I mentioned in ESXi Lessons Learned 2 that Jumbo Frames were not supported for the VMkernel. It seems that it’s a mistake in the ESXi Config Guide as mentioned in this blog article on the VMware ESXi Chronicles Blog. Charu already contacted me about it but we needed to wait to update you guys before we received the definitive green light.
I am happy to say that this is merely an error in the documentation. In fact, ESXi 4.0 DOES support Jumbo Frames on VMkernel networking interfaces. The correction will hopefully appear in a new release of the documentation, but in the meantime, go ahead and configure Jumbo frames for your ESXi 4.0 hosts.