During a server implementation I was working on the network configuration and stumbled across the “TCP Chimney Offload” feature which should be disabled. So I would like to disable.
TCP Chimney Offload is a networking technology that helps transfer the workload from the CPU to a network adapter during network data transfer. In Windows Server 2008, TCP Chimney Offload enables the Windows networking subsystem to offload the processing of a TCP/IP connection to a network adapter that includes special support for TCP/IP offload processing. TCP Chimney Offload is available in all versions of Windows Server 2008 and Windows Vista. Both TCP/IPv4 connections and TCP/IPv6 connections can be offloaded if the network adapter supports this feature.
To check that run “Netstat -T” locally on the affected server and examine the output. It will look something like this…
Proto Local Address Foreign Address State Offload State
TCP Server:ldap Server.domain.com:1047 ESTABLISHED InHost
If the “Offload State” shows the value InHost this means the server is still handling the load itself (so it should be save anyway to delete this feature). If you wish to temporarly disable the “TCP Chimney Offload” you can use the command (no reboot needed):
Netsh int ip set chimney DISABLED
To disable the “TCP Chimney Offload” you need to use:
netsh int tcp set global chimney=disabled
If you wish to enable it again use the following:
netsh int tcp set global chimney=enable