Network and Cluster Infrastructure
You can find the Network Infrastructure manual in the SAP Service Marketplace under alias TI (technical infrastructure):
http://service.sap.com/ti
There are the following different installation scenarios for the SAP Web Application Server.
Server
There are the following installation options on the server side:
ABAP + J2EE add-in
The scenario of an
SAP System that can run Java and ABAP applications is described in 
SAP Web Application
Server with ABAP and J2EE.
For large
installations with several SAP Web AS instances, you can use the SAP Web
Dispatcher, to have a defined access point for your system and to
implement load balancing.
J2EE only
You want to use
the SAP Web AS for J2EE applications in productive operation. The architecture of such a system is described
in the Architecture
Manual.
Development Environment: SAP NetWeaver Developer Workplace
You can install the following components:
· SAP NetWeaver Developer Studio
· J2EE-only Server (without cluster)
Features
The documentation contains the following information:
SAP Web Application
Server with ABAP and J2EE
Load Balancing Between
Many J2EE Instances