how to limit bandwidth on VMXNET3?

Hi!

Could someone tell me how can I limit bandwidth on vNIC?

I am using 10 Gig pNIC and have a VM with VMXNET3.

Is there possibilities to limit bandwidth to 500Mbps?

I also have another question:

I set speed in vNIC settings (in guest OS Windows 7) to 1 Gbps (still with 10 GbE pNIC), but write tests showed 200MBps.

How can in be?

Thanks in advance.