 of the IPv6 address of the device 10 as the destination device and the MAC address assigned to the device 10. In the gateway 3, the notified address information is held in the address allocation table 141 for a certain period of time. The holding time (Life Time) is notified by the AMS 1. Such neighborhood advertisements are preferably highly reliable. For example, the reliability of the notification frame can be increased by encrypting the notification frame using the IEEE 802.15.4 function.

  Next, processing during communication between devices in the second communication network N2 will be described with reference to the flowchart of FIG. In the following description, it is assumed that the device 21 communicates toward the device 22. It is assumed that the devices 21 and 22 have already acquired addresses.

  When the device 21 starts communication toward the device 22, it is determined whether or not the address information of the device 22 is registered by searching the address assignment table 171 of the device 21 (step S30). If it is determined in step S30 that the address information of the device 22 is registered (step S30; YES), the process proceeds to step S33.

  If it is determined in step S30 that the address information of the device 22 is not registered (step S30; NO), an inquiry is made to the AMS 1 as to whether or not the address information of the device 22 is registered (step S31). ). In step S31, since the device 21 makes an inquiry to a specific device (AMS1), it can be performed by unicast.

  In response to the inquiry, the AMS 1 searches the address assignment table 61 and notifies the device 21 of whether or not the address information of the device 22 is registered (step S32). When the address information of the device 22 is registered in the address assignment table 61 of the AMS 1, the device 21 acquires the address information and holds it in the address assignment table 171 in the device 21 for a certain period of time. The holding time (Life Time) is notified by the AMS 1.

  When the registration of the address information of the device 22 is confirmed, the device 21 creates a frame having the 16-bit MAC address of the device 22 as the destination address and the 16-bit MAC address of the device 21 as the source address. IPv6 packet data is stored in this frame and transmitted to the device 22 (step S33), and this process ends. The pseudo header shown in FIG. 10B is used as the header of the packet data stored in step S33.

  Note that if the device 21 cannot confirm the registration of the address information of the device 22, data cannot be transmitted to the device 22. Steps S31 and S32 are performed in order not to transmit data to a node that does not exist in the second communication network N2. However, depending on the operation policy of the second communication network N2, the processes of steps S31 and S32 can be omitted.

  Next, device registration deletion processing in the second communication network N2 will be described with reference to the flowchart of FIG.

  When the device 21 is removed from the PAN, the device 21 transmits a registration deletion request message to the AMS 1 (step S40). Upon receiving the registration deletion request, the AMS 1 deletes the address information of the device 21 from the address assignment table 61, and transmits a message notifying the device 21 of the completion of registration deletion (step S41).

  Next, a message requesting cancellation of the 16-bit MAC address assignment is transmitted from the device 21 to the PAN coordinator 2 (step S42). The request message in step S42 is transmitted by communication using a 64-bit MAC address. Next, the PAN coordinator 2 transmits a message notifying that the allocation cancellation process is completed to the device 21 (step S43), and the registration deletion process is completed. The notification message in step S43 is transmitted by communication using a 64-bit MAC address.

  Note that the processing of steps S42 and S43 is to cancel the assignment of 16-bit MAC addresses, and when the IEEE802.15.4 specification is defined, it is desirable to perform according to this specification.

  Here, for a device whose Life Time value is set to a finite value in the address allocation table 61 of the AMS 1, when the Life Time value of the device becomes 0 as described above, a certain time (for example, 30 seconds) After the elapse of time, the entry of the device is deleted.

  For example, assume that the value of the Life Time of the destination device becomes 0 while the device 21 in the second communication network N2 is communicating with the destination device. At this time, in the device 21, the entry of the destination device is deleted from the address assignment table 171. However, since communication with the destination device has to be continued, the AMS 1 is assigned an address by inquiring the address of the destination device from the device 21 to the AMS 1.

  Since the AMS 1 does not release the previously used address for a certain period of time as described above, the AMS 1 refreshes the Life Time of this address to a predefined value and notifies the device 21 of it. The device 21 can again enter the destination device in the address assignment table 171 and continue communication. On the other hand, after the Life Time value of the destination device becomes 0, if there is no address inquiry to the AMS 1 even after a predetermined time has elapsed, the AMS 1 deletes the entry of the destination device. Further, a registration deletion request is sent from the AMS 1 to the PAN coordinator 2, and the entry is also deleted from the PAN coordinator 2.

  As described above, according to the communication system 100 of the present embodiment, the IPv6 address of the device in the second communication network N2 is used by adding the MAC address of the device to the dummy prefix of the second communication network N2. As a result, since the devices in the first communication network N1 are recognized as devices in the same network, end-to-end communication is possible without developing an application gateway for each communication protocol. Further, since IPsec (Security Architecture for Internet Protocol) can be used in the devices in the second communication network N2, end-to-end security can be ensured.

  In addition, by managing the IPv6 address and MAC address in association with each device in the system, using a space-saving pseudo header that excludes the IP address part from the IPv6 header, instead of using a 16-bit MAC address The size of the packet data can be saved.

  Further, each of the devices in the AMS 1, the gateway 3, and the second communication network N2 has an address assignment table in which an IPv6 address and a MAC address are associated with each device, so that unnecessary inquiries can be omitted.

  In addition, since the devices in the second communication network N2 can transmit the neighbor search packet to the specific device (AMS1) by unicast, it is possible to reduce the traffic load due to multicast transfer. In particular, even in the devices in the second communication network N2, having an address assignment table eliminates the need for a neighbor search. Even when a neighbor search is performed in order to confirm the existence of the partner node, it may be performed by unicast as described above.

  In addition, since the gateway 3 can manage the presence of the devices in the second communication network N2, it is possible to omit data transfer to devices that do not exist.

  Note that the description in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

  For example, the communication between the gateway 3 and the AMS 1 and the communication between the AMS 1 and the PAN coordinator 2 do not have to conform to the second communication network N2. For example, these communications may be applied to an IP network.

  In the present embodiment, the case where the AMS 1, the PAN coordinator 2, and the gateway 3 are separate devices has been described, but devices in which the functions of these devices are arbitrarily combined may be used. For example, by mounting the functions of the AMS 1, the PAN coordinator 2, and the gateway 3 on the same device, the function as the above-described management device can be realized by a single device. As a result, exchange of information among the AMS 1, the PAN coordinator 2, and the gateway 3 is omitted, and efficient communication becomes possible.

  Further, in the present embodiment, the case where the second communication network N2 is a network based on IEEE802.15.4 has been shown, but the address assignment function triggered by the inquiry for the neighbor search, the packet data from the first communication network N1 side, and the like. Address allocation function triggered by reception, unicasting of neighbor search, confirmation of device existence, etc. are performed in networks based on wireless communication standards other than IEEE802.15.4 such as WiMAX (Worldwide Interoperability for Microwave Access). Is also applicable.

  When the PAN coordinator 2 has a function of detecting that a device in the second communication network N2 has disappeared from the PAN, the AMS 1 may perform registration deletion processing of the device using the event as a trigger. .

  In this embodiment, the Life Time value of each address set in the address allocation table of the gateway 3 and the devices in the second communication network N2 is notified from the AMS1, but the gateway 3, the second Since each device in the communication network N2 holds the Life Time defined in the system, the notification from the AMS 1 can be omitted.

The figure which shows the structure of the communication system which concerns on embodiment of this invention. The block diagram which shows the principal part structure of AMS. The figure which shows the data structure of the address allocation table memorize | stored in the memory | storage part of AMS. The block diagram which shows the principal part structure of a gateway. The figure which shows the data structure of the address allocation table memorize | stored in the memory | storage part of the gateway. The block diagram which shows the principal part structure of the apparatus in a 2nd communication network. The figure which shows the data structure of the address allocation table memorize | stored in the memory | storage part of the apparatus in a 2nd communication network. The flowchart which shows the address registration process performed at the time of starting of the apparatus in a 2nd communication network. The flowchart which shows the process at the time of access from the apparatus in a 1st communication network to the apparatus in a 2nd communication network. The figure which shows the structure (b) of the header (a) of an IPv6 header, and the pseudo header which remove | excluded the IP address part from the header of IPv6. The figure which shows an example of the frame format of IEEE802.15.4. The flowchart which shows the process at the time of access from the apparatus in a 2nd communication network to the apparatus in a 1st communication network. The flowchart which shows the process at the time of communication between the apparatuses in a 2nd communication network. The flowchart which shows the registration deletion process of the apparatus in a 2nd communication network. The figure which shows the structure of the communication system with which the 1st communication network defined based on IPv6 and the 2nd communication network defined based on IEEE802.15.4 were mutually connected.

Explanation of symbols

1 AMS
2 PAN coordinator 3 Gateway 4, 11, 13, 15 Communication unit 5, 12, 16 Control unit 6, 14, 17 Storage unit 10 Device 21, 22 Device 61, 141, 171 Address assignment table 100 Communication system N1 First communication network N2 Second communication network

Claims (7)

In a communication system for interconnecting a first communication network defined based on an Internet protocol and a second communication network having a communication protocol different from that of the first communication network,
A first device in the first communication network;
A second device in the second communication network;
A management device for managing communication between the first communication network and the second communication network,
The second communication network is a network in which a data transmission amount is limited as compared with the first communication network, and communication with lower power consumption than the first communication network is possible.
The management device
The IP address of the first device in the first communication network and the address in the second communication network are stored in association with each other, and the IP address of the second device in the first communication network and the second communication network Having an address assignment table storing addresses in association with each other;
The IP address of the second device in the first communication network is a dummy prefix preset in the second communication network so that the second device is recognized as a device in the first communication network. An address of the second device in the second communication network is added,
When transmitting the data transmitted from the second device to the first device, the IP address of the second device in the first communication network as a source address based on the address information stored in the address assignment table An IP address in the first communication network of the first device is set as a destination address. The management device
When transmitting the data transmitted from the first device to the second device, a pseudo header obtained by removing the transmission source address and the destination address from the header portion of the data is used, and the address information stored in the address allocation table is used. 2. The method according to claim 1, wherein an address in the second communication network of the first device is set as a transmission source address of the data, and an address in the second communication network of the second device is set as a destination address. The communication system described. The second device is
An address assignment table for holding the IP address of the first device in the first communication network and the address in the second communication network in association with each other for a predetermined time;
When starting communication with the first device, if the address information of the first device is not held in the address assignment table in the second device, the address information is inquired of the management device. The communication system according to claim 1 or 2. In the address allocation table of the second device, the IP address in the first communication network and the address in the second communication network of another device in the second communication network are further held in association with each other for a predetermined time. ,
The second device is
When starting communication with another device in the second communication network, if the address information of the other device is not held in the address assignment table, the address information is inquired of the management device. The communication system according to claim 3. The second device is
When transmitting data to the first device, a pseudo header obtained by removing a transmission source address and a destination address from the header portion of the data is used, and based on address information stored in an address assignment table in the second device. The address in the second communication network of the second device is set as the source address, and the address in the second communication network of the first device is set as the destination address. Communications system. The management device
When data is transmitted from the first device to the second device, or when data is transmitted from the second device to the first device, the address assignment table in the management device includes The communication system according to any one of claims 1 to 5, wherein when the address information of the two devices is not registered, the data to be transmitted is discarded.   The communication system according to any one of claims 1 to 6, wherein the second communication network is a wireless communication network.

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