process flow of offhost backup via data mover

Hi All,

I have a query about the off host backup via data mover.

As per doc http://www.symantec.com/docs/HOWTO50658 it says that client passes some information about how data is mapped and rest is being done by backup agent.  In this case media server is data mover

My question is what data is being sent by client and does bpbkar process should run on backup agent  and client both or it will still run only on  client.