Skip navigation, view page content (access key = C)

Begin OSU masthead and toolbar

The Ohio State University
www.osu.edu
  1. Help
  2. Campus map
  3. Find people
  4. Webmail

Ohio State University logo Office of Information Technology Technology Support Center (8help)

Vista: TCP window scaling not compatible with some network hardware.



There is an incompatibility between Microsoft Windows Vista and some network equipment. Equipment possibly affected includes: Routers, VPN Endpoints, and Firewalls that use Stateful Packet Inspection (SPI).

Among most commercial firewalls that utilize Stateful Packet Inspection, the OSU Fire Marshall is one that is affected by this issue.

The problem has to do with the TCP window resizing feature in Vista and Stateful Packet Inspection. Possible symptoms exhibited include:

  • Web traffic works OK
  • Email through client software sends but will not receive or times out when downloading messages (POP or IMAP)
  • Slow or no network file server access.
  • Other random network timeouts or connectivity problems.
  • Slowness or freezing in web browsing or other applications including VPN connections.

To disable TCP Windows Scaling In Vista:

  1. Note: This command MUST be run as administrator
  2. Locate the Command Prompt icon/executable file under Start->Accessories
  3. Right-click on the icon and select "Run as administrator"
  4. Type:

    netsh interface tcp set global autotuninglevel=disabled

  5. Reboot the computer.
To verify the settings on the workstation, use the command:

netsh interface tcp show global

The results of this command should be: 

TCP Global Parameters
_____________________

Receive-Side Scaling State                 : enabled
Chimney Offload State                      : enabled
Receive Window Auto-Tuning Level           : disabled
Add-On Congestion Control Provider         : ctcp
ECN Capability                             : disabled
RFC 1323 Timestamps                        : disabled
To enable TCP Windows Scaling In Vista:
  1. Note: This command MUST be run as administrator
  2. Locate the Command Prompt icon/executable file under Start->Accessories
  3. Right-click on the icon and select "Run as administrator"
  4. Type:

    netsh interface tcp set global autotuninglevel=normal

  5. Reboot the computer.


Current Record: 3253

Create Date: 01-02-2007
Last Reviewed: 10-07-2007
Please give us your feedback!
Was this document helpful?  




Home

 

return to top