Monitoring Network Usage
vCenter Server's charts provide a wonderful tool for measuring the network usage of a VM or a host.
Monitoring network usage requires a slightly different approach than monitoring CPU or memory. With either CPU or memory, reservations, limits, and shares can dictate how much of these two resources can be consumed by any one VM. Network usage cannot be constrained by these mechanisms. Because VMs plug into a VM port group, which is part of a vSwitch on a single host, how the VM interacts with the vSwitch can be manipulated by the virtual switch's or port group's policy. For instance, if you need to restrict a VM's overall network output, you would configure traffic shaping on the port group to restrict the VM to a specific amount of outbound bandwidth. Unless you are using vSphere Distributed Switches or the Nexus 1000V third-party distributed virtual switch, there is no way to restrict VM inbound bandwidth on ESXi hosts.
