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Server 2012R2 Broadcom 1Gb NIC transfer speeds dropping to below 20Mb/sec

Hi Experts,

I have done a clean install upgrade on a Dell Poweredge R420 from Server2008R2 to Server2012R2 Hyper-V but my data transfer over the LAN is struggling.  Before the upgrade I was able to transfer at around 111Mb/sec.  Now, it will start out at around the same 111Mb/sec but after a minute or two it drops down to an average of around 15 - 20Mb/sec.  Some research has recommended updating the drivers on the Broadcom NetXtreme NICs to the latest.  I have done so but no improvement.  The only thing I can think of is that I have my 2 NICs in a teamed LAN setup.  I am thinking of unteaming them to see what the speed is like on a single NIC (in the middle of a large VHD transfer at the moment so can't try it yet).  I've also updated the PERC controllers firmware and drivers just in case.

It's definitely a software issue as I was able to transfer off the same hardware prior to the OS upgrade with no issues.  

Just to be clear I am transferring from one LAN host to another, there are no VMs involved at this point.

No AV on the host either.

Any suggestions would be very welcome.
Avatar of Tony Giangreco
Tony Giangreco
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I've had the same problem in a teamed setup using a Dell 2950. After breaking the team and disabling the 2nd network adapter, it worked much better.

Hope it helps!
Avatar of Philip Elder
Broadcom Gigabit NICs have VMQ (Virtual Machine Queues) turned on by default for all ports.

Here's why that setting needs to be disabled: Broadcom Gigabit and VMQ.

Please disable VMQ on _all_ Gigabit ports and reboot.

Things will settle down after that.
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Solution was a separate issue not part of the question.