How to determine if TCP Chimmney Offloading is working

Posted on 9. June 2008 by Bennett

The TCP Chimmney Offload feature was introduced in Windows Server 2003 SP2.  It can offload certain functions from the OS to the network adapter card.  A lot of our newer HP Servers have a Broadcomm Ethernet chipset that supports this function.   It isn’t without its issues.  To determine if it is in use you can run the netstat –nt command like this:

C:\>netstat -nt

 Active Connections

   Proto  Local Address          Foreign Address        State           Offload State
  TCP    192.168.4.97:445        192.168.4.13:2167       ESTABLISHED     InHost
  TCP    192.168.4.97:1433       192.168.4.95:3560       ESTABLISHED     InHost
  TCP    192.168.4.97:1433       192.168.4.95:3617       ESTABLISHED     InHost

The last column shows the offload status.  In this example the offload state is shown as InHost for all connections, so TCP offload is not enabled.

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