Tag Archives: computer-network

Windows Vista Network Tip

The user known as “alpha” emailed me the following excerpt from Tim Anderson’s ITWriting:

The Microsoft Windows Vista OS enables the TCP Window Scaling option by default (previous Windows OSes had this option disabled). The TCP Window Scaling option is described in RFC 1323 (TCP Extensions for High Performance), and allows for the device to advertise a receive window larger than 65 K than TCP originally specified. This is useful in the higher speed networks of today, where more data can be outstanding on the wire before it is acknowledged. This slow performance, or dropped TCP connections is caused by some versions of Cisco IOS® Firewall software not supporting the TCP Window Scaling option. This causes it to have a much smaller TCP window than the endpoints actually have. This causes the Cisco IOS router that runs the IOS Firewall feature set to drop packets that it believes are outside the TCP window, but which really are not.

So, through many firewalls, many protocals fall apart. And here is a solution, that worked perfectly for me, and several of my clients clients. Drop to a command prompt and run:

netsh interface tcp set global autotuninglevel=disabled

If the command returns this response, “Set global command failed on IPv4 The requested operation requires elevation”, then you need to do this: Click start (windows symbol), Accessories, right click on “Command Prompt”, then choose “Run as Administrator”, then try the netsh command (above) again.

And appended the following:

Which could be why a number of people have experienced poor net connections since moving to vista. While this isn’t directly vistas problem (tho the enabling of non-standard things by default is a boneheaded manuvour) it does show how the tech world has steadfastly refused to take note of the changes that came with the new flavour of MS’s operating system, as well as highlighting the failure to implement any kind of feature check within the OS itself too… wouldn’t it be cool if windows reported these problems to you “windows has detected a problem with your networking, click here to load standard protocal settings, click here to do nothing and not bother you again with this message”. And that last part “click here to no bother you with this message” is something I am dieing to have because I’m fed up of having my computing interrupted by crap that I already know about because I just clicked on the button to do it!!

Oh how I wish the “pro” versions of their software was actually designed with the pro in mind!