You are right that multicast can only be used with OSD, but not provisioning. This is because multicast with OSD is an automated process where the coreserver (or PXE rep) will reboot managed machines into WinPE, who will report to the Core Server and the core server consequently sending out the targeted multicast.
You have 2 mechanisms that you help you here though, if you want to provision a large amount of machines in the shortest possible time:
- You could send out the image using targeted multicast to a secondary partition, if there's enough space. Then use provisioning to deploy this image to the first partition and perform any additional configuration / actions (either within WinPE or post OS configuration).
- You can use the PXE holding queue, in order to lower the network load.
From Configure > Services > OS Deployment, add a PXE representative from the Available proxies list to the Holding queue proxies list
The PXE representative will then place the computer in the holding queue. The computer boots, will start in managed WinPE and will enter the queue.
Once in the queue, the computer will do nothing until an OS Deployment task is assigned and run. Multicast is available here, so the image needs to be sent only once per subnet.
You can use PXE holding queue + multicast to effectively distribute images. Then use a regular distribution method to deploy the machines that previously failed (eg. where no 2nd partition with enough space to hold the image is available).