Cisco Unity

Configuring and Troubleshooting Dual NICs for Cisco Unity

Document ID: 46266

Updated: Feb 02, 2006



This document describes how to properly configure Cisco Unity to work with two Network Interface Cards (NICs) when Cisco Unity is integrated with a CallManager. Voice messaging does not work as expected if it is not properly configured.



There are no specific requirements for this document.

Components Used

This document applies to all versions of Cisco Unity integrated with a Cisco CallManager.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.


Refer to Cisco Technical Tips Conventions for more information on document conventions.


Many enterprise customers who source their own hardware purchase a platform that has two NICs. If these NICs are not configured properly, voice messaging does not work correctly, and you experience problems such as one-way audio or a Message Waiting Indicator (MWI) malfunction. This document indicates the supported configuration for dual NICs.

Problems with Active-active Load Sharing Configuration

If you configure dual NICs for active-active load sharing, which means that 50 percent of the traffic is handled by each NIC, one-way audio and MWI problems can result. This setup is currently not supported on a Cisco Unity server.

How Active-active Load Sharing Can Result in One-way Audio

These factors can cause dual NICs to result in one-way audio during call processing with a Cisco CallManager integration (using Skinny protocol):

  • With a Skinny integration, you have to send your IP address to the other side of the call.

  • You determine your IP address by repeating through the NICs and returning the IP address of the first NIC you find.

  • In a dual NIC configuration, you can choose the IP address of the wrong NIC, which causes the one-way audio issue.


There are two supported configurations for installation of Cisco Unity on a platform with two NICs:

  1. Disable one of the NICs.

  2. Configure the NICs in an active-passive manner.

Active-passive Fault Tolerance

Note: The IBM Cisco Media Convergence Server (MCS) servers cannot use the MCS Network Teaming Driver that is included with the Hewlett-Packard servers.

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 (no subnets with each NIC on a different subnet) is supported.

Note: The second interface cannot be configured with a different IP address to be used as a management interface for Terminal Services.

Confirm the Dual NIC Configuration on a Cisco Unity Server

To confirm that the NICs are configured correctly, perform these steps:

  1. Ensure that both NICs are set up for either adapter fault tolerant mode (AFT) or for network fault tolerant (NFT). For more information about how to do this, refer to the documentation provided by the NIC manufacturer or server vendor.

  2. If an MCS-7825H, MCS-7835H, or MCS-7845H server is configured, use the network teams property sheet of the Compaq Network Teaming and Configuration Utility (CPQNTAC, also known as NCU) in order to configure NFT teaming.

    Note: Using the Remote Deployment Utility (RDU), the CPQNTAC utility can be installed from the Hewlett-Packard SmartStart disc that was shipped with the server.

    If an IBM MCS-7815I, MCS-7855I, or MCS-7865I server is configured, use the Advanced Control Suite of the Broadcom NetXtreme Ethernet utilities to configure AFT teaming.

    For the MCS-7835I and MCS-7845I servers, use the teaming wizard on the Advanced tab of the Intel PROSet II Ethernet utilities to configure AFT teaming.

  3. Restart the Cisco Unity server for any changes to take effect.

Related Information

Updated: Feb 02, 2006
Document ID: 46266