JPH04167841A - Lan system - Google Patents

Abstract

PURPOSE:To improve the communication processing capability of an equipment side up to its own limit by connecting plural LAN interface devices to one device so as to decentralize a load. CONSTITUTION:An ARP request received by a LAN controller LCP30-1 in which the reception of a multiple address frame is allowed is given to an ARP processing section 24. The processing section 24 checks whether or not an inter- net address in an ARP request is coincident with its own address. When dissident, the ARP request is aborted. On the other hand, when coincident, a load table 22 is referenced and the LCP with a least load is selected as an ARP request reply source among LCP30-1-30-n (e.g. LCP30-n). The processing section 24 generates the ARP reply taking the LAN address of the LCP 30-n as a sender address. A reply of sending the generated ARP reply to a LAN cable 11 is requested to the LCP30-n via a bus 12-n.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to a LAN system in which communication between a plurality of devices is carried out via a LAN.
The present invention relates to a distributed control system in which an AN control device (LCP) is provided to perform distributed control of transmission and reception.

(Prior art) Generally, CS SMA/CD (Carrier
SenseMultiple Access / Co
In a LAN system that applies the 11Ision Detection) method, for example, a LAN system compliant with IEEE (Institute of Electrical and Electronics Engineers) 802.3, the LAN
A unique LAN address (an address consisting of 6 bytes) is assigned to each device such as computers that communicate with each other via the LAN.

By specifying this LAN address as the destination address and sending the frame onto the LAN, the source device can transmit the frame to the intended destination device (destination).

The LAN address can be stored in advance in a database within the device, or by using TCP/IP (Trans
Mission Control Protocol
/InternetProtocol) ARP
(Address Re5solutionProtoc
This is determined by a protocol called ol). Usually, ARP is used in consideration of versatility.

An outline of ARP is described below.

First, ARP is an address for identifying a device on TCP/IP (called an Internet address).
AN7 dress (LAN compliant with IEE E802.3)
This is a protocol for determining the address. Assume here that device A wants to communicate with another device B via LAN. This communication requires that device A knows the inknet address of device B. This Internet address may be stored in a file (database) within device B, or may be notified by a name server, which is one of the applications on the network.

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

■Device A is an AR that has the Internet address of device B.
The P request is transmitted on the LAN as a broadcast frame (a frame with a broadcast address addressed to all devices on the LAN). This ARP request (ARP request frame) includes the LAN address of device A as the source address (source LAN
address).

(2) All devices on the LAN receive this ARP request.

(2) Among the devices that have made the ARPARP request, any device other than device B whose Internet address included in the ARP request is different from its own Internet address discards this ARP request.

(2) On the other hand, a device whose inknet address included in the ARP request matches its own Internet address, that is, device B, returns a response to this ARP request (referred to as an ARP response) to device A. This ARP response is the received ARP response.
Since the message is sent by specifying the LAN address of the source device A that is set in the RP request, it is received only by device A and is not received by other devices.

■When device A receives an ARP response, it uses the source LAN address set in the response to connect device B's LAN.
Can you get the address?

■As a result, device A will transmit to device B from now on using the AR
This is done using the LAN address obtained from the ARP response to the P request.

By the way, each device that communicates with each other via LAN and L
A LAN interface mechanism is provided between each device and the AN to connect the device to the LAN. This LA, N interface mechanism is a LAN control device (
LAN Control Processor). The LAN control device (hereinafter referred to as LCP) has a transmission function that sends frames on the LAN in response to requests from corresponding devices, monitors frames flowing on the LAN, and sends its own LAN address (or broadcast address). It has a receiving function that only captures frames that have

In recent years, the 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 other hand, the amount of processing in LCP increases, so in large-scale systems, processing in LCP becomes a bottleneck, and there is a problem in that the amount that can be processed on the equipment side is limited by the processing capacity of LCP and reaches a plateau.

(Problem to be solved by the invention) As mentioned above, in conventional LAN systems, as the system scale increases, processing at the LAN interface mechanism (LCP), which is located between the LAN and devices such as computers and handles frame transmission and reception, becomes more difficult. There was a problem in that capacity became a bottleneck and it was not possible to increase the amount of communication processing per unit time on the device side.

This invention was made in view of the above circumstances, and its purpose is to increase the processing capacity of the entire LAN interface mechanism connected to one device by connecting multiple LAN interface mechanisms to one device and distributing the load. To provide a LAN system in which the communication processing ability of a device side is increased to its own limit by improving the communication processing capability of the device side, and furthermore, the other device does not need to be aware of which LAN interface mechanism is to be used.

[Structure of the Invention] A LAN interface mechanism (L) in which a unique LAN address is assigned to at least one of a plurality of devices in the LAN system implemented as
In addition to connecting a plurality of LCPs, a device to which the plurality of LCPs are connected is equipped with a load monitoring means for monitoring the load status of the plurality of LCPs, and a load monitoring means for monitoring the load status of the plurality of LCPs, and a load monitoring means for monitoring the load status of the plurality of LCPs, and a load monitoring means for monitoring the load status of the plurality of LCPs.
A broadcast frame (to obtain the LAN address of the communication partner) is received, and a response to the ARP request (ARP
The present invention is characterized by being provided with processing means (ARP processing means) for selecting an LCP with a light load as a response source based on the load monitoring result of the load monitoring means when it is necessary to return a response (response) to the ARP request source. It is something to do.

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

(Function) In the above configuration, the broadcast frame reception control means in a device to which multiple LCPs are connected, for example device B, selects one of the multiple LCPs and receives the broadcast frame. grant permission. As a result, when another device in the LAN system, for example, device A, sends an ARP request on the LAN to obtain a LAN address from the Internet address of device B, the device B
is the only LCP that is permitted to receive broadcast frames among the multiple LCPs connected to device B.
ARP requests are received only at This received ARP
The request is passed to ARP processing means within device B.

The ARP processing means monitors the load monitoring means when the inknet address of self-device B is included in the passed ARP request, and therefore when self-device B must return a response (ARP response) to the ARP request. Based on the results, select one of the multiple LCPs connected to device B.
Select the LCP with the least load at that time as the ARP response source, set the LAN address specific to the selected LCP in the ARP response (as the LAN address of device B), and send the ARP response to the same LCP. Make a request. As a result, the selected (requested) LCP returns an ARP response to device A that made the ARP request. Device A responds to ARP while device B (the ARP response source LCP connected to)
LAN address of device B can be obtained, and communication with device B can be performed via the LCP that returned the ARP response.

In the above state, when an ARP request is sent using a broadcast frame to communicate with another device C7<i device B, the AR
Since the load on the LCP that returned the P response is large due to frame transmission and reception with device A, another LCP
selected as the ARP response source. As a result, the newly selected LCP will transmit and receive frames to and from device C, thereby achieving load distribution. However, the device that needs to communicate with device B (the ARP requesting device) simply sends the same ARP request (broadcast frame to obtain the LAN address of the communication partner) as before, and performs no transmission/reception. The LAN address of the LCP on the destination device side, which is the object of the communication, can be known as the LAN address of the destination device, and even if a plurality of LCPs are connected to the destination device, there is no need to be equally 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 the same figure, 10 is C8MA/
CD-based LAN, such as IEE 802.3
A LAN 11 is a LAN cable that serves as a communication medium for the LAN 10. 20 is an information processing device, 3
0-1.3O-2-30-n is located between the LAN 10 and the information processing device 20, and receives frames from the LAN10 (LAN cable 11) for the information processing device 20 and sends them to the LAN 10. LCP controls the frame transmission of
(LAN control device). L CP 30-1~3
0-n each have a unique LAN address (IEEE
802.3 compliant LAN address) is assigned. This is equivalent to allocating n LAN addresses to the information processing device 20.

L CP 3O-1-30-n is bus 12-L~12-
It is connected to the information processing device 20 by transceiver cables 13-1 to 13-n (via transceivers not shown) to the LAN cable 11 of LANIO. The LAN cable 11 of the LAN 10 also has m devices (hereinafter referred to as PC/WS) such as personal computers or workstations 40-1, 40-2-40-m connected to the LCP (
(not shown). P C / W S
40-1 to 40-m communicate with the information processing device 20,
Alternatively, they communicate with each other 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 3l-i (i=1 to n) allows (if turned on)/prohibits (if turned off) the LCP 30-1 to receive broadcast frames on the LAN cable 11 of the LAN 10. ), and the information processing device 20 (the broadcast frame reception control unit 23 described later)
operated by.

The information processing device 20 has an LCP connected to the information processing device 20.
Total amount of transmission and reception per unit time of 30-1 to 30n -1
2 = LCP load monitoring unit 21 to measure, transmission/reception amount of LCP 30-1 to 30-n measured by LCP load monitoring unit 21 Load table held as the load amount of LCP 30-1 to 30-n 22, L CP 30-1-30
-n1-) (Broadcast frame reception control unit 23 that selects the LCP 30-D for broadcast frame reception and turns on the broadcast frame reception permission flag 31-j in the selected LCP 30-i. , and an ARP processing unit 24.The ARP processing unit 24 processes the ARP request when the ARP request is received by the LCP 30-j that is permitted to receive broadcast frames. , when it is the request destination, returns an ARP response to the request source using one of the LCPs 30-1 to 30-n.

FIG. 2 shows the processing (ARP
2 is a flowchart for explaining the processing procedure.

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

First, the broadcast frame reception control unit 23 in the information processing device 20
selects one of the n LCPs 30-1 to 30-n, for example, LCP 30-1, and selects this LCP 3
0-1 is permitted to receive broadcast frames. This is achieved by turning on the broadcast frame reception permission flag 31-1 inside the LCP 30-1. In this embodiment, the broadcast frame reception permission flag 31-j
(i = 1~n) is off, the corresponding L
CP 30-i is LAN cable 1 of LAN 10
Do not import broadcast frames on 1. On the other hand, when the broadcast frame reception permission flag 31-1 is on, L
The CP 30 - 1 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 31-1 in the LCP 80-1 is selectively turned on, the LCP
Only LCP 30-1 among 30-1-30-n receives the broadcast frame on LAN cable 11.

The reason why control over broadcast frame reception as described above is necessary is as follows. That is, each LCP30-1 to 30-
If n is allowed to receive broadcast frames, all LC
P 30-1 to 30-n receive the same broadcast frame, and the information processing device 20 checks the identity of these broadcast frames and discards all but one frame. This is because extra processing is required.

Note that if the LCP 30-1, which has entered the broadcast frame reception enabled state by turning on the broadcast frame reception permission flag 31-1, fails and the information processing device 20 detects this, the information processing device 20 Performs the following controls. That is, the information processing device 20 first logically separates the failed LCP 30 from the service, and then disconnects the remaining LCP 30-2 to 30-3.
Select 1-) LCP from 0-n. Next, the information processing device 20 attempts to continue the broadcast frame reception process by turning on the broadcast frame reception permission flag in the selected LCP.

On the other hand, LCP load monitoring 21 in the information processing device 20
Each LCP 30-1~ connected to the information processing device 20
30-n total amount of transmission and reception per unit time) IIJ L,
Set in the load table 22. The contents of this load table 22 are updated at regular time intervals and managed so as to always indicate the latest transmission/reception amount, that is, the latest load status of the L CPs 30-1 to 30-n. Note that the amount of transmission and reception may be appropriately selected, whether it is the total amount of transmission or reception, or the number of times, which can be easily realized and requires less load.

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

It is now assumed that the need arises for the PC/WS 40-1 to communicate with the information processing device 20. At this time, the PC/WS 40-1 has the IEE E802.3 of the information processing device 20 (the LCP connected to it).
Assume that the LAN address is unknown. In this case, PC/
As mentioned in the (Prior Art) section, the WS 40-1 sends an ARP request for obtaining the LAN address of the information processing device 20 from the Internet address of the information processing device 20 to the LAN cable of the LAN 1O using a broadcast frame. 11
Send to. ARP request on this LAN cable 11 (
A broadcast address is used as the destination address (ARP request frame), and p is used as the source address (source address).
The LAN address of C/W 840-1 is used.

The ARP request frame on the LAN cable II described above is received by the LCP 30-1 among the LCPs 30-1 to 30-n, which is permitted to receive broadcast frames (the reception permission flag is turned on). Also, the above ARP
Since the request frame is a broadcast frame, the P C/W
It is also received on the S 40-2 to 40-m sides.

Since the Internet address included in this ARP request frame is the Internet address of the information processing device 20, this ARP request frame is discarded by devices other than the information processing device 20.

Now, LCPs that are permitted to receive broadcast frames
30-1 is the PC/WS40- on the LAN cable 11
When a broadcast frame from AR 1 is received, the same frame (AR
P request) is transferred 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 this embodiment, the ARP request is passed to the ARP processing unit 24 in the information processing device 20 (step Sl).

When the ARP processing unit 24 receives an ARP request, it extracts the Internet address present in the ARP request, and sets the address to its own Internet address (the information processing device 2
0 (inknet address)) (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 this embodiment, if the inknet address in the received ARP request matches its own Internet address, the ARP processing unit 24 determines that it must return an ARP response, Proceed to the next step.

First, the ARP processing unit 24 examines the load table 22 that has been updated 21st period for LCP load monitoring, and determines the LCP 30
From -1 to 30-■, the LCP with the least load at that time is selected as the ARP request response source (step S3). Here, it is assumed that L CP 30-n is selected.

When the ARP processing unit 24 selects the LCP 30-n as the ARP request response source, the ARP processing unit 24 selects the LA of the LCP 30-n.
N address is the source address (of the information processing device 20), and P C is the source address of the received ARP request.
An ARP response is created with the LAN address of /WS 40-1 as the destination address (step S4).

After creating an ARP response to be returned to the PC/WS 40-1 (ARP request source), the ARP processing unit 24 sends a bus to the LCP 30-n selected in step S3 so as to transmit the ARP response onto the LAN cable 11. 12-n (step S5). As a result, the series of ARP processing for the ARP request in the ARP processing unit 24 ends.

Upon receiving the request from the ARP processing unit 24, the LCP 30-n sends the ARP response (ARP response frame) created by the ARP processing unit 24 onto the LAN cable 11. This ARP response is the ARP specified by its destination address.
It is received by the requesting PC/WS 40-1.

The PC/WS 40-1 determines the IEE E802.3 of the information processing device 20 (the LCP 3O-n connected to it) from the source address of the received ARP response.
By obtaining a LAN address and using this LAN address as the destination address, TCP/
Start IP communication. At this time, P.C.
The transmission frame from the /WS 40-1 is received by the LCP 30-n to which the LAN address indicated by the destination address in the frame is assigned, and is passed to the information processing device 20. Therefore, P'C/WS 40-1
is the information processing device 2 without being aware of L CP 30-n.
Can communicate with 0.

In this way, when communication between the PC/WS 40-1 and the information processing device 20 is performed via the LCP 30-n, the load on the L and CF2O-n increases. In this state, when one of the PC/WS 40-2 to 40-m, for example, PC/WS 40-2, attempts to communicate with the information processing device 20 and sends out an ARP request using a broadcast frame, the information processing device Due to the ARP processing of the ARP processing unit 24 in 20, LCPs other than LCP 30-n are now
Selected as the RP response source. And the selected LC
ARP response from P or ARP request source (P C/W S 4
O-2). As a result, the PC/WS 40-2 uses the newly selected L to communicate with the information processing device 20.
This can be done via the CP (and without any awareness of the LCP). Similarly, m PCs/
When the W S 40-1 to 40-m attempt to communicate with the information processing device 20 almost in parallel, each P
A LAN address unique to each LCP is returned to the C/WSs 40-1 to 40-m in an ARP response from a different LCP (if the number of LCPs is greater than the number of PCs/WSs). For this reason, each PC/WS 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 on the LCPs is distributed.

In addition, in the above embodiment, IEE 802.11
The present invention is capable of transmitting and receiving broadcast frames.
It can be applied to all LAN systems that send broadcast frames to know the LAN address of a communication partner.

= 21- Also, in the above embodiment, the information processing device (20) to which a plurality of LCPs (L to N control devices) is connected
Although a case has been described in which there is one information processing apparatus, the present invention is also applicable to a system in which a plurality of information processing apparatuses having a similar configuration are provided.

Furthermore, it is also possible to connect a plurality of LSPs to a PC/WS (personal computer or workstation). However, it is wasteful to connect multiple LSPs to devices that rarely communicate in parallel with a large number of devices.

[Effects of the Invention] As detailed above, 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 multiple LAN interface mechanisms such as L
Regardless of the processing capacity and buffer capacity of the AN interface mechanism, the communication processing capacity can be improved up to the performance limit of the specific device itself. Moreover, the side communicating with the specific device need not be equally aware of which LAN interface mechanism to communicate through, but only need to be aware of the other device (specific device) as in the past. Also, even if the LAN interface mechanism fails, other LAN
Reliability is improved because the interface mechanism allows processing to continue.

[Brief explanation of drawings]

FIG. 1 is a LAN system chart according to an embodiment of the present invention. 10...LAN, 11...LAN cable, 12-1
~12-n...Bus, 13-1~13-n...Transceiver cable, 20...Information processing device, 21...
・LCP load monitoring unit, 22...Load table, 23.
... Broadcast frame reception control unit, 21 = ARP processing unit, 30-1. -3O-n-L CP (L A N11
I control device, LAN interface mechanism), 31-1
~31-n...Broadcast frame reception permission flag (F)
, 40-1-40-m-P C/WS 0 Applicant's agent Patent attorney Takehiko Suzue

Claims (2)

[Claims] (1) In a LAN system in which communication between multiple devices is performed via a LAN (Local Area Network), at least one of the multiple devices is located between that device and the LAN to transmit and receive frames. load monitoring means for connecting a plurality of LAN interface mechanisms to which unique LAN addresses are assigned, and monitoring the load status of the plurality of LAN interface mechanisms to the device to which the plurality of LAN interface mechanisms are connected; When the LAN interface mechanism receives a broadcast frame for acquiring the LAN address of a communication partner and it is necessary to return a response to the frame to the broadcast frame sender, the load monitoring result of the load monitoring means is also transmitted. A LAN system comprising: a processing means for selecting a LAN interface mechanism with a light load as a response source, and a plurality of LAN interface mechanisms are connected to one device to perform load distribution. (2) The device to which the plurality of LAN interface mechanisms are connected is further provided with a broadcast frame reception control means that permits only one of the plurality of LAN interface mechanisms to receive the broadcast frame; 2. The LAN system according to claim 1, wherein only the LAN interface mechanism permitted by the reception control means receives the broadcast frame.