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Error Recovery Enhancement Procedure

IP.com Disclosure Number: IPCOM000080492D
Original Publication Date: 1973-Dec-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Powers, JT: AUTHOR

Abstract

This is a program method of inserting a programmable delay, to increase the probability that the retry of a polling operation will be successful.

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Error Recovery Enhancement Procedure

This is a program method of inserting a programmable delay, to increase the probability that the retry of a polling operation will be successful.

Certain systems of communication line control (e.g., IBM 2265 used with OSBTAM) use one or more "throw away" line control characters such as EOT, to ensure that all terminals on a multipoint line are properly reset before transmitting a polling sequence.

The figure describes how the count of such throw away characters may be adjusted during error recovery retry operation (for example, in the case of no response to a poll), to increase the probability that the recovery procedure will be successful. In this case, the count is used as a programmable delay, the duration of which is adjusted upwards as the number of attempts at retry increases.

The increment used is calculated such that the delay provided at the line speed used is sufficient to postpone the transmission of the actual polling or addressing sequence, for a period comparable to the duration of the median transmission line fault (drop-out, noise burst, etc.). The effect is that on the first retry, probability is high that a temporary line fault will no longer exist, and that this probability increases with succeeding attempts, up to a preset maximum at which error recovery is abandoned.

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