Error detection/correction and fault detection/recovery – Data processing system error or fault handling – Reliability and availability
Reexamination Certificate
1998-06-18
2001-07-10
Le, Dieu-Minh T. (Department: 2184)
Error detection/correction and fault detection/recovery
Data processing system error or fault handling
Reliability and availability
C370S242000, C370S389000
Reexamination Certificate
active
06260161
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to a troubleshooting method and a communication system by which a communication trouble such as mistranslation of data can be detected and a trouble factor can be specified, in a loop-structure network.
2. Prior Art
There is a conventionally known troubleshooting system for a communication apparatus in a loop structure network, as disclosed in Open-laid Japanese Patent Application KOKAI Publication No. 63-246946.
In the troubleshooting system, a monitor communication apparatus sets a monitor indicator in a data frame, and another communication apparatus which receives the data frame resets the monitor indicator when transmitting the data frame. Therefore, in case where the monitor communication apparatus receives a monitor indicator already set, it means that an abnormal data frame which has not been received by any communication apparatus has occurred.
Accordingly, when such an abnormal data frame is detected, the monitor communication apparatus detects the address of the sender or receiver of the abnormal data frame. As a result of this, the communication apparatus which causes the trouble can be specified.
However, in such a troubleshooting system for a communication apparatus in a conventional loop structure network, for example, when a monitor indicator which should have been set and transmitted is reset and transmitted by a trouble in a monitor communication apparatus, even a data frame transmitted from a communication apparatus causing a trouble has a reset monitor display, and therefore, there is a problem that detection of a communication apparatus causing a trouble is impossible.
In addition, in a monitor communication apparatus, the communication apparatus causing a trouble is detected by receiving a data frame having a monitor indicator set as above. As a result of this, there is a problem that it is impossible to detect the communication apparatus causing a trouble in case where a monitor indicator is reluctantly reset and transmitted, even though a trouble is caused in the communication apparatus.
Also, in a monitor communication apparatus, the communication apparatus causing a trouble is detected by receiving a data frame having a set monitor indicator. Therefore, there is a problem that a communication apparatus is erroneously detected as causing a trouble if a monitor indicator reluctantly is set and transmitted even though the communication apparatus does not cause a trouble.
Further, the communication apparatus causing a trouble is specified by detecting the address of a sender or receiver of an abnormal data frame. Therefore, there is a problem that the communication apparatus causing a trouble cannot be correctly detected if the source address or receiver address itself is incorrect.
SUMMARY OF THE INVENTION
The present invention has been made in view of the problem described above, and has an object of providing a troubleshooting method and a communication system in which a communication apparatus that has caused a trouble and a trouble factor thereof can be correctly specified and detected.
In order to achieve the above object, there is provided a troubleshooting method for each of communication apparatuses constituting a loop structure network, comprising the steps of: generating a monitor data including at least a source address, a destination address, and an additional data while changing the additional data so as not to sequentially generate same two monitor data by each of the communication apparatuses; attaching the monitor data to data body to form and transmit a data frame by each of the communication apparatuses; comparing two monitor data with each other attached to a new data frame and a data frame received in a preceding time every time the new data frame is received, by each of the communication apparatuses; and perceiving occurrence of a trouble, when a comparison result indicating coincidence between the two monitor data is detected, by each of the communication apparatuses.
According to a preferred embodiment of the present invention, upon sequentially transmitting plural data frames to one destination address, each of the communication apparatuses generates plural monitor data having plural additional data which are different from each other and transmits each of the plural monitor data together with the data body.
According to a preferred embodiment of the present invention, each of the communication apparatuses generates the monitor data with a different additional data for every transmission of the data frame and transmits the monitor data together with the data body.
According to a preferred embodiment of the present invention, each of the communication apparatuses previously stores address data of the communication apparatuses connected with the loop structure network; and when the comparison result indicating the coincidence between the two monitor data is detected, detects whether or not a destination address included in the monitor data of the new data frame exists in the address data; when the destination address does not exist, determines that a trouble has occurred due to address mistranslation in a communication apparatus positioned adjacently in an upstream side of own communication apparatus; and when the destination address exists, has predetermined communication with a communication apparatus designated by the destination address thereby to determine whether or not the designated communication apparatus is capable of receiving data, and then when the designated communication apparatus is capable of receiving data, determines that a trouble due to destination address mistranslation has occurred in a communication apparatus positioned adjacently in an upstream side of own communication apparatus and when the designated communication apparatus is not capable of receiving data, determines that a trouble has occurred due to a receiving error in the designated communication apparatus.
According to a preferred embodiment of the present invention, each of the communication apparatuses previously stores address data of the communication apparatuses connected with the loop structure network; and when the comparison result indicating the coincidence between the two monitor data is detected, detects whether or not a source address included in the monitor data of the new data frame exists in the address data; when the source address exists, detects whether or not a destination address included in the monitor data of the new data frame exists in the address data, and then when the destination address does not exist, determines that a trouble due to destination address mistranslation has occurred in a communication apparatus positioned adjacently in an upstream side of own communication apparatus and when the destination address exists, has predetermined communication with a communication apparatus designated by the destination address thereby to determine whether or not the designated communication apparatus is capable of receiving data, and then when the designated communication apparatus is capable of receiving data, determines that a trouble due to destination address mistranslation has occurred in a communication apparatus positioned adjacently in an upstream side of own communication apparatus and when the designated communication apparatus is not capable of receiving data, determines that a trouble has occurred due to a receiving error in the designated communication apparatus; when the source address does not exist, detects whether or not a destination address included in the monitor data of the new data frame exists in the address data, and then when the destination address does not exist, determines that a trouble due to destination address mistranslation and source address mistranslation has occurred in a communication apparatus positioned adjacently in an upstream side of own communication apparatus and when the destination address exists, determines that a trouble due to destination address mistranslation has occurred in a communi
Le Dieu-Minh T.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Yazaki -Corporation
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