RWIN Won't Change-OOL 15mps

**GoOffroad** · 03-21-07, 11:09 AM

Hey,
Just got OOL yesterday and already trying optimize everything. I've tried using DRTCP-CableNuts-TCPOptimizer.

They all say they've changed the RWIN value from the 65700 to 375220 or more. After restart though and doing the TCP/IP Analyzer or tweak test they say it has not been changed at all from the 65536.

I have no clue what's going on so any help is very much appreciated.

Thanks

« SpeedGuide.net TCP Analyzer Results »
Tested on: 03.21.2007 12:04
IP address:

TCP options string: 020405b40103030201010402
MSS: 1460
MTU: 1500
TCP Window: 65700 (multiple of MSS)
RWIN Scaling: 2
Unscaled RWIN : 16425
Reccomended RWINs: 64240, 128480, 256960, 513920
BDP limit (200ms): 2628kbps (329KBytes/s)
BDP limit (500ms): 1051kbps (131KBytes/s)
MTU Discovery: ON
TTL: 113
Timestamps: OFF
SACKs: ON
IP ToS: 00000000 (0)

**trogers** · 03-21-07, 11:13 AM

RWIN at 65536 means you are using Vista which does not have a TCP/IP stack that can be tweaked. Vista has an auto-tuning function that adjust RWIN to suit the latency of your connections.

**GoOffroad** · 03-21-07, 11:20 AM

So I have no control at all? Damn Vista

Guess I shouldn't complain.

**mccoffee** · 03-21-07, 11:31 AM

Trogers is right though you should be able to change the rwin 65536 doesn't always mean vista troggers that is also the defualt for xp and 98 2k i think too just a friendly reminder fyi

The auto tunning stack is greatly inmproved by microsoft though in it's latest version of vista it may not need it in some case you may want to try it though depending on your cicrumstances.

Did you reboot after saving changes ????

**mccoffee** · 03-21-07, 11:40 AM

I'm humbly pround to admit i've made a mistake after looking at my vista machine tha tis tweak he is right you might be stuck.

MTU is optimized for PPoE DSL broadband. If not, consider raising MTU to 1500 for optimal throughput.
MSS = 1452
MSS is optimized for PPPoE DSL broadband. If not, consider raising your MTU value.
Default TCP Receive Window (RWIN) = 66792
RWIN Scaling (RFC1323) = 2 bits (scale factor of 4)
Unscaled TCP Receive Window = 16698

RWIN is not fully optimized (even though it is a comparatively large number). The unscaled RWIN value is lower than it should be. Also, RWIN being close to and above 65535 does not justify the header overhead of enabling TCP 1323 Options. You might want to use one of the recommended RWIN values below.

RWIN is a multiple of MSS
Other RWIN values that might work well with your current MTU/MSS:
511104 (MSS x 44 * scale factor of 8)
255552 (MSS x 44 * scale factor of 4)
127776 (MSS x 44 * scale factor of 2)
63888 (MSS x 44)
bandwidth * delay product (Note this is not a speed test):

Your TCP Window limits you to: 2672 kbps (334 KBytes/s) @ 200ms
Your TCP Window limits you to: 1069 kbps (134 KBytes/s) @ 500ms
MTU Discovery (RFC1191) = ON
Time to live left = 47 hops
TTL value is ok.
Timestamps (RFC1323) = OFFSelective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349) = 00000000 (0)

**mccoffee** · 03-21-07, 11:45 AM

After a second check over the settings i noticed that windows scailing was not on what's odd though I set it to 1 in cablenut its like vista ingores it totally hmm..

Not sure why it's just ingoring it this requires me to do some reasearch and some more testing it's odd.

**mccoffee** · 03-21-07, 12:21 PM

after digging I found this phill is going to have his work cut out for him he he.

Changes to TCP/IP Registry Values

Many of the TCP/IP registry values supported in Windows XP and Windows Server 2003 are not supported by TCP/IP in Windows Vista and Windows Server “Longhorn.” You can configure additional TCP/IP settings with command-line parameters for the following Netsh commands at a Windows command prompt with administrator-level permissions:
· netsh interface ipv4 set interface
· netsh interface ipv4 set global
· netsh interface ipv6 set interface
· netsh interface ipv6 set global

**GoOffroad** · 03-21-07, 12:49 PM

i guess vista users will have to wait and see...thanks for the help

**trogers** · 03-21-07, 08:58 PM

Originally Posted by mccoffee

Trogers is right though you should be able to change the rwin 65536 doesn't always mean vista troggers that is also the defualt for xp and 98 2k i think too just a friendly reminder fyi

Windows default RWIN value for the older operating systems before Vista is 65535.

So when I see any TCP Analyzer reporting RWIN at 65536, and especially with small unscaled RWIN, somtimes starting at 256, I would suspect the OS is Vista.

**100 010 00** · 03-22-07, 02:39 AM

Originally Posted by trogers

Windows default RWIN value for the older operating systems before Vista is 65535.

17520 is the right value for the default rwin

**trogers** · 03-22-07, 06:49 AM

Originally Posted by 100 010 00

17520 is the right value for the default rwin

Nope. Default RWIN in Windows means an untweaked RWIN value produced by an original Window Registry.

17520 is a tweaked value for MTU 1500 (MSS x 12) and is not optimum for other MTUs like 1492 or less.

**mccoffee** · 03-22-07, 08:33 AM

Originally Posted by 100 010 00

17520 is the right value for the default rwin

f

the 17520 is the default with scailing on

**100 010 00** · 03-22-07, 08:55 AM

Actually default rwin is a routing value. It depends from your bandwidth. It starts from 8192, jumps to 17520 and 65535 for speeds up to 1mbit

**mccoffee** · 03-22-07, 06:13 PM

Originally Posted by trogers

Windows default RWIN value for the older operating systems before Vista is 65535.

So when I see any TCP Analyzer reporting RWIN at 65536, and especially with small unscaled RWIN, somtimes starting at 256, I would suspect the OS is Vista.

come to think about your right troggers i'm on crack today and that day

**Drlawgr** · 10-24-08, 07:33 PM

Hi guys,
just found this site, which has some REALLY good info! So glad I found you!

Just built a new PC, and I installed Vista...damn Vista!!!

Same story as everyone else... I get half the speed I was getting with my old XP pc... I've lost my sleep with it!!! Have been looking and searching everything, until I found this post...

Here is my info...

« SpeedGuide.net TCP Analyzer Results »
Tested on: 10.24.2008 20:25

TCP options string: 020405ac01010402
MSS: 1452
MTU: 1492
TCP Window: 65340 (multiple of MSS)
RWIN Scaling: 0 bits
Unscaled RWIN : 65340
Recommended RWINs: 63888, 127776, 255552, 511104, 1022208
BDP limit (200ms): 2614kbps (327KBytes/s)
BDP limit (500ms): 1045kbps (131KBytes/s)
MTU Discovery: ON
TTL: 46
Timestamps: OFF
SACKs: ON
IP ToS: 00000000 (0)

and I'm getting SICK!!! My connection is 6,500-7,000... using my old XP pc I download with 500-600 Kbytes/s... my new Vista (Business 64-bit with SP1 installed) will only download with 300-330 Kbytes/s

Autotuning is off... I run TCPOptimizer, but the value of RWIN does not change!!!

So, is there a solution about it??? Have we come with something around it???

**Drlawgr** · 10-24-08, 09:26 PM

Guys,
I've tried ALL POSSIBLE combinations about it, and still can't find a solution!

But read this please!

"""TCP Auto-Tuning

To turn off the default RWIN auto tuning behavior, (in elevated command prompt) type:

netsh int tcp set global autotuninglevel=disabled

The default auto-tuning level is "normal", and the possible settings for the above command are:

disabled: uses a fixed value for the tcp receive window. Limits it to 64KB (limited at 65535).
higlyrestricted: allows the receive window to grow beyond its default value, very conservatively
restricted: somewhat restricted growth of the tcp receive window beyond its default value
normal: default value, allows the receive window to grow to accommodate most conditions
experimental: allows the receive window to grow to accommodate extreme scenarios (not recommended, it can degrade performance in common scenarios, only intended for research purposes. It enables RWIN values of over 16 MB)"

So if using DISABLED, the TCP RWIN DOES NOT CHANGE VALUE! That gives it a FIXED 64kb.
Even though in the Registry the numbers shown, are the ones you have input in the TCOptimizer... but when you go to
www.speedguide.net/analyzer.php
you still get a FREAKING TCP RWIN of 65340...

I also tried the "experimental" mode of auto-tuning, that supposedly leaves it free to grow, but still nothing!!!

HELP ANYONE???

**trogers** · 10-27-08, 09:11 PM

Try rebooting the comp after setting autotuning to normal.

**Drlawgr** · 10-27-08, 10:14 PM

So you tell me to have autotuning in "normal" and not in "experimental" which is for very high speeds?

**trogers** · 10-27-08, 10:42 PM

Originally Posted by Drlawgr

So you tell me to have autotuning in "normal" and not in "experimental" which is for very high speeds?

Experimental is for experiments.

**Drlawgr** · 10-27-08, 10:51 PM

but only in "experimental" I have this small increase in my speed... I've read that it is used by research institutes to transfer their "stuff"; too large files that need to move at more than 16Mbs...

I'll try what you say though, and keep you posted...