Some of this came from this http://blogs.technet.com/b/askpfeplat/archive/2013/03/10/windows-server-2012-hyper-v-best-practices-in-easy-checklist-form.aspx

This article discusses setting up Jumbo Frames on a Hyper-V server with Windows Server 2012 using the new Hyper-V extensible switch. I setup Jumbo Frames on the Hyper-V host itself with the iSCSI, Live Migration and CSV networks. I also setup Jumbo Frames within the actual virtual machine, only if iSCSI is used at the virtual machine level. Generally the management network and LAN traffic is not included in this, as Jumbo Frames need to be enabled on every switch which is physically situated between the sender and the receiver node.

Check if jumbo frames is configured on any NICs.

Get-NetAdapterAdvancedProperty -DisplayName "Max Ethernet Frame Size", "Jumbo Packet"

Consider that the physical NIC port which is attached to the Hyper-V extensible switch is called "Ethernet 2". Setup jumbo frames by declaring DisplayName as "Jumbo Packet" or "Max Ethernet Frame Size".

Get-NetAdapterAdvancedProperty -Name "Ethernet 2" -DisplayName "Max Ethernet Frame Size" | Set-NetAdapterAdvancedProperty -RegistryValue "9216"

Check for jumbo frames on the vNICs.

Get-NetAdapterAdvancedProperty -DisplayName "Jumbo Packet", "Max Ethernet Frame Size"

Consider that your vNICs are named vEthernet (iSCSI), vEthernet (CSV) and vEthernet (LiveMigration). Run the following to setup jumbo frames on the vNICs, by declaring DisplayName as "Jumbo Packet" or "Max Ethernet Frame Size"

Get-NetAdapterAdvancedProperty -Name "vEthernet (LiveMigration)", "vEthernet (iSCSI)", "vEthernet (CSV)" -DisplayName "Jumbo Packet" | Set-NetAdapterAdvancedProperty -RegistryValue "9014"

Finally, test by running the following Ping command.

ping 10.99.1.147 -f -l 8000 -t