If you’re taking full advantage of some of the great new hardware that is out there, then you’ll need to invest in 10 Gigabit networking. 192+ GB of RAM is a lot of VMs to live migrate, backup, etc. In fact, 1 GbE is not enough to Live Migrate (or VMotion for that matter) that much RAM from one host to another in a realistic time frame.
I wish I could say that I’ve got a lot of material for you on this topic – but I haven’t the equipment. But Didier van Hoye has done the work and shared his findings on his blog. Out of the box, he found he couldn’t use the full capacity of the network. With some tuning, he got much more throughput. With the tweaks that Didier has documented, you can get the same results on Windows Server 2008 R2.
Keep in mind though that even you have a 10 Gb LAN, you might get only ~10% out of it if you have certain processor and more than 48 Gb of RAM. One of our clients spent some valuable time in finding the issue… Here is the hotfix http://support.microsoft.com/kb/2517329