JPH0433431A - Lan connection device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a LAN connection device that interconnects a plurality of LANs (local area networks) and realizes communication between stations located in different LANs. It is.

[Prior art] Fig. 4 shows how multiple LANs connecting multiple stations are connected to the LAN.
A conceptual diagram of a configuration in which connection is made using a connection device 13 is shown. That is, stations 111, 112, 113 are connected to the transmission line 11.
LAN#1 is configured by connecting the station 12 to the transmission line 12.
LAN #2 is configured by connecting 1°122.123. Then, the LAN connection device 13 connects these two LAs.
N is connected.

The LAN connection device 13 has a "station address" and "Which LA is the station?"
Check which network the station with the destination address of the received frame is connected to, and if the destination station and source station are not connected to the same LAN, The frame is transferred to the LAN to which the destination station is connected, and if the destination station is connected to the same LAN, the frame is not transferred and the frame is discarded. If the destination address of the received frame and information indicating which network the destination station is connected to are not stored, the frame is transferred to the interconnected LAN.

As an example, station 111 and station 112 connected to the same LAN
Consider the communication of The LAN connection device 13 receives the frame transmitted from the station 111, and checks to which LAN the destination station 112 is connected. LAN connection device 1
If the address of the station 112 and the information that the station 112 is connected to LAN #1 are stored in 3, the frame is not transferred to the other LAN. If the address is not stored, the frame is not transferred to the other LAN. Transfer the frame to #2.

Next, station 111 and station 1 connected to different networks
Consider communication with 21. LAN connection device 13 is station 111
Station 12, which is the destination station, receives the frame transmitted from
Find out which LAN 1 is connected to. The address of the station 121 and the LAN$ of the station 121 are sent to the LAN connection device 13.
If information indicating that the LAN is connected to LAN #2 is stored, the frame is transferred to the other LAN, LAN #2.

Similarly, if it is not stored, the other LAN L
Transfer the frame to AN#2.

FIG. 2 shows an example of the configuration of a conventional LAN connection device.

In Fig. 2, the transmission line 11 has stations 111, 112° 113
are connected to form LAN #1.

Furthermore, stations 121, 122, and 123 are connected to the transmission line 12, forming a LAN 4t2.

The frame transmitting/receiving unit 21 is connected to LAN #1,
The frame transmitting/receiving section 25 is connected to LAN #2.

The frame transmitting/receiving unit 21.25 inspects the frame received from the LAN, and if there is no error, the frame is transferred to the buffer RAM.
24, while the signal line 61 or 6
2, an interrupt signal is sent to the control unit 23.

The control unit 23 is a circuit that controls the entire LAN connection device 132, and is composed of a microprocessor and a memory in which a program is stored.

The LAN information storage unit 22 of the LAN connection device 132 is
The address of the station connected to N and which LA the station is connected to.
LAN#1 or LAN#2) is stored.

This LAN information storage section 22 is composed of a memory.

Here, communication from the station 111 to the station 121 connected to different LANs will be taken as an example.

The frame transmitter/receiver 21 receives the "frame transmitted by the station 111" from the transmission line 11, checks for errors, stores the frame in the buffer RAM 24 via the internal bus 51, and transmits the frame via the signal line 61. and sends an interrupt signal to the control unit 23.

The control unit 23 retrieves the “destination address of the received frame”, that is, the “address of the station 121” from the buffer RAM 24 via the internal bus 51,
In order to check whether the station 121 is connected to the LAN #2 or to the LAN #2, using the address of the station 121 as a clue, the LAN information storage unit 22 connects the station 121 to the LAN #1 via the internal bus 51. Is it LAN#2?
Search for information indicating whether it is connected to the

In this example, "station 121 address" and [station 121 address]
is connected to LAN#2" is the information that the LA
If it is stored in the N information storage section 22, the control section 2
3 instructs the frame transmitting/receiving section 25 to take out the "received frame" from the buffer RAM 24 and transmit it.

In addition, in the configuration shown in FIG. 2, in order to quickly determine which LAN the destination address of the received frame is connected to, the L
LA that incorporates a method to quickly search AN configuration information
There are also examples of N-connected devices.

However, the configuration shown in FIG. 2 has the following drawbacks. In other words, most of the frames on the LAN are sent to stations on the same LAN, and most of the frames do not need to be relayed by the LAN connection device, so the frame transmission/reception unit does not need to relay them.
This results in the reception of frames that would otherwise be discarded, and the frame transmitter/receiver 21 or 25 and buffer R
The problem is that AM24 cannot be used efficiently.

FIG. 3 shows a configuration example of a LAN connection device that eliminates the above-mentioned drawbacks and interconnects LANs using the LEEB802.4)-Kunpassing bus method as the medium access control method.

The frame transmitter/receiver 21 is connected to LAN #1 via a frame detector 31 and a switch 33, and the frame transmitter/receiver 25 is connected to LAN #2 via a frame detector 36 and a switch 34. .

The frame detectors 31 and 36 extract information indicating the type of frame (i.e., data transfer frame or token) and the destination address of the frame from the frame received from the LAN, and send the information to the determiner 32 via the internal bus 54 or 55. ．．
35, information indicating the type of frame and the destination address of the frame, while sending the frame to switching devices 33 and 34.

The LAN information storage unit 22 of the LAN connection device 133 is a LAN
It stores the addresses of the stations that make up the network and data indicating which LAN the station is connected to (ie, LAN #1 or LAN #2). This LAN information storage section 22 can be configured using, for example, a RAM.

The determiners 32 and 35 determine whether the "received frame" is a token or a data transfer frame that requires relaying, based on the information passed from the frame detectors 31 and 36 and the information in the LAN information storage section 22. Judgment, signal line 63.64
A control signal is sent to the switch 33, 34 via the switch 33, 34, and only tokens and data transfer frames that require relaying are sent to the frame transmitter/receiver 21, 25.

The frame transmitting/receiving sections 21.25 receive the frames sent via the switching devices 33 and 34, and transfer them to the buffer RAM 2.
4, while the signal line 61 or 62
An interrupt signal is sent to the control section 23 via the control section 23.

The control unit 23 is a circuit that controls the entire operation of the LAN connection device 133, and is composed of a microprocessor and a memory in which a program is stored.

The following three examples are shown as operation examples of the LAN connection device 133.

(1) When the LAN connection device receives a token from the transmission line 11, the frame detector 31 transmits information indicating that the received frame is a token to the determiner 3 via the internal bus 154.
Send to 2. The determiner 32 sends a control signal to the switch 33 via the signal line 63, and instructs the switch 33 to switch to contact a. The switch 33 switches to contact a and sends the token to the frame transmitting/receiving section 21. After processing the received token, the frame transmitting/receiving unit 21 transmits the token to the transmission line 11 via the signal line 65.

(2) The communication frame detector 31 from the station 111 to the station 121 belonging to a different LAN receives the frame transmitted by the station 111 over the transmission line 11, and contains information indicating the frame for data transfer and "destination of the received frame." address” i.e. station 1
The 0 determiner 32 sends the address of 21 to the determiner 32 via the internal bus 54, searches the information stored in the LAN information storage unit 22 via the internal bus 53,
It is determined whether it is connected to AN#1 or LAN#2. In this example, "Address of station 121" and "Station 121 is connected to LAN #2" are used.
Assuming that this information has already been stored in the LAN information storage unit 22, the determiner 32 sends a control signal to the switch 33 via the signal line 63, instructing it to switch to contact a. The switch 33 switches to contact a and sends the "received frame" to the frame transmitting/receiving section 21. The frame transmitting/receiving unit 21 receives the [frame transmitted by the station 111], inspects it for errors, stores the frame in the buffer RAM 24 via the internal bus 51, and sends the frame to the control unit 23 via the signal line 61. Send an interrupt signal.

The control unit 23 causes the frame transmitting/receiving unit 25 to take out the “received frame” from the buffer RAM and transmit it.
instruct. The frame transmitter/receiver 25 transmits the frame to the transmission line 12 via the signal line 66.

(3) Stations 111 to 112 connected to the same LAN
The communication frame detector 31 receives the "frame transmitted by the station 111" from the transmission line 11, and detects the information indicating the data transfer frame and the destination address of the received frame, that is, the frame transmitted by the station 111.
The 0 determiner 32 sends the address of 2 to the determiner 32 via the internal bus 54, searches the information stored in the LAN information storage unit 22 via the internal bus 53, and the station 112
It is determined whether it is connected to AN#1 or LAN#2. In this example, "Address of station 112" and "J
If this information has already been stored in the LAN information storage unit 22, the determiner 32 sends a control signal to the switch 33 via the signal line 63, instructing the switch to switch. The switch 33 switches the contact to ``to automatically discard the received frame J by not sending it to the frame transmitting/receiving section 21''.

The LAN connection device with the configuration shown in FIG. 3 sends only frames that need to be relayed to the frame transmitting and receiving sections 21 and 25.
The frame transmitting/receiving sections 21, 25 and the buffer RAM 24 are used more efficiently than the LAN connection device having the configuration shown in FIG. Furthermore, since frames that do not require relaying are automatically discarded, frames can be discarded at high speed.

[Problems to be Solved by the Invention] However, the LAN connection device with the configuration shown in FIG.
Frames that do not need to be relayed are sent to the frame transmitting/receiving section, and the frame transmitting/receiving section inspects the frames and stores them in buffer R.
After being stored in the AM, the frame is transferred via a frame transmitting/receiving unit connected to the other LAN, which causes the following problems. That is, although it is sufficient for the frame to be inspected by the "frame destination station," the frame is also inspected by the LAN connection device, so frame relay processing takes time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a LAN connection device that eliminates the drawbacks of the prior art described above and can relay frames at high speed.

[Means for Solving the Problems] A LAN connection device of the present invention interconnects LANs each having a plurality of stations configured to transmit and receive frames including a destination station address and a source address, and A LA that transfers communication data to the LAN where the destination station is located only when the station is not on the same LAN as the source station, thereby realizing data transfer even between stations that are not on the same LAN.
In the N-connection device, a detector that detects the destination station and a LAN
A frame transmitter and a switch for each LAN are installed in the LAN connection device, and when a frame that needs to be relayed is received by the switch, the frame transmitter for the LAN with the destination station is installed. This configuration allows frames to be transferred between stations that are not on the same LAN.

If the LAN connection device is a token-passing type device that interconnects LANs, each LAN is equipped with a detector that detects the type of frame and the destination station, and a token transmitter/receiver that controls transmission rights within the LAN. The switching device may have one for each, and when the switching device does not receive the token, the token is passed to the token transmitting/receiving section.

Further, even if the LAN connection device is a device that interconnects LANs using the IEEE802.4 token passing bus method as a medium access control method, a detector for detecting the type of frame and the destination station and a It is possible to have one token transmitting/receiving section for each LAN for controlling transmission rights, and to pass the token to the token transmitting/receiving section when the switching device receives the token.

[Operation] The LAN connection device of the present invention transmits frames that need to be relayed.
Since the frame is directly passed to the frame transmission unit for the LAN where the destination station is located, the time required for frame inspection, which was conventionally required, can be omitted, and the time required for frame relay can be shortened.

[Embodiment] Hereinafter, as an embodiment of the present invention, IE is applied to the medium access method.
Using EE802.4 token passing bus method,
A LAN connection device that interconnects LANs will be explained with reference to FIG.

FIG. 1 shows an example of the configuration of a LAN connection device according to the present invention.

Stations 111, 112, 113 are connected to the transmission line 11, and L
AN#1 is configured. Furthermore, a station 12 is connected to the transmission line 12.
1, 122, and 123 are connected to form LAN #2. The part corresponding to the conventional frame transmitting/receiving section 21.25 (FIG. 3) is divided into a token transmitting/receiving section 41.44 and a frame transmitting section 42.43, which includes a frame detector 31, a token transmitting/receiving section 41. Frame transmitter 4
2 is connected to LAN #1, and includes a frame detector 36, a token transmitting/receiving section 44. Frame transmitter 43 is connected to LAN #2. In addition, with the aim of relaying frames at high speed by directly sending frames that need to be relayed to a frame transmitter connected to the relay destination LAN,
The switches 33 and 34 have three switching positions, contacts a, b, and c, and in the switch 33 connected to one frame detector 31, the contacts are connected to the frame transmitter 43 and the buffer. In the switch 34 connected to the RAM 242 and connected to the other frame detector 36, the frame transmitter 42 and the buffer RA are connected.
M241 is connected.

The frame detectors 31 and 36 extract information indicating the type of frame (i.e., data transfer frame or token) and the destination address of the frame from the frame received from the LAN, and send the information to the determiner 32 via the internal bus 54 or 55. ．．
35, information indicating the type of frame and the destination address of the frame, while sending the frame to switching devices 33 and 34.

The LAN information storage unit 22 of the LAN connection device 131 is
Data indicating the addresses of the stations forming N and which LAN the station is connected to (ie, LAN #1 or LAN #2) are stored. This LAN information storage section 22 is configured using, for example, a RAM.

The determiners 32 and 35 determine whether the "received frame" is a token or a data transfer frame based on the information passed from the frame detectors 31 and 36 and the information in the LAN information storage unit 22, By sending a control signal to the switch 33.34 via the line 63.64 to switch, only the token is sent to the token transmitting/receiving section 41.44, and the buffer RAM 242.24 regarding the destination LAN is sent.
Only data transfer frames that need to be relayed are sent to No. 1.

The token transmitting/receiving units 41 and 44 each have a LAN#1
and controls the transmission right in LAN #2, and when the transmission right is acquired, it notifies the frame transmitting section 42, 43 that transmission is possible via the signal line 67, 68.

The frame sending/receiving section 42 and 43 includes the token sending/receiving section 41.
．． 44, the frames stored in the buffer RAMs 241 and 242 are taken out and transmitted to LAN #1 and LAN #2, respectively.

The following three examples are shown as operation examples of the LAN connection device 131.

(1) When the LAN connection device 131 receives a token from the transmission line 11 The frame detector 31 transmits information indicating that the received frame is a token to the determiner 3 via the internal bus 54.
The 0 determiner 32 sends a control signal to the switch 33 via the signal line 63, and instructs the switch 33 to switch to contact a. The switch 33 switches to contact a and sends the token to the token transmitting/receiving section 41. After processing the token, the token transmitting/receiving unit 41 transmits the token to the transmission line 11.

(2) Stations 111 to 121 connected to different LANs
The communication frame detector 31 receives the "frame transmitted by the station 111" from the transmission line 11, and detects information indicating the frame for data transfer and the destination address of the received frame, that is, the frame transmitted by the station 12.
The 0 determiner 32 sends the address of 1 to the determiner 32 via the internal bus 54, searches the information stored in the LAN information storage unit 22 via the internal bus 56, and
It is determined whether it is connected to N#1 or LAN#2. In this example, if the information “station 121 address” and “station 121 is connected to LAN #2” are already stored in the LAN information storage unit 22, the determiner 32 and sends a control signal to the switch 33, instructing it to switch the contact. The switch 33 switches the contact to send the received frame to the buffer RAM 242.

When informed by the token transmitter/receiver 44 that the frame can be transmitted, the frame transmitter 43 takes out the frame stored in the buffer RAM 242 and transmits it to the transmission line 12 .

In this way, the LAN connection device 131 directly transmits frames that are determined to need to be relayed to the LAN# where the destination station is located.
2, the time required for frame inspection, which was conventionally required, can be omitted, and the time required for relay processing can be significantly shortened.

(3) Stations 111 to 112 connected to the same LAN
The communication frame detector 31 receives the "frame transmitted by the station 111" from the transmission line 11, and sends information indicating the data transfer frame and the "destination address of the received frame", that is, the address of the station 112, to the internal bus. 54, the determiner 32
The 0 determiner 32 searches for information stored in the LAN information storage section 22 via the internal bus 56, and sends it to the station 112.
It is determined whether it is connected to LAN #1 or LAN #2. In this example, [station 112
If the address J and the information "station 112 is connected to LAN #1" are already stored in the LAN information storage unit 22, the determiner 32 transmits the control signal to the switch 33 via the signal line 63. and instructs it to switch to contact C. The switch 33 switches to contact C to prevent the received frame from being sent to the buffer RAM 242 and automatically discards the frame.

Non-token-passing LAN that does not use tokens
The LAN connection device that interconnects the devices can be realized using the configuration shown in FIG. 1 except that the token transmitter/receiver section is removed.

[Effects of the Invention] As described above, according to the present invention, the following effects can be obtained. In other words, by passing frames that need to be relayed directly to the frame transmitter for the LAN where the destination station is located, the time required for frame inspection, which was previously required, can be eliminated and the time required for frame relay can be shortened. This allows frames to be relayed at high speed.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a LAN connection device according to an embodiment of the present invention, FIGS. 2 and 3 are configuration diagrams of a conventional LAN connection device, and FIG. 4 is a configuration diagram of a conventional LAN connection device, and FIG. It is a conceptual diagram of a conventionally known connection. In the figure, 11 is a transmission line, 111 to 113 are stations, 12 is a transmission line, 121 to 123 are stations, 133 is a LAN connection device body, 21.25 is a frame transmitting/receiving unit, 22 is a LAN information storage unit, 241, 242 is a buffer RAM, 31.36 is a frame detector, 32.35 is a determiner, 33.34 is a switch, 41.44 is a token transmitting/receiving section, 42.43 is a frame transmitting section, 54 to 56 are internal buses, 63 .64 indicates a signal line. Patent Applicant Hitachi Cable Co., Ltd. Representative Patent Attorney Nobuo Kinutani

Claims (1)

[Claims] 1. A LAN including a plurality of stations configured to transmit and receive frames including a destination station address and a source address is interconnected, and the destination station of the frame is on the same L as the source station.
A detector for detecting a destination station and a LAN in a LAN connection device that transfers communication data to a LAN where the destination station is located only when the destination station is not on the AN, and realizes data transfer even between stations that are not on the same LAN. A frame transmitter and a switch for each LAN are installed in the LAN connection device, and when a frame that needs to be relayed is received by the switch, the frame transmitter for the LAN with the destination station is installed. A LAN connection device characterized in that it is capable of passing frames to stations and transferring frames between stations that do not exist on the same LAN. 2. The LAN connection device is a token passing type LA
It is a device that interconnects between N and N, and has a detector for detecting the type of frame and the destination station, and a token transmitting/receiving section for controlling transmission rights within the LAN, one for each LAN, and the switching device Claim 1 characterized in that when the token is received, the token is passed to the token transmitting/receiving section.
LAN connection device described. 3. The LAN connection device uses IE in the medium access control method.
L using EE802.4 token passing bus method
It is a device that interconnects between ANs, and has a detector for detecting the type of frame and the destination station, and a token transmitting/receiving section for controlling transmission rights within the LAN, one for each LAN, and the switching device 2. The LAN connection device according to claim 1, wherein when the token is received, the token is passed to the token transmitting/receiving section.