Browse Prior Art Database

REAL TIME FAULT MONITOR FOR LOCAL AREA NETWORKS

IP.com Disclosure Number: IPCOM000006458D
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2002-Jan-04
Document File: 2 page(s) / 109K

Publishing Venue

Motorola

Related People

Vijay Nadkarni: AUTHOR

Abstract

This invention offers a protocol to monitor faults, in a real-time fashion, within the local area network that supports Smart Repeater truoked systems. By distribut- ing the generation of word frame interrupt synchroniza- tion pulses to all repeaters, sequentially, the repeaters are effectively made to send "I am alive" indications at frequent periodic intervals. When a given repeater fails to generate its WFI signal, the other repeaters are immedi- ately alerted to the fact that something is wrong either with the cabling or the circuitry on that repeater. Such early detection of faults allows the repeater site to take pre-emptive corrective action, and minimizes attempts to transfer messages across broken or disconnected cables or to inactive repeaters.

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MOTOROLA INC. Technical Developments Volume 15 May 1992

REAL TIME FAULT MONITOR FOR LOCAL AREA NETWORKS

by Vijay Nadkarni

  This invention offers a protocol to monitor faults, in a real-time fashion, within the local area network that supports Smart Repeater truoked systems. By distribut- ing the generation of word frame interrupt synchroniza- tion pulses to all repeaters, sequentially, the repeaters are effectively made to send "I am alive" indications at frequent periodic intervals. When a given repeater fails to generate its WFI signal, the other repeaters are immedi- ately alerted to the fact that something is wrong either with the cabling or the circuitry on that repeater. Such early detection of faults allows the repeater site to take pre-emptive corrective action, and minimizes attempts to transfer messages across broken or disconnected cables or to inactive repeaters.

  The local area network in a Smart Repeater system, shown in Figure 1, consists of two primary sets of multi- drop links, the data bearing network (DLAN, for Data Local Area Network) and the synchronization network (carrying WFI, or word frame interrupt synchroniza- tion pulses). In genera the DLAN carries messages in a multi-drop fashion between repeaters. The transmission of these messages occurs at random intervals and is dependent on user t&tic and system needs.

  A major issue that a Smart Repeater site will have to deal with is faults on the local area network. These can be broadly classified as:
a) Inactive repeaters (due to malfunctioning circuitry or power outage)
b) Cable breaks

  The system that is proposed constantly monitors the network and detects faults almost as they occur. Its operation may be understood by referring to Figure 2. This approach distributes the Word Frame Interrupt (WFI) synchronization pulse generation across the network. Essentially, the repeaters assert WFI in a rotation sequence. The first repeater activates its WFI driver, asserts the WFI pulse, and tristates the driver. Follow-

ing this, the next repeater, which has synchronized with the WFI from the previois repeater, asserts its WFI pulse. Generation of subse(luent WFI signals is handled by the other repeaters, in sequence. Eventually, after all the repeaters have generatea th<i pulses, the cycle starts over with the first repeater. The sequence followed for WFI generation is determined ahead of time, at system initialization. For the...