To see the
current configuration for the autoTuningLevel
parameter, follow these steps:
|
1. |
Click
Start
 ,
click All Programs,
and then click Accessories.
|
|
2. |
Right-click Command Prompt,
and then click Run as
Administrator.
If you are prompted for an administrator password
or for confirmation, type the password, or click
Continue.
|
|
3. |
At the
command prompt, type the following command, and
then press ENTER:
netsh
interface tcp show global
The
value for the autoTuningLevel parameter is
listed as Receive Window
Auto-Tuning Level. |
The
following list includes all possible values for the
autoTuningLevel parameter:
|
• |
disabled
Fix the receive window at the default value. |
|
• |
highlyrestricted
Allow for the receive window to grow beyond the
default value, but do so very conservatively. |
|
• |
restricted
Allow for the receive window to grow beyond the
default value, but limit such growth in some
scenarios. |
|
• |
normal
Allow for the receive window to grow to accommodate
almost all scenarios. |
|
• |
experimental
Allow for the receive window to grow to accommodate
extreme scenarios.
Note The experimental
value can decrease performance in common scenarios.
This value should be used only for research
purposes. |
The TCP
receive window size is the maximum amount of received
data in bytes that can be buffered at the same time
on the receiving side of a connection. The sending
host can send only that amount of data before waiting
for an acknowledgement and for a receive window
update from the receiving host. The TCP/IP stack in
Windows Vista tunes itself in most environments by
using larger default window sizes than in earlier
versions of Microsoft Windows. Instead of using a
hard-coded default receive window size, TCP
automatically adjusts the window size to increase the
percentage of full-sized TCP segments that are used
during bulk data transmission. This helps limit the
number of segments that are sent when large sets of
data are transmitted. When auto-tuning is enabled in
Windows Vista, Receive Window Auto-Tuning continually
determines the optimal true receive window size by
measuring the bandwidth delay product and the
application retrieve rate. Then, Receive Window
Auto-Tuning adjusts the maximum receive window size
based on the changing network conditions.
