Understanding network speed in VM's

[Brandon7a]

I have an EMC CX300 Fibre Channel SAN with 4 ESX 3.5 hosts. I am running VI3 on my vCenter server. When I copy GB of files between 2 VM's, what determines the rate of transfer? I would like to know what causes the rate of transfer when the VM's are located on the same host and the rate of transfer when the VM's are located on different hosts.

Thanks 

[weinstein5]

When they are on the same host connected to the same virtual switch the network traffic remains internal to the host and performance is improved. While on different hosts the traffice will traverse the physical network and be exposed to the issues of an IP network including contention.