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Thread: Google Chrome blocks RWIN ?

  1. #1
    SG Enthusiast Rollingstone's Avatar
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    Google Chrome blocks RWIN ?

    Default TCP Receive Window (RWIN) = 65536
    RWIN Scaling (RFC1323) = 1 bits (scale factor: 2^1=2)
    Unscaled TCP Receive Window = 32768

    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.
    If you use Google Chrome, TCP Analyzer will show TCP Window 65536 while in Firefox + IE + Safari + Opera, it displays an another number (same 127776 in my case) !

    What a strange issue !
    Last edited by Rollingstone; 07-10-09 at 08:29 PM.
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  2. #2
    XP + akbarri's Avatar
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    but my TCP Analyzer Result are normal
    Chrome 2.0.172.33 = Firefox 3.5 = IE8
    (i'm not checking @ Opera & Safari)

    What is the version of that Google Chrome anyway??

    # OS: Windows, Linux # Browser: Blink, Gecko, Presto, Webkit + Squid + Bind

  3. #3
    SG Enthusiast Rollingstone's Avatar
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    What is the version of that Google Chrome anyway?
    Chrome 3.0.187.1 and Chrome 2.0.174.0 !

    Win XP SP2 !
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    What makes you: "...waking up in the morning so excited about & wanna FLY out of the door ?"

  4. #4
    Junior Member Streetspirit's Avatar
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    Exclamation

    Quote Originally Posted by Rollingstone View Post
    Chrome 3.0.187.1 and Chrome 2.0.174.0 !

    Win XP SP2 !

    This is truly odd. I just got the same thing, a 64K TCP RWIN. It was however, correctly analyzed by DSLReports' JAVA based tweak analyzer however I am seeing the 64K window here using the TCP Analyzer.

    Perhaps the fault lies with some interaction between Chrome's Javascript engine and the code here. Definitely something to watch...


    I'm using XP SP3 / Chrome 3.0.193.0 (Latest development version.)

    Ref:

    DSLReports results: http://www.dslreports.com/tweakr/blo...nXP&via=normal

    Speedguide results: " Default TCP Receive Window (RWIN) = 65536
    RWIN Scaling (RFC1323) = 1 bits (scale factor: 2^1=2)
    Unscaled TCP Receive Window = 32768

    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."

    --
    Rgds

  5. #5
    Junior Member Streetspirit's Avatar
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    Curious issue...

    @ Rollingstone ,

    I'm curious what a JAVA based analyzer would report on your system. Could you please visit http://www.dslreports.com/tweaks and test with the Java tweak test tool. Many thanks in advance.

    --
    Regards

  6. #6
    SG Enthusiast Rollingstone's Avatar
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    It was however, correctly analyzed by DSLReports' JAVA based tweak analyzer however I am seeing the 64K window here using the TCP Analyzer.
    Same thing here !

    RWIN correctly analyzed by DSLReports Analyzer & Nitro NDT tested in Google Chrome 3 ! But TCP Analyzer didn't !
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  7. #7
    Junior Member Streetspirit's Avatar
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    Incorrect RWIN Results when using Google Chrome

    Quote Originally Posted by Rollingstone View Post
    Same thing here !

    RWIN correctly analyzed by DSLReports Analyzer & Nitro NDT tested in Google Chrome 3 ! But TCP Analyzer didn't !

    I'm fairly sure it's not accurate and is a script interaction of some sort. However, it would be nice if the powers that be here take a look.

    Here are my results with Chrome and with Firefox:

    BROWSER: Firefox 3.0.11

    Code:
     SpeedGuide.net TCP Analyzer Results  
    Tested on: 07.11.2009 11:20 
    IP address: 24.190.xx.xxx 
    Client OS: Windows XP 
     
    TCP options string: 020405b40103030401010402 
    MSS: 1460 
    MTU: 1500 
    TCP Window: 921600 (NOT multiple of MSS) 
    RWIN Scaling: 4 bits (2^4=16) 
    Unscaled RWIN : 57600 
    Recommended RWINs: 64240, 128480, 256960, 513920, 1027840 
    BDP limit (200ms): 36864kbps (4608KBytes/s)
    BDP limit (500ms): 14746kbps (1843KBytes/s) 
    MTU Discovery: ON 
    TTL: 116 
    Timestamps: OFF 
    SACKs: ON 
    IP ToS: 00000000 (0)
    Browser: Google Chrome v3.0.193.0
    Code:
     SpeedGuide.net TCP Analyzer Results  
    Tested on: 07.11.2009 11:19 
    IP address: 24.190.xx.xxx 
    Client OS: Windows XP 
    
    TCP options string: 020405b40103030101010402 
    MSS: 1460 
    MTU: 1500 
    TCP Window: 65536 (NOT multiple of MSS) 
    RWIN Scaling: 1 bits (2^1=2) 
    Unscaled RWIN : 32768 
    Recommended RWINs: 64240, 128480, 256960, 513920, 1027840 
    BDP limit (200ms): 2621kbps (328KBytes/s)
    BDP limit (500ms): 1049kbps (131KBytes/s) 
    MTU Discovery: ON 
    TTL: 116 
    Timestamps: OFF 
    SACKs: ON 
    IP ToS: 00000000 (0)
    Hope that the admins look at this problem.

    --
    Cheers-

  8. #8
    XP + akbarri's Avatar
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    Quote Originally Posted by Rollingstone View Post
    Chrome 3.0.187.1 and Chrome 2.0.174.0 !

    Win XP SP2 !
    Both are Development Version, maybe u can this issue to Google Chrome Forum
    http://www.google.com/support/forum/p/Chrome
    http://googlechromecommunity.com
    http://chromespot.com
    Last edited by akbarri; 07-11-09 at 01:49 PM.

    # OS: Windows, Linux # Browser: Blink, Gecko, Presto, Webkit + Squid + Bind

  9. #9
    SG Enthusiast Rollingstone's Avatar
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    Both are Development Version, maybe u can this issue to Google Chrome Forum
    http://www.google.com/support/forum/p/Chrome
    http://googlechromecommunity.com
    http://chromespot.com
    But tested in Java based Analyzer , RWIN in Chrome correctly analyzed ! (same as other browsers)
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  10. #10
    Administrator Philip's Avatar
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    Interesting, I'll take a look.

    Can you please PM me or post here the full URL of the Analyzer resuts page under the different browers ?

    Thanks

  11. #11
    SG Enthusiast Rollingstone's Avatar
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    Did you mean TCP Analyzer or Java-based Analyzer ?

    OK, here we go :

    TCP Analyzer URLs under different browsers :

    Chrome 3.0.187.1


    http://www.speedguide.net/analyzer.php?
    DATA_OFFSET=40&TCP_Options_string=020405ac0103030101010402&IP_MTU_DISCOVER=1&WIN=32768&RWIN=65536&MSS=1452&SCALE=1&TTL=42&TSOPT=0&SACK_PERM=1&IP_TOS=0&IP=123.21.x&timestamp=1247389731

    Firefox 3.0.11


    http://www.speedguide.net/analyzer.php?
    DATA_OFFSET=40&TCP_Options_string=020405ac0103030101010402&IP_MTU_DISCOVER=1&WIN=63888&RWIN=127776&M SS=1452&SCALE=1&TTL=42&TSOPT=0&SACK_PERM=1&IP_TOS=0&IP=123.21.x&timestamp=1247389745

    Opera 9.64

    http://www.speedguide.net/analyzer.php?
    DATA_OFFSET=40&TCP_Options_string=020405ac0103030101010402&IP_MTU_DISCOVER=1&WIN=63888&RWIN=127776&M SS=1452&SCALE=1&TTL=42&TSOPT=0&SACK_PERM=1&IP_TOS=0&IP=123.21.x&timestamp=1247389775

    IE 6

    http://www.speedguide.net/analyzer.php?
    DATA_OFFSET=40&TCP_Options_string=020405ac0103030101010402&IP_MTU_DISCOVER=1&WIN=63888&RWIN=127776&M SS=1452&SCALE=1&TTL=42&TSOPT=0&SACK_PERM=1&IP_TOS=0&IP=123.21.x&timestamp=1247389820

    Safari 4

    http://www.speedguide.net/analyzer.php?
    DATA_OFFSET=40&TCP_Options_string=020405ac0103030101010402&IP_MTU_DISCOVER=1&WIN=63888&RWIN=127776&M SS=1452&SCALE=1&TTL=42&TSOPT=0&SACK_PERM=1&IP_TOS=0&IP=123.21.x&timestamp=1247389920
    Last edited by Rollingstone; 07-12-09 at 04:42 AM.
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  12. #12
    Administrator Philip's Avatar
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    Thanks for the quick reply...

    From this, it seems that Chrome is doing somehing different during the TCP handshake betwen the Analyzer server and the browser, I'll have to take a closer look but it will take some time, it is not trivial.

  13. #13
    Ah, seems if I found the culprit of my issue

    This seems to effect only Server 2003 in our situation.

    When using IE on Server 2003

    SpeedGuide.net TCP Analyzer Results
    Tested on: 10.25.2011 15:46
    IP address: xx.xx.xxx.xx
    Client OS: Windows Server 2003

    TCP options string: 020405ac0103030201010402
    MSS: 1452
    MTU: 1492
    TCP Window: 261360 (multiple of MSS)
    RWIN Scaling: 2 bits (2^2=4)
    Unscaled RWIN : 65340
    Recommended RWINs: 63888, 127776, 255552, 511104, 1022208
    BDP limit (200ms): 10454kbps (1307KBytes/s)
    BDP limit (500ms): 4182kbps (523KBytes/s)
    MTU Discovery: ON
    TTL: 52
    Timestamps: OFF
    SACKs: ON
    IP ToS: 00000000 (0)

    Then using Google Chrome 14.0.835.202 m Windows

    SpeedGuide.net TCP Analyzer Results
    Tested on: 10.25.2011 15:11
    IP address: xx.xx.xxx.xx
    Client OS: Windows Server 2003

    TCP options string: 020405ac0103030101010402
    MSS: 1452
    MTU: 1492
    TCP Window: 65536 (NOT multiple of MSS)
    RWIN Scaling: 1 bits (2^1=2)
    Unscaled RWIN : 32768
    Recommended RWINs: 63888, 127776, 255552, 511104, 1022208
    BDP limit (200ms): 2621kbps (328KBytes/s)
    BDP limit (500ms): 1049kbps (131KBytes/s)
    MTU Discovery: ON
    TTL: 52
    Timestamps: OFF
    SACKs: ON
    IP ToS: 00000000 (0)

    Other OS with Google Chrome work fine XP XP X64

  14. #14
    Administrator Philip's Avatar
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    Hmm, note the two different "TCP Option strings"... The problem seems to be different RWIN value advertised by your browser, not a different value reported by the tool.

    Seems to me that Chrome is changing TCP options, that is overstepping what a browser should be doing if that is the case, IMHO...

    Thanks for sharing that.

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