Naoken Blog

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Article Summary: This article provides information on configuring jumbo frames in a Server Core installation of Windows Server 2008 with Broadcom network adapters

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Jumbo frames are Ethernet frames (packets) capable of carrying more than 1500 bytes of data, typically up to 9000 bytes. They are commonly utilized in iSCSI networks to improve performance but can be used in other network scenarios as well. Configuring jumbo frames in a Server Core installation of Windows Server 2008 requires a netsh command and registry modification.

1. To configure Windows to accept jumbo frames on the network adapter, type the following at an elevated command prompt:
   
   netsh interface ipv4 set subinterface "Local Area Connection" mtu=<MTUSetting> store=persistent
   
   In this command, "Local Area Connection" (which must be enclosed in quotes) represents the name of the network adapter you wish to modify. MTUSetting is usually set to 9000 for jumbo frames but can vary depending on the network infrastructure.
   
   To confirm the settings, type the following:
   
   netsh interface ipv4 show subinterfaces

2. If you are still unable to connect using jumbo frames, you will need to edit the registry as follows:
   1. Open Registry Editor and find HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E97D-E325-11CE-BFC1-08002BE10318}.
   2. Search for MTU.
   3. There will be one or more registry keys that will contain a REG_SZ value named MTU, as shown below. Change all of these from 1500 to 9000:
      
      
      
      Note: This image was taken from a PowerEdge R710. The numbers of the registry keys will not always be 0037-0040. For example, on a PowerEdge R905 used for testing, the corresponding numbers were 0065-0069.

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