Setting Up Basic Parameters
I found it pretty easy to get load balancing working on the E650GX simply by setting up some basic parameters, such as defining server clusters and some load balancing rules. For example, if you had nine servers running a Web application, you would plug each of those servers into an internal port on the E650GX appliance and then place those servers into logical clusters-perhaps creating three logical clusters with three servers occupying each cluster. Since cluster definitions are done logically, it is a simple matter to make any changes, which provides a great deal of deployment flexibility. Administrators can also define VLANs (virtual LANs) based on ip address segments, which can speed up local requests and reduce latency by isolating local traffic to the same logical segment.Policies based on Layer 7 are a little more sophisticated and incorporate traffic analysis to determine how to load balance the member clusters. That works by identifying administrator-defined protocols to trigger a load balancing policy to route traffic to a particular cluster. Policies that incorporate Boolean logic can handle particular requests based on administrator-defined events. Those policies can be used to reroute traffic if a server fails to respond (failover routing) or to route based on a schedule.
The E650GX offers numerous load balancing options. These include "Match Rules and Custom Load-Balancing Policies," which define policies based on Layer 4 requests, Layer 7 requests or using Boolean logic. The simplest load balancing policies are defined using Layer 4 parameters, such as least connections, fastest response, adaptive and round robin, as well as a server-based, agent-based algorithm. The agent-based algorithm proves to be the most accurate, as long as the monitoring agent is installed on each server in the cluster.