MDC Gateway Load-Balancing, Failover, and Failback

The following gateway settings determine how the Message Delivery Component (MDC) service performs load-balancing, failover, and/or failback between gateways:

• Server type (Primary or Backup)
• Order in the gateway definition list
• Whether the gateway definition is enabled or not

To configure gateway definitions for load-balancing, failover, or failback

1. Start the MDC Configuration Utility.
2. Select the delivery method you want to configure (SMS Delivery, Email Delivery, or Voice Delivery).

3. All the available gateway definitions for the delivery method are listed on the gateways section, e.g. Voice Gateways for voice delivery.

   Enable the gateway definitions that you want to use by selecting their respective checkboxes in the Enabled column.

4. The order of the gateway definitions determines how MDC prioritizes between gateways during failover and failback. The higher a gateway definition is in the list, the higher its priority.

   Use Move Up and Move Down below the gateways section to configure the gateway definition order.

5. To configure the server type of a gateway definition, select it in the gateway list of the delivery method you are configuring. Then, select the appropriate radio button from the Server Type section.

MDC performs load-balancing between ALL enabled gateway definitions set to Primary (Server Type).

If there are no enabled primary gateways, then MDC will use the first enabled backup gateway in the gateways list. If that gateway is unavailable or becomes unreachable, then MDC will failover to the next enabled backup gateway in the list.

If all enabled primary gateways become unavailable, then MDC will failover to the next backup gateway in the gateways list. As long as there are any available primary gateways enabled, MDC will periodically test if any of those primary gateways are already available. MDC will then re-connect to any and all primary gateways that become available (i.e. failback).