Hello, Xen Fans, Clients, Partners, and Fellow Citrites!

This blog is intended to address (and answer) a common question that is asked of support: “Is there anyway to make a VMs network interface run higher than 1GiB?”

The question is completely understandable – especially on a Windows VM – where the VMs are leveraging bare-metal network cards with 10GiB capabilities.  The VM is stood up, PV tools are installed, and poof: the OS reports their virtual NIC  (or multiple, virtual NICs) as being “1 GiB” capable.

In reality, this is a hard coded value from the PV drivers and why the OS reports the maximum speed of the interface as such.

Digging further into reality, this is only what is being “displayed” and not what the VM’s virtual NICs are capable of: this is explained in each release within the Guest.pdf documentation we offer.

For XenServer 6.2, specifically, this document can be found at  http://support.citri…04221/guest.pdf and under Appendix A, the explanation of the network speed advertised is broken down for you.

So, if you have 4 10GiB NICs you are leveraging for VMs that state their virtual NICs are only 1GiB capable, rest assured this is not the case!  As with all networking, QoS settings, and design: the bandwidth available is what will be used by networked devices (virtual or real) for TCP related operations.

*** Edit ***

Thanks to an invaluable XenServer resource – you know who you are – I was reminded of a scenario I had forgotten!

In a configuration where XenServer has bonded 10 GiB NICs for VM traffic (VIFs), the PV drivers in Windows can advertise a speed of 2 GiB.  This is due to the fact that the underlying speeds of the physical network are detected during PV driver install and, again, hardcoded as the visual “maximum speed value” for virtual NICs.

This references http://discussions.citrix.com/topic/351069-xenserver-62-10gb-ethernet-and-rss/

*** End Edit ***

And this is from my virtual desktop to you!