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Thread: Why wont my MSS and MTU values change?

  1. #1
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    Question Why wont my MSS and MTU values change?

    Ive tried numerous times to tweak these setting and after each reboot these setting are still the same as before. Heres test results.

    TCP options string = 02040218010303000101080a000000000000000001010402

    MTU = 576
    MTU value seems to be optimized for dial-up. Consider increasing your MTU to 1500 for better throughput.

    MSS = 536
    Maximum useful data in each packet = 524, which is less than MSS because of Timestamps, or other TCP/IP options used.
    MSS is not fully optimized for broadband (although it might work well for slower connections). Consider increasing your MTU value.

    Default Receive Window (RWIN) = 65535
    RWIN Scaling (RFC1323) = 0 bits
    Unscaled Receive Window = 65535
    Note: Under Windows 9x, if you have RWIN set to any other value, and the Analyzer reports 65535 you might need to install the MS Vtcp386 fix.
    For optimum performance, consider changing RWIN to a multiple of MSS.
    Other values for RWIN that might work well with your current MTU/MSS:
    523136 (MSS x 122 * scale factor of 8)
    261568 (MSS x 122 * scale factor of 4)
    130784 (MSS x 122 * scale factor of 2)
    65392 (MSS x 122)

    bandwidth * delay product:
    Your RcvWindow limits you to: 2621.4 kbps (327.675 KBytes/s) @ 200ms
    Your RcvWindow limits you to: 1048.56 kbps (131.07 KBytes/s) @ 500ms

    MTU Discovery (RFC1191) = ON

    Time to live left = 116 hops
    TTL value is ok.

    Timestamps (RFC1323) = ON
    Note: Timestamps add 12 bytes to the TCP header of each packet, reducing the space available for useful data.

    Selective Acknowledgements (RFC2018) = ON

    IP type of service field (RFC1349)= 11100000
    Precedence (priority) = 111 (Network Control)
    Delay = 0 (normal delay)
    Throughput = 0 (normal throughput)
    Reliability = 0 (normal reliability)
    Cost = 0 (normal cost)

    HELP!!!!

  2. #2
    R.I.P. 2013-11-22 blebs's Avatar
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    http://forums.speedguide.net/cgi-bin...&f=14&t=000107

    Kris read this thread, it should help you out. DRTCP from DSLreports.com!
    Success is a lousy teacher. It seduces people into thinking they can't lose. -Bill Gates

  3. #3
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    Angry

    Results after DRTCP. The strange thing is that everything seems to be set up right in the registry. Hmmmmmm...............

    TCP options string = 020402180103030201010402

    MTU = 576
    MTU value seems to be optimized for dial-up. Consider increasing your MTU to 1500 for better throughput.

    MSS = 536
    Maximum useful data in each packet = 536, which is equal to MSS.
    MSS is not fully optimized for broadband (although it might work well for slower connections). Consider increasing your MTU value.

    Default Receive Window (RWIN) = 256960
    RWIN Scaling (RFC1323) = 2 bits
    Unscaled Receive Window = 64240
    For optimum performance, consider changing RWIN to a multiple of MSS.
    Other values for RWIN that might work well with your current MTU/MSS:
    523136 (MSS x 122 * scale factor of 8)
    261568 (MSS x 122 * scale factor of 4)
    130784 (MSS x 122 * scale factor of 2)
    65392 (MSS x 122)

    bandwidth * delay product:
    Your RcvWindow limits you to: 10278.4 kbps (1284.8 KBytes/s) @ 200ms
    Your RcvWindow limits you to: 4111.36 kbps (513.92 KBytes/s) @ 500ms

    MTU Discovery (RFC1191) = ON

    Time to live left = 52 hops
    TTL value is ok.

    Timestamps (RFC1323) = OFF

    Selective Acknowledgements (RFC2018) = ON

    IP type of service field (RFC1349)= 01010000
    Precedence (priority) = 010 (immediate)
    Delay = 1 (low delay)
    Throughput = 0 (normal throughput)
    Reliability = 0 (normal reliability)
    Cost = 0 (normal cost)

  4. #4
    R.I.P. 2013-11-22 blebs's Avatar
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    You have a head scratcher there! Is there an AOL Dial-up adaptor present in your network configuration? If not, go to start/run/type regedit and then see if you can find any folder from below that has the 576 MTU in it and see if you can find what adapter it is with. The thing I don't understand is, if you used the speedguide tweak (unless you did the tweak manually) all of the folders should have 1500 MTU in them. Everything else looks good. If we can just get the right MTU present You'll smile

    HKEY_LOCAL_MACHINE\
    System\CurrentControlSet\Services\Class\NetTrans\000n (Where "000n" is your TCP/IP protocol. It contains "TCP/IP" assigned to the "DriverDesc" value. "n" can be any number from 0 to 9)
    MaxMTU="1500" (string var) Note: If you're using DSL and your ISP has implemented PPPoE, you must set MaxMTU to 1492 or less.
    Success is a lousy teacher. It seduces people into thinking they can't lose. -Bill Gates

  5. #5
    Lobo
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    I hate to go to another site to steal, but, go to www.speedcorp.net Tweaks section, download MAXMTU to your desktop, click on MAX MTU on desktop to enter MTU everywhere in you registry, MTU should set MSS, reboot, retest, repost

  6. #6
    TCP/IP Dude rmrucker's Avatar
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    1) What type of connection is this? Cable, DSL, DSL w/PPPoE, Satellite, Dial-up??

    It is NOT likely a straight cable connection. If it was cable, this problem would be solved by now. Cable uses the MaxMTU entry for your NIC -- and you have set that. PPPoE does NOT use the entry, so settng this for PPPoE is not likely going to help you.

    2) Did you previously apply any OTHER speed patches -- for example, a speed patch for Dial-up? Remove/Unistall anything you may have installed before coming here.

    3) Are you SHARING your Internet Connection over more than one computer?? This would include ICS, Sygate, WinGate, Router/hub, etc. Frequently these are set up incorrectly.

    4) How many "Network Components" are listed in Control Panel | Network?

  7. #7
    Super Good Guy! dannjr's Avatar
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    Originally posted by rmrucker:
    1) What type of connection is this? Cable, DSL, DSL w/PPPoE, Satellite, Dial-up??

    PPPoE does NOT use the entry, so settng this for PPPoE is not likely going to help you.
    UHH... if you don't balance the network adapter, with the PPPoE adapter, you can get stalls and freeze conditions...
    heres just one example of that.. http://www.dslreports.com/faq/faq#156.
    My connection weather on the router or the PPPoE if I don't get it set it goes in the Toilet

    What type of connection is this...

  8. #8
    Super Good Guy! dannjr's Avatar
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    turn timestamps on
    thats this seting
    Tcp1323Opts=dword setting is three 3

    Just went through this with a couple of other connections...

  9. #9
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    First to answer some questions. I have a ADSL connection with PPPoATM, All other tweeks have been uninstalled, Ive tried cablenut and aslo manually entering the values into my registry with no success. 15 network components, and i am not sharing my connection. Here are the rults after installing MAX MTU and rebooting.

    TCP options string = 020402180103030201010402

    MTU = 576
    MTU value seems to be optimized for dial-up. Consider increasing your MTU to 1500 for better throughput.

    MSS = 536
    Maximum useful data in each packet = 536, which is equal to MSS.
    MSS is not fully optimized for broadband (although it might work well for slower connections). Consider increasing your MTU value.

    Default Receive Window (RWIN) = 256960
    RWIN Scaling (RFC1323) = 2 bits
    Unscaled Receive Window = 64240
    For optimum performance, consider changing RWIN to a multiple of MSS.
    Other values for RWIN that might work well with your current MTU/MSS:
    523136 (MSS x 122 * scale factor of 8)
    261568 (MSS x 122 * scale factor of 4)
    130784 (MSS x 122 * scale factor of 2)
    65392 (MSS x 122)

    bandwidth * delay product:
    Your RcvWindow limits you to: 10278.4 kbps (1284.8 KBytes/s) @ 200ms
    Your RcvWindow limits you to: 4111.36 kbps (513.92 KBytes/s) @ 500ms

    MTU Discovery (RFC1191) = ON

    Time to live left = 52 hops
    TTL value is ok.

    Timestamps (RFC1323) = OFF

    Selective Acknowledgements (RFC2018) = ON

    IP type of service field (RFC1349)= 01010000
    Precedence (priority) = 010 (immediate)
    Delay = 1 (low delay)
    Throughput = 0 (normal throughput)
    Reliability = 0 (normal reliability)
    Cost = 0 (normal cost)


    I need help............

  10. #10
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    If your PPOE is Enternet software then the tweaks will not work go into your registry, and after backing up the registry go into
    HOTKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\Net\0002
    under 0002 there is an entry for MaxFrameSize "1454"
    change this number to "1492"
    reboot and the recheck at Speedguides analyzer, if your pages wont load then drop this number by 2 at a time, but 1492 works perfect on mine
    Leave the othert tweeks in place if you dont have any trouble.

  11. #11
    R.I.P. 2013-11-22 blebs's Avatar
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    Kris: Hang in there, sooner or later it will be figured out!
    I'm now out of my league and would direct and ask dannjr or rmrucker to take over on this one. Even cablenut if your on tonight! Lobo, no disrespect meant. If you can help on PPPoE, have at it buddy!
    Success is a lousy teacher. It seduces people into thinking they can't lose. -Bill Gates

  12. #12
    Lobo
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    I can't touch this much as I don't know enough about it but 576 is a dial up MTU and it's in one of those Net Trans folders at:
    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\Netrans

  13. #13
    Super Good Guy! dannjr's Avatar
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    Originally posted by Martiangod:
    If your PPOE is Enternet software then the tweaks will not work go into your registry, and after backing up the registry go into
    HOTKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\Net\0002
    under 0002 there is an entry for MaxFrameSize "1454"
    change this number to "1492"
    reboot and the recheck at Speedguides analyzer, if your pages wont load then drop this number by 2 at a time, but 1492 works perfect on mine
    Leave the othert tweeks in place if you dont have any trouble.
    didn't we just go over this it works if the MaxFrameSize in HOTKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\Net\000x not nessasrly in 0002 is two low this will run you down to the setting your reading
    Also look in the adapter under network properties for the PPP adapter and look for MaxFrameSize if the adapter is too low you will need to increase this to the maximum also... which should not exceed 1492..
    Sorry I wish I would have remembered this one also...
    You may also want to run that FAQ I listed above...

  14. #14
    Lobo
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    An please do turn timestamps on as mentioned above

  15. #15
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    Ok, I finnaly did it. There wasnt a "MaxFrameSize" present in my registry, so i entered it. Whats the difference between PPPoE and PPPoATM? I have bellsouth fastaccess and am supposed to be capable of getting 1.5mbit/s down and 256kbit/s up. On speed test I average around 11xxkbits/s and around high hundreds low two hundres up. Is this the best i am going to be able to get? When downloading from places like www.happypuppy.com i usually get on average about 150KB/s. Is this ok? Here are my tweak results now. I appreciate all of the help.


    TCP options string = 020405ac010303030101080a000000000000000001010402

    MTU = 1492
    MTU seems to be optimized for PPPoE... If you are not on a PPPoE connection, consider increasing your MTU to 1500 for optimal throughput.

    MSS = 1452
    Maximum useful data in each packet = 1440, which is less than MSS because of Timestamps, or other TCP/IP options used.
    MSS is optimized for PPPoE. If you are not on a PPPoE connection, consider increasing your MTU value.

    Default Receive Window (RWIN) = 511104
    RWIN Scaling (RFC1323) = 3 bits
    Unscaled Receive Window = 63888
    RWIN is a multiple of MSS
    Other values for RWIN that might work well with your current MTU/MSS:
    255552 (MSS x 44 * scale factor of 4)
    127776 (MSS x 44 * scale factor of 2)
    63888 (MSS x 44)

    bandwidth * delay product:
    Your RcvWindow limits you to: 20444.16 kbps (2555.52 KBytes/s) @ 200ms
    Your RcvWindow limits you to: 8177.664 kbps (1022.208 KBytes/s) @ 500ms

    MTU Discovery (RFC1191) = ON

    Time to live left = 52 hops
    TTL value is ok.

    Timestamps (RFC1323) = ON
    Note: Timestamps add 12 bytes to the TCP header of each packet, reducing the space available for useful data.

    Selective Acknowledgements (RFC2018) = ON

    IP type of service field (RFC1349)= 10111000
    Precedence (priority) = 101 (CRITIC/ECP)
    Delay = 1 (low delay)
    Throughput = 1 (high throughput)
    Reliability = 0 (normal reliability)
    Cost = 0 (normal cost)

  16. #16
    Super Good Guy! dannjr's Avatar
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    Yeah... finaly something worked right....

    PPPoE = Point-to-Point Protocol over Ethernet
    PPPoA = Point-to-Point Protocol over ATM

    Most PPPoE and PPPoA connections still go over ATM

    If you have a 1.5 connection the most your supposed to be able to get is about 80% personally I didn't stop there did you do the FAQ above that I pointed out just not nessarly to you this will help bind the PPPoE adapter with the network adapter..
    It will also keep the nasty freeze away...

    Also to avoid a problem in win98SE you might consider doing this
    http://support.microsoft.com/support.../Q243/1/99.ASP

    The Speedguide Web tweak is a big help with surfing...

    You might want to decrease your Rwin a touch also biggest aint nesssarly best...It can actually slow you down....

    Glad you got it...
    Dan

  17. #17
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    PPPoE seems to be a hot topic the last day or two. Seeing more and more posts regarding it. Funny thing I'm seeing, is this has been rehashed several times in the last day or two regarding MaxFrameSize, Dont even have to go through months of posts to come up with the answer for this one. Its this darn Speedguide connection analyzer causing this, i swear it is
    another BTW, glad it helped, we hashed this one out in another forum a couple days ago so it was fresh on the mind, glad to help a little

    BTW, great analyzer, wouldnt have spotted the MTU tweeks were not doing what they were supposed to do without it...

    [ 03-15-2001: Message edited by: Martiangod ]

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