what is the IO path from VM(in ESX) to the VVOLS(in storage container) via PE?

Hi,

     I am new in implementing vvols and I have a query in regard with IO communication between a VM (in ESX) and to its specific vvol(in storage container) via PE . Is it one PE per vvol or one PE per storage container(iSCSI or NFS)? Please do explain 1:1 mapping of VM to vvol via PE?