Communicator Web Access Load Balancer Requirements (2007 R2 Beta)
[This is preliminary documentation and is subject to change. Blank topics are included as placeholders.]
When two or more Communicator Web Access servers are deployed to support a single virtual server, you must use a hardware load balancer. The load balancer must be deployed before you can add servers to it. This topic describes the requirements and recommended configuration for configuring a load balancer for the 2007 R2 release of Communicator Web Access. For details about deploying a hardware load balancer and connecting servers to it, see the documentation for the load balancer.
Load Balancer Configuration Requirements
The following load balancer configuration requirements must be met for successful load balancing of Communicator Web Access servers:
- The load balancer must support PING of the Communicator Web Access server through a TCP port, typically 80/443, which is opened by the Communicator Web Access server.
- The load balancer service check retry interval and TCP idle timeout must be configurable and set to 30 seconds and 92 seconds, respectively.
- The load balancer must support either IP address forwarding or source network address translation (NAT).
- If the load balancer supports only source NAT, and not IP address forwarding, it must support source NAT pooling if it is to support more than 65,000 concurrent connections.
Load Balancer Connectivity Requirements
The following connectivity requirements must be met for successful load balancing of Communicator Web Access servers:
- The virtual IP (VIP) address of the load balancer must support the Address Resolution Protocol (ARP).
- The VIP address of the load balancer must have only a single DNS registration, including a FQDN that is called the array FQDN.
- The VIP address of the load balancer must have one or more client ports. The port can be TCP port 80, SSL port 443, or a port defined by the system administrator.
- The load balancer must support HTTP/SSL affinity.
- The Communicator Web Access servers must have access to Active Directory Domain Services (AD DS).
- The administrative computer must be able to connect directly to each Communicator Web Access server behind the load balancer without going through the load balancer.
- Each Communicator Web Access server behind the load balancer must be able to connect with Office Communications Server 2007 by using mutual TLS (MTLS) on port 5061.
Recommendations for Load Balancer Configuration
The following recommendations for configuring the load balancer will help ensure optimal load balancing, but they are not required:
- The load balancer should have a setting for maximum number of connections to each Communicator Web Access server behind the load balancer.
- The load balancer should be capable of a slow start, in which the load on the servers is increased gradually.
- The TCP idle timeout should be at least twice the maximum client polling interval.