I believe you cannot do multicasting with WinPE (and possibly Linux) only DOS

@g00ner:  MultiCasting in Linux works just fine.

@DTCPP:  Make sure there isn't anything in the network that would prevent multicasting.  Some networks are set up to prevent multicasting (or broadcast storms).  You might check with your networking group to make sure nothing like that is set up on your switches/routers.

 Thanks guys. I am going to setup Ghostcast as a test to see if this is a network issue or not. Our networking team tells me everything should be working correctly.
I will post again once I know more.

WinPE does support multicasting and is our preferred option here.  However, remember that multicasting doesn't work well with seperate VLAN environments.

 Thanks for correcting me Palvaran,

Looks like it is only the PXE part of the process that does not support multicasting, see Altiris KB Article 17890 "WinPE is not capable of receiving the PXE boot file via multicasting"

 Hi DTCPP,

For your troubleshooting, just remember that when multicasting the image is send from the server to the computer nominated as the multicast master by DS. The other computers should then hunt as mutlicast 'slaves' to join the master session.

This means that if all your destination computers for multicast are on the same switch, then this should proceed without a hitch. I'd try (if possible) this scenario first. If you imaging endpoints span multiple switches without IGMP snooping you'll certainly end up with a lot of unicast sessions.

But, so we can get a better idea  of what isn't happening, can you explain exactly what you are doing, and what is happening on the clients?