JP3178350B2 - Interworking equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a local area network (hereinafter referred to as "LA") using a common address system.
N ") between each other via a wide area network (hereinafter referred to as" WAN ") using another address system. In particular, the present invention relates to an interworking device for connecting a LAN and a WAN.

[0002]

2. Description of the Related Art As a technique for interconnecting LANs via a WAN, the present inventors have proposed an LA using an ATM network.
IEICE Technical Report SSE9
4-135 (1994-10), "Study of Virtual LAN Construction Method in ATM Connectionless Communication". Regarding this technology, Ethernet is used as LAN, and ITU-T Recommendation I. 364, F.R. 81
2 B-ISDN (Broadband Service Integrated Digital Network)
A connectionless service will be described as an example.

FIG. 1 shows a network connection configuration using an interworking device. Interworking device 2 in WAN1
And LANs 5 to 7 are connected to the interworking devices 2 to 4, respectively. Although a plurality of terminals are connected to the LANs 5 to 7, FIG. 1 shows the terminals 8 and 9 accommodated in the LAN 5, the terminals 10 accommodated in the LAN 6, and the terminals 11 accommodated in the LAN 7. FIG. 1 also shows the MAC (medium access control) address specified points 101 to 104 of the terminals 8 to 9 and the LAN side MAC address specified points 10 to 104 of the interworking devices 2 to 4.
5 to 107, and the WAN side E.E. 164 address defining points 111 to 113 are shown.

[0004] Each of the interworking devices 2 to 4 is LA
In order to interconnect the N5 to N7 and the WAN1, the IP (Internet Protocol) address of a terminal accommodated in the own LAN is managed by detecting an address resolution signal transmitted by the terminal. Interworking devices 2 to 4
Also provides the WAN side with ITU-T Recommendation E. 164 (ISD
N-number plan), an address (referred to as “E.164 address”), and a W
The communication via the AN1 is transmitted to the E.E.
This is performed using 164 addresses. In addition, the interworking devices 2 to 4 are connected to the IP address of the terminal under their own device and the WAN E.E. By broadcasting or individually notifying the combination information with the 164 address to other interworking devices and managing the information in each of the interworking devices 2 to 4,
From the destination IP address of the packet transmitted by the terminal under its own device, the E.P. 164 addresses can be known.

[0005] Here, a case where a packet is transferred from the terminal 8 to the terminal 11 will be described as an example. In this case, the interworking device 4 determines in advance the IP address of the terminal 11 and the E.I. The combination information with the 164 address is notified to the interworking apparatuses 2 and 3. Upon receiving the IP packet addressed to the terminal 11 from the terminal 8, the interworking apparatus 2 uses the destination IP address of the interworking apparatus 4 of the interworking apparatus 4 to which the terminal 11 is connected. 164 address and its I
The P packet is encapsulated in the WAN1 packet format and transferred to the interworking device 4 via the WAN1.
Upon receiving the encapsulated packet, the interworking device 4 extracts the original IP packet and
Transfer to the terminal 11 according to the P address.

FIG. 2 shows a configuration example of an interworking device.
This interworking apparatus includes a control circuit unit 21 and a control unit 2
2. WAN interface control unit 23, buffer unit 24
And a LAN interface control unit 25, which are connected by a bus 26. The control circuit unit 21 includes an address management unit 27, an IP packet transfer unit 28, and an address conversion table 29. 1
It manages 64 addresses and controls the transfer of IP packets. The control unit 22 controls the entire interworking device. The WAN interface control unit 23 terminates the WAN interface and sends the IP packet to the CLNAP (Conn.
ectionless Network Access Protocol) packet and transfer it to the WAN, or extract an IP packet from a CLNAP packet received from the WAN and transfer it to the buffer unit 24. The buffer unit 24 stores packets transferred between the WAN and the LAN. LA
The N interface unit 25 terminates the LAN interface, extracts an IP packet from the MAC frame received from the LAN and transfers it to the buffer unit 24, or encapsulates the IP packet from the buffer unit 24 into a MAC frame and transmits it by LAN interface. I do.

A method for managing a terminal IP address by this interworking device will be described. The LAN interface control unit 25 transmits the IP address of the terminal from the LAN interface.
When receiving the address resolution signal in which the address and the MAC address are described, it notifies the control unit 22 via the bus 26. The control unit 22 activates the address management unit 27,
The IP address and E.E. The combination with the 164 address is registered in the address conversion table 29. The combination of addresses registered in the address conversion table 29 is called an “entry”. If the same entry has already been registered, that entry is left as it is. Once an entry is registered in the address conversion table 29, the address management unit 27
An address resolution signal is transmitted to each terminal in the AN according to the table, and a response is awaited. If a response to the address resolution signal is received from the terminal, the terminal is determined to be connected, and the entry in the table is maintained. However, if there is no response, it is determined that the terminal has left the LAN, and the entry is deleted. By repeating the above operation, the address conversion table 29 stores the latest information of the terminal connected to the local LAN.
The P address is maintained.

Next, each time the address management table 29 is updated, the interwork apparatus broadcasts the information to another interwork apparatus using an address change notification packet. An address change notification packet from another interworking device is received by the WAN interface control unit 23. When the WAN interface control unit 23 receives the address change notification packet, the control unit 22 activates the address management unit 27 and sets the address conversion table 29
Update the contents of Thereby, the IP packet transfer unit 28
When transferring a packet, the E.P.P. refers to the address translation table 29 to determine which E.D. It can be seen whether the data should be transferred to the interworking device indicated by the 164 address. Further, by maintaining and managing the address conversion table 29 automatically by the address management unit 27, communication can be continued even when the terminal is moved to a LAN under another interworking device.

FIG. 3 shows an example of the contents of the address conversion table 29. Here, there are three interworking devices,
81-422-59-4263, 81-42 respectively.
2-59-4200, 81-422-59-4000 164 addresses have been assigned. The Iwork shown in FIG.
The terminal of the P address is registered.

FIG. 4 shows a flow of main processing in the related art by the address management unit 27. When an address resolution signal is received from the LAN, if an entry for the IP address does not already exist, an entry is added to the address conversion table and an address change notification packet is transmitted to another interworking device. When an address change notification packet is received from the WAN without receiving the address resolution signal from the LAN, the IP address and E.E. The information with the 164 address is added as an entry. If there is no reception information from either the LAN or the WAN, the address conversion table is used,
An address resolution signal addressed to the IP address of the terminal accommodated in the own LAN is transmitted. At this time, if there is no response, it is determined that the terminal of the IP address has left,
Delete the corresponding entry in the address translation table.
By repeating the above processing, automatic maintenance of the address management table can be realized.

Next, the same LAN under the interworking device
A communication method between terminals in the network will be described. When the terminal communicates with another terminal in the same LAN, the transmitting terminal inquires the MAC address corresponding to the IP address of the destination terminal by an address resolution procedure, knows the MAC address described in the response packet from the terminal, and transmits. The terminal registers the correspondence between the IP address and the MAC address as an entry in the address resolution table. The MAC address obtained by the transmitting terminal from the address resolution table
By providing the packet at the beginning of the P packet, communication with the destination terminal becomes possible. The entry in the address resolution table of the transmitting terminal is deleted after a certain period of time has elapsed. When the entry is deleted, the MAC address of the destination terminal is obtained again by transmitting the address resolution signal again.

A case will be described where a terminal exists under an interworking apparatus and communication is performed with a terminal connected to a LAN under another interworking apparatus. In this case, similarly to the case in the same LAN, the transmitting terminal transmits an address resolution signal to the same LAN. However, in this case, since the destination terminal does not exist on the same LAN, the interworking device returns its own MAC address. Upon receiving this response, the transmitting terminal registers the IP address of the destination terminal and the MAC address of the interworking device in the address resolution table, assigns the MAC address to the head of the packet according to the entry, and temporarily sends the MAC address to the interworking device. Forward. In the interworking apparatus, the E.E.R. of the interworking apparatus accommodating the destination IP address is determined by the address conversion table. 164 addresses are obtained. This address is added to the packet, and the packet is transferred to the interworking device accommodating the destination terminal.

A method of transferring an IP packet inside the interworking apparatus at this time will be described with reference to FIG. 2 again. In the interworking apparatus, the IP packet received from the LAN interface control unit 25 is temporarily stored in the buffer unit 24, and the IP packet transfer unit 28 executes the packet transfer. At this time, the IP packet transfer unit 28 refers to the address conversion table 29 and
E. address corresponding to the address 164 address, and the E.E. The IP packet is transferred to the WAN interface control unit 23 together with the 164 address. The WAN interface control unit 23 controls the E.E. IP based on 164 addresses
Encapsulates the packet in a CLNAP packet and sends it to the WAN
Send to When a packet is received from the WAN, the WAN interface
The IP packet is extracted from the AP packet and transferred to the buffer unit 24. The IP packet transfer unit 28 verifies the match between the destination IP address of the packet and the IP address of the terminal of the self-contained LAN by using the address conversion table 29, and transfers the packet to the LAN interface control unit 25 if they match. Then, the packet is relayed to the own LAN. On the other hand, if they do not match, the packet is discarded.

[0014] CLNAP conforms to ITU-T Recommendation I.T. 3
64 is a protocol of a connectionless service specified in, for example, "Chapter 6 of Picture Network ATM Bible". The packet format of the address resolution signal is RFC826, "An Ether
net Address Rersolution Protocol. "

[0015]

In FIG. 1, the terminal 8
~ 11 were communicating with each other and then the terminal 8
Has moved from LAN5 to LAN6. At this time,
When the interworking device 3 receives from the terminal 8 an address resolution signal describing the new IP address,
It notifies all other interworking devices that the terminal 8 has been connected under its own device. As a result, all the interworking devices transmit packets addressed to the IP address of the terminal 8 to the E.O. The communication can be performed using the 164 addresses. However, previously L
Communication between the terminal 8 and the terminal 9 in the AN 5 is temporarily disabled. This is because the terminal 9 previously communicated directly with the terminal 8, and the MAC address of the terminal 8 is still held in the address resolution table of the terminal 9 corresponding to the IP address of the terminal 8. Since the terminal 8 which is the destination terminal has moved to another LAN 6, the terminal 9 temporarily
However, this is due to the fact that an attempt is made to directly send to the MAC address of the terminal 8 until the address resolution table times out. The MAC address in the address resolution table means the physical address of the next device to be sent to transfer to the corresponding IP address. However, since the terminal 8 has already left the LAN 5, the terminal 8 continues to send data to a partner without a destination.

Until the terminal 8 leaves the LAN 5 and is connected again to any LAN, the terminal 9 may continue to transfer data as long as the address resolution table is held for the terminal 8. is there. In this case, data is continuously transmitted to a terminal that does not exist, which is wasteful.

As described above, when a terminal moves, communication may be interrupted due to the fact that the address resolution table of the terminal having communication history with the terminal retains the state before the movement. , There is a possibility of continuing to send data to a terminal that does not exist. The time until the address resolution table is initialized varies depending on the terminal. However, considering that the time to hold the address resolution table is generally several minutes to several tens of minutes, communication may not be possible during this period. There is.

The present invention solves such a problem, and when a terminal moves, updates the address resolution table of a terminal that has communicated with the terminal to the state after the movement, and thereby stops communication interruption or invalid communication. An object of the present invention is to provide an interworking device capable of eliminating data transmission.

[0019]

An interworking apparatus according to the present invention connects a local area network using a first address system to a wide area network using a second address system different from the first address system. Means for mutually transferring packets between the first address system and another local area network using a common address system via this wide area network, and a wide area from a terminal accommodated in the other local area network. Means for managing the address of each terminal accommodated in the local area network to which it is connected, for transferring packets arriving via the network to the destination terminal, and terminals accommodated in other local area networks And its local area network in the first address system Means for storing the correspondence with the address in the second address system for transferring the packet via the wide area network, and when a new terminal is accommodated in the local area network to which the own terminal is connected, the terminal Registering the address in the first address system with the means for managing the address, and transferring the address and the address in the second address system for transferring the packet to the local area network via the wide area network via the wide area network. And a means for adding to the means for storing an address in the first address system and an address in the second address system for a new terminal arriving via the wide area network. In the work device, the hand to be memorized by the additional means Means for notifying each terminal accommodated in the local area network to which the user is connected, so that a packet addressed to the address in the first address system added to (i) is transferred to oneself. Features.

Means for confirming the existence of a terminal accommodated in the local area network to which the terminal is connected, and management when a terminal is determined to have left the local area network by the confirming means. Means for removing the terminal address from the means for
It is preferable to further comprise means for notifying each terminal accommodated in the local area network of the deleted address so that a packet addressed to the address is transferred to itself.

Using B-ISDN as a wide area network and Ethernet as a local area network,
A case will be described in which an IP address is used as the first address system and a number system defined by the B-ISDN numbering plan is used as the second address system.

In this case, the interworking device of the present invention
If another interworking device notifies that a new terminal has been connected to the LAN managed by the device, or detects that the terminal has left, the I / O of the terminal is determined.
An address resolution signal describing the P address and the MAC address assigned to the LAN of the own device is created and transmitted to the LAN managed by the own device. As a result, the source LA
The entry of the mobile terminal in the address resolution table of the terminal connected to N is rewritten from the MAC address of the mobile terminal to the MAC address of the interworking device. Therefore, the communication interruption time is eliminated, and invalid data transfer to a terminal that does not exist can be suppressed.

That is, since the address resolution table of the terminal left on the source LAN is immediately updated, communication with the destination terminal is immediately resumed without waiting for the address resolution table to time out naturally. it can. Also,
Even if the terminal has left the LAN and has not yet been connected to any LAN, the address resolution table for the moving terminal is immediately rewritten to the MAC address of the interworking device. By instructing the calling terminal to interrupt the communication, useless data transmission can be suppressed.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is embodied by the same configuration as the interworking apparatus shown in FIG. However, the address management by the address management unit 27 is different from the conventional one.

FIG. 5 shows an address management unit 2 embodying the present invention.
7 shows a processing flow. When an address resolution signal is received from the LAN, the IP address is already
If there is no entry for the address, the entry is added to the address translation table and an address change notification packet is transmitted to another interworking device. When an address change notification packet is received from the WAN without receiving the address resolution signal from the LAN, the IP address and E.E. The information with the 164 address is added as an entry. Further, an address resolution signal having the IP address of the added entry and the MAC address of the own device as a transmission source is transmitted to the own LAN. If there is no received information from either the LAN or the WAN, the local LAN according to the address conversion table is used.
Transmits an address resolution signal addressed to the IP address of the terminal accommodated in the terminal. If there is no response, it is determined that the terminal with the IP address has left, and the corresponding entry in the address conversion table is deleted. Further, an address resolution signal using the IP address of the deleted entry and the MAC address of the own device as a transmission source is transmitted to the own LAN.

The IP address of the additional entry and the M of the own device
By transmitting an address resolution signal with the AC address as the transmission source, a certain terminal leaves the LAN and transmits to another L.
When the terminal has moved to the AN, the terminal that has been communicating with the terminal that has moved from before, immediately stores its own address resolution table from the MAC address of the moved terminal to the MAC address of the interworking device according to the address resolution signal. And communication with the moved terminal can be continued without interruption of communication.

By transmitting an address resolution signal using the IP address of the deleted entry and the MAC address of its own device as a transmission source, even if a terminal simply leaves the LAN, the terminal that has already left the LAN can be used. The terminal that was communicating with
The MA of the terminal that has left its address resolution table
It is possible to immediately rewrite the C address to the MAC address of the interworking device, and to transfer data addressed to the terminal that has left the network to the interworking device. Therefore, by issuing a transmission suppression instruction from the interwork apparatus, useless data transfer can be suppressed.

[0028]

As described above, according to the present invention,
Since the time for interrupting communication with the moved terminal can be reduced, smooth communication can be continuously performed even when the terminal is used while being carried to a geographically distant place. Further, since it is not necessary to wait for restoration of communication for several minutes to tens of minutes until the address resolution table is initialized unlike the related art, the convenience of the interworking apparatus is improved. Further, it is possible to prevent useless communication such as transmission of data having no destination, and the fact that the sender is unaware that the data has been discarded, as in the related art.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a network connection configuration using an interworking device.

FIG. 2 is a block diagram illustrating a configuration example of an interworking device.

FIG. 3 is a diagram showing an example of the contents of an address conversion table.

FIG. 4 is a diagram showing a flow of main processing in the related art by an address management unit.

FIG. 5 is a diagram showing a flow of processing by an address management unit according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 WAN 2-4 Interworking device 5-7 LAN 8-11 Terminal 21 Control circuit unit 22 Control unit 23 WAN interface control unit 24 Buffer unit 25 LAN interface control unit 26 Bus 27 Address management unit 28 IP packet transfer unit 29 Address conversion Tables 101 to 104, 105 to 107 MAC address defined points 111 to 113 164 address specified point

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-129550 (JP, A) JP-A-2-214349 (JP, A) JP-A-7-200454 (JP, A) JP-A-10-1998 56473 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/46 H04L 12/28 H04L 12/66

Claims (1)

(57) [Claims] 1. A local network using a first address system.
Rear network is different from this primary address system
Connects to a wide area network using the second address system
Via the wide area network.
Other local areas that use a common addressing scheme
For transferring packets to and from the network
And from a terminal housed in another local area network
Address packets arriving via the wide area network
To transfer to the destination terminal,
Address of each terminal accommodated in the local area network
Means to manage and in front of terminals housed in other local area networks
Addresses in the first address system and their local
To the area network via the wide area network
The second addressing scheme for forwarding packets.
To store the correspondence with the addresses to be connected, and to the local area network to
When a terminal is accommodated, the first
Register the address in the address system to the managing means.
Record the address and its local area network.
Network to the network via the wide area network.
Address in the second addressing scheme for sending
Means for notifying others via the wide area network
And a new terminal arriving via the wide area network
Addresses and previous addresses in the first addressing system
And the address in the second address system.
An interworking apparatus provided with
AndThe local area network is an internet protocol
Is a col net, The wide area network is a broadband service integrated digital
A net, The first address system is based on an Internet protocol.
Address system defined by The second address system is a broadband service integrated digital
Is a numbering system specified by the network numbering plan, Before adding to the storing means by the adding means
For the addresses in the first address system,
Just as packets addressed to the address are forwarded to you,
Housed in a connected local area network
For notifying each terminalWhen, On your local area network
Address resolution signal according to the first address system received
The local area network to which you are connected.
To the address resolution signal from the terminal.
Means for confirming the presence of the terminal by the presence or absence of a response to This means that any terminal can check its local
If it is determined that you have left the area network
A method of deleting the terminal address from the managing means.
Steps and For a deleted address, packets addressed to that address
The local area network so that
Means for notifying each terminal accommodated in the work; Octopus with
And an interworking device.