Don't send data to a master node. Send it to the Indexers withing the cluster. Review outputs.conf for the forwarders, and the distributed architecture of Splunk.
http://wiki.splunk.com/Community:Getting_data_into_Splunk
If you setup the output of the forwarder to output to each indexer, Splunk will auto load balance for you and send to all the configured indexers.
should I open connection and send the same data to each Indexer in a cluster?