Browse Prior Art Database

REDUNDANCY PROTOCOL

IP.com Disclosure Number: IPCOM000008926D
Original Publication Date: 1999-Jan-01
Included in the Prior Art Database: 2002-Jul-24
Document File: 4 page(s) / 125K

Publishing Venue

Motorola

Related People

Di Jin: AUTHOR [+2]

Abstract

This invention provides a more reliable commu- nication protocol for redundant radio network gate- way (RNG) configuration used in the DataTAC 5000 wireless data network. The new design would prevent a synchronization problem in the event of a network failure.

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MOmOLA Technical Developments

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REDUNDANCYPROTOCOL

by Di Jin and Ming Wong

INTRODUCTION

  This invention provides a more reliable commu- nication protocol for redundant radio network gate- way (RNG) configuration used in the DataTAC 5000 wireless data network. The new design would prevent a synchronization problem in the event of a network failure.

  With the current design, a network problem could cause the RNG pair to synchronize improper- ly. 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 net- work service interruption, making switchover unde- sirable. Also, a RNG switchover test with a network failure is one of the DataTAC's standard ATP tests which makes this synchronization problem very vis- ible to the customer.

ARBITRATION REDUNDANCY PROTOCOL

  In a DataTAC 5000 system, the redundancy of the RNG is made possible by having two computers operate in a Master/Standby relationship. During normal operation, the Master RNG is the active RNG in the DataTAC system. The other RNG in the Standby state monitors the Master RNG and if it detects any problem it switches to the Master state and becomes the active RNG.

  The mechanism for detecting a problem and synchronizing the RNGS is by using the arbitration protocol, which involves having each RNG continu- ously send status messages to its peer. The status message contains the current and default state of the sender. RNG access level and access level time delay. By monitoring the messages of its peer (or lack of such messages) an RNG may deduce the sta- tus of its peer, and thus its own status. This means that if RNG does not receive status messages from its peer, it will assume that its peer is down, and decides its own status to the Master.

  According to this protocol, if a network failure happens, both RNGs will not get the status mes- sages from its peer, and both decide to become the Maste...