JPS61287349A - Address duplication detecting system - Google Patents

Abstract

PURPOSE:To ensure the detection by exchanging an ID exchange command and an ID exchange response between plural devices so as to detect the duplication of address. CONSTITUTION:A network system communicating equally with optional opposite party between plural equipments is provided with a means 4 sending an ID exchange command XID command addressed to the own equipment included in the data part of a random number NR, a timer means 11 to supervise an ID exchange response and the XID response from an opposite equipment at the transmission of the XID command and a means 6 receiving and analyzing the XID command. Further, the means 4 receiving the XID response and sending the XID command to a sender equipment, a means 7 receiving the XID response and analyzing it, a means 8 comparing the random number of the received XID response with the random number NR added to the sending XID command and a counter means 12 counting the retransmission number of times of the XID command are provided. Then the duplication of address is detected by exchanging the XID command and the XID response for plural number of times.

Description

[Detailed Description of the Invention] [Summary] In a network system in which multiple devices communicate equally with arbitrary parties, address duplication is avoided by exchanging ID exchange commands (XID commands) and ID exchange responses (XID responses). The configuration to be detected is shown.

[Industrial application field]

The present invention relates to a system in which arbitrary devices belonging to one network communicate on an equal basis, and particularly relates to an address duplication detection method in such a system. An example of a target system is CSMA/C
D (Carrier 5ence Multiple
Access with Co11sion Dete
LAN (Location) method, token method, etc.
cal Area Network).

[Problems to be solved by the prior art and the invention] In a network system in which multiple devices communicate equally with any other party using a shared transmission path, the address of the device joining the network is unique within the system. Uniquely determined.

When device A transmits a frame as shown in FIG. 2 to device B, it sends the frame with the address of device B as the destination address and the address of device A as the source address. However, when transmitting one frame to multiple devices, a group address separately defined for each duplicate device can also be used as the destination address. However, it is always necessary to use a system-intentionally defined device address as the source address.

If two or more devices with the same address exist in the system, normal communication cannot be guaranteed.

Such device address duplication may occur due to a device address setting error. Particularly in an environment such as a LAN where devices can be easily connected and systems are not centrally managed, this can easily occur, so some kind of prevention or detection means is required.

As methods for detecting address duplication, there are conventional methods that utilize the characteristics of access methods such as the token ring method, and methods that do not depend on the access method.

This method is related to a method that does not depend on the access method. The conventionally considered method will be explained below with reference to FIG. Device A sends an ID exchange command (X
ID command). This method has the premise that the XID command sent by the own device can be received. Therefore, device A receives the XID command sent by itself and responds with an ID exchange response (XI
D response) is sent back. Therefore, device A receives one XID response to the transmitted XID command. If there is a device A' with the same device address "a" as device A as shown in FIG.
The XID command sent by device A is received, and an XID response is sent to device A. In this case, device A is
Two XID responses will be received. After transmitting the XID command, device A counts the number of times the XID response is received, and if the number is 2 or more, it can issue i+ address duplication.

As mentioned earlier, this method is based on the premise that it can receive the XID command sent by its own device, so it is difficult for devices that do not have separate buffers or CRC circuits for sending and receiving. The drawback is that it cannot be applied.

[Means for solving problems]

The present invention provides a means for transmitting an ID exchange command (hereinafter referred to as an XID command) addressed to the device itself, which includes a random number in the data section, in a network system in which a plurality of devices communicate equally with any other party; When sending an XID command, an ID exchange response (hereinafter referred to as
a timer means for monitoring the XID response (referred to as an and a means for comparing the random number of the received XID response with a random number added to the transmitted XID command, and a counter means for counting the number of times the XID command is retransmitted. This system detects address duplication by exchanging multiple times.

〔Example〕

FIG. 1 is a diagram showing the device configuration of one embodiment of the present invention, FIG. 4 is a diagram showing an operation example of the embodiment (in the case of no duplicate addresses), and FIG. 5 is a diagram showing another operation example of the embodiment (no duplicate addresses). FIG. 6 is a diagram showing an example of the frame format of the XID command, and FIG. 7 is a diagram showing an example of the frame format of the XID response.

In FIG. 1, 1 is a transmission control section, 2 is a data processing section,
3 is a transmission path, 4 is a transmission section, 5 is a reception section, 6 is an XID command analysis section, 7 is an XID response analysis section, 8 is a random number comparison section, 9 is an XID response creation section, 10 is an XI
11 is a timer, 12 is a retransmission counter, and 13 is a random number generator.

The operation of the embodiment of the present invention will be explained below.

First, the operation of this system will be explained using FIG.

In FIG. 4, device A transmits an XID command addressed to itself (DA="a") in order to check for address duplication. FIG. 6 shows an example of the frame format of the XID command used in the present invention.

Assume that the random number in the data part is sent with ra appended to it. If device A is a device capable of independent transmission and reception, device A receives the XID command sent by itself and returns the XID response shown in FIG. 7 to the sender (in this case, its own device). .

In this case, since device A is in the XID response waiting state (timer is running), the R bit is set to “1” (XID
This means that the message was received while waiting for a response. ), the random number is set to the same value ra as the random number added to the transmitted XID command, and an XID response is transmitted.

When device A receives this XID response, since R in the data part is “1”, the random number (ra)
and the random number attached to the previously sent XID command (
ra). In this case, since they both match in ra, the XID response is discarded, and the XID response is further monitored without stopping the timer. Thereafter, when the timer expires, the XID command is retransmitted. Increase the number of retransmissions of the XID command by 1. In this way, when the number of retransmissions exceeds a specified value, it is assumed that there is no other device with the same address as device A, and the retransmission of the XID command is terminated.

If device A is a device that cannot operate independently for transmission and reception, device A
Since the device cannot receive the XID command sent by its own device, the timer ends without receiving the XID response. In this case as well, after repeating the retransmission of the XID command a specified number of times, it is assumed that no duplicate address exists, and the retransmission of the XID command is terminated.

Now, in FIG. 5, consider the case where there is a device A' having the same address "a" as device A.

In this case, when device W' receives the XID command sent by device A, it sets the R bit to o'' (meaning that it was received without waiting for an XID response) and sets the
Send ID response. When device A receives this XID response, since the R bit of the data field is "O", it detects address duplication.

Next, consider a case where device A and device A' having the same address "a" transmit XID commands at the same time. In this case, both devices A and A' receive an XID response from the other device whose R bit is 1''.The random number in the received XID response is the same as the random number added to the XID command sent by the own device before that. If they are different, it can be recognized as an XID response sent by another device, and address duplication can be detected.If devices A and A' are both sending XID commands with the same random number, the received
Since it matches the random number of the ID response, it is not regular with the XID response sent by the own device and is discarded. In this case, the timer expires and both devices retransmit the XID command as described above. Since the random number of the XID command is newly determined for each retransmission, devices A and A' can be expected to transmit XID commands with different random numbers attached by the predetermined number of retransmissions.

As described above, according to the method of the present invention, address duplication can be reliably detected.

〔Effect of the invention〕

According to the present invention, it is possible to provide a method that can reliably detect address duplication in all devices having duplicate addresses.

Further, according to the present device, it is possible to provide an address duplication detection method that does not depend on the access method.

Furthermore, according to the present invention, it is possible to provide an address duplication detection method that can be applied to devices that cannot transmit and receive signals independently.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the device configuration of one embodiment of the present invention, Fig. 2 is a diagram showing an example of a frame format, Fig. 3 is a diagram showing an example of address duplication detection using the conventional method, and Fig. 4 is a diagram showing the present invention. An example of the operation of the invention (with no duplicate addresses)
Figure 5 is an example of the operation of the present invention (when there are duplicate addresses).
FIG. 6 is a diagram showing an example of the frame format of the XID command, and FIG. 7 is a diagram showing an example of the frame format of the XID response. In FIG. 1, 1 is a transmission control section, 2 is a data processing section,
3 is a transmission path, 4 is a transmission section, 5 is a reception section, 6 is an XID command analysis section, 7 is an XID response analysis section, 8 is a random number comparison section, 9 is an XID response creation section, 10 is an XI
11 is a timer, 12 is a retransmission counter, and 13 is a random number generator. Figure 3D: Star Dove Limiter DA: Address here address (DA = "b" is 'ai5 exemption Q frame) SA: Oshikamaru address <sA-"α"
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: 2〉Tochiri Miku frame format summary 11 block 2 Figure thorny direction 2' address urn tribe masubaho 1 beggar 3 required (Q): 10 command nlH arrow missing F1 meeting (b)X
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Claims (1)

[Scope of Claims] In a network system in which a plurality of devices communicate equally with arbitrary parties, there is provided a means for transmitting an ID exchange command (hereinafter referred to as an XID command) addressed to the device itself that includes a random number in the data part
10), timer means (11) for monitoring an ID exchange response (hereinafter referred to as an XID response) from the other device when transmitting the XID command, and means (6) for receiving and analyzing the XID command. , means (9) for transmitting the XID response to the source device of the received XID command, means (7) for receiving and analyzing the XID response, a random number of the received XID response, and a received XID
It is equipped with a means (8) for comparing the random number attached to the command, and a counter means (12) for counting the number of times the XID command is retransmitted, and when receiving the XID command, it is determined whether or not the XID response is being waited for. If the information is received while waiting for the above XID response, the previously received XI
If an XID response is received whose data field contains the same random number as the random number added to the data field of the D command, and the XID response is received while the timer is operating after receiving the XID command, the information in the data field is If it indicates that the response was not received while waiting for a response, it is assumed that the response is from another device that has the same address as the own device, address duplication is detected, and it is determined that the response was received while waiting for an XID response. If the received XID response random number is compared with the random number added to the transmitted XID command, and if they match, the XID response is discarded and the XID response is continued.
The ID response is monitored, and if there is a mismatch, it is assumed that the response is from another device with the same address as the own device, and address duplication is detected. When the timer means expires, a new random number is issued again. an address duplication detection method, characterized in that the address duplication detection method is configured to transmit an XID command having a value of .