TCP Chimney Offload Compatibility with Other Applications and Features

Updated: September 22, 2010

Applies To: Windows Server 2008 R2

When TCP Chimney Offload offloads processing for a connection, other features or applications that depend on having direct access to the connection data may not work. For instance, Netmon will not capture offloaded traffic. Other features, when enabled, may make particular connections ineligible for offload; for example, because IPsec may need to inspect all packets to enforce a particular encryption algorithm, connections covered by an IPsec policy will not be offloaded. The table below shows how TCP Chimney Offload coexists with other common programs and services.


Application or feature Compatible? Details

Windows Firewall


If Windows Firewall is configured to allow a given TCP connection, connection processing will be offloaded; however, there is a known issue in Windows Server 2008 R2 with certain firewall rules where offloaded connections are uploaded and will not be offloaded again.

Other Firewalls

Implementation specific

Some firewalls are compatible. See your firewall vendor’s documentation for details.

IPsec policy


Processing for TCP connections that are part of IPsec policy will not be offloaded so that IPsec can inspect packets to provide the desired security.

Network adapter teaming, also known as load balance and failover

Implementation specific

Some manufacturers’ network adapter teaming solutions are compatible. See your manufacturer’s documentation for details.



Network monitoring tools

Implementation specific

Some network monitoring tools will work alongside TCP Chimney Offload, but will not monitor connections whose processing has been offloaded.

Network load balancing


Cluster service


Processing for TCP connections that use the network fault tolerant driver (netft.sys) are not offloaded.

Network address translation(NAT) and Internet Connection Sharing (ICS)


If either of these features is enabled, processing for connections is not offloaded.

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