Browse Prior Art Database

In Line Data Transmission Monitor

IP.com Disclosure Number: IPCOM000051869D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 3 page(s) / 29K

Publishing Venue

IBM

Related People

Meikle, AG: AUTHOR [+2]

Abstract

An in-line data transmission monitor examines the instantaneous conditions of the interface leads in a teleprocessing system to obtain information from which data transmission error rates and line utilization can be derived without interference with data flow.

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In Line Data Transmission Monitor

An in-line data transmission monitor examines the instantaneous conditions of the interface leads in a teleprocessing system to obtain information from which data transmission error rates and line utilization can be derived without interference with data flow.

The monitor 1 is shown in the figure connected to the digital interface between data terminal equipment, consisting, for example, of teleprocessing system 2 and IBM 3705 Communications Controller 3, and data communication equipment, consisting, for example, of an analogue full duplex line 4 and IBM 3872 modem 5 operating in continuous carrier mode.

At the end of each transmission sample period, generated by predetermined timed intervals from an internal clock or by counting bits, for example, 10/5/, 10/6/ or 10/7/ bits, the monitor 1 communicates accumulated data to a host system for analysis. In the arrangement shown, a number of independent monitors 1a to 1n are connected via common control logic 6 to the keyboard interface 7 of an IBM 3277 display station 8, controlled by IBM 3271 control unit 9 with access to host software support 10. In the implementation described, the software support is provided as a PL/I analysis program running on an IBM System/370 processor.

During idle periods when data is not being transmitted, a continuous stream of binary one bits is transmitted over the link. Examination of the received data stream should result in the detection of a continuous stream of binary one bits, and any deviation from this condition indicates that an error has occurred. The monitor exploits this fact to derive a non-disruptive measurement of bit and block error rates.

At any point in time a link must be in one of three modes, namely, GAP, DATA or LOSS mode. When operating in GAP mode, the interface conditions indicate that the link is operating normally and is capable of transmitting data, but no data sequence is currently on the interface. The continuous idle bit stream of binary ones transmitted during this mode of operation is monitored by monitor 1 and occurrences of zero bits are recorded in a counter within the monitor. Since zero bits are error bits, th...