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Monitoring TCP Chimney and Virtual Machine Chimney

Updated: September 22, 2010

Applies To: Windows Server 2008 R2

This topic provides a reference of commands and tools you can use to check the operational status of TCP Chimney Offload. If you are using Virtual Machine Chimney, using these diagnostic commands and tools on the management operating system shows the status of TCP Chimney Offload only for the management operating system, not for virtual machines. Run the commands from within the virtual machine operating system to return TCP Chimney Offload information for the virtual machine.

You can use the netsh interface tcp show global command to check whether the operating system has TCP Chimney Offload enabled, disabled, or in default mode. For more information about operating system modes for TCP Chimney Offload, see Using TCP Chimney Offload. For more information about changing the operating system mode, see Using Netsh Commands to Enable or Disable TCP Chimney Offload.

  1. To open an elevated Command Prompt window, click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.

  2. At the Command Prompt, type netsh interface tcp show global, and then press ENTER.

    The command returns a table of TCP Global Parameters.

  3. Note the value of the Chimney Offload State (automatic, enabled, or disabled).

When the operating system status of TCP Chimney Offload is enabled or automatic, you can use the netsh interface tcp show chimneystats command to view the status of TCP Chimney Offload for each of the adapters connected to the operating system. This provides a “snapshot” of TCP Chimney Offload operation. When you use the command without specifying a network identifier (Idx), this command can be useful for identifying network adapters that are not correctly enabled for TCP Chimney Offload and for viewing general information about offload effectiveness. When you use the command with a network identifier, it provides more detail about TCP Chimney Offload operation for that particular network connection.

  1. To open an elevated Command Prompt window, click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.

  2. At the command prompt, type netsh interface tcp show chimneystats and then press ENTER.

  3. The command returns information for each network adapter recognized by the operating system. Evaluate the results using the guidance in the command output.

  1. To open an elevated Command Prompt window, click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.

  2. At the command prompt, type netsh interface tcp show chimneystats Idx, where Idx is the network identifier of the network whose statistics you want to check, and then press ENTER.

Use the netstat -t command to find out which of the currently established TCP connections on the system are being offloaded.

  1. To open an elevated Command Prompt window, click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.

  2. At the command prompt, type netstat –t, and then press ENTER.

You can use Windows Performance Monitor to view how TCP Chimney Offload is performing, both in real time and by collecting log data for later analysis. For more information about using Performance Monitor and performance counters, see Using Performance Monitor on Microsoft TechNet.

Four performance monitor counters were added in Windows Server 2008 R2.

noteNote
Performance counters for TCP Chimney Offload are available in the Per Processor Network Interface Card Activity group under Available counters when you create a new data collector. A counter is available per network adapter and per processor. Select Instances of selected object under Available counters to view a different adapter.

TCP Chimney Offload performance counters

Performance counter Description

TCP Offload Receive Indications/sec

The average rate, in incidents per second, at which the Windows Network Driver Interface received a TCP offload call from a network interface.

TCP Offload Send Request Calls/sec

The average rate, in incidents per second, at which the TCP/IP protocol requested a TCP offload transmission on a network interface.

TCP Offload Receive Bytes/sec

The average rate, in bytes per second, at which TCP offload data was delivered by a network interface.

TCP Offload Send Bytes/sec

The average rate, in bytes per second, at which TCP offload data was delivered to a network interface.

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