Dell Emulex Family of Adapters - Manual (Page 689)

Emulex Drivers for Windows User Manual P010077-01A Rev. A
4. Troubleshooting
Troubleshooting the NIC Drivers
689
TCP Offload Failure
The following table lists common reasons why TCP offloads do not occur and their
suggested fixes.
Note: Packet sniffing applications such as Ethereal or Microsoft Network Monitor, do
not see TCP offloaded packets.
Table 4-4 Troubleshooting TCP Offload Failures
Reasons for No TCP Offload Solutions
Chimney offload is disabled on
the system. For Windows Server 2008 and Windows Server 2008 R2
To determine whether Chimney offload is enabled or disabled, at
the command line type
netsh interface tcp show global
To enable Chimney offload, at the command line type
netsh interface tcp set global chimney=enabled
To disable Chimney offload, at the command line type
netsh interface tcp set global chimney=disabled
For Windows Server 2008 and Windows Server 2008 R2
To verify whether offloading is enabled type
netstat -nt
This command displays a list of connections and their offloading
state.
Offloads are disabled for
specific ports or applications. To view any TCP ports or applications that may be configured to
disable TCP offload, at the command line type
netsh interface tcp show chimneyports
netsh interface tcp show chimneyapplications
A third-party firewall is running. The Windows firewall does not affect TCP offload, but third-party
firewalls may prevent TCP offloads. Uninstall third-party firewall
software to allow TCP offloads.
In the network properties, some
intermediate drivers prevent
offloading. Go to Network Connections > Properties and clear check boxes
for unused drivers. In particular, Network Load Balancing and some
third-party drivers prevent offloads.
IPSec is enabled. Disable IPSec.
IP NAT is enabled. Disable IP NAT.
The driver supports an Advanced
Property to disable TCP
offloading. Make sure TCP offloading is enabled.
The TCP connection uses using
IPv6. The driver supports offloading TCP connections only with IPv4.