Load balancing products can be used to distribute HTTP requests among Web servers running on multiple physical machines.
The Dispatcher component of Load Balancer, which is part of the WebSphere Edge Components, is an IP sprayer that performs intelligent load balancing among Web servers based on server availability and workload capacity as the main selection criteria to distribute the requests. Refer to Chapter 4, Introduction to WebSphere Edge Components for details.
Figure 3-10 illustrates a horizontal scaling configuration that uses an IP sprayer on the Load Balancer Node to distribute requests between Web servers on multiple machines.
Figure 3-10 IP sprayer horizontally scaled topology
The Load Balancer Node sprays Web client requests to the Web servers. The Load Balancer is configured in cascade. The primary Load Balancer communicates to his backup through a heartbeat to perform failover, if needed, and thus eliminates the Load Balancer Node as a single point of failure.
Both Web servers perform load balancing and failover between the appservers (cluster members) through the Web server plug-in.
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Tip: The Web server and Load Balancer can be collocated. |
If any component on Server C, D, E, or F fails, the other ones can still continue receiving requests.