RWIN values?????

[BigAmp]

OK I'm sick of writing out the same RWIN values time and time again, so I'm going to writing a program in VB to calculate them for people.

so far I'm going with MTU's of 1500 and 1492 with MSS's.
and scale factors of 1, 2, 4, 8.
I need to info from you all, what are some good numbers to us t multiply the MSS by, ie. the show 46 on the Analyzer here, I have found that 44 and 32 work for me. what other number should I but in?

[Lobo]

mnosteele52
Senior Member

Registered: Jul 2001
Location: Chesapeake, VA
Posts: 467
All you need to know is keep your RWIN an even multiple of your MSS. Your MSS value is 1460 so multiply 1460 times any EVEN number to come up with an RWIN (for optimum throughput) i.e. 1460 x 176 = 256960.

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mnosteele
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02-14-2002 10:20 PM



earthmofo
Senior Member

Registered: Nov 2000
Location: Providence, RI USA
Posts: 568
It doesn't need to be an even number ie: 2,4,6.....ect.

The correct way to calculate RWIN is:

(Maximum Bandwidth * Anticipated Latencey) / 8

Example for a 1500 download cap with 150 ms pings (latencey):

1500 * 150 / 8 = 28125

To make it a multipule of MSS divide by 1460 then round to the nearest whole number:

28125 / 1460 = 19.263698 or 19

Then multiply by MSS:

19 * 1460 = 27740 which will be the RWIN value.

After calculating the optimum value for your connection it can be increased by the use of Windows Scaling (for any value over 65535 Tcp13230pts must be set to 1):

27740 * 4 = 110960
27740 * 5 = 138700
27740 * 6 = 166440
27740 * 7 = 164180
27740 * 8 = 221920
27740 * 9 = 249660
27740 * 10 = 277400
27740 * 11 = 305140
27740 * 12 = 332880
27740 * 13 = 360620
27740 * 14 = 388360
27740 * 15 = 416100
27740 * 16 = 443840

and so on.

The most important variable when calculating RWIN is Latencey. The best way to determine latencey is to ping the websites you visit most often or all the sites listed in your Favorites folder. Ping all the sites and record the average ping times. Add the times then divide by the total number of sites pinged. This should give you the Latencey value to use to calculate your RWIN.




:)

[MadDoctor]

Where is 256960? Darn I like that number!

[CaptainSpeleo]

BigAmp:

256960 is the recommended DefaultReceiveWindow(RWIN) value for a MaxMSS of 1460(which is a common value for broadband connections). That value is reached by multiplying MaxMSS by 176.

Another recommended RWIN value is 256256 for a MaxMSS of 1456. That value is also reached by multiplying MaxMSS by 176.

A multiple of 176 is not engraved in stone. As long as you use an even multiple, you can go lower or higher.

http://9337387.home.icq.com/index.html

[BigAmp]

will I've got Version 1 done, I just have to put it on the net some where and you can till me what you like and dislike / want.

[BigAmp]

Ok here it is give it a try and telll me what you think!

http://www.geocities.com/simsimeon2002/downloads/rwin.zip

right ckick the link and do a "Save Target As..."

[Lobo]

Latency?:) :) help intructions, XP PPPoE RWIN default RWIN is 1480?

[mnosteele52]

I've tried every size RWIN and there is no "one size fits all", I have used the "proper" formula that includes average download speeds, latency, your caps etc. and to be honest the one I have been using lately (51100) seems to work the best for me. I did not figure it out with the formula I just tried ones using the speed test in my signature and I'm using the highest one I can without having ANY retransmitted packets.... and believe it or not my speed is better than ever before. Try what I did with the speed test I suggest (it will tell you how many retransmitted packets), once you have found the size that you get few or no retransmitted packets save that size and use it for a while and see how it goes. Just keep your RWIN a multiple of your MSS (for Cable 1460, DSL 1460, DSL PPPoE 1452, XP PPPoE 1440). Just something to try.:nod: :nod: :)

[Lobo]

Who cares about retransmitted packets if throughput is faster?:)

[BigAmp]

Ok in just over 12 hours 1.1 is made, I was sleeping sorry!
any ways same deal here, I just put the XP PPPoE MTU in the Latency in later this week with a few more upgrade from v2.

http://www.geocities.com/simsimeon2002/downloads/rwin_1.1.zip

right ckick the link and do a "Save Target As..."

again till me what you think.

[Lobo]

Does above link work?:)

[BigAmp]

thanx for the heads up Lobo, its working now.