WebSphere clusters (farms)
IBM® WebSphere® Application Server Network Deployment (WebSphere Application Server ND) provides high availability through clusters, a collection of servers that work together as a server farm and can be managed as a single server. You can deploy, start, and stop all servers in the cluster as a single entity.
Servers in a WebSphere Application Server cluster are copies of an original WebSphere Application Server. They function as separate individual servers, yet their configuration is based on the same template configuration from an original server. Clusters can be used to group together cloned servers. WebSphere Application Server clusters together with clones are equivalent to Oracle WebLogic Server clusters, both of which are server farms.
Web clients can connect to the cluster through a proxy HTTP server. For WebSphere Application Server Network Deployment, the proxy HTTP server uses the WebSphere Application Server Network Deployment web server plug-in. The web server plug-in for supported web server can forward HTTP requests to the cluster of application servers.
Another way to balance a load is to use a hardware load balancer. In that case, the server can be hosted on either the base version of WebSphere Application Server or WebSphere Application Server Network Deployment. The Content Engine Web Services (CEWS) HTTP transport load can also be balanced by using a hardware load balancer, but WebSphere Application Server Network Deployment is required for balancing the EJB transport load, if EJB transport is used.