Use the Relay Server documentation to further understand how to use Relay Server to support clustering in an Unwired Platform environment.
This System Administration Guide for Unwired Platform, gives some overview and context for administrators who want to install and configure Relay Server in a production environment, as opposed to using the hosted service used by development/test environnments. However, for complete details, read the Relay Server User Guide.
If you are viewing this guide as a PDF, you can locate the referenced document at http://infocenter.sybase.com/. Go to Sybase Unwired Platform 1.5.2 > System Administration for Unwired Platform > Environment Setup > Relay Server Setup > Relay Server Documentation to launch this PDF.