NT Reg hacks w/ PPPoE DSL?

[shadrach]

After reading through all of the SpeedGuide.net hack pages and posts, I think I'm doing this correctly...

I have an aDSL G.Lite connection with a SpeedStream 5260, and am running EnterNet 300 PPPoE software on NT4 SP5.

The largest non-fragmented value my ISP supports is 1426, making my MaxMTU 1454; a bit lower than the PPPoE recommended value of 1492.

So, using this formula I can find the largest TCPWindowsSize value between 0-65535:
(MaxMTU - 40) * X
(1454 - 40) * 46 = 65044

Question is, I was using the recommended TCPWindowSize of 64240, but after changing it 65044, I saw no difference in download speeds. the new value is not only larger, it is now a multiple of the MaxMTU, which should get better performance? If the TCPWindowSize doesn't really need to be a multiple of the MaxMSS, then why not just set the value to 65535?

Did I mess up the math, or have I maxxed out my performance?

Jeff -> More curious than greedy...

[dannjr]

You have me getting curious Why you would use such a low number to start with 64240 is only if your using NT as a server If your NT box is up to date you may be able to run a larger scaled value. I'm not positive on that because I run win2k pro & my Rwin is large.
scaling enabled.

But if you are doing it according to the tweak page then it would come out to 62216 with a MSS of 1414..-40 of your MTU
Now let me guess your using Enternet 100 or 300 for your connection.
If thats so then use this value MTU 1454 in your registry but do the math as if it where a MTU of 1492 Then the TcpWindowSize would be 63888 This only applies to TcpWindowSize

Basically its 44* MSS = TcpWindowSize

MaxMTU well in the registry it should be MTU i hope thats what your using for the entry.

As fare as you maxing out your preformance I have no Idea because I don't know what you have as your subscribed speed and I am greedy I get more than what I pay for on my DSL line. Same Modem(router)

from the tweak page. I realize this is from win98 but the math applies.
"For best results RWIN has to be a multiple of MSS (MaxMTU-40) lower than 65535 times a scale factor that's a power of 2, i.e. 44 x 1460 = 64240 x 2^2 = 256960. If you choose to use a RWIN lower than 65535, you can simply make it multiple of MSS and turn scaling off"

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[Speedy]

Originally posted by dannjr:
"For best results RWIN has to be a multiple of MSS (MaxMTU-40) lower than 65535 times a scale factor that's a power of 2, i.e. 44 x 1460 = 64240 x 2^2 = 256960. If you choose to use a RWIN lower than 65535, you can simply make it multiple of MSS and turn scaling off"


I realized that (MTU-40) x 255 also works very well when scaling is active.

Please, don't ask me why! But maybe you have an expanation?!

[dannjr]

Hi speedy
I use that all the time I'm just wondering how that will effect NT it wouldn't hurt to try its a global setting so it won't kill the OS.
Originally posted by Speedy:
I realized that (MTU-40) x 255 also works very well when scaling is active.

Please, don't ask me why! But maybe you have an explanation?!



[This message has been edited by dannjr (edited 12-16-2000).]

[shadrach]

This is straight from the Speedguide.net Registry Tweaks page as well:

HKEY_LOCAL_MACHINE\
SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
"TcpWindowSize"="64240" (DWORD decimal var, range 0-65535. It has to be a multiple of MSS for best results, i.e. (MaxMTU-40) x number... Recommended settings to try are 64240, 32120 and 8760 , in that order)

Therefore 65044 is the largest allowable value that is a multiple of MSS.

To verify:

Is MSS defined simply as (MaxMTU - 40) or is it something else?

Is RWIN the same as TCPWindowsSize?

Is it possible to go over 65535 for TCPWindowSize in NT 4.0 Workstation?

[shadrach]

BTW:
-------------------------------------------------------------------
12/16/00 02:10
HKLM\SYSTEM\CCS\Services\NTSPPPOE5\Parameters\Tcpip\MTU=1454
HKLM\SYSTEM\CCS\Services\Tcpip\Parameters\TcpWindowSize=65044 (MTU-40x46)
http://www.speedtest.net/
Total bytes downloaded: 10240 bytes Throughput: 1.30 Mbps ~ 1333 Kbps
Total bytes downloaded: 51200 bytes Throughput: 1.26 Mbps ~ 1290 Kbps
Total bytes downloaded: 204800 bytes Throughput: 1.23 Mbps ~ 1260 Kbps
Total bytes downloaded: 1048576 bytes Throughput: 1.22 Mbps ~ 1250 Kbps
Total bytes downloaded: 2097152 bytes Throughput: 1.21 Mbps ~ 1240 Kbps
http://download.cnet.com/downloads/0-10045-101-3623687.html
Peak 238 KBps ~ 1.86 Mbps ~ 1905 Kbps
Avg 158 KBps ~ 1.23 Mbps ~ 1260 Kbps

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