Office Communications Server 2007 R2 is available only in a 64-bit edition, which requires 64-bit hardware and the 64-bit edition of Windows Server. A 32-bit edition is not available with this release. The exception is Office Communications Server Administrative Tools, which is available both in a 64-bit and a 32-bit edition.

The following operating system updates are prerequisites for deploying Office Communications Server 2007 R2:

• Microsoft Knowledge Base article 953582, "You may be unable to install a program that tries to register extensions under the IQueryForm registry entry in Windows Server 2008 or in Windows Vista" at http://go.microsoft.com/fwlink/?LinkId=131392 .
  
  This update must be installed before you install Office Communications Server 2007 R2 Administrative Tools onlyin the following situations:
  
  
  • On computers running Windows Vista, on which you install Remote Server Administration Tools (RSAT).
    
    
  • On computers running Windows Server 2008, if the server role Active Directory Domain Services role is added.
    
    
• Microsoft Knowledge Base article 953990, “AV at mscorwks!SetAsyncResultProperties” at http://go.microsoft.com/fwlink/?LinkId=131394 .
  
  This update applies to Windows Server 2003 with SP2 and Windows Server 2008.
  
  

For details about Enterprise Edition operating system and hardware requirements, see Office Communications Server Infrastructure Requirements.

AD DS must be prepared for Office Communications Server 2007 R2 before you can deploy Office Communications Server 2007 R2, Enterprise Edition. Enterprise Edition also requires that the following be deployed in your environment:

• Domain Name System (DNS)
  
  
• Public key infrastructure (PKI)
  
  
• Microsoft .NET Framework 3.5 (64-bit)
  
  
• Microsoft Visual C++ 2008 redistributable
  
  
• IPv4 addresses and networking protocols
  
  
• Hardware load balancer
  
  

You must prepare certificates using the PKI so that you can configure mutual TLS (MTLS) between Office Communications Servers. Setup prompts you to install the .NET Framework and the Visual C++ 2008 redistributable, and it automatically installs them if they are not already installed on the computer.

For details about these prerequisites, see Environmental Requirements.

A hardware load balancer is required in an Enterprise pool that has more than one Enterprise Edition server. The load balancer performs the critical role of delivering scalability and high availability across multiple servers that are connected to a centralized database on the Office Communications Server Back-End Database.

Before a hardware load balancer can connect to the Office Communications Server Enterprise pool, you must configure the following:

• A static IP address for servers within your pool.
  
  
• Source network address translation (SNAT). Using a load balancer in the destination network address translation (DNAT) configuration is not supported. Using a load balancer in SNAT mode is required. However, be aware that each SNAT IP address on the load balancer limits the maximum number of simultaneous connections to 65,000. If you deploy load balancer in SNAT mode, ensure that you configure a minimum of one SNAT IP address for each group of 65,000 users. (The open number of connections generally corresponds to the number of active users.) For example, in a deployment supporting 100,000 users, you would configure two SNAT IP addresses.
  
  

  Note:
  Although DNAT is not supported for the Enterprise pool or for Communicator Web Access, both DNAT and SNAT are supported for Edge Servers and HTTP.

• A VIP address and associated DNS record for the load balancer. For details, see DNS Requirements for Servers.
  
  

  Important:
  The following requirements apply to all load balancers that are deployed in an Office Communications Server 2007 R2 Enterprise pool. For details about configuring and deploying a particular brand and model of hardware load balancer, see the documentation that is included with the product of your choice.

A load balancer for an Enterprise pool must meet the following requirements:

• Expose a VIP Address through Address Resolution Protocol (ARP). The VIP must have a single DNS entry called the pool FQDN and must be a static IP address.
  
  
• Allow multiple ports to be opened on the same VIP. The following ports are required.
  
  

  Table 1. Hardware Load Balancer Ports That Are Required for Office Communications Server 2007 R2

  Port required	Virtual IP	Port use
  5060	Load balancer VIP used by the Front End Servers	Client to server SIP communication over TCP
  5061	Load balancer VIP used by the Front End Servers	Client to Front End Server SIP communication over TLS SIP communication between Front End Servers over MTLS
  5065	Load balancer VIP used by the Front End Servers	Used for incoming SIP listening requests for application sharing over TCP
  5069	Load balancer VIP used by the Front End Servers	Used by QoE Agent on Front End Servers, needs to be open only if this pool sends QoE data to Monitoring Server
  135	Load balancer VIP used by the Front End Servers	To move users and perform other pool level Windows Management Instrumentation (WMI) operations over DCOM
  444	Load balancer VIP used by the Front End Servers	Communication between the internal components that manage conferencing and the conferencing servers
  443	Load balancer VIP used by the Web Components Server	HTTPS traffic to the pool URLs

  Note:
  If you deploy a load balancer for computers that are running applications such as Conferencing Attendant, Conferencing Announcement Service, Response Group Service, and Outside Voice Control, you must also configure the load balancer with the ports used by each application, as described in Dial-In Conferencing Support, Response Group Service Support, and Outside Voice Control, respectively.

• Provide TCP-level affinity. This means that the load balancer must ensure that TCP connections can be established with one Office Communications Server in the pool and all traffic on that connection will be destined for that same Office Communications Server.
  
  
• Have an IP address on each Front End Server that is directly routable within the internal network (specifically to allow communications between Front End Servers across different pools).
  
  
• Ensure that the load balancer provides a configurable TCP idle-timeout interval with its value set to 20 minutes or greater. This value must be 20 minutes or higher because it should be above the following values:
  
  
  • Maximum SIP connection idle timeout of 20 minutes (this is the major determining value).
    
    
  • SIP Keep-alive interval 5 minutes.
    
    
  • Maximum REGISTER refresh interval of 15 minutes in absence of keep-alive checks.
    
    
• Enable TCP resets on idle timeout.
  
  
• Ensure that Front End Servers within a pool behind a load balancer are capable of routing to each other. There can be no NAT device in this path of communication. Any such device will prevent successful RPC between Front End Servers within a pool.
  
  
• Ensure that Front End Servers behind a load balancer have access to the Active Domain Directory Services environment.
  
  
• Ensure that Front End Servers have static IP addresses that can be used to configure them in the load balancer. In addition, these IP addresses must have DNS registrations (referred to as Front End FQDNs).
  
  
• Ensure that any computer running Office Communications Server 2007 R2 administrative tools is able to route through the load balancer to both the Pool FQDN and the Front End FQDN of every Front End Server in the pool or pools to be managed. In addition, there can be no NAT device in the path of communication to the Front End Servers to be managed. Again, this is a restriction enforced by the usage of the RPC protocol by DCOM.
  
  
• Use a load balancer that allows for adding and removing servers to the pool without shutting down.
  
  
• Use a load balancer that supports a least-connections-based load balancing mechanism. This means that the load balancer will rank all Office Communications Server servers based on the number of outstanding connections to each of them. This rank will then be used to pick the Office Communications Server to be used for the next connection request.
  
  
• Use a load balancer that is capable of monitoring server availability by connecting to a configurable port for each server.
  
  

  Important:
  The monitor for ports 135 and 444 should open TCP connections to port 5060 or 5061 for determining server availability. Attempting to monitor ports 135 and 444 on the servers will cause the load balancer to incorrectly detect these servers to be available, because these ports are open even though Office Communications Server is not running.

We strongly recommend that you read Planning and Architectureto determine the features, functionality, and topology required by your organization before you begin deploying Enterprise Edition.

The deployment process for Enterprise Edition is described in the following table.

Table 2. Enterprise Edition Deployment Process