Tactical Software Tech Note


All Tech Notes

Automatic Failover to Backup Modem Servers and License Managers

Note: The features described below assume the use of version 4.8 or later.

Using Backup Modem Servers

Starting in version 4.8, Tactical Software's redirectors have a failover feature to prevent dialout failures when a modem server stops responding.  This could be due to a hardware failure or when the modem pool reaches its capacity.

The failover feature allows you to enter more than one modem server (either as an IP address or DNS name) in a space-separated list in the DialOut/EZ Control Panel.  If DialOut/EZ is unable to make a connection to the first modem server in the list, it will try the second, then third, etc. until it finds a modem server that accepts a TCP/IP connection or the list is exhausted.

This feature also works with the DialOut/EZ Configuration Wizard, thus allowing users to see what modem servers are not responding to TCP connection attempts.

By default, DialOut/EZ will attempt to connect to each modem server until the Microsoft TCP/IP stack determines that a connection cannot be made.  However, this amount of time can be over 20 seconds due to the TCP/IP stack's behavior.  To control this behavior, there is a new Advanced Setting in DialOut/EZ called "Attempt Server Connections for xxxx ms".  We recommend checking this Advanced Option if entering more than one modem server in DialOut/EZ's "IP Address of Server" field.  The default of 2000ms (two seconds) should be fine for most networks.

If using a second hardware modem server is cost prohibitive, a Windows PC with modems can be made into a backup modem server with our TacServe COM Port Server and accessed with any Tactical DialOut/EZ client.

You can use the Presets file to pre-configure any number of settings for IP Address.

Using Backup License Managers

Starting in DialOut/EZ Site Edition v4.8, the location of the License Manager under the Licensing button accepts a space-separated list of up to four IP addresses or DNS names.  DialOut/EZ will try every License Manager listed until it receives a license or the list is exhausted.