Installing a front-end load balancer (optional)
You install a load balancer in front of the web servers in an IBM® WebSphere® Application Server cluster installation if your installation requires very high availability. This configuration is called an IP sprayer topology.
About this task
Steps for installing a front-end load balancer are specific to external vendors and are not provided in this documentation.
Do not install a load balancer directly in front of a WebSphere Application Server cluster without a web server between the load balancer and the cluster. Web servers with the WebSphere Application Server workload management plug-in adjust to changes in the cluster topology such as adding or removing nodes. Load balancers do not have this functionality, and must be manually reconfigured.
Make sure to configure session
affinity in the load balancer. There are several methods to achieve
session affinity. The method that you choose depends on the product
that you use and the forwarding mechanism that you configure. Mechanisms
include media access control (MAC) address forwarding, Network Access
Translation/Network Address Port Translation (NAT/NAPT) forwarding,
and content-based forwarding. Layer 2 load balancers (load balancers
that operate at the MAC layer) generally achieve session affinity
by using a stickiness to source IP address
approach. Layer
3 and higher load balancers (load balancers that operate at the IP
layer and above) typically achieve session affinity by using passive
cookies or a content-based technique. Session affinity with HTTP servers
is typically achieved by using these techniques.