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Thread: Help me tweak my 1024kbs line and MTU, RWIN plz (RWIN=1412)

  1. #1

    Unhappy Help me tweak my 1024kbs line and MTU, RWIN plz (RWIN=1412)

    This is the result:

    MTU = 1452
    MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better throughput. If you are using a router, it could be limiting your MTU regardless of Registry settings.
    MSS = 1412
    MSS is not optimized for broadband. Consider increasing your MTU value.
    Default TCP Receive Window (RWIN) = 1412
    RWIN Scaling (RFC1323) = 0 bits
    Unscaled TCP Receive Window = 1412

    RWIN seems to be set to a very small number. If you're on a broadband connection, consider using a larger value.
    RWIN is a multiple of MSS
    Other RWIN values that might work well with your current MTU/MSS:
    519616 (MSS x 46 * scale factor of 8)
    259808 (MSS x 46 * scale factor of 4)
    129904 (MSS x 46 * scale factor of 2)
    64952 (MSS x 46)
    bandwidth * delay product (Note this is not a speed test):

    Your TCP Window limits you to: 56.48 kbps (7.06 KBytes/s) @ 200ms
    Your TCP Window limits you to: 22.592 kbps (2.824 KBytes/s) @ 500ms
    Consider increasing your RWIN value to optimize TCP/IP for broadband.
    MTU Discovery (RFC1191) = ON
    Time to live left = 57 hops
    TTL value is ok.
    Timestamps (RFC1323) = OFF
    Selective Acknowledgements (RFC2018) = ON
    IP type of service field (RFC1349) = 00000000 (0)

    I did all the tips but it can't change.
    I'm using zoom x5 5554 and 1024kbps/512kbps

    plz help me. thx in advance
    Last edited by boy84hn2002; 04-07-06 at 11:35 AM.

  2. #2
    some one plz help me.

  3. #3
    Elite Member trogers's Avatar
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    I suspect your MTU value is restricted by your router and you will need to access into it to reset the MTU value: 1500 for Cable and 1492 for PPPoE DSL.

  4. #4

    About the Zoom ADSL X5 modem...

    This pertains to the following;

    Model: 5654 (ADSL 1/2/2+ compatible)
    Series: 0228 through 0240

    You need help tweaking your MTU you say. Now before I go any further there is something you need to know before you start messing with the registry settings in Windows trying to get the best connection bandwidth
    and lower latency.

    What can be adjusted in the current Zoom firmware for this modem is;

    MTU or Maximum Transfer Units in bytes, it's set currently for 1,500 which is standard for Ethernet framing and ADSL that is using IPoA also know as TCP/IP over ATM (Asyncronous Transfer Mode). PPPoE is another standard that is overlayed on top of a physical interface, in other words PPPoE is TCP/IP over Ethernet over the top of another topology that doesn't necessarily directly support Point to Point Protocol over Ethernet (like ATM). In order to use PPPoE you and your ISP have to use this protocol in tandem, not many of them use this if you are using the ATM whether it be xDSL / T1 / T3 connectivity.

    Most use the IPoA standard as it is easier to implement in the central office (CO) and downline to the Customer Premise Equipment (CPE). With this being said, the difference in MTU is quite small.

    IPoA MTU = 1500
    IPoE MTU = 1492

    This is only half of the story as to why this is important to match the MTU with your ISP, the MTU on your computer(s), on your modem router must match what your ISP has had it set at in order to avoid fragmentation.

    Here is the other part that is not directly user configurable, the TTL on the X5modem router is set statically for 64 milliseconds, this is great for LAN to LAN connectivity but not great for Internet communications, the suggested setting for maximum time that packets are allowed to live in the receive window for the modem should be 128 milliseconds, as should the setting be for your NIC card or embedded chipset.

    While you can change the TCP/IP options all you want on your computers that will not be inherited by the router unfortunately, as there is no option to set the TTL value for packets in the receive buffer of the modem, only the MTU can be set.

    Even if you set the your computer's TCP/IP to optimum settings via the Speed Guide TCP Optimizer, you still go through the unoptimized router of the ADSL modem that causes the packets to fragment and have other problems, that can cause lag issues in games or streaming media.

    If the TTL is set too high you don't drop packets but your Internet speed will be compromised, you will be slower indeed, going to low will cause quite a few packets to be dropped and the need for packets to be retransmitted. A/V files or games will become choppy or become unresponsive if there is an interruption of the streaming media when error correction / detection has not been implemented.

    I have contacted Zoom pertaining to this particular problem and working for a solution to fix this, I have offered to reprogram the firmware for them with all the options that you would normally find in a full TCP/IP stack with full security as well. Most commercial market products don't have all the bells and whistles for security and optimizing bandwidth and / or latency issues let alone load balancing. These ironically use the same chipsets and memory capacities as the professional / corporate grade products use. The only difference is the firmware implemented and the options that are written in the firmware.

    Now, if you want to get into your modem, assuming nothing has changed
    including the adminstration user name and password, let alone the IP address of it.

    For Ethernet based connectivity, enter this in on your address bar of your browser.

    http://10.0.0.2

    Then hit enter.

    Optionally the USB based connectivity, enter this in on your address bar of your browser.

    http://10.0.0.3

    Then hit enter.

    Username:

    admin

    Then click on the Password box;

    Password:

    zoomadsl

    Then click "Ok"

    Once you are in, there are a bunch of Icons on the top of the web page,
    click on the "Advanced Setup icon with the wrench on it". Under the "Configuration" heading there is a series of buttons you can click on, select "LAN", then the "LAN Configuration" for the X5 ADSL modem pops up.
    Bear in mind this setting is only for Intranet use only, meaning the router and the other computers on the inside or intranet, not the WAN interface that goes to the Internet. Here you can adjust your MTU setting but be advised that if your MTU doesn't match what the MTU is on your WAN side where your ISP is, you will get fragmentation.

    Something that should be noted is that the TTL parameter is specifically linked to your receive buffer only (also seen as received window in Microsoft Windows aka RWIN), not the transmit side.

    Even if you set your RWIN value a lot higher than what the standard windows scaling suggests, it does help alleviate some packet loss or packet death but since the TTL value on the router doesn't match what your ISP or computers have it set at, this can become a problem.

    I bet you are wondering why it is set at a lower value than what is suggested for Time to Live, the answer is simple, the majority of the memory in the X5 is set up for the operations side of the modem, that includes the stateful packet inspection (SPI) firewall and network address translation (NAT) protocol in place, there is quite a bit more room to handle data but they have said it's reserved for future use. Ironically the future use is to have all the bells and whistles selectable and set the TTL to whatever you want from 32 to 255 ms.

    I know this has got to tick you off a little, as it does me, but I have made the offer to make things more appealing to all users not just the power users.

    What I would suggest you to do is to find out if you are using IPoE or IPoA, then set your MTU on your computer and on the modem according, then save the parameters for the X5, then write it to flash memory as it tell you that you need to.

    Then I know this sound counter productive but to set your system like this with SG's TCP Optimizer until we can get a firmware update that gives us full control of the Zoom ADSL X5 Modem Router.

    Open the TCP Optimizer:

    Set the following parameters in this order.

    1. Slide the Connection Speed slider all the way to the right, so it reads 20000.

    2. Select the Custom Settings radio button in the lower right hand section of the application.

    3. Select whether or not you have PPPoE or not, that will automatically adjust the MTU for you.

    4. Goto the TCP-1323 Options, deselect windows scaling.

    5. Goto the TCP Receive Window box and key in this number, 528400. Alternatively if you have a lot of RAM in your computer, like over 512 MB, I have mine set at 1048576 and get even better performance with the Qwest Megabit service, 1.5 Mbps down / 768 kbps up.

    6. Select MTU Discovery for "Yes".

    7. Select Black Hole Detect for "No".

    8. Select Selective Acks for "Yes".

    9. Key in 2, for the Max Dup Acks box.

    10. Leave the TTL for 64 ms even though is would be the incorrect setting for fluid gaming or high end A/V streaming events. The reason why you leave it at 64 ms, is you have to remember you cannot change your router TTL yet so the point is mute unfortunately.

    At this point, hit "Apply" to change the setting for your local computer you are on.

    You will need to restart your computer after you do this. Another couple of things that can cause slow speeds or unrealized bandwidth are the following.

    Since the front end of DSL for both the ISP and the CPE equipment is "ANALOG" and not "DIGITAL" you are dealing with the analog domain of signal to noise ratios, transmit and receive power in decibels,etc.

    What screws up the signal the most on any transmission medium is the injection of noise and corruption of clocking or skewing of clocks. The further you are away from the CO or ISP where you line terminates into their system is the more chances for noise to interfere with your communications with your ISP. What I would like you to do is get into your "Advanced Settings" again of your modem and go here, to copy down your signal information for me and I will tell you if you are in the red or the green. Meaning if the phone company needs to fix something if it is in the red.

    Under the "Status" heading, click on the ADSL Status button, then copy the local and remote; SNR, Line Attenuation, and Transmit power in dB. One word of caution, these figures do get updated every 2 to 5 seconds, just get the numbers for one time or unless you see huge changes in the number like over a decade change. Such as SNR Margin from 16.5 dB goes down to 6.5 dB, then you would have a real problem with noise on your circuit.

    If you can get the SNR sufficiently high and the transmit power on your end a little higher you can acheive better upload speeds. Also if you can cut down the noise coming from the ISP or CO side and boost the receive signal and quality your download speed will increase as well, the latency does tend to drop off when there is less noise on the telephone circuit.

    There are some other things to check but I won't get into that right now, that is a whole new area for you to explore and I don't know if you have that background or could get the tools you need to investigate further.


    I would like to appologize for the length of this posting but bear in mind when working with multiple devices on your LAN setting just one station and / or device is not enough. While changing the TCP/IP setting on a dial-up modem is much easier, there is no router and other devices it has to go through, just your modem to your ISP's modem, from there the MTU framing gets resized for transmission over other types of connections. Example, dial up modems usually have an MTU of 576 at the ISP and have a TTL of 64 or 128. You can have a lower TTL on packets of this size because the smaller the packet is the quicker it can be processed.

    By the way, don't try to set your Ethernet connection to MTU of 576, you will get a lot of fragmentation. For more information look up the Ethernet framing standards, disregard anything refering to jumbo frames, you need not worry about those.

    Got other questions about the modem or computers in general, I can answer them for you.

  5. #5
    Quote Originally Posted by alex_barringer View Post
    This pertains to the following;

    Model: 5654 (ADSL 1/2/2+ compatible)
    Series: 0228 through 0240

    You need help tweaking your MTU you say. Now before I go any further there is something you need to know before you start messing with the registry settings in Windows trying to get the best connection bandwidth
    and lower latency.

    What can be adjusted in the current Zoom firmware for this modem is;

    MTU or Maximum Transfer Units in bytes, it's set currently for 1,500 which is standard for Ethernet framing and ADSL that is using IPoA also know as TCP/IP over ATM (Asyncronous Transfer Mode). PPPoE is another standard that is overlayed on top of a physical interface, in other words PPPoE is TCP/IP over Ethernet over the top of another topology that doesn't necessarily directly support Point to Point Protocol over Ethernet (like ATM). In order to use PPPoE you and your ISP have to use this protocol in tandem, not many of them use this if you are using the ATM whether it be xDSL / T1 / T3 connectivity.

    Most use the IPoA standard as it is easier to implement in the central office (CO) and downline to the Customer Premise Equipment (CPE). With this being said, the difference in MTU is quite small.

    IPoA MTU = 1500
    IPoE MTU = 1492

    This is only half of the story as to why this is important to match the MTU with your ISP, the MTU on your computer(s), on your modem router must match what your ISP has had it set at in order to avoid fragmentation.

    Here is the other part that is not directly user configurable, the TTL on the X5modem router is set statically for 64 milliseconds, this is great for LAN to LAN connectivity but not great for Internet communications, the suggested setting for maximum time that packets are allowed to live in the receive window for the modem should be 128 milliseconds, as should the setting be for your NIC card or embedded chipset.

    While you can change the TCP/IP options all you want on your computers that will not be inherited by the router unfortunately, as there is no option to set the TTL value for packets in the receive buffer of the modem, only the MTU can be set.

    Even if you set the your computer's TCP/IP to optimum settings via the Speed Guide TCP Optimizer, you still go through the unoptimized router of the ADSL modem that causes the packets to fragment and have other problems, that can cause lag issues in games or streaming media.

    If the TTL is set too high you don't drop packets but your Internet speed will be compromised, you will be slower indeed, going to low will cause quite a few packets to be dropped and the need for packets to be retransmitted. A/V files or games will become choppy or become unresponsive if there is an interruption of the streaming media when error correction / detection has not been implemented.

    I have contacted Zoom pertaining to this particular problem and working for a solution to fix this, I have offered to reprogram the firmware for them with all the options that you would normally find in a full TCP/IP stack with full security as well. Most commercial market products don't have all the bells and whistles for security and optimizing bandwidth and / or latency issues let alone load balancing. These ironically use the same chipsets and memory capacities as the professional / corporate grade products use. The only difference is the firmware implemented and the options that are written in the firmware.

    Now, if you want to get into your modem, assuming nothing has changed
    including the adminstration user name and password, let alone the IP address of it.

    For Ethernet based connectivity, enter this in on your address bar of your browser.

    http://10.0.0.2

    Then hit enter.

    Optionally the USB based connectivity, enter this in on your address bar of your browser.

    http://10.0.0.3

    Then hit enter.

    Username:

    admin

    Then click on the Password box;

    Password:

    zoomadsl

    Then click "Ok"

    Once you are in, there are a bunch of Icons on the top of the web page,
    click on the "Advanced Setup icon with the wrench on it". Under the "Configuration" heading there is a series of buttons you can click on, select "LAN", then the "LAN Configuration" for the X5 ADSL modem pops up.
    Bear in mind this setting is only for Intranet use only, meaning the router and the other computers on the inside or intranet, not the WAN interface that goes to the Internet. Here you can adjust your MTU setting but be advised that if your MTU doesn't match what the MTU is on your WAN side where your ISP is, you will get fragmentation.

    Something that should be noted is that the TTL parameter is specifically linked to your receive buffer only (also seen as received window in Microsoft Windows aka RWIN), not the transmit side.

    Even if you set your RWIN value a lot higher than what the standard windows scaling suggests, it does help alleviate some packet loss or packet death but since the TTL value on the router doesn't match what your ISP or computers have it set at, this can become a problem.

    I bet you are wondering why it is set at a lower value than what is suggested for Time to Live, the answer is simple, the majority of the memory in the X5 is set up for the operations side of the modem, that includes the stateful packet inspection (SPI) firewall and network address translation (NAT) protocol in place, there is quite a bit more room to handle data but they have said it's reserved for future use. Ironically the future use is to have all the bells and whistles selectable and set the TTL to whatever you want from 32 to 255 ms.

    I know this has got to tick you off a little, as it does me, but I have made the offer to make things more appealing to all users not just the power users.

    What I would suggest you to do is to find out if you are using IPoE or IPoA, then set your MTU on your computer and on the modem according, then save the parameters for the X5, then write it to flash memory as it tell you that you need to.

    Then I know this sound counter productive but to set your system like this with SG's TCP Optimizer until we can get a firmware update that gives us full control of the Zoom ADSL X5 Modem Router.

    Open the TCP Optimizer:

    Set the following parameters in this order.

    1. Slide the Connection Speed slider all the way to the right, so it reads 20000.

    2. Select the Custom Settings radio button in the lower right hand section of the application.

    3. Select whether or not you have PPPoE or not, that will automatically adjust the MTU for you.

    4. Goto the TCP-1323 Options, deselect windows scaling.

    5. Goto the TCP Receive Window box and key in this number, 528400. Alternatively if you have a lot of RAM in your computer, like over 512 MB, I have mine set at 1048576 and get even better performance with the Qwest Megabit service, 1.5 Mbps down / 768 kbps up.

    6. Select MTU Discovery for "Yes".

    7. Select Black Hole Detect for "No".

    8. Select Selective Acks for "Yes".

    9. Key in 2, for the Max Dup Acks box.

    10. Leave the TTL for 64 ms even though is would be the incorrect setting for fluid gaming or high end A/V streaming events. The reason why you leave it at 64 ms, is you have to remember you cannot change your router TTL yet so the point is mute unfortunately.

    At this point, hit "Apply" to change the setting for your local computer you are on.

    You will need to restart your computer after you do this. Another couple of things that can cause slow speeds or unrealized bandwidth are the following.

    Since the front end of DSL for both the ISP and the CPE equipment is "ANALOG" and not "DIGITAL" you are dealing with the analog domain of signal to noise ratios, transmit and receive power in decibels,etc.

    What screws up the signal the most on any transmission medium is the injection of noise and corruption of clocking or skewing of clocks. The further you are away from the CO or ISP where you line terminates into their system is the more chances for noise to interfere with your communications with your ISP. What I would like you to do is get into your "Advanced Settings" again of your modem and go here, to copy down your signal information for me and I will tell you if you are in the red or the green. Meaning if the phone company needs to fix something if it is in the red.

    Under the "Status" heading, click on the ADSL Status button, then copy the local and remote; SNR, Line Attenuation, and Transmit power in dB. One word of caution, these figures do get updated every 2 to 5 seconds, just get the numbers for one time or unless you see huge changes in the number like over a decade change. Such as SNR Margin from 16.5 dB goes down to 6.5 dB, then you would have a real problem with noise on your circuit.

    If you can get the SNR sufficiently high and the transmit power on your end a little higher you can acheive better upload speeds. Also if you can cut down the noise coming from the ISP or CO side and boost the receive signal and quality your download speed will increase as well, the latency does tend to drop off when there is less noise on the telephone circuit.

    There are some other things to check but I won't get into that right now, that is a whole new area for you to explore and I don't know if you have that background or could get the tools you need to investigate further.


    I would like to appologize for the length of this posting but bear in mind when working with multiple devices on your LAN setting just one station and / or device is not enough. While changing the TCP/IP setting on a dial-up modem is much easier, there is no router and other devices it has to go through, just your modem to your ISP's modem, from there the MTU framing gets resized for transmission over other types of connections. Example, dial up modems usually have an MTU of 576 at the ISP and have a TTL of 64 or 128. You can have a lower TTL on packets of this size because the smaller the packet is the quicker it can be processed.

    By the way, don't try to set your Ethernet connection to MTU of 576, you will get a lot of fragmentation. For more information look up the Ethernet framing standards, disregard anything refering to jumbo frames, you need not worry about those.

    Got other questions about the modem or computers in general, I can answer them for you.
    Dear Alex Ive read your tips and Id like to know if its possible apply them in my situation,Im from Brazil my speed are 1024 down and 512 up,would improve if I put 528400 at TCP receive window?and uncheck windows scaling?
    Thanks for your help

  6. #6

    Unhappy help me tweak my speed line 128 kb very slow

    SpeedGuide.net TCP Analyzer Results
    TCP options string = 020405340402080abdbbf8450000000001030308
    MTU = 1372
    MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better throughput. If you are using a router, it could be limiting your MTU regardless of Registry settings.
    MSS = 1332
    MSS is not optimized for broadband. Consider increasing your MTU value.
    Default TCP Receive Window (RWIN) = 5888
    RWIN Scaling (RFC1323) = 8 bits (scale factor: 2^8=256)
    Unscaled TCP Receive Window = 23

    RWIN seems to be set to a very small number. If you're on a broadband connection, consider using a larger value.
    For optimum performance, consider changing RWIN to a multiple of MSS.
    Other RWIN values that might work well with your current MTU/MSS:
    63936 (up to 2 Mbit lines, depending on latency. MSS * 48)
    127872 (1-5 Mbit lines, depending on latency. MSS * 48 * 2)
    255744 (2-14 Mbit lines, depending on latency. MSS * 48 * 2^2)
    511488 (8-30 Mbit lines, depending on latency. MSS * 48 * 2^3)
    1022976 (25-60 Mbit lines depending on latency. MSS * 48 * 2^4)
    bandwidth * delay product (Note this is not a speed test):

    Your TCP Window limits you to: 236 kbps (29 KBytes/s) @ 200ms
    Your TCP Window limits you to: 94 kbps (12 KBytes/s) @ 500ms
    Consider increasing your RWIN value to optimize TCP/IP for broadband.
    MTU Discovery (RFC1191) = ON
    Time to live left = 89 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) = 00000000 (0)

    please help me for speed up my line adsl 128kb up to 1024 kb or better speed

    my modem model : asus wl-am602
    i'm in iran ,
    tankc
    please send to my email
    Please earlier...

  7. #7
    fem the retarded rabbit mccoffee's Avatar
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    Location
    Cleveland, Ohio, United States
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    Actually I know few people that use that 1452 and had luck with it for pppoe technically it should match the isp
    Comptia a+ n+

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