JP2698701B2 - LAN system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a LAN system in which communication between a plurality of devices is performed via a LAN, and in particular, a plurality of LAN controls for one device. The present invention relates to a distributed control method in which a device (LCP) is provided to perform distributed control of transmission and reception.

(Conventional technology) Generally, CSMA / CD (Carrier Sence Multiple Access / C
In a LAN system that applies an ollision detection (ollision detection) method, for example, a LAN system compliant with IEEE (Institute of Electrical and Electronics Engineers) 802.3, each device such as a computer that communicates with each other via the LAN is provided with a unique LAN address (for each device). (Address consisting of 6 bytes). The transmission source device can transmit the frame to the destination device (transmission destination) by designating the LAN address as the destination address and transmitting the frame to the LAN.

The LAN address can be stored in a database in the device in advance, or can be stored in TCP / IP (Transmission Control).
ol Protocol / Internet Protocol (ARP)
lution Protocol). Usually, ARP is used in consideration of versatility. The outline of ARP is described below.

First, ARP is a protocol for obtaining a LAN address (LAN address conforming to IEEE802.3) from an address (called an Internet address) for identifying a device on TCP / IP. Here, one device A is connected to another device B via LAN
Let's say you want to communicate via For this communication, it is assumed that the device A knows the Internet address of the device B. The Internet address may be stored in a file (database) in the device B, or may be stored in one of the applications on the network.
One name server.

Now, in order for the device A to know the LAN address of the device B, the following procedure is usually performed.

Device A is an ARP with the Internet address of device B
The request is transmitted on the LAN in a broadcast frame (a frame having a broadcast address destined for all devices on the LAN). In the ARP request (ARP request frame), the LAN address of the device A is set as the source address (source LAN address).

All devices on the LAN receive this ARP request.

Among the devices that have received the ARP request, a device having an Internet address different from its own Internet address in the ARP request, that is, a device other than the device B, discards the ARP request.

On the other hand, the device whose Internet address in the ARP request matches its own Internet address, that is, device B, returns a response to the ARP request (referred to as an ARP response) to device A. Since the ARP response is transmitted by designating the LAN address of the source device A set in the received ARP request, the ARP response is received only by the device A, and is not received by other devices.

Upon receiving the ARP response, the device A can obtain the LAN address of the device B from the source LAN address set in the response.

As a result, the device A makes the subsequent transmission to the device B an ARP
This is performed using the LAN address obtained from the ARP response to the request.

By the way, each device that communicates with each other via LAN
A LAN interface mechanism for connecting the device to a LAN is provided for each device. This LAN interface mechanism is a LAN control device (LAN Control Processo).
r). The LAN control device (hereinafter referred to as LCP) has a transmission function of transmitting a frame on the LAN in response to a request from the corresponding device, and monitors a frame flowing on the LAN,
It has a reception function that takes in only frames with its own LAN address (or broadcast address).

In recent years, a TCP / IP protocol has been implemented in firmware for this LCP to reduce the load on devices such as computers connected to the LCP. However, on the contrary, since the processing amount in the LCP increases, the processing in the LCP becomes a bottleneck in a large-scale system, and the amount that can be processed on the device side is limited by the processing capacity of the LCP, and there is a problem that the processing level is leveled off.

(Problems to be Solved by the Invention) As described above, in the conventional LAN system, when the system scale becomes large, a LAN interface mechanism (LC) for transmitting and receiving frames between the AAN and a device such as a computer.
There was a problem that the processing capacity in P) became a bottleneck, and it was not possible to increase the amount of communication processing per unit time on the device side.

The present invention has been made in view of the above circumstances, and an object thereof is to connect a plurality of LAN interface mechanisms to one device and distribute the load, thereby processing capacity of the entire LAN interface mechanism connected to one device. It is an object of the present invention to provide a LAN system which can improve the communication processing capacity of the device side to its own limit, without having to be conscious of using the LAN interface mechanism of the partner device.

[Configuration of the Invention] (Means for Solving the Problems) In a LAN system in which communication between a plurality of devices is performed via a LAN, at least one of the plurality of devices in the system includes: A plurality of LAN interface mechanisms (LCPs) to which unique LAN addresses are assigned are connected, and a load monitoring means for monitoring a load state of the plurality of LCPs on a device to which the plurality of LCPs are connected, and one of the LCPs. When a broadcast frame for an ARP request (to obtain the LAN address of the communication partner) is received and a response (ARP response) to the ARP request needs to be returned to the ARP request source, the load of the load monitoring means is increased. LC with light load based on monitoring results
Processing means (ARP processing means) for selecting P as a response source.

The present invention is further characterized in that a broadcast frame reception control means for giving permission to receive broadcast frames to one of the plurality of LCPs is further provided in a device to which the plurality of LCPs are connected.

(Operation) In the above configuration, a device to which a plurality of LCPs are connected, for example, the broadcast frame reception control means in the device B selects one of the plurality of LCPs and receives a broadcast frame. Give permission. Accordingly, when another device in the LAN system, for example, the device A transmits an ARP request for obtaining the LAN address from the Internet address of the device B on the LAN by a broadcast frame,
The ARP request is received only in one of the plurality of LCPs connected to the device B that is permitted to receive the broadcast frame. This received ARP request is passed to ARP processing means in device B.

The ARP processing means checks the monitoring result of the load monitoring means when the passed ARP request includes the Internet address of the own device B, and therefore, when the own device B must return a response to the ARP request (ARP response). From the plurality of LCPs connected to the own device B, select the LCP with the least load at that time as the ARP response source, and set the unique LAN address of the selected LCP to (the device B's Set in the ARP response (as a LAN address) and request the LCP to send the ARP response. As a result, the selected (requested) LC
P returns an ARP response to ARP requesting device A. Device A is ARP
Response from device B (LCP to ARP responder connected to)
Obtained LAN address, returned ARP response for communication with device B
Can be performed via LCP.

In the above state, in order for the other device C to communicate with the device B
When an ARP request is sent by a broadcast frame, the load of the LCP that returned the ARP response earlier has increased due to the frame transmission / reception with device A, so another LCP will be selected as the ARP response source in the future. You. As a result, the newly selected LCP
Performs frame transmission / reception with the device C, thereby achieving load distribution. In addition, the device that needs communication with the device B (the ARP requesting device) sends the same ARP request (broadcast frame for acquiring the LAN address of the communication partner) as in the past.
Simply send the LCP
Can be known as the LAN address of the partner device, and even if a plurality of LCPs are connected to the partner device, there is no need to be conscious of which LCP to use.

(Embodiment) FIG. 1 is a block diagram of a LAN system according to an embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a LAN of the CSMA / CD system, for example, a LAN conforming to IEEE802.3, and reference numeral 11 denotes a LAN cable serving as a communication medium of the LAN 10. 20 is an information processing device, 3
.., 30-n are located between the LAN 10 and the information processing apparatus 20.
This is an LCP (LAN control device) that manages frame reception from 11) and frame transmission to the LAN 10. Each LCP 30-1 to 30-n has a unique LAN address (compliant with IEEE802.3).
LAN address). This is information processing device 2
This is equivalent to assigning n LAN addresses to 0. The LCPs 30-1 to 30-n are connected to the information processing device 20 by buses 12-1 to 12-n, and LAN cables of the LAN 10 (via transceivers not shown) by transceiver cables 13-1 to 13-n. Connected to 11. LAN1
0 LAN cable 11 also includes m units of personal computers or workstations (hereinafter referred to as PC / W
40-m are connected via LCP (not shown). The PCs / WSs 40-1 to 40-m communicate with the information processing device 20 or mutually via the LAN 10.

The LCPs 30-1 to 30-n have broadcast frame reception permission flags (F) 31-1 to 31-n. The broadcast frame reception permission flag 31-i (i = 1 to n) indicates that the LCP 30-i
To allow (in the case of ON) / inhibit (in the case of OFF) the reception of the broadcast frame on the LAN cable 11 of the information processing apparatus 20 (the broadcast frame reception control unit 23 described later therein). Operated by

The information processing apparatus 20 includes an LCP 30-1 connected to the information processing apparatus 20.
LCP load monitoring unit 21 that measures the transmission / reception amount per unit time of ~ 30n, LCP 30-1 measured by LCP load monitoring unit 21
The load table 22, in which the transmission / reception amount of 30-n is held as the load amount of LCPs 30-1 to 30-n, selects one of LCPs 30-1 to 30-n (LCP30-i) for receiving broadcast frames. , The broadcast frame reception flag 31-i in the selected LCP 30-i
And a function block of an ARP processing unit 24. ARP processing unit 24
When the ARP request is received by the LCP 30-i permitted to receive the broadcast frame, the ARP request is processed. When the ARP request is requested, the request is transmitted using one of the LCPs 30-1 to 30-n. ARP response is returned.

FIG. 2 shows the processing (ARP processing) of the ARP processing unit 34 shown in FIG.
It is a flowchart for demonstrating a procedure.

 Next, the operation of the configuration shown in FIG. 1 will be described.

First, the broadcast frame reception control unit 13 in the information processing device 20
Is one of n LCPs 30-1 to 30-n, for example, LCP
30-1 is selected, and reception of a broadcast frame is permitted to this LCP 30-1. This is realized by turning on the broadcast frame reception permission flag 31-1 inside the LCP 30-1. In this embodiment, when the broadcast frame reception permission flag 31-i (i = 1 to n) is off, the
The LCP 30-i does not capture a broadcast frame on the LAN cable 11 of the LAN 10. On the other hand, the broadcast frame reception permission flag
When 31-i is on, the LCP 30-i takes in the broadcast frame on the LAN cable 11 and passes it to the information processing device 20. Therefore, in the above example where the broadcast frame reception permission flag 30-1 in the LCP 30-1 is selectively turned on, the LCP3
Only LCP30-1 of 0-1 to 30-n is LAN cable 1
Receive the broadcast frame on 1.

The reason why it is necessary to control the reception of the broadcast frame as described above is as follows. That is, if the broadcast frame reception is permitted for each of the LCPs 30-1 to 30-n, all the LCPs 30-1
30-n receive the same broadcast frame, and in the information processing device 20, extra processing such as confirming the identity of these broadcast frames and discarding other frames except for one. Is necessary.

If the LCP 30-1 in the broadcast frame receivable state due to the turning on of the broadcast frame reception permission flag 31-1 fails and the information processing device 20 detects that the LCP 30-1 has failed, the information processing device 20 The following control is performed. That is, the information processing device 20 first logically separates the failed LCP 30-1 from the service, and one of the remaining LCPs 30-2 to 30-n.
Select Next, the information processing apparatus 20 turns on the broadcast frame reception permission flag in the selected LCP, thereby continuing the broadcast frame reception processing.

On the other hand, the LCP load monitoring unit 21 in the information processing device 20 measures the amount of transmission / reception per unit time of each of the LCPs 30-1 to 30-n connected to the information processing device 20, and sets the measured amount in the load table 22. The contents of the load table 22 are updated at regular time intervals, and always have the latest transmission / reception amount, that is, LCPs 30-1 to 30-n.
Is managed so as to indicate the latest load state. Regarding the transmission / reception amount, the total amount or the number of transmission / reception may be appropriately selected from those which can be easily realized and have a small load.

Here, as described above, the ARP processing unit 24 in the information processing device 20 receives the ARP request while the broadcast frame reception control unit 23 and the LCP load monitoring unit 21 are operating in the information processing device 20. The process of selecting an appropriate LCP and returning an ARP response using the LCP (ARP process) will be described with reference to the flowchart of FIG.

Now, it is assumed that the PC / WS 40-1 needs to communicate with the information processing device 20. At this time, PC / WS40-1
The information processing device 20 (the LCP connected to it)
02.3LAN address is unknown. In this case PC / WS
As described in (Prior Art), 40-1 is based on the Internet address of the information processing apparatus 20 and the LAN of the information processing apparatus 20.
An ARP request for obtaining an address is transmitted to the LAN cable 11 of the LAN 10 by a broadcast frame. This LAN cable 1
The broadcast address is used as the destination address of the ARP request (ARP request frame) on 1 and the LAN address of the PC / WS 40-1 is used as the source address (source address).

The ARP request frame on the LAN cable 11 described above is LCP3
The broadcast frame reception is permitted (the reception permission flag is turned on) among the LCPs 30-1 from 0-1 to 30-n. Since the ARP request frame is a broadcast frame, it is also received on the PC / WS 40-2 to 40-m side. Since the Internet address included in the ARP request frame is the Internet address of the information processing device 20, the ARP request frame is discarded by devices other than the information processing device 20.

By the way, LCP30- which is permitted to receive broadcast frames
When receiving a broadcast frame from the PC / WS 40-1 on the LAN cable 11, the 1 transfers the frame (ARP request) to the information processing device 20 via the bus 12-1. If the broadcast frame transferred to the information processing device 20 is an ARP request as in the present embodiment, the ARP request is passed to the ARP processing unit 24 in the information processing device 20 (step S1).

Upon receiving the ARP request, the ARP processing unit 24 extracts the Internet address present in the ARP request, and checks whether the address matches its own Internet address (the Internet address of the information processing device 20) ( Step S2). If they do not match, the ARP processing unit 24 discards the received ARP request and waits for the next ARP request.

On the other hand, as in the present embodiment, when the Internet address in the received ARP request matches its own Internet address, the ARP processing unit 24 determines that it must return an ARP response, and thereafter, Proceed to step.

First, the ARP processing unit 24 checks the load table 22 that is periodically updated by the LCP load monitoring unit 21, and selects the LCP with the least load at that time from the LCPs 30-1 to 30-n as an ARP request response source. (Step S3). Here, LCP30
It is assumed that −n is selected.

When selecting the LCP 30-n as the ARP request response source, the ARP processing unit 24 sets the LAN address of the LCP 30-n to (the information processing device).
An ARP response with the destination address being the LAN address of the PC / WS 40-1, which is the source address of the received ARP request, is created (step S4).

ARP processing unit 24 should return A to PC / WS40-1 (RRP request source)
When the RP response is created, the LCP 30-n selected in step S3 is requested via the bus 12-n to transmit the ARP response on the LAN cable 11 (step S5). Thus, a series of ARP processing for the ARP request in the ARP processing unit 24 ends.

The LCP 30-n receiving the request from the ARP processing unit 24 transmits the ARP response (ARP response frame) created by the ARP processing unit 24 to the LAN.
Send out on cable 11. This ARP response is received by the PC / WS 40-1 of the ARP request source specified by the destination address.

The PC / WS 40-1 determines the I / O address of the information processing device 20 (the LCP 30-n connected to the information processing device 20) from the source address of the received ARP response.
By obtaining the EEE802.3 LAN address and using this LAN address as the destination address, TCP / IP communication with the information processing device 20 is started. At this time, PC / WS40-1
Is received by the LCP 30-n to which the LAN address indicated by the destination address in the frame is assigned and passed to the information processing device 20. For this reason, PC / WS4
0-1 can communicate with the information processing device 20 without being aware of the LCP 30-n.

As described above, when communication between the PC / WS 40-1 and the information processing apparatus 20 is performed via the LCP 30-n, the load on the LCP 30-n increases. In this state, when, for example, the PC / WS 40-2 among the PCs / WSs 40-2 to 40-m attempts to communicate with the information processing device 20 and sends out an ARP request by a broadcast frame, By the ARP processing of the ARP processing unit 24,
This time, LCPs other than LCP30-n are selected as ARP response sources. Then, the ARP response is sent from the selected LCP to the ARP request source (P
Returned to C / WS40-2). As a result, PC / WS40-2
Communication with the information processing device 20 can be performed via the newly selected LCP (and without any awareness of the LCP). Similarly, m PCs / WS40-1 to 40
In the case where −m intends to communicate with the information processing device 20 almost in parallel, a unique LAN address of the LCP is sent to each PC / WS 40-1 to 40−m from a different LCP. A
Returned in the RP response (when the number of LCPs is larger than the number of PCs / WSs). Therefore, each of the PCs / WSs 40-1 to 40-m can communicate with the information processing device 20 almost in parallel via different LCPs, and as a result, the load of the LCP is distributed.

In the above-described embodiment, the case where the present invention is applied to a LAN system compliant with IEEE802.3 has been described.However, the present invention can transmit and receive broadcast frames, and transmits broadcast frames in order to know the LAN address of a transmission destination. It can be applied to all LAN systems that send data.

Further, in the above-described embodiment, the case has been described in which one information processing device (20) is connected to a plurality of LCPs (LAN control devices). However, the present invention is also applicable to a system provided with a plurality of information processing devices having the same configuration. It is possible. PC / WS (personal computer or workstation) also has multiple LS
It is also possible to connect P. However, multiple LSPs are used for devices that rarely communicate in parallel with many devices.
It is useless to connect.

[Effect of the Invention] As described above in detail, according to the present invention, in a LAN system in which communication between a plurality of devices is performed via a LAN, a unique LAN address is assigned to at least one of the plurality of devices. By connecting a plurality of LAN interface mechanisms that can be connected, communication between the connected device (called a specific device) and the plurality of devices can be performed in parallel through the plurality of LAN interface mechanisms. Regardless of the processing capacity and buffer capacity of the LAN interface mechanism, the communication processing capacity can be improved to the limit of the performance of the specific device itself. In addition, the side that communicates with the specific device only needs to be aware of the partner device (specific device) in the same manner as in the related art, without being aware of which LAN interface mechanism to communicate with. Further, even if the LAN interface mechanism fails, processing can be continued by another LAN interface mechanism, so that reliability is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a LAN system according to an embodiment of the present invention, and FIG. 2 is a flowchart for explaining a processing procedure of the ARP processing unit 24 shown in FIG. 10 ... LAN, 11 ... LAN cable, 12-1 to 12-n ... Bus, 13
-1 to 13-n: transceiver cable, 20: information processing device, 21: LCP load monitoring unit, 22: load table, 23: broadcast frame reception control unit, 24: ARP processing unit, 30-1 to 30-n
... LCP (LAN controller, LAN interface mechanism), 31-
1-31-n Broadcast frame reception permission flag (F), 40-
1 to 40-m ... PC / WS.

Claims (2)

(57) [Claims] In a LAN system in which communication between a plurality of devices is performed via a LAN (Local Area Network), at least one of the plurality of devices transmits and receives a frame between the device and the LAN. To do
Load monitoring means for connecting a plurality of LAN interface units to each of which a unique LAN address is assigned, and monitoring the load status of the plurality of LAN interface units on the device to which the plurality of LAN interface units are connected; When a broadcast frame for acquiring the LAN address of the communication partner is received by the mechanism and a response to the frame needs to be returned to the broadcast frame transmission source, the load is monitored based on the load monitoring result of the load monitoring means. And a processing means for selecting a light LAN interface mechanism as a response source, and performing load distribution by connecting a plurality of LAN interface mechanisms to one device. 2. A broadcast frame reception control means for permitting broadcast frame reception to only one of said plurality of LAN interface mechanisms is further provided in said equipment to which said plurality of LAN interface mechanisms are connected. 2. The LAN system according to claim 1, wherein the broadcast frame is received only by the LAN interface mechanism permitted by the reception control means.