Hi Sam, I have resolved my issue! The NICs on the Host are unable to take a value of > 9000 for the JumboPackets in the Registry. Setting them to 9014 did not work - as they must have reverted to using 1500 (even though the registry value remains at 9014) Therefore if I set the registry value to 9000 for eah NIC - the Ping command works. Regards Simon
I am trying to setup Jumbo Frames on my Virtualised System. To do this I have done the following: 1) Enable Jumbo Frames on my Dell MD3220i SAN by checking the "Enable jumbo frames" box for each port and setting the MTU value to 9000. 2) Enable Jumbo Frames on my iSCSI switch (Dell PowerConnect 7024) by setting the "Maximum Frame Size" to 9216 on all ports. (I then power cycled the Switch and confirmed that the settings had saved) 3) Enable Jumbo Frames on my Host (Hyper-V Server 2008 R2 Core OS) by using the following command on each NIC: netsh interface ipv4 set subinterface "Adapter Name" mtu=9000 store=persistent I also edited the registry to update the *JumboPacket key to 9014 on all relevant NICs I then rebooted the host for the changes to take effect. To test my configuration - I used the standard ping command to attempt to ping the SAN (192.168.130.101) from the Host (192.168.130.3). The results I got are: ping -f -l 1472 192.168.130.101 (This is ok - and I get a standard reply) ping -f -l 1476 192.168.130.101 (This is ok - and I get a standard reply) ping -f -l 1477 192.168.130.101 (This is bad - I get a "Request timed out.") ping -f -l 8972 192.168.130.101 (This is bad - I get a "Request timed out.") ping -f -l 8973 192.168.130.101 (For this I get "Packet needs to be fragmented but DF set.")   I am pretty sure this means that the Jumbo Frames config is not working - but I am fresh out of ideas. Any help will be much appreciated.
Enabling Jumbo Frames on MD3220i SAN