JP3230519B2 - Network relay device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network relay device used in a computer communication network system.

[0002]

2. Description of the Related Art Local area networks (LANs)
Conventionally, there are repeaters, bridges, gateways and the like as devices for connecting each other. They only serve to relay transmissions across networks. The connection (particularly, gateway) between the LANs is LA.
N may be slower than the transfer rate, and the response is often very slow when accessing via a number of relay devices. FIG. 6 shows an example of remote access in a conventional LAN network. The workstation WS is connected to LAN-1. LAN-
2, LAN-3 and LAN-4, and gateways GW1 to GW6 are connected between the LANs via a dedicated or public line. The file server FS is connected to the LAN-4. When the target file F stored in the file server FS is accessed from the workstation WS of the LAN-1, it is necessary to always relay all the gateways GW1 to GW6.

[0003]

In such a conventional technique, when accessing a file on a distant LAN, it is necessary to transfer information through several networks or gateways. Response), and there was a problem that the traffic volume of the network was large.

[0004] It is an object of the present invention to solve such problems of the prior art, improve network response, and reduce network traffic.

[0005]

A network relay device according to the present invention comprises a first network communication unit, a second network communication unit, a storage unit for storing a file,
When a file transfer command is received via the first network communication unit, it is checked whether or not the target file exists in the storage unit when the target file of the file transfer command is transferred to a transfer request source. If the target file of the transfer command does not exist, the transfer command of the target file is sent out via the second network communication means, and the file is created on the server via the first network communication means. Control means for temporarily buffering the entire target file of the creation instruction in the storage means to release the job of the creation request source and instructing the target server of the creation instruction to create a file. , And the storage means stores a file transmitted in response to the transmitted transfer instruction.

[0006]

In the network relay device of the present invention (FIG. 2), the control means (23) transmits a file transfer command from the first network to the first network communication means (2).
If received via 1), first, it is checked whether or not the file to be subjected to the transfer instruction exists in the storage means (24). If the command is to instruct the reading of a file, if it is the first access, it does not exist in the storage means, so that it is connected to the second network via the normal path via the second network communication means (22). Send a transfer command. Accordingly, when the file read from the second network is received via the second network communication means, the file is transferred to the transfer request source via the first network communication means, and the read file is used for subsequent use. For storage in a storage means. in this case,
Frequently accessed files can be accessed without transferring between networks, so that the response of file access across networks can be improved. The control means (23)
When a command to create a file from the first network to the server is received via the first network communication means (21), the entire file targeted by the creation command is temporarily buffered in the storage means. Release the work of the creation requester. Then, a file creation command is sent to the target server via the second network communication means.
In this case, the entire file is temporarily buffered in the storage device of the relay device, and the work of the file creation request source can be released even if the actual file creation has not been completed. In addition, network traffic can be reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment)
In the network system shown in FIG. 6, the caching means is provided in a relay device for relaying bidirectional communication between two LANs.

FIG. 2 is a diagram showing the configuration of the relay device of the present embodiment. This relay device has two systems of network communication devices 21 and 22 and a storage device 24 for caching, and has a configuration in which the control device 23 manages them.

When a read command is received from one of the network communication devices, the file is read according to the flowchart of FIG. That is, the distant LA
It is assumed that the file reading of N - 4 is instructed from the workstation WS on the LAN-1 (step 31).
Then, the network communication device 21 informs the control device 23 that the command has been issued. The control device 23 stores the file to be accessed designated by the command in the storage device 2.
4 is checked (step 31).

The storage device 24 has a file index table indicating a correspondence between a file identifier of a cached file and a storage location of the file. The file index table also records the access status (frequency of use, etc.) of the file. The file identifier includes a server name, a directory name, a file name, and the like, and the file storage position is represented by a head address of a storage area in the storage device 24. Using this index table, it is checked whether the specified file exists in the storage device.

When there is no file to be accessed in the storage device 24, the control device 23 prepares for storing a file sent from a distant LAN via a dedicated line / public line. That is, it is determined whether or not the storage device has a sufficient storage area (step 3).
3). If there is no empty area in the storage device 24, based on the access status recorded in the file index table, the file that has not been accessed for the longest time is deleted from the storage device 24 to create an empty area ( Step 3
4).

When there is an empty area in the storage device 24,
The control device is connected to the remote L via the network communication device 22.
Send file transfer command to AN-4 (step 3)
5).

When the network communication device 22 receives a file from the remote LAN-4 in response to the file transfer command, the network communication device 22 passes the transmitted file to the control device 23. The control device 23 stores it in an empty area of the storage device 24 (step 36) and transfers the file to the work station on the LAN-1, which is the file transfer request source (step 37).

When the command from the workstation WS on the LAN-1 is to write to the file server FS on the other LAN-4, that is, when the command is a file creation command, the file is created in accordance with the flowchart of FIG. .

Assuming that a command to create a file is issued from the workstation WS on the LAN-1 to the remote file server FS on the LAN-4 (step 41), the network communication device 21 notifies the control device 23 of the instruction.
Tell

The control device 23 checks whether or not the storage device 24 has a sufficient storage area (step 42). If there is no empty area in the storage device 24, the file that has not been accessed for the longest time is erased from the storage device 24 to create an empty area for storing the file instructed to be created (step 43). ).

When the storage device has a sufficient free space, the file requested to be created is stored in the storage device 24.
(Step 44).

Next, the control device 23 instructs the network communication device 21 to create a file toward the LAN-4.

In short, in this embodiment, caching means is provided in the relay device, and a file existing in a remote LAN is temporarily stored in a caching storage device. When a command to transfer (read) a file on the remote LAN is issued to the relay device, first, the storage device of the relay device is checked, and if a corresponding file exists in the storage device, only the storage device of the relay device is stored. You only need to access it. The access route at that time is shown in FIG.
It only goes through WS, LAN-1, and GW1.
When a file that does not exist in the storage device of the relay device is accessed, the conventional route WS, GW1, dedicated / public line, GW2, LAN-2, GW3, dedicated / public line,
GW4, LAN-3, GW5, dedicated / public line, GW6
Then, while relaying the file on the distant LAN-4, a copy is made in the storage device of the relay device. As described above, each time a new file is read, a copy is stored in the storage device. Therefore, in the second and subsequent read accesses, only communication from the workstation WS to the relay device GW1 is required, and communication on another LAN is required. No longer. Therefore, the speed of communication between LANs is improved, and the response of the network is increased. Also, when a workstation requests file creation to a file server on a remote LAN, the entire file is temporarily buffered in the storage device of the relay device, and even if the actual file creation has not been completed, the file creation request source is not sent. Work can be released, so that network response can be improved and network traffic can be reduced.

In the embodiment, the case where the caching means is provided in the relay device GW1 is exemplified. However, the caching means can be provided for each LAN, or for one or more arbitrary LANs.

(Second Embodiment) The second embodiment has a configuration in which caching means is provided in a file server, which is called a network file cache server NFCS. FIG. 5 shows the network file cache server N
A network communication device 51 for communicating with a network, a storage device 52 for storing files and also used for caching,
And a control device 53 for controlling these.

The caching function of the storage device 52 and the control device 53 is almost the same as that of the first embodiment. When the control device 53 receives a read command from the workstation WS via the network communication device 51, 1
The file is read out according to the flowchart of FIG. 3 described in the embodiment. The control device 53 receives the file creation command from the workstation WS via a network communication device 51, executes the <br/> creation of files according to the flow diagram of FIG. 4 described in the first embodiment I do.

[0023]

According to the present invention, frequently accessed files can be accessed without transferring between LANs, so that the response to file access over a network can be improved. Further, since traffic between LANs can be reduced, the response of non-cached communication can be improved. That is, the substantial communication capacity of the network can be increased. Further, when a file creation request to the server is requested, the entire file is temporarily buffered in the storage device of the relay device, and the work of the file creation request source can be released even if the actual file creation has not been completed. Therefore, network response can be improved and network traffic can be reduced.

In the storage device of the present invention, a remote L
Since there is a copy of the file on the AN, LA
Access is possible even when the connection between N is disconnected, and the reliability of network communication can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a relay device provided with caching means in the first embodiment.

FIG. 3 is a flowchart showing an operation when a read request occurs.

FIG. 4 is a flowchart showing an operation when a file creation request occurs.

FIG. 5 is a diagram showing a configuration of a file server provided with caching means in a second embodiment.

FIG. 6 is a diagram showing a configuration of a conventional LAN network.

[Explanation of symbols]

WS: workstation, GW1 to GW6: repeater (gateway), LAN-1 to LAN-4: local area network, FS: file server, 21 and 22
2, 61 ... network communication device, 23, 63 ... control device, 24, 62 ... storage device.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 12/66 H04L 12/46 H04L 12/28 G06F 13/00 G06F 12/00

Claims (1)

(57) [Claims] 1. A first network communication unit, a second network communication unit, a storage unit for storing a file, and a file transfer command when a file transfer command is received via the first network communication unit. When transferring the target file of the transfer command to the transfer request source, it is checked whether or not the target file exists in the storage unit, and if the target file of the transfer command does not exist, the transfer command of the target file is transferred to the transfer unit. When the command is sent out via the second network communication means and a command to create a file to the server is received via the first network communication means, the entire target file of the creation command is temporarily stored in the storage means. Control means for buffering to release the work of the creation request source and instructing the target server of the creation instruction to create a file Wherein the storage unit stores a file transmitted in response to the transmitted transfer command.