In the Cisco CallManager, the Network Teaming Driver can be used in order to enable the functionality for the failover fault-tolerant network adapters. This driver works with Cisco Media Convergence servers that have dual network interface cards (NICs) installed. With this functionality, the standby NIC can handle all IP traffic if the primary NIC fails.
There are two supported configurations for installation of Cisco Unity on a platform with two NICs:
Disable one of the NICs.
Configure the NICs in an active-passive manner.
Cisco Unity does support dual NICs configured in an active-passive manner for fault tolerance. In this NIC configuration, the primary (active) NIC handles 100 percent of the traffic. Only in the event that it goes down, does the secondary NIC become active and handle 100 percent of the traffic. Therefore, only one IP address and one network is supported, no subnets with each NIC on a different subnet.