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I just switched my VM's to the paravirtualized NICs from the E1000 in attempt to squeeze a bit more performance out of my VMs. It seems like there is a bit better network response using them. I've had a few odd issues with them so far and was wondering if that was normal for this interface or not.

Host: Win 7 X86 with 2 NICs - one on the company LAN and one on an outside line to the internet
Guests: Win XP and Win 7, 2 NICS, one each bound through a bridged network to each physical NICs

Typically I just uncheck the "cable connected" selection of the virtual NIC that I don't want active. I sometimes switch from the LAN to the internet by unchecking one and checking the other NICs "cable connected" selection. This worked fin in the E100 but the paravirtual NICs act weird.

When the cable connected box is UNchecked the virtual NIC will still show as connected and assign a PIP address, on the E1000 it would show as disconnected.

Sometimes the guest will just NOT grab an IP and bind to the physical adapter, I have to shut down guest then host and it will typically come up the next time. NIC show the "limited" networking warning in Win 7 and a PIP address sin Win XP even though the "cable connect" is checked.

I can get by with this behavior but it takes a bit more tweaking then when I used the E1000 virtual adapter type.

Anyone else see this type of weirdity on the paravirtual NICs?

Yes, I have noticed that toggling the "Cable connected" checkbox on a virtio-net "adapter" does not always have the same effect it does on other adapters (I used to use this trick to force a renewal of an IP lease when bridged to a wireless NIC, but with virtio it didn't always work). I assumed this was because simulating physical features was not a goal of this adapter, and didn't bother myself too much about it.