An Update on Windows TCP AutoTuningLevel

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    An Update on Windows TCP AutoTuningLevel


    Posted: 12 Aug 2016
    Like all modern operating systems Windows has receive window auto-tuning to dynamically adjust the receive buffer size to the throughput and latency of the link. Disabling this feature will definitely limit your Internet speeds. Auto-tuning is consistent throughout all variants of TCP and present in all modern operating systems. In the modern Internet the range of latencies and throughput speeds that must be accommodated is simply too large to manage statically and must be adjusted dynamically. If you have changed your AutoTuningLevel to disabled, please reset it to normal in order to restore your Internet speeds using the following commands in an elevated command prompt:


    PS C:\WINDOWS\system32> netsh int tcp set global autotuninglevel=normal
    Ok.

    PS C:\WINDOWS\system32> netsh interface tcp show global
    Querying active state...

    TCP Global Parameters
    ----------------------------------------------
    Receive-Side Scaling State : enabled
    Chimney Offload State : disabled
    NetDMA State : disabled
    Direct Cache Access (DCA) : disabled
    Receive Window Auto-Tuning Level : normal
    Add-On Congestion Control Provider : none
    ECN Capability : disabled
    RFC 1323 Timestamps : disabled
    Initial RTO : 3000
    Receive Segment Coalescing State : disabled
    Non Sack Rtt Resiliency : disabled
    Max SYN Retransmissions : 2
    TCP Fast Open : enabled

    Some of the confusion may have originated from a misinterpretation of a blog post which suggests disabling heuristics with the following command:

    Code:
    netsh interface tcp set heuristics disabled

    Heuristics is a feature that can interfere with auto-tuning and disabling it can improve Internet speeds and in fact heuristics have already been disabled in Windows 8.1 and greater. Auto-Tuning on the other hand should NEVER be disabled.


    Source: An Update on Windows TCP AutoTuningLevel | Networking Blog
    Brink's Avatar Posted By: Brink
    12 Aug 2016



  1. Posts : 20,583
    Win-7-Pro64bit 7-H-Prem-64bit
       #1

    Hi interesting is this good or bad lost in Caveman English translation :)
    An Update on Windows TCP AutoTuningLevel-default.jpg
      My Computer


  2. Posts : 15
    Windows 7 Ultimate x64 / Linux Mint 19 MATE VM
       #2

    OK, here is mine:

    Microsoft Windows [Version 6.1.7601]
    Copyright (c) 2009 Microsoft Corporation. All rights reserved.
    C:\Windows\system32> netsh int tcp set global autotuninglevel=normal
    Ok.

    C:\Windows\system32>netsh interface tcp show global
    Querying active state...
    TCP Global Parameters
    ----------------------------------------------
    Receive-Side Scaling State : enabled
    Chimney Offload State : automatic
    NetDMA State : enabled
    Direct Cache Acess (DCA) : disabled
    Receive Window Auto-Tuning Level : normal
    Add-On Congestion Control Provider : none
    ECN Capability : disabled
    RFC 1323 Timestamps : disabled
      My Computer


  3. Posts : 4,776
    Microsoft Windows 7 Home Premium 64-bit 7601 Multiprocessor Free Service Pack 1
       #3

    Related reading material:

    SG :: Windows 7, Vista, 2008 Tweaks

    Here's what I see for default windows settings:

    An Update on Windows TCP AutoTuningLevel-tcp-autotuninglevel.jpg

    Here's settings I've always used:

    An Update on Windows TCP AutoTuningLevel-tcp-autotuninglevel-2.jpg

    Here's what the command shows:

    An Update on Windows TCP AutoTuningLevel-tcp-autotuninglevel-3.jpg
      My Computer


  4. Posts : 20,583
    Win-7-Pro64bit 7-H-Prem-64bit
       #4

    I see now they were showing win-8.. and 10 settings
    An Update on Windows TCP AutoTuningLevel-win-7-left-win-8.1-right.png
      My Computer


  5. Posts : 1,167
    W10 32 bit, XUbuntu 18.xx 64 bit
       #5

    Curious does this do anything? Saw that in the link.

    Code:
    netsh interface tcp set heuristics disabled
      My Computer


  6. Posts : 72,043
    64-bit Windows 11 Pro for Workstations
    Thread Starter
       #6

    groze said:
    Curious does this do anything? Saw that in the link.

    Code:
    netsh interface tcp set heuristics disabled
    Hello groze, :)

    That would disable heuristics, but it's disabled by default.

    Heuristics is a feature that can interfere with auto-tuning and disabling it can improve Internet speeds and in fact heuristics have already been disabled in Windows 8.1 and greater.
      My Computer


  7. Posts : 111
    Windows 8 Pro x64
       #7

    Brink said:
    groze said:
    Curious does this do anything? Saw that in the link.

    Code:
    netsh interface tcp set heuristics disabled
    Hello groze, :)

    That would disable heuristics, but it's disabled by default.

    Heuristics is a feature that can interfere with auto-tuning and disabling it can improve Internet speeds and in fact heuristics have already been disabled in Windows 8.1 and greater.
    I went ahead and ran the command on my Windows 8 box.
      My Computer


  8. Posts : 1,167
    W10 32 bit, XUbuntu 18.xx 64 bit
       #8

    On mine it shows enabled on windows 7 sp1

    Code:
    C:\Windows\system32>netsh interface tcp show heuristics 
    TCP Window Scaling heuristics Parameters
    ----------------------------------------------
    Window Scaling heuristics         : enabled
    Qualifying Destination Threshold  : 3
    Profile type unknown              : normal
    Profile type public               : normal
    Profile type private              : normal
    Profile type domain               : normal
      My Computer


  9. Posts : 72,043
    64-bit Windows 11 Pro for Workstations
    Thread Starter
       #9

    groze said:
    On mine it shows enabled on windows 7 sp1

    Code:
    C:\Windows\system32>netsh interface tcp show heuristics 
    TCP Window Scaling heuristics Parameters
    ----------------------------------------------
    Window Scaling heuristics         : enabled
    Qualifying Destination Threshold  : 3
    Profile type unknown              : normal
    Profile type public               : normal
    Profile type private              : normal
    Profile type domain               : normal
    Yep, it's only disabled by default in Windows 8.1 and greater.
      My Computer


 
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