Preventing router from changing MaxTcpWindowSize

[tomcatonnet99]

Just noticed the MaxTcpWindowSize in the registry for winxp keeps being changed automatically despite re-setting permissions to administrator access only, even denying the system access to it; for some strange reason and I suspect its the netgear router that keeps changing the value from 130640 ( which gives me a good speed even when data-capped - at least a better dial up speed!! ) to 16400 (which just slows it down heaps!!) now using the same service providers' wireless modem didn't make any changes to the registry but using their wireless modem card inserted in the wireless router is the culprit I guess...

Does anybody have any ideas as to preventing Tcp Window size from being automatically changed ?? coz its a value the user should be free to set and the ISP could govern the data transmission speeds ( NOT ! how fast I'm able to unpack the package received at my end!)

Note: IP analyser shows window size as 130640 though checking the registry infact shows 16400! ( despite my repeatedly having to change the value and re-starting the machine!! )

any help would be appreciated ..........pls

thanks

« SpeedGuide.net TCP Analyzer Results »
Tested on: 08.21.2008 09:59
IP address: 203.211.xx.xxx

TCP options string: 0204058a0103030101010402
MSS: 1418
MTU: 1458
TCP Window: 130640 (NOT multiple of MSS)
RWIN Scaling: 1
Unscaled RWIN : 65320
Reccomended RWINs: 65228, 130456, 260912, 521824
BDP limit (200ms): 5226kbps (653KBytes/s)
BDP limit (500ms): 2090kbps (261KBytes/s)
MTU Discovery: ON
TTL: 53
Timestamps: OFF
SACKs: ON
IP ToS: 00000000 (0)

[mccoffee]

A few things try an analyzer without the router just to see what is what plus part of the slowdown is your mtu is off 1500 for cable and 1492 for dsl pppoe

The analyzer before xp2 use to pick up the tcpwindowsize after xp2 it picks up the default window size which is an afd parameter.

If you change all three to the same value the analyzer will read the same value ,so give that shot as well.

[tomcatonnet99]

yes despite being pppoe it doesn't allow any changes to MTU the interface on NEtgear router has the MTU value set by default to 1458 with no way of changing it ( that value box is inactive ) changing the same in the registry had no effect...
question: is MaxTcpWindowSize the same as TcpWindowSize Dword?? how did you mean all three (which ones are you referring to pls?)

[tomcatonnet99]

Could someone please help with my original question thanks..........

Wish this forum used a more forum friendly software where one can easily track and trace ones posts and replies ... would be great seeing that feature here; or advise on how best to use this forum

[tomcatonnet99]

the only other registry entry that I can think of which has a figure close to 16400 is the Lansman buffer size 16384, would you think thats being set for all adapters ? including my wireless?? and how do I prevent it from doing that to Tcp/ip window size - which I would like to leave at 130640...

Any suggestions :confused:

[mccoffee]

http://support.microsoft.com/kb/224829 this will further explain all three values default recive window tcp window siae ,and global maxtcpwindow size

I would look into upgrading your firmware for your touter that mtu for pppoe is off by alot which is probably slowing you down a ton.

IF you set all three values the same for the window size it should show up that number in the analyzer.