Browse Prior Art Database

REDUNDANT LINK

IP.com Disclosure Number: IPCOM000009077D
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2002-Aug-06
Document File: 3 page(s) / 111K

Publishing Venue

Motorola

Related People

Ming Wong: AUTHOR

Abstract

This Redundant Link provides a more reliable communication link for the redundant RNG config- uration used in the DataTAC 5000 wireless data net- work. With the current design, a network problem in the DataTAC 5000 could cause the RNG pair to synchronize improperly making the whole network unstable. One network problem is when a 1ObaseT repeater fails causing the RNGs to switchover. As soon as the failed 1ObaseT repeater recovers, the RNGs resume communication but fail to synchro- nize properly resulting in another switchover. If the 1ObaseT repeater fails intermittently the RNGs would also switchover intermittently! Each RNG switchover causes a DataTAC network service inter- ruption, which is undesirable. Having the Redundant Link, this unnecessary RNG switchover can be prevented so the DataTAC network can be mom reliable.

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Page 1 of 3

@ MOTOROLA

Technical Developments

REDUNDANT LINK

by Ming Wong

INTRODUCTION

  This Redundant Link provides a more reliable communication link for the redundant RNG config- uration used in the DataTAC 5000 wireless data net- work. With the current design, a network problem in the DataTAC 5000 could cause the RNG pair to synchronize improperly making the whole network unstable. One network problem is when a 1ObaseT repeater fails causing the RNGs to switchover. As soon as the failed 1ObaseT repeater recovers, the RNGs resume communication but fail to synchro- nize properly resulting in another switchover. If the 1ObaseT repeater fails intermittently the RNGs would also switchover intermittently! Each RNG switchover causes a DataTAC network service inter- ruption, which is undesirable. Having the Redundant Link, this unnecessary RNG switchover can be prevented so the DataTAC network can be mom reliable.

RNGREDUNDANCY

  In DataTAC 5000, the redundancy of the RNG is made possible by having two RNGs operate in a Master/Standby relationship. During normal opera- tion, the Master RNG is the active RNG in the DataTAC system. The other RNG in the Standby state is passive which only monitors the Master RNG and if it detects any problems it switches to the Master state and becomes the active RNG.

  The mechanism for detecting a problem is by the means of having both RNGs continuously send- ing status messages to each other. One example showing how this works is when the Master RNG encounters a power failure. With Master RNG down, it fails to send status messages to the Standby RNG. The Standby RNG detects no status message, it then switches to Master state and becomes the active RNG in the network.

  This redundancy mechanism fails with a net- work problem. When a' network problem occurs between the RNG pair, they can not synchronize because they can no longer hear each other. This causes both RNGs to assume the Master state. When the network problem recovers, the RNGs detects each other in the ,Master state. This causes them to content for the Master state because only one RNG can be Master. The result causes unneces- sary RNG switchov...