Ethtool on VMWare

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I'm trying to determine the speed of my ethernet uplinks using ethtool on my VM (a VMware ESX Server).

Running the command gives the following output:

~> ethtool eth0
Settings for eth0:
    Current message level: 0x00000007 (7)
    Link detected: yes

This obviously doesn't contain the information I'm looking for, that would be displayed on a non-VM machine. Is it possible to use this command to determine uplink speed on VMWare VMs?

Thanks, Paul

vmware-esx
ethtool
asked on Server Fault Dec 3, 2009 by Symmetric

3 Answers

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That looks like you used the "flexible" adapter type in the VM configuration, which looks like the AMD PCnet32 ethernet controller which uses the pcnet32 driver. If you create your VM with a different adapter type, e.g. e1000, you will get the e1000 driver which will give you more useful ethtool output.

answered on Server Fault Dec 3, 2009 by Shannon Nelson
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I've seen inconsistent correspondence between reported link speed and actual bandwidth in VMware. I'd suggest using something like iperf to get a measured result.

answered on Server Fault Dec 3, 2009 by xenny
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The NIC in the VM is connected to a software switch which only then in turn uplinked to physical ports - you'll never get a real speed although you can get the uplink speed via the VM SDK tools.

answered on Server Fault Dec 3, 2009 by Chopper3

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