How to enable and test Jumbo Frames in ESXi 5.1 and later.

Steps to enable and test Jumbo Frames:

• To enable Jumbo Frames in ESXi 5.1 and later:

  Jumbo frames for all iSCSI adapters in vSphere 5.1 can be configured using the UI. This applies to Software iSCSI,Dependent Hardware iSCSI and Independent Hardware iSCSI adapters.
   
  To enable Jumbo Frames for software and dependent hardware iSCSI adapters in the vSphere Web Client, change the default value of the MTU parameter:
  1. Browse to the host in the vSphere Web Client navigator.
  2. Click the Manage tab, and click Networking.
  3. Click Virtual Switches, and select the vSphere switch that you want to modify from the list.
  4. Click Edit Settings.
  5. On the Properties page, change the MTU parameter.
     
     This step sets the MTU for all physical NICs on that standard switch. The MTU value should be set to the largest MTU size among all NICs connected to the standard switch. ESXi supports the MTU size up to 9000 Bytes.
   
  To enable Jumbo Frames for independent hardware iSCSI adapters in the vSphere Web Client, change the default value of the MTU parameter:
   
  Use the Advanced Options settings to change the MTU parameter for the iSCSI HBA.
  1. Browse to the host in the vSphere Web Client navigator.
  2. Click the Manage tab, and click Storage.
  3. Click Storage Adapters, and select the independent hardware iSCSI adapter from the list of adapters.
  4. Under Adapter Details, click the Advanced Options tab and click Edit.
  5. Change the value of the MTU parameter.

• Testing VMkernel Jumbo Frames connectivity:

  The vmkping command sources a ping from the local VMkernel port
   
  To initiate a vmkping test from the console of an ESX Server host:
  1. Connect to the ESX/ESXi host using an SSH session
  2. Run the vmkping command with the -s and -d options.
     
     # vmkping -d -s 8972 x.x.x.x
     
  3. Also, You can specify which vmkernel port to use for outgoing ICMP traffic with the -I option:
     
     # vmkping -I vmkX -s 8972 x.x.x.x