Digi APPLICATION NOTE 34 User Manual

Application Note 34

Configuring ADSL to backup to PSTN/ISDN with

automatic testing and recovery back to ADSL.

UK Support

29 December 2009

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Contents

1 Introduction ............................................................................................................................................... 2

1.1 Outline ............................................................................................................................................... 2

1.2 Assumptions ...................................................................................................................................... 2

1.3 Corrections ........................................................................................................................................ 3

1.4 Version ............................................................................................................................................... 3

2 Configuration ............................................................................................................................................. 4

2.1 Configure PPP 1 (ADSL) ...................................................................................................................... 4

2.2 Configure PPP 4 (PSTN) ...................................................................................................................... 6

2.3 Configure the Default Routes ............................................................................................................ 8

2.4 Configure the Firewall ....................................................................................................................... 9

2.5 Save configuration ........................................................................................................................... 10

3 Testing ..................................................................................................................................................... 11

3.1 Simulate a failure ............................................................................................................................. 11

4 Configuration Files ................................................................................................................................... 11

4.1 Digi Transport Configuration Files ................................................................................................... 11

4.2 Digi Transport Firmware Versions ................................................................................................... 12

1 INTRODUCTION

1.1 Outline

The document describes how to configure a Digi Transport router to fail over to PSTN when there is a
problem with the main ADSL connection. Once the ADSL connection is working again the router will test it
by sending pings and then revert back to ADSL and drop the PSTN connection.
This application note uses PPP 4 (PSTN) as the failover interface, however, if the router being conf i gured
has ISDN, simply configure PPP 2 (ISDN) instead of PPP 4. The same configuration can be applied to the
ISDN interface.

For failover from ADSL to a cellular network, plea se see Application Note 34a as the configuration is slightly
different.

1.2 Assumptions

This guide has been written for use by technically competent personnel with a good understandin g of the
communications technologies used in the product, and of the requirements for their specific application.
Configuration: This application note assumes that the router will be connecting to a cellular n etwork.

This application note applies to;

Models shown: Digi Transport DR64 router with ADSL & PSTN running firmware version 5081.
Other Compatible Models: All Digi Transport products.

Firmware versions: 4905 or later.

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