Gigabit not working with Hyper-V VMs (?)

windows-server-2008 networking virtualization hyper-v gigabit

6,485

I get 26 MB/s (quick test) with my 1 Gb Network through Hyper-V.

Make sure in the settings for the guest that you are not using a 'Legacy Network Adapter'. That alone will kill performance. However, to use the 'Network Adapter' instead, you will need to install integration services in the guest (supported in Windows 2008, but you'll need to update the Windows 2008 RTM install with the later Hyper-V integration services).

6,485

sfider

I'm a generalist. I solve problems, I connect things, I automate everything I touch. I have a deep background in both Dev and Ops; wearing multiple hats at the same time comes naturally to me. I'm driven by working with great people, interesting challenges and a sense of helping others.

Updated on September 17, 2022

Comments

sfider almost 2 years

So we got a shiny new 48-port switch that supports Gigabit. Between two computers, with CAT5e cables I get 20-35 MB/s, which I guess could be improved even more with CAT6 cables. But for some reason, between a Hyper-V VM (also running W2008) and my computer, I only get 100 mbit/s speeds, even tho the Hyper-V host computer it is connected to the switch with a CAT6 cable and uses a Gigabit network card (and the VM uses the same). Any ideas why?

Edit: One thing that may be possible is that the traffic somehow gets routed thru our router which can only do 100 mbits. But why (would it)?
- Spence almost 15 years
  
  Category 5e cables will run gigabit Ethernet fine. You've got something other than a cabling problem wrong if you're seeing such performance.
sfider almost 15 years

"Again, when you say "100mbit speeds" do you mean the speed tops out at (but usually reaches) the speed you'd expect for a 100mbit NIC" Exactly. I use total commander for copying which shows the actual transfer rate.
sfider almost 15 years

I also tested it when there was pretty much no load on the switch.
Axel almost 15 years

If it reliably tops out at 100mbit it could be that HyperV is explicitly trying to exactly emulate a 100Mbit NIC, if that is possible (again I've not used HyperV yet myself, VMWare is my main area of expertise in the VM world). What does the guest OS report the virtual netwrok card as?