Configuring WebSphere proxy server for load balancing in a SIP Proxy/Registrar cluster

In a Sametime deployment, you can configure multiple Media Manager servers into clusters to provide high availability of resources: you can create a SIP Proxy/Registrar cluster and a Conference Manager cluster. Each cluster of Media Manager servers must be fronted with at least one WebSphere proxy server to process client requests; however, you should deploy at least two proxy servers plus a load balancer (IBM Load Balancer is included in the Sametime kit) to ensure that the workload is distributed equitably among the back-end servers. If a back-end server is unavailable this configuration additionally allows for Connections to fail over to other servers in the cluster.

When you deploy proxy servers and a load balancer in front of a cluster, you provide a single IP address (the load balancer's address, known as the "cluster address") for all clients; client requests are handled by the load balancer, which distributes them among the available proxy servers to balance the workload. The proxy servers forward the client requests to the clustered servers on the back-end, which process the requests and then send responses directly to the clients.

To support the use of a load balancer with WebSphere proxy servers, you must configure each proxy server as explained in this section to ensure they communicate properly with the load balancer.