Would somebody mind testing out this new rwin formula I have for XP/2k:
x=your cap in bits
mss=your mss (usually 1460)
mtu=your mtu (usually 1500)
e.g: If you cap is is 1.5mb/sec multiply 1.5*1000000 to get your cap in bits.
x/8*1460/1500=TcpWindowSize
If the value is an odd integer or has decimels:
Divide by 1460. Round that number to the nearest even integer, and multiply by 1460.
Multiply the final value by 10 and set that number to be your DefualtRcvWindow.
Need RWIN formula tested.
With a 3000/256 cap my value using your formular would be 3650000 which would be too high.
Why not use the correct formular?
(Maximum Bandwidth * Anticipated Latencey) / 8
Maximum Bandwidth = your cap in bytes
To make it a multipule of MSS simply divide by 1460, round the result to the nearest whole number then multiply by 1460.
The most important variable in calculating an RWIN Value is Latency and yours doesn't consider it.
Why not use the correct formular?
(Maximum Bandwidth * Anticipated Latencey) / 8
Maximum Bandwidth = your cap in bytes
To make it a multipule of MSS simply divide by 1460, round the result to the nearest whole number then multiply by 1460.
The most important variable in calculating an RWIN Value is Latency and yours doesn't consider it.
"A never ending quest for knowledge as with knowledge comes wisdom"
Main System running Windows XP Pro: Intel Celeron 2.4 Ghz, 1 Gig Ram, 2 80 gig WD 7200 rpm HD's, Radeon 9200 Pro, Envision EN9110 19" LCD Display, HP 9500 CD-RW, D-Link DFE-530TX+ PCI Adapter, D-Link DI-704P Router, Motorola SB5100 Cable Modem with Cox HSI
Main System running Windows XP Pro: Intel Celeron 2.4 Ghz, 1 Gig Ram, 2 80 gig WD 7200 rpm HD's, Radeon 9200 Pro, Envision EN9110 19" LCD Display, HP 9500 CD-RW, D-Link DFE-530TX+ PCI Adapter, D-Link DI-704P Router, Motorola SB5100 Cable Modem with Cox HSI
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mnosteele52
- Posts: 11913
- Joined: Tue Jul 24, 2001 12:00 pm
- Location: Chesapeake, VA
The formula doesn't contain the necessary data to properly configure your RWIN and will give you a ridiculously high value. I have yet to see any connection that truly benefits from a RWIN above 64240, in some cases it might help but most it won't. From testing and helping others tweak their connections the majority of people with caps of 1500 on up reach their caps with 64240.... this is just my opinion from my experience...... I'm not saying don't use or try a larger value..... just that I personally have seen no benefit from it. 
