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The Sysplex Distributor is a z/OS Communication Server function that provides a single visible IP address to the network for the entire Parallel Sysplex and balances TCP/IP workload within the sysplex.
The Sysplex Distributor consists of a primary distributor stack denoted by a primary DVIPA (possibly a backup stack VIPA) and a set of target stacks. An inbound packet destined for that DVIPA flows through the primary distributor stack which then forwards the packet over an internal link to the selected target stack. Only inbound requests go through the distributor stack. The distributor consults other system information, including capacity information provided by WLM, to make the routing decision. Figure 8-6 shows Sysplex Distributor in a Parallel Sysplex environment.
Figure 8-6 Sysplex Distributor
The IBM-recommended implementation is that if you are running in a sysplex, set up your TCP/IP network with Sysplex Distributor to increase availability and aid in workload balancing.
Sysplex Distributor routes and balances TCP/IP requests. It is not capable of making content-based decision. It acts as a secondary workload balancer in a WebSphere environment, located behind the HTTP plug-in of the HTTP server on z/OS or on other platforms. It balances IIOP requests and sessionless HTTP requests. In a Web application serving environment, Sysplex Distributor is complementary to other balancing techniques such as CISCO and WAS Edge Components.
