JP2958388B2 - Network relay device, relay method, and server - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

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

[Prior art]

Devices that connect local area networks (LANs) include repeaters, bridges, and gateways. They only serve to relay transmissions across networks. In addition, the connection between LANs (especially gateways) may be slower than the transfer speed of LANs, and when accessing via a number of relay devices, the response is often very slow. Was. 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 are provided outside of these, and gateways GW1 to GW6 are connected between the respective LANs via dedicated or public lines. A file server FS is connected to 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.

[Problems to be solved by the invention]

In such a conventional technique, when accessing a file on a distant LAN, it is necessary to transfer information through several networks or gateways. There was a problem that the traffic volume was large. SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the related art, improve the response of the network, and reduce the traffic of the network.

[Means for Solving the Problems]

A network relay device according to the present invention includes a second network communication unit that performs communication via a first network and a second network communication unit that performs communication with a second network via a dedicated line or a public line. Requesting a target file of the command via the second network communication means in response to a file transfer command received from another device via the first network communication means. Control means for checking whether or not the target file exists in the storage means when transferring the original file, and transmitting a transfer command for the target file via the second network communication means if the file does not exist; And the storage means stores a file transmitted in response to the transmitted transfer command. Further, the network relay method of the present invention is a network relay method for a network in which a first network and a distant second network are connected via a dedicated device or a public line via a relay device. A device receives a file transfer command from the first network, and checks whether the target file exists in the device when transferring the target file to the request source in response to the command, and determines whether the target file exists in the device. In this case, a transfer command of the target file is transmitted to the second network, and a file transmitted in response to the transmitted transfer command is stored in a storage unit. The network server according to the present invention may further include a network communication unit that controls communication with the network, a storage unit that stores a file, and a file transfer command received from another device on the network via the network communication unit. Correspondingly, when transferring the target file of the command to the request source via the network communication means, it is checked whether the target file exists in the storage means, and if the file does not exist, the network communication means And control means for transmitting the transfer instruction of the target file via the storage means, and the storage means stores the file transmitted in response to the transmitted transfer instruction. A network file transfer method according to the present invention is a network file transfer method for a network system in which a plurality of networks are connected to each other to enable mutual access, wherein a server is connected to at least one network, and In response to the command, when the target file of the command is transferred to the request source, it is checked whether or not the target file exists in the server. A transfer command is transmitted to the network, and a file transmitted in response to the transmitted transfer command is stored in the server.

[Operation]

In the network relay device (FIG. 2) of the present invention,
When the control means (23) receives a file transfer command from the first network to the second network via the first network communication means (21), the control means (23) first stores the file to be subjected to the transfer command in the storage means. Check if it exists in (24). If the command is to instruct the reading of a file, if it is the first access, it is not in the storage means, and is transferred to the second network via the normal path via the second network means (22). Send command. When the file read from the second network is received via the second communication means in response thereto, 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. According to the network relay device of the present invention, frequently accessed files can be accessed without transferring in a network-like manner, so that the response of file access over a network can be improved. In the network relay method according to the present invention, the first network and the remote second network are connected via a relay device having storage means. When the relay device receives a file transfer command from the first network, the relay device checks whether or not the file targeted by the command exists in the storage unit of the relay device. If it does not exist, the transfer command of the target file is transmitted to the second network, and stored in the file storage means transmitted in response to the transmitted transfer command. Therefore, when the target file is not held in the storage unit when the transfer command is received, the file from the second network is stored in the storage unit of the relay device. This eliminates the need for transfer between networks, thereby improving the response to file access. In the network server (FIG. 5) of the present invention, when the control means (53) receives a file transfer command via the network communication means (51), the control object (53) stores the command target file in response to the command. Check to see if it exists. As a result, if the target file does not exist, the transfer command of the target file is sent out via the network communication means. The storage means stores the file transmitted in response to the transmitted transfer command. According to the network server of the present invention, frequently accessed files are stored in storage means in the network server, and can be accessed without transferring between networks. Response can be improved. According to the network file transfer method of the present invention, a server is connected to at least one network in a network system in which a plurality of networks are connected to each other so as to be mutually accessible. The server accepts a file transfer command and checks in response to the command whether the target file exists on the server. As a result, if the file does not exist, a transfer command of the target file is transmitted to the network, and the file transmitted in response to the transmitted transfer command is stored in the server. Therefore, according to the network file transfer method of the present invention,
Frequently accessed files are stored in the storage means in the server, so that the response to file access over a network can be improved.

【Example】

(First Embodiment) In this embodiment, in a network system as 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 a 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 these devices are managed by a control device 23. 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, when a command to read a file from the remote LAN-4 is issued from the workstation WS on the LAN-1 (step 31), the network communication device 21 notifies the control device 23 of the command. The control device 23 checks whether or not the file to be accessed specified by the instruction exists in the storage device 24 (step 31). The storage device 24 has a file index table indicating the correspondence between the file identifier of the cached file and the storage location of the file. Also,
The file index table also records the access status of the file (such as frequency of use). 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 checked whether or not the storage device has a sufficient storage area (step 33). If there is no empty area in the storage device 24, the file that has not been accessed for the longest time is deleted from the storage device 24 based on the access status recorded in the file index table to create an empty area ( Step 34). If there is an empty area in the storage device 24, the control device sends a file transfer command to the remote LAN-4 via the network communication device 22 (step 35). Upon receiving the 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 request source of the file transfer (step 37). Command from workstation WS on LAN-1 is sent to other LAN
When writing to the file server FS-4, that is, when the command is a file creation command, the file creation is executed in accordance with the flowchart of FIG. LAN-4 far from workstation WS on LAN-1
If the file server FS is instructed to create a file (step 41), the network communication device 21 informs the control device 23 that the command has been issued. The control device 23 checks whether or not the storage device 24 has a sufficient storage area (step 42). Storage device
If there is no empty area in the file 24, the file which has not been accessed for the longest time is deleted 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 sends the LA
Instruct file creation to N-4. In short, in the first embodiment, caching means is provided in a relay device, and files existing in a distant LAN are temporarily stored in a caching storage device.
When a command to transfer (read) a file on the remote LAN to this relay device is issued, first check the storage device of the relay device, and if there is a corresponding file in this, only to the storage device of the relay device You only need to access it. The access route at that time is shown in FIG.
And via 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 / Copy the file to the storage device of the relay device while relaying the file on the remote LAN-4 via the public line, GW6. 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 the communication from the workstation WS to the relay device GW1 is sufficient, and the other Ls.
AN communication is not required. Therefore, the speed of communication between LANs is improved, and the response of the network is increased. Also, when the workstation requests file creation to a file server on the remote LAN, the entire file is temporarily buffered in the storage device of the relay device,
Since the work of the file creation request source can be released even if the actual file creation has not been completed, the network response can be improved and the network and traffic can be reduced. In the embodiment, the case in which the caching means is provided in the relay device GW1 is exemplified. However, the caching means can be provided in each LAN, or in 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. Figure 5 shows the network file cache server NFCS
It has a network communication device 51 that manages communication with the network, a storage device 52 that stores files and is used for caching, and a control device 53 that controls these devices. The function of caching by 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, the first execution is performed. The file is read out according to the flowchart of FIG. 3 described in the example. When the controller 53 receives a file creation command from the workstation WS via the network communication device 51, the controller 53 creates a file in accordance with the flowchart of FIG. 4 described in the first embodiment.

【The invention's effect】

According to the invention, frequently accessed files are LA
Since access can be made without transferring data between N networks, the response of 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. In addition, since a copy of a file on a remote LAN exists in the storage device according to the present invention, even when the connection between LANs is disconnected due to an accident or the like, access is possible, and reliability of network communication can be improved. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first 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 is generated. FIG. 4 is a flowchart showing the operation when a file creation request occurs. FIG. 5 is a diagram showing a configuration of a file server provided with caching means in the second embodiment. FIG. 6 is a diagram showing a configuration of a conventional LAN network. WS: Workstation, GW1 to GW6: Repeater (gateway), LAN-1 to LAN-4: Local area network, FS
... file server, 21, 22, 51 ... network communication device, 23, 53 ... control device, 24, 52 ... storage device.

Continuation of the front page (56) References JP-A-59-221132 (JP, A) JP-A-61-286920 (JP, A) JP-A-62-286137 (JP, A) JP-A-63-201845 (JP) JP-A-63-227233 (JP, A) JP-A-2-153443 (JP, A) JP-B-4-63418 (JP, B2) U.S. Pat. No. 4,855,906 (US, A) Proceedings, 15th Conference on Local Computer Network s, Sep. 30, 1990, Sheu TL. et al, "Experimental Availability of Cach Memories for In- terconnect Controllers", pages. 188-194 (58) Fields investigated (Int. Cl. ⁶ , DB name) H04L 12/28 G06F 12/00 G06F 13/00 WPI (DIALOG) JICST file (JOIS) INSPEC (DIALOG)

Claims (10)

(57) [Claims] A first network communication means for performing communication via a first network; a second network communication means for performing communication with a second network via a dedicated line or a public line; A storage unit for storing, in response to a file transfer instruction received from another device via the first network communication unit, transferring a target file of the instruction to a request source via the second network communication unit A control unit that sends out a transfer command of the target file via the second network communication unit if the target file exists in the storage unit and checks if the file does not exist. Wherein the storage means stores a file transmitted in response to the transmitted transfer command. Network relay device used in the work system. 2. The network relay device according to claim 1, wherein said storage means has a file index table indicating a correspondence between a file identifier and a storage location of the file. 3. The network relay device according to claim 2, wherein an access status of each file is also recorded in the file index table, and the storage area is managed based on the access status. 4. The network relay device according to claim 3, wherein a file having a low frequency of use is deleted to generate a free area based on the access status. 5. The network relay device according to claim 3, wherein a file that has not been accessed for the longest time is deleted to generate a free area based on the access status. 6. A network relay method in which a first network and a remote second network are connected via a dedicated line or a public line via a relay device, wherein the relay device issues a file transfer command. Is received from the first network, and when the target file is transferred to the request source in response to the command, it is checked whether the target file exists in the device. A network relay method, wherein a transfer command is transmitted to the second network, and a file transmitted in response to the transmitted transfer command is stored in a storage unit. 7. A network communication means for controlling communication with a network, a storage means for storing a file, and a file transfer command received from another device on the network via the network communication means. When transferring the target file of the command to the request source via the network communication unit, it is checked whether the target file exists in the storage unit, and if the file does not exist, the file is not transmitted through the network communication unit. Control means for transmitting a transfer command for the target file, and wherein the storage means stores a file transmitted in response to the transmitted transfer command, wherein Network server used. 8. The network relay device according to claim 7, wherein said storage means has a file index table indicating a correspondence between a file identifier and a storage location of the file. 9. The network relay device according to claim 8, wherein an access status of each file is also recorded in the file index table, and a storage area is managed based on the access status. 10. A network file transfer method for a network system in which a plurality of networks are connected to each other to enable mutual access, wherein a server is connected to at least one network, and the server accepts a file transfer command. In response to the command, when transferring the target file of the command to the request source, it is checked whether or not the target file exists in the server. If the target file does not exist, the transfer command of the target file is transmitted to the network. Storing the file transmitted in response to the transmitted transfer command in the server.