Network within one vSwitch

[Andy90]

At the moment, I am thinking about the following thing:

VM (A) and VM (B) are connected to the same vSwitch.

Which bandwidth can be reached, when you copy data from VM (A) to VM (B) within the same vSwitch?

Normally, this transfer doesn't go over the physical network interface of the ESX-Server, or?

Does there exist any limits for the bandwidth between two VMs (connected to the same vswitch) from the OS (windows Server 2008 R2) or is there a limit of the vswitch (i.e. 1 GByte?)

Does some one has any experience with this?

[Tsjo]

Hi there,

can't say what bandwidth can be reached but if both VMs are connected to the same vSwitch the traffic is routed locally without the use of an physical nic.

Bandwidth limit may occur depending on which network driver your VM is using, for example using vmxnet instead of e1000 usually improves performance.

[rickardnobel]

Andy wrote:

Does there exist any limits for the bandwidth between two VMs (connected to the same vswitch) from the OS (windows Server 2008 R2) or is there a limit of the vswitch (i.e. 1 GByte?)

No, there is no limit and the actual bandwidth will be a combination of the performance of the physical server hardware and the quality of the TCP/IP stack inside the guest operating systems. I have seen, at least in tests, VMs getting somewhere near 20 Gbit/s inside. This was some Linux distribution together with iPerf network load tool.