In side-by-side migrations, a new Office Communications Server 2007 R2 server is deployed alongside the Live Communications Server 2005 server. After the new configuration is fully validated, users are moved from the original configuration to the new configuration. This method requires additional servers during the migration. System names and pool names must be different in the new configuration.

The supported migration path for Office Communications Server 2007 R2 uses an outside-in methodology. An in-place migration is not supported and a rolling upgrade of Enterprise pools is also not supported.

Mixed server versions in a pool are not supported. In addition, because of the move to the 64-bit host server and the schema changes to the supporting back-end databases, in-place migration is not supported.

Side-by-side migration offers the following benefits:

This approach, however, imposes the following costs:

You can use existing Live Communications Server Access Proxy Domain Name System (DNS) records and IP addresses for your Office Communications Server 2007 R2 Edge Server, but you need additional IP addresses and DNS records to fully support Office Communications Server 2007 R2 features.

The minimum SQL Server for Office Communications Server 2007 R2 is SQL Server 2005 with Service Pack 2. You need a separate SQL Server or instance to support the Office Communications Server 2007 R2 pool. To support Office Communications Server 2007 R2 Enterprise Edition, you may need to upgrade SQL Server 2005.

Office Communications Server 2007 R2 Edge Server roles support a Live Communications Server 2005 pool. However, you need to consider how you will deploy the Office Communications Server 2007 R2 Edge Server roles before you move active users to the new pool. Because of the need to establish additional structure for the new Edge Servers in the side-by-side migration, you need new DNS entries and firewall routing to have both systems active at the same time. This coexistence may impact external and remote user experience and may change the timing of your user migration to the new pool. For details, see Understanding Coexistence.

Because of the need for a new edge structure that replaces the Live Communications Server Access Proxy, and because the Office Communications Server 2007 R2 Edge Server will service the existing Live Communications Server pool, replacing the Live Communications Server Access Proxy with the Office Communications Server 2007 R2 Edge Server is the recommended first step in the migration path.

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