Communications Server Mediation Server: Dual NIC Issue


There have been several great blog posts on the Internet concerning the Mediation Server dual NIC configuration or single NIC with multiple IP addresses in Communications Server 2007 R2. In this article, Greg Anthony shares an additional scenario that explains why both Mediation Server network interfaces need to be on physically distinct and separate subnets.

Author: Greg Anthony

Publication date: March 2010

Product version: Microsoft Office Communications Server 2007 R2

There have been several great blog posts on the Internet concerning the Mediation Server dual NIC configuration or single NIC with multiple IP addresses in Communications Server 2007 R2. I wanted to share an additional scenario that explains why both Mediation Server network interfaces need to be on physically distinct and separate subnets.

The issue as reported was that outbound calls from Office Communicator to the PSTN were delayed up to 10 seconds before connecting Communicator to the external called party. Basically, when the person receiving the call answered the phone, the Communicator user did not hear the called party answer. Then the called party would hang up because they did not hear a response from the calling party.

When I first started troubleshooting the issue, the topology and configuration of the Mediation Server looked correct. It had two network adapters each with a separate IP address configured for separate and distinct subnets. This topology is shown in Figure 1.

Read the complete article in the Technical Library.

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