Optimize and Increase BitTorrent (BT) Download Speed in Vista
Windows Vista, like Windows XP SP2 or XP SP3, has also limit the number of concurrent simultaneous half-open TCP connections or sync packets that the system can establish at any one time. To make thing worse, the TCP/IP network protocol stack in Windows Vista has been rewritten so that Vista can auto adapt and optimize network settings according to network connection configuration. The changes to Vista networking may make peer-to-peer downloading and uploading such as BitTorrent (BT) network crawling at slow speed.
P2P users using BitTorrent client such as uTorrent, BitComet, ABC, Azureus, or eDonkey network client such as eMule resorts various workarounds in order to speed up the torrents download speed. Other than the usual port forwarding in router, firewall setting to unblock the BT client or other P2P client, and tweaking of options in the client itself, some users use patched tcpip.sys that remove the half-open connection limit imposed by Microsoft.
If you don’t want to modify or patch the the tcpip.sys of the system, here’s another workaround which you can try if the change will solve the slow download problem and increase the P2P BitTorrent or ED2K download speed.
By default, Vista enables Receive Window Scaling and uses a RWIN (TCP/IP Receive Window) of 256 bytes with a scale factor of 8 (256^2*8=64K bytes) when performing the handshake, which allows the maximum size of RWIN at 16,776,960 bytes. Some older routers, switches, servers or network equipments do not negotiate the scale factor, and will always communicate with a RWIN of 65536 bytes. Thus in when Vista connects with 256 bytes RWIN, the connection speed will have slow start or dropped automatically.
The following command will set the TCP Auto Tuning feature to highly restricted, which allows the TCP/IP window to grow beyond its default value, and instructs Vista to use RWIN of 16,384 bytes with a scale factor of 2 (16384^2*2=64K bytes), with a maximum size of 262,140 bytes. Open an elevated command prompt to run the command.
netsh interface tcp set global autotuninglevel=highlyrestricted
If restricting TCP/IP Auto Tuning level doesn’t help, try the other values possible for the autoTuningLevel parameter:
- disabled – Fix the receive window at the default value, which is 65536 bytes RWIN.
- 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.
Reboot the computer after changing this setting. The changing the autotuninglevel will also solve problems such as slow loading of website’s web page, or web site sending data slowly or drops the data completely as described in KB929868, or other slow connection problem such as slow downloading of POP3 email.
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Entries (RSS)
November 2nd, 2009 18:13
i get the following message when i try running the command “The following command was not found: interface tcp set global autotuninglevel=highlyrestricted”. am i doing something wrong?
January 25th, 2009 00:50
[...] a few minutes I have read from this site about this command: netsh interface tcp set global autotuninglevel=highlyrestricted [...]
January 15th, 2009 00:53
[...] default, the TCP/IP half open connection limited value is 10. The patch is required to increase and optimize P2P networking such as BT speed, and to avoid or fix Event ID 4226 from occurring in the [...]
January 15th, 2009 00:03
netsh
interface
tcp
set global autotuninglevel=highlyrestricted
should say Ok when completed.
December 27th, 2008 03:25
[...] is slowing to crawl, causing the download is taking age to complete, and you can’t find ways to speed up the torrent, here’s the HTTP web download links to the image. Download Windows 7 build 6956 Setup [...]
December 23rd, 2008 12:04
opened command prompt but nothing worked… to me theres nothing to undo… says the commands arent real
December 6th, 2008 14:55
Can anyone clarify if the above steps works or not? If it doesn’t how do you undo it? I am looking at trying the run the command prompt. netsh interface tcp set global autotuninglevel=highlyrestricted
October 29th, 2008 23:41
[...] download slow like crawling? With the popularity of post like ways to increase torrent speed, it looks like a lot of users have been facing slow torrents downloading speed using desktop BT or [...]
October 1st, 2008 23:51
[...] to utorrent instead of it trying to use both. I googled a bit and came across plenty of sites like this. Might be something you could check out. __________________ .: Bob :. He Lives in a pineapple [...]
May 18th, 2008 01:38
[...] Improve torrent speed and fix slow or even not moving downloading and uploading speed when using P2P programs. (see how to optimize torrent speed in Vista) [...]
May 3rd, 2008 19:39
Im having problems with this.. something like TrueVector always stops responding and needs to be closed.. How can i resotre/undo this changes???