First, well done. Making HII images within 2 months of using DS is pretty good! So, you've done the hard part. The easy part is deployment - DS natively and transparently can handle the multicast if you let it.

To explain, when you drop an imaging job onto a bundle of computers (say 10 for the sake of argument) Delployment Server will select from one of those clients the master. It then sends the image to this machine, which then multicasts that image data to the rest of the computers. The trick in all this is understanding that there is a multicast threshold. This threshold defines the minimum number of computers which must be simultaneously imaged in order for the multicast engine to be invoked.

I think the default the threshold is 4, and this can be tweaked using the Deployment Server Configuration program (under Start-Menu -> Programs -> Altiris -> Deployment Server). Once in the Deployment Server Configuration Utility, click the Options button and you can configure within the Disk Imaging tab your threshold.

In order for this threshold to kick-in, you must use the Deployment Server 'Distribute Disk Image' tasks. Just select your image within the task wizard (don't try to override with extra switches) and then everything should just work.

Kind Regards,
Ian./

 This could be many things i'm afraid, so here are some pointers...

1. Is this reproducible? If you initiate the job again do you get the same results. Your imaging downturn might be due to load on the server (full AV scan / backup in progress?), or a drop in bandwidth due to QoS implementations on other network services or other network 'glitch'
    
2. What happens is you try imaging in different automation environments (you have the choice of DOS/Linux/WinPE). If you have a discrepancy it might be driver related in which case a driver upgrade might help
    
3. In the past i've seen switch auto-negotiation issues on ports which can lead to terrible imaging speeds. Might be worth logging into the switches and confirming the ports are set to the correct speed (100/1000) and that they are full duplex. The fact that you imaging starts off being fast though lends me to think that the negotiation is OK. Worth double-checking though.
    
4. You might have a badly performing machine. Do you have any deep suspicions about any of the hardware you are imaging. DS should drop computers from multicast sessions if they hold up imaging, but might be worth trying to remove any computers you are suspicious of from the imaging pool.

As an aside, if you are multicasting to deploy public area/lab computers (and thus intend to do this frequently) its worth perhaps looking into storing the image locally on the client computer's harddisks. Imaging will be super fast then!

Kind Regards,
Ian./