nic configuration on a linux virtual machine (rackspace)

Question

I am trying to check my nic speed and duplex setting on a vm I have at rackspace. It is centos 6.4.

When I run:

# ethtool eth0
Settings for eth0:
    Link detected: yes

This is all I get back.

When I run mii-tool, I get an error:

mii-tool eth0
SIOCGMIIPHY on 'eth0' failed: Operation not supported

score 3 · Accepted Answer · answered Jul 12 '15 at 17:57

3

That is completely expected when you're running those commands from within a VM.

Rather than completely emulating a physical NIC your hypervisor is offering a paravirtualised network adapter which, with a compatible driver for the VM, offers much more performance with lower overhead.

You don't have a real network card and therefore you can't manipulate it as if it were. There simply is no link speed and there are no duplex settings for the VM, all of that if off-loaded to the hypervisor.

I'm not certain if Rackspace is using KVM virtio technology or using Xen but the concept is the same.

answered Jul 12 '15 at 17:57

HBruijn

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Rackspace Cloud is running Xen – QuentinMoss Jul 12 '15 at 20:42
Ok, thanks, so how do you figure out the speed & duplex you are getting? – Joelio Jul 13 '15 at 00:11
From the product specs and measuring/benchmarking e.g. with https://iperf.fr/ - – HBruijn Jul 13 '15 at 06:38

nic configuration on a linux virtual machine (rackspace)

1 Answers1