Dear Mohan,
client machine and endpoint server having hearbeat rate and sends some request from client machine to server. client machine runing with 2 main services i.e EDPA and WDP and both are complementory to each other. In case any of this service is not runing then other one restart the services. client commuincate with server on port 8000
Please refre below thread for more details
https://www-secure.symantec.com/connect/forums/dlp-clients-are-not-communicating-dlp-server-symantec
https://www-secure.symantec.com/connect/forums/endpoint-dlp-agents-installation