For the more experienced and used to the ups and downs of IT industry, the jump from ESX4.1 to ESX5.0 represented access to a more friendly environment. The following article compares the pain of setting the MTU value of Jumbo Frames from 1500 to 9000 in ESX4.1 and the relief brought by version 5.0.
It is well known that in order to take full advantage of the Jumbo Frames support, you have to be consistent in settings all across your virtual infrastructure. This means adjusting values at the vSwitch, as well as the Storage Heartbeat VMkernel Port and iSCSI VMkernel Ports. In addition, the physical switch layer must be configured to support Jumbo Frames.
Here it is the trail of vCLI commands in ESX4.1 for a vSwitch2 example:
First, we create the vSwitch:
esxcfg-vswitch –a vSwitch2
Then, we enable Jumbo Frames on the vSwitch:
esxcfg-vswitch –m 9000 vSwitch2
Following step is to assign VMkernel port to the newly created vSwitch2:
esxcfg-vswitch –A iSCSI1 vSwitch2
Then we set up the MTU value on the vmknic:
esxcfg-vmknic –a –i 192.168.1.102 –n 255.255.255.0 –m 9000 iSCSI1
To verify the configuration enter the following command:
This will show the VMkernel ports that are assigned to the vSwitch.
Here it is the Properties window of vSwitch2:
And here it is an example for a more approachable set up of Jumbo Frames usage in ESX5:
To enable Jumbo Frames, select the vSwitch created for iSCSI connectivity and click Properties.
1. Select the vSwitch; you will see under the Advanced Properties pane on the right the MTU is defaulted to 1500. By clicking the Edit button this value can be changed to 9000.
2. Select the General tab and under the Advanced Properties change the MTU from 1500 to 9000 and click OK.
As an important note, all other components need same adjustment. Using Properties pane of the Standard vSwitch apart from vSwitch itself, the Storage Heartbeat and each of the iSCSI# VMkernel Ports must be configured on same value.
When this is complete click Close to exit out of the vSwitch Properties page.
In the end, we would like to stress out that Jumbo Frames are fully dependent on your physical infrastructure, which should be able to accommodate them.
Happy usage of ESX!