Dial or cellular backup is used where there is normally a broadband connection, but some level of network connectivity is required in the event of a broadband outage. Once enabled and configured, the dial or cellular backup feature is automatically invoked, mitigating a loss of network access due to broadband outage.

The Dial Backup configuration is retrieved from the AT&T Administration Server as part of the VPN Gateway Device Query, which is issued every 24 hours and following power-up. If all necessary parameters have been configured correctly in the profile, the Dial Backup will be fully configured without the need for user intervention. The user can also set up Dial Backup via the VPN Gateway web interface.

The dial or cellular backup will be invoked automatically if the broadband connection fails and tunnel and/or dial automation is configured.

There are situations where it is cost prohibitive to send much data over the backup connection. To help alleviate the amount of data that is sent via backup, the profile for the VPN Gateway in the AT&T Administration Server will allow the administrator to limit some services when the VPN Gateway is in backup mode. These services will each have an individual field in the AT&T Administration Server that controls whether they are allowed in backup or not. That means some services could potentially be allowed in backup mode while others are not.

• Netflow – This is only launched when a tunnel comes up. It will not be launched if the VPN Gateway is in backup mode and this traffic isn’t allowed via backup.
• Remote syslog – This is also only launched when a tunnel comes up. It will not be launched if the VPN Gateway is in backup mode and this traffic isn’t allowed via backup.
• SNMP traps/informs – Nothing will be sent if this traffic isn’t allowed via backup.

The items above are traffic originated by the VPN Gateway. SNMP polling is different in that it is traffic in response to a request that did not originate on the VPN Gateway.

• SNMP polling – The VPN Gateway will not respond to SNMP polling requests if it is in backup mode and SNMP polling traffic isn’t allowed via backup.