JP3823674B2 - COMMUNICATION METHOD AND COMMUNICATION CONTROL DEVICE WITH PROTOCOL CONVERSION - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a communication method and a communication control apparatus that involve network protocol conversion.
[0002]
[Prior art]
As a technique for performing IPv4 and IPv6 packet conversion in order for a host connected to an IPv4 (Internet Protocol version 4) network and a host connected to an IPv6 (Internet Protocol version 6) network to communicate with each other, for example, JP-A-10-023072 There are techniques described in the issue.
[0003]
[Problems to be solved by the invention]
In recent years, mobile computing using mobile phones and wireless LANs has been actively used, and the number of subscribers has been increasing. In addition, IPv4 addresses have been depleted, and it has become difficult to secure a sufficient number of global addresses to accommodate a large number of users in a wireless access network. In metropolitan areas, it is necessary to accommodate more than 1 million users in the network, and IPv6 addresses will be assigned to mobile terminals. If IPv6 is used, a vast address space (128 bits) can be used, so the problem of address exhaustion can be solved. However, since the transition to IPv6 for the entire Internet still takes time, it is necessary to place an IPv6 / IPv4 translator with a function for mutual conversion of IPv6 packets and IPv4 packets somewhere in the IP access network during the transition period. is there.
[0004]
An object of the present invention is to perform IPv6 / IPv4 format conversion, and with regard to an address assignment operation, an IPv6 DHCP server that actually appears to an IPv6 DHCP (Dynamic Host Configuration Protocol) server from an IPv6 client and actually assigns an address. Is to realize a device that acts as an adapter that looks like an IPv4 client.
[0005]
[Means for Solving the Problems]
A function to convert IPv6 packets from users to IPv4 based ISP (Internet Service Provider) / corporate intranet into IPv4 format on LNS (L2TP Network Server) devices that make up mobile VPN (Virtual Pass Network), In the dynamic address assignment operation by DHCP, the difference between IPv6 client function as IPv6 DHCP server, IPv4 DHCP server function as IPv4 client, and IPv6 and IPv4 procedure difference. With the function to absorb, IPv6 DHCP client is accommodated in IPv4 DHCP server.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an apparatus (protocol conversion apparatus) according to the present invention will be described with reference to the drawings. The embodiment of the present invention described below is an example using L2TP as a protocol for VPN tunneling in the distributed IP network 1, and a communication network using the apparatus of the present invention is placed in another tunneling protocol. However, it can be applied.
[0007]
FIG. 1 is an example of a network configuration and protocol stack for realizing a mobile IPv6 network.
[0008]
The network consists of an IP access network, ISP networks 11 and 12, and the Internet 13, and the IP access network consists of a radio access network 4 and a GGSN (Gateway GPRS Suport Node) device 8, a distributed IP network 1, and LNS devices 9 and 10. Can communicate with the Internet 13 by connecting to the ISP 11 from the wireless access network 4 through the distribution network 1 and through the LNS device 9.
[0009]
The wireless access network 4 is a GPRS (General Packet Radio Service) developed method of the 3rd generation mobile phone standard IMT-2000 (3GPP TS23.060 v.3.1.0 "General Packet Radio Service (GPRS) Service Description; Stage 2") An example will be described with reference to the network. The IP access network (wireless access network 4 and distributed IP network 1) is an IPv6-based network.
[0010]
A mobile tunnel (GTP tunnel) is set between the base station 6 and the exit (GGSN) 8 of the radio access network. The RADIUS server 7 performs tunnel management and user authentication. In addition, GGSN8 sets up a VPN tunnel using L2TP (IETF RFC2661 Layer Two Tunneling Protocol "L2TP") between LNS devices 9 and 10 installed at each ISP, and users of each ISP are subscribed using the VPN tunnel. Assign to ISP. The LNS device 9 terminates the L2TP tunnel and PPP.
[0011]
There are a method using the GGSN (LAC) device 8 and a method using the LNS devices 9 and 10 as the IPv6 / v4 translator required for communication between the IPv6 network and the IPv4 network.
[0012]
(1) The GGSN device must accommodate all users of the radio access network in the area covered by the GGSN device. Therefore, in order to perform IPv6 / v4 packet conversion in the GGSN device 8, it is necessary to secure an IPv4 address that can sufficiently accommodate the users under the control.
[0013]
(2) In the method performed by the LNS devices 9 and 10, VPN tunnels are allocated to each ISP in advance.For example, if there are 1 million subscribers and 20 ISPs, the users who access the LNS device 8 of each ISP are Since it can be narrowed down to about 50,000 on average, if each ISP has a class B IPv4 address, it can accommodate about 60,000 users, and prepare a sufficient number of v4 global addresses for v6 addresses FIG. 2 shows a configuration diagram of an apparatus (protocol conversion apparatus) according to the present invention that can accommodate a large number of users exceeding 1 million as a whole. The protocol conversion device includes a control device 201, an access network connection unit 204, a data buffer storage device 205, and an ISP network connection unit 206. The control device 201 includes an arithmetic device 202 and a storage device 203.
[0014]
The access network connection unit 204 has a layer 2 protocol termination function, an IP and UDP termination function, an L2TP termination function, and a PPP termination function. And a function of reading out an IPv6 packet to be transmitted from the data buffer storage device 205.
[0015]
The ISP network connection unit 206 has a layer 2 protocol termination function, and writes a received IPv4 packet to the data buffer storage device 205 in accordance with an instruction from the control device 201 and the IPv4 packet to be transmitted from the data buffer storage device 205. Has the function of reading.
[0016]
The data buffer storage device 205 receives the data write command from the access network connection device 204 and transmits the IPv6 packet received by the access network connection unit 204 to the storage area and the data read command from the access network connection unit 204. It has a function of reading out the IPv6 packet to be transmitted from the storage area and sending it to the access network connection apparatus 204.
[0017]
In addition, the function of writing the IPv4 packet received by the ISP network connection unit 206 in response to the data write command from the ISP network connection device 206 and the IPv4 packet to be transmitted according to the data read command from the ISP network connection device 206 It has a function of reading from the storage area and sending it to the ISP network connection unit 206.
[0018]
In addition, according to the instruction of the control device 201, the information of the header area of the IPv6 packet and IPv4 packet stored in the storage area is read and sent to the control device 201, and stored in the storage area according to the instruction of the control device 201. It has a function to rewrite the header area information of IPv6 packets and IPv4 packets.
[0019]
FIG. 3 shows the configuration of information stored in the storage device 203. It has a DHCPv4 server record 300 for storing the address of the DHCPv4 server, and a DHCPv6 server record 301 for storing an IPv6 address when the LNS device 8 operates as a DHCPv6 server.
[0020]
In order to associate the IPv6 address assigned to the terminal with the IPv4 address, an IPv6 address upper 64-bit field 302 and an address management table 303 as shown in FIG. In the IPv6 upper bit field, the device control unit 201 sets a network-specific value (upper 64 bits of the allocated IPv6 address) that each ISP gives to the mobile access network.
[0021]
Of the 128-bit IPv6 address assigned to each terminal, the upper 64 bits are unique to the ISP to which it belongs, and the upper 64 bits of the IPv6 address of all terminals belonging to one ISP are the same. Yes. The lower 64 bits are the MAC address unique to the terminal. Therefore, the upper 64 bits of the IPv6 address of the terminal are stored in a common IPv6 upper bit record 302, and only the lower 64 bits of the MAC address portion is stored in the IPv6 address field 305 of the address management table 303. The consumption of the area can be reduced.
[0022]
The address management table 303 includes an empty flag field 304, an IPv6 address field 305, an allocation flag 306, an IPv4 address field 307, a session ID field 308, and a timer field 309. The empty flag field 304 is set to 1 if a value is set in the IPv6 address field 305 of the same address, and is set to 0 otherwise. The IPv6 address field 305 is a 64-bit field, and the value of the lower 64 bits of the IPv6 address assigned to the IPv6 terminal 5 is set. An IPv6 address in which the value of the IPv6 upper bit field 302 is the upper 64 bits and the value of the IPv6 address field 305 is the lower 64 bits is the IPv6 address actually assigned to each terminal. The assignment flag 306 is 1 if the IPv6 address field 305 and the IPv4 address field 307 of the same address are set, that is, 1 if the IPv6 address assigned to the terminal is associated with the IPv4 address, and 0 otherwise. Set. The IPv4 address field 307 is a 32-bit field, and an IPv4 address associated with the IPv6 address assigned to the terminal 5 is set. The session ID field 308 is a 16-bit field, and the session ID of the L2TP tunnel used for communication between the terminal 5 and the LNS 9 is set. There is a one-to-one correspondence between an IPv6 address and a session ID, and the IPv6 terminal 5 can be identified by the session ID. When searching whether an IPv6 terminal is registered from the address management table 303, the session ID field 308 (16 bits) can be searched faster than the IPv6 address field 305 (64 bits).
[0023]
The timer field 309 is set to an initial value when the IPv6 address field 305 and the IPv4 address field 307 are associated with each other, and whenever communication with the IPv6 terminal corresponding to the address occurs. In the timer field 309, all address values are periodically decremented by the device control unit 201, and when the timer field 309 of a certain address becomes 0, it is determined that communication has not been performed by the control device 201 for a certain period of time. The association of the IPv4 address at that address is released. Specifically, the IPv4 address unassignment is requested to the DHCPv4 server, and the values of the assignment flag field 306 and the IPv4 address field 307 are reset.
[0024]
An IP address assignment process necessary for the terminal 5 to receive an IPv6 address assignment and start communication will be described with reference to FIGS.
[0025]
The terminal 5 in FIG. 1 broadcasts a DHCP Solicit message toward the base station 6. It reaches LNS8 through access network 4 and distribution IP network 2. When the access network connection unit of the received LNS device 9 (FIG. 2-204) confirms that it is DHCP Solicit by looking at the OP code of the DHCP message according to the instruction of the control device 201 (400), the MAC address from the client hardware address field (505), the empty flag field 304 is searched from the youngest number, the 0 field is found, stored in the IPv6 address field 305, and 1 is written in the empty flag field 304 (506) (401). Also, the session ID 502 is extracted from the L2TP header of the received message (507), and registered in the session ID field 308 of the record stored in the IPv6 address field 305 (508) (402). Next, the record allocation flag 306 stored in the IPv6 address field 305 is set to 0 (403).
[0026]
Next, the control device 201 broadcasts a DHCPDISCOVER message to the IPv4 network through the ISP network connection unit 206 (404). Thereafter, when the ISP network connection unit 206 that has received the DHCP message from the DHCPv4 server confirms that it is DHCPOFFER by looking at the OP code according to the instruction of the control device 201 (405), the DHCP server address 603 in the server IP address field of the message Is extracted (605) and stored in the DHCPv4 server record 300 (606) (406). Next, the MAC address 602 is extracted from the client hardware address field of the DHCPOFFER message (604) and stored in the register of the control device 201. The allocation flag 306 is searched for an address of 0. If it is 0, the IPv6 address field 305 is compared with the MAC address stored in the register of the control device 201, and if they match, the session ID field 308 of the aforementioned record is compared. The value is stored in the register of the control device 201 (407).
[0027]
Next, the control device 201 transmits a DHCP Advertise message toward the terminal 4 through the access network connection unit 204 to the tunnel of the session ID stored in the register (408). Next, the terminal 5 that has received the DHCP Advertise message transmits a DHCP Request message to the LNS device 9 in order to obtain an IPv6 address. When the received access network connection unit 204 confirms that it is a DHCP Request by looking at the OP code of the DHCP message according to the instruction of the control device 201, the MAC address 702 is extracted from the client hardware address field of the message (704). (409). Next, the control device 201 transmits a DHCPREQUEST message to the DHCPv4 server at the address stored in the DHCPv4 server record 300 through the ISP network connection unit 206 (410). After that, when the ISP network connection unit 206 that has received the DHCP message from the DHCPv4 server confirms that it is DHCPACK by looking at the OP code according to the instruction of the control device 201 (411), the MAC address is set to (807) from the client hardware address field of the message (411). ), The assigned IPv4 address is extracted from the assigned IP address field and stored in the register of the control device 201 (808). The allocation flag 306 is searched for a record of 0. If it is 0, the IPv6 address field 305 is compared with the MAC address stored in the register in the process 807 (412) and the IPv4 address field of the above record matches The IPv4 address stored in the register in step 808 is stored in 307 (413). Next, in order to indicate that an IPv4 address has been assigned, the above-mentioned record assignment flag 306 is set to 1 (414).
[0028]
Next, the control device 201 creates an IPv6 address in which the value of the IPv6 upper bit record 302 is the upper 64 bits, and the MAC address stored in the register in the process 807 is the lower 64 bits, and the same address is transmitted through the access network connection unit 204. A DHCP Reply message storing the IPv6 address is transmitted to the terminal 5 through the tunnel of the session ID in the session ID field 308 (415). Next, an initial value is stored in the timer field 309 of the record (422).
[0029]
If a DHCPNAK message indicating that an IPv4 address cannot be assigned is received from the DHCPv4 server in processing 611 (418), the control device 201 sends a DHCP Reply message with 19 (Resources unavailable) set in the status field via the access network connection unit 204. Transmit to terminal 5 (419). Next, the allocation flag 306 is searched and the address 0 is searched. If it is 0, the IPv6 address field 305 and the MAC address stored in the register in the process 107 are compared and if they match, the free flag 304 of the same address is set. It is set to 0 and the values of the IPv6 address field 305 and the session ID field 308 are cleared (420). In processes 405, 409, and 418, if no DHCP message is received for a certain period of time, the process ends.
[0030]
A process when the terminal transmits an IPv6 packet toward the Internet and the LNS device 9 receives and converts the packet into an IPv4 packet and transmits the packet toward the Internet will be described with reference to FIGS.
[0031]
When the terminal 5 in FIG. 1 transmits an IPv6 packet toward the Internet 13, it reaches the LNS 9 through the radio access network 4 and the distribution IP network 1 (1000). The access network connection unit 204 in the LNS device that received the IPv6 packet from the terminal 5 extracts the session ID from the L2TP header according to the instruction of the control device 201 (1204), and then the control device 201 uses the session ID field of the address management table 303. 308 is searched from the young number (1206), and an address matching the extracted session ID is found (1001).
[0032]
Next, the value of the IPv6 address field 305 of the same record is compared with the lower 64 bits of the source IPv6 address of the received packet to confirm that they match (1002). At this time, when the association between the IPv4 address and the IPv6 address is released and the IPv4 address allocation flag 306 of the same record is 0 (1003), the control device 201 passes through the ISP network connection unit 206 to the IPv4 network (ISP network). Broadcasts a DHCPDISCOVER message (1004).
[0033]
After that, when the ISP network connection unit 206 that has received the DHCP message from the DHCPv4 server in the ISP network 11 confirms that it is DHCPOFFER by looking at the OP code of the received DHCP message according to the instruction of the control device 201 (1005), the control is performed. The device 201 extracts the DHCP server address in the server IP address field of the DHCP message and stores it in the DHCPv4 server record 300 (1006).
[0034]
The control device 201 transmits a DHCPREQUEST message (1301) to the DHCPv4 server at the address stored in the DHCPv4 server record 300 through the ISP network connection unit 206 (1007). After that, the ISP network connection unit 206 that has received the DHCP message from the DHCPv4 server confirms that it is DHCPACK by looking at the OP code of the received DHCP message according to the instruction of the control device 201 (1008), and then assigns the received DHCPACK message. The IPv4 address in the IP address field is stored (1403) in the IPv4 address field of the record found in the process 1001 (1009).
[0035]
Next, the control device 201 sets the IPv4 address assignment status flag to 1 to indicate that an IPv4 address has been assigned to the aforementioned record (1010).
[0036]
The control device 201 extracts the lower 32 bits from the destination IPv6 address of the received IPv6 packet (1507), the destination IPv4 address (1503), and the value of the IPv4 address field of the record found in the processing 1001 is the source IPv4 address As (1504), the received IPv6 packet is converted into an IPv4 packet (1505) (1011).
[0037]
The control device 201 transmits the IPv4 packet converted into the IPv4 network (ISP network) through the ISP network connection unit 206 (1012). Further, the initial value is reset in the timer field of the above-mentioned record (1013).
[0038]
When the DHCPNAK is received in the process 1008 (1015), the control device 201 transmits a DHCP Reconfigure message to the terminal 5 through the access network connection unit 204, and the IPv6 address assignment to the terminal 5 is released (1017). Next, the empty flag field, IPv6 address field, session ID field, and timer field of the record found in the process 1001 are cleared (1017).
[0039]
If the IPv4 address assignment status flag is 1 in process 1003, processes 1004 to 1010 are skipped.
[0040]
If the session ID is not found in process 1001 and if the IPv6 address field value of all records in process 1002 does not match the lower 64 bits of the source IPv6 address of the received packet, the packet is discarded. And the process ends (1017).
[0041]
The process when the LNS9 receives an IPv4 packet sent from the Internet 13 to the terminal 5, converts the received IIPv4 packet into an IPv6 packet, and transmits it to the terminal 5 is explained using FIG. 16 and FIG. To do.
[0042]
An IPv4 packet is transmitted from the Internet 13 toward the terminal 5, and the packet reaches the LNS device 9. The ISP network connection unit 206 that has received the packet stores the source IPv4 address and the destination IPv4 address of the packet in the register of the control device 23 in accordance with instructions from the control device 201 (1707, 1708, processing 1600).
[0043]
Next, when the control device 201 searches the IPv4 address field 307 in the address management table for a lower number and matches the destination address stored in the register in the process 1600 (1601), the value in the IPv6 upper bit memory 302 is set to the upper 64 bits. , IPv6 address (1705) with the IPv6 address field 305 value of the same record as the lower 64 bits is set as the destination IPv6 address, the upper 96 bits are set as 0, and the source IPv4 address stored in the register in processing 107 is set as the lower 32 bits The received IPv4 packet with the “IPv4 Compatible IPv6 address” (1704) as the source address is converted into an IPv6 packet (1602). Then, the control device 201 transmits the converted IPv4 packet to the terminal 5 through the access network connection unit 204 (1603). If a value matching the destination IPv4 address is not found in the process 1601, the received IPv4 packet is discarded (1604) and the process ends.
[0044]
The program recording the processing of the present embodiment is traded by a computer-readable storage medium or directly downloaded from a server, etc., and the communication control of the present embodiment is performed by installing this program in the computer as appropriate. A device can be configured.
[0045]
【The invention's effect】
By applying the present invention, it is possible to accommodate a large number of terminals assigned with IPv6 addresses. In addition, by performing header conversion between IPv6 and IPv4, it is possible to communicate with a host on the Internet. In addition, the LNS mediates between the DHCP server and the terminal, so that a dynamic IP address can be assigned to the terminal.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of a configuration of a mobile IPv6 network and a protocol stack.
FIG. 2 is a block diagram showing a schematic configuration of an apparatus according to the present embodiment.
FIG. 3 is an explanatory diagram of a structure of a storage device.
FIG. 4 is an operation explanatory diagram of connection control according to the present embodiment.
FIG. 5 is an explanatory diagram of the operation of the apparatus when a DHCP Solicit message is received.
FIG. 6 is an explanatory diagram of the operation of the apparatus when a DHCPOFFER message is received.
FIG. 7 is an explanatory diagram of the operation of the apparatus when a DHCP Request message is received.
FIG. 8 is an explanatory diagram of the operation of the apparatus when a DHCPACK message is received.
FIG. 9 is a sequence diagram of connection control by the apparatus of the present invention.
FIG. 10 is an explanatory diagram showing the operation of the apparatus when an IPv6 packet is received.
FIG. 11 is an explanatory diagram of the operation of the device when an IPv6 packet is received.
FIG. 12 is an explanatory diagram showing the operation of the apparatus when an IPv6 packet is received.
FIG. 13 is an explanatory diagram of the operation of the apparatus when transmitting a DHCPREQUEST message.
FIG. 14 is an explanatory diagram of the operation of the apparatus when a DHCPACK message is received.
FIG. 15 is an explanatory diagram of the operation of the apparatus when generating and transmitting an IPv4 packet.
FIG. 16 is an explanatory diagram of the operation of the device when an IPv4 packet is received.
FIG. 17 is an explanatory diagram of the operation of the device when an IPv4 packet is received.
[Explanation of symbols]
1: IP access network
2: Distribution IP network
3: Distribution IP network
4: Wireless access network
5: Device
6: Base station
7: Radius server
8: GGSN
9: LNS
10: LNS
11: ISP
12: ISP
13: Internet
201: Control device
202: Arithmetic unit
203: Storage device
204: Access network controller
205: Data buffer storage device
206: ISP network connection device

Claims (6)

Storing the MAC address and session ID of the terminal received from the terminal in the IPv6 network in the record of the conversion table;
Attaching the MAC address of the terminal to the DHCPv4 server, requesting the server address of the DHCPv4 server,
In response to the server address request of the DHCPv4 server, a reply message including the MAC address of the terminal and the server address of the DHCPv4 server is received.
Based on the MAC address of the terminal included in the reply message, the corresponding session ID is extracted from the conversion table, and a DHCP query including the MAC address of the terminal and the session ID is transmitted.
Upon receiving a first allocation request from the terminal for the DHCP inquiry, a second allocation request including a server address of the DHCPv4 server and a MAC address of the terminal is transmitted.
A communication method involving protocol conversion for storing an IPv4 address allocated from the DHCPv4 server in response to the second allocation request in a record in which the MAC address of the terminal is stored. When an IPv6 packet is received from the terminal, a session ID in the IPv6 packet is extracted, the conversion table is referenced based on the session ID, and an IPv4 address is extracted from a record in which the session ID is stored. The communication method with protocol conversion according to claim 1, wherein the IPv6 packet is converted into an IPv4 packet by adding an IPv4 address and transferred. Upon receipt of an IPv4 packet to the terminal, an IPv4 address in the IPv4 packet is extracted, the translation table is referenced based on the IPv4 address, and an IPv6 address is extracted from a record in which the IPv4 address is stored. The communication method with protocol conversion according to claim 1, wherein the IPv4 packet is converted into an IPv6 packet by attaching the IPv6 address, and the packet is transferred. In a communication control device having an arithmetic device that performs protocol conversion processing and a storage device connected to the arithmetic device,
When the computing device receives the MAC address and session ID of the terminal from a terminal in the IPv6 network, the computing device stores the MAC address and session ID of the terminal in association with each other in the storage device, and stores the terminal in the DHCPv4 server. Generating and transmitting a server address request of the DHCPv4 server including the MAC address of the DHCPv4 server, receiving a reply message including the MAC address of the terminal and the server address of the DHCPv4 server in response to the server address request of the DHCPv4 server; A session ID corresponding to the MAC address of the terminal included in the answer message is read from the storage device, and a DHCP query including the MAC address of the terminal and the session ID is generated and transmitted. First allocation required from the terminal Is generated and transmitted, the second allocation request including the server address of the DHCPv4 server and the MAC address of the terminal is transmitted, and the IPv4 address allocated from the DHCPv4 server in response to the second allocation request is A communication control device that stores in the storage device in association with the MAC address of the terminal. The arithmetic device receives an L2TP packet from the terminal, extracts the session ID from the L2TP header of the L2TP packet, and extracts the MAC address from the DHCP Solitit of the L2TP packet, whereby the storage device The communication control device according to claim 4, wherein the MAC address and the session ID are stored in association with each other. A computer-readable recording medium having recorded thereon a program for causing a computer to execute the procedure according to claim 1.

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