VMware ESXi – Test Jumbo Packets using VMKping

So first off we need to setup Jumbo frames in a few places.

  • ESXi host
  • Switch the ESXi host and Storage is plugged into
  • Storage device

As per VMware ESXi 5.0 and above, you need to also setup iSCSI Port Binding.

Ensuring its setup correctly

On your host, you need to setup Jumbo frames on the vSwitch used for storage connectivity, and the VMkernels you have created.

2014-09-25_11-52-05 2014-09-25_11-52-17 2014-09-25_11-52-28 2014-09-25_11-53-00

On your switch you need to enable Jumbo frames.

On HP switches, you do this at the VLAN Level,2014-09-25_11-53-42

Or on Cisco switches, this can be done at the interface level2014-09-25_12-07-54

Check your manuals and online first for your switch though.

And finally check your storage device, on the Nimble its simple, as you set it against the data connection.


How to test Jumbo frames using VMKping

On your ESXi host, log in via SSH, and the command is going to be;

vmkping -I [vmkernel] -s [byte size] [Destination IP]

Below is the full output of the functions you can use and we need to ensure that we use the correct case when specifying the functions, as you can see;

  • -s = Specify byte size
  • -S = Network stack to debug

I’ve highlighted the functions we are using today.


So now for the simple bit, using the commands above to ping your Storage controllers IP. Below is screenshot for you to identify your VMKernel port.


And heres my output when I’ve used it for my latest project




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