Detecting and isolating errors occurring in data communication in a multiple processor system

A method for isolating detection of suspected correctness of data communicated between a plurality of data processing elements through a communication network that includes a router element for routing the data, comprising the steps of:

• sending the data by one of the plurality of data processing elements with address information of a destination one of the plurality of data processing elements and a tag data element having a first digital state that indicates the data is correct;
• receiving and checking the data at the router element to change the first digital state of the tag data element to a second digital state and to report the error if the correctness of the data is suspect;
• and
• forwarding the data and tag data element from the router element to the destination one of the plurality of data processing elements.

In a processing system having plurality of data receiving/sending units interconnected by a communications network for communicating data, the communications network having a number of intermediate devices, including first and second intermediate devices, for receiving and re-transmitting the data, the processing system including a maintenance diagnostic system coupled to the first and second intermediate devices and the data receiving /transmitting units, a method of isolating detection of suspect correctness of the data, comprising the steps of:

• sending the data from a one of the plurality of sender/receiver units to another of the plurality of the sender/receiver units through the data communications network such that at least the first intermediate device and then the second intermediate device receives and transmits the data;
• sending with the data a data/command element set to a first state to identify the data as being correct;
• receiving and checking the data and the data/command element at each of the first and second intermediate devices for errors and, if an error is found and the data/command element is set to the first state,
• (i) changing the data/command element from the first state to a second state to indicate the data as being suspect, and
• (ii) reporting the error to the maintenance diagnostic system when found.

A method for isolating detection of the correctness of data communicated between a plurality of data processing elements through a communication network that includes at least one router element for routing the data, comprising the steps of:

• sending the data by one of the plurality of data processing elements with a tag data element set to a first digital state that indicates the data is correct;
• receiving and checking the data at the router element to change the first digital state of the tag data element to a second digital state if an error is detected in the data and reporting the error only if the accompanying tag data element is set to the first digital state when received;
• forwarding the data and tag data element from the router element to a destination one of the plurality of data processing elements;
• and
• receiving and checking the data at the destination one of the plurality of data processing elements to report a detected error in the data only if the tag data element is set to the first digital state when received.