Network Boot - WinPE - Multicast

Hi there,

When network booting a workstation from the server, once the workstation has downloaded winpe.wim it reboots and loads winpe environment. 

What is the correct command line syntax, to join a multicast session as a client for 4 machines and then start the session on one machine as the master. I have tried multiple options / commands but cant get it working. 

img.exe --session TESTSESSION does not work 

img.exe -session name: test -address: x.x.x.x - Role: Client --- does not work. 

img.exe -session name: TEST -session address: x.x.x.x -session Role: client -- does not work 

I am looking for the exact command / syntax to start the session on one as master, and then join the session from 4 other machines as clients. 

Many thanks

Mark