ISDN external TA - getting only 64k of 128k - Linux

This is a discussion on ISDN external TA - getting only 64k of 128k - Linux ; We have a D-Link 128K external TA connected to a P-IV system running RedHat Linux 8.0 (kernel 2.4) using serial comms port (16550 UART). At present i connect to the inet by manually dialling the TA using minicom and then ...

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Thread: ISDN external TA - getting only 64k of 128k

  1. ISDN external TA - getting only 64k of 128k

    We have a D-Link 128K external TA connected to a P-IV system running
    RedHat Linux 8.0 (kernel 2.4) using serial comms port (16550 UART). At
    present i connect to the inet by manually dialling the TA using
    minicom and then running pppd -detach /dev/ttys0. Whatsoever i've
    done, i m unable to get 128K Rx speed. The average Rx is just around
    52k - 60kbps (6-7KBps).

    The TA supports 128K for which i've to use AT%A2=6 (MLPPP), also the
    portspeed is set to 230400bps in the pppd options, which the TA
    supports. The dial command : ATD172225 and my ISP uses PAP
    authentication (pap-secrets - OK). While i have no problems while
    connecting or afterwards, the connection is stable but the only
    bottleneck is the 60k downlink that i m getting.

    I've calculated the Rx throughput by checking the /var/log/messages to
    record the pppd startup time and the ifconfig to record the Rx data
    received (in BYTES and not bits). ifconfig ppp0 reports no or very few
    (2-5) packet errors. About 50-60 WinXP clients have been configured to
    access proxy services which squid (2.5 stable) provides.

    When i tried ATD172225&172225, the TA reported error. I tried putting
    spaces around & but couldn't suceed. I have no telephones connected to
    the TA. But when i connected a phone to both the ports 1 after
    another, i found both the lines busy (silence). intrestingly, as
    mentioned in the manual "the BACP/BOD functionality will automatically
    freeup 1-b channel when the user picks up the receiver" i didn't get
    any such result. both the lines remain silent without getting any
    dailtone. Are bot the channels really being used? This setup is at
    our college. I've convinced the admin there to use linux+squid over
    WinXP+NAT. the performance is better in linux as compared to WinXP but
    Rx still is low on both the OSes.

    The responses I receive after entering AT commands are :
    PROTOCOL : MLPPP 128k
    CONNECT 230400

    I've tried using a shell script "pppd connect 'chat -v ......" for
    connection. but all in vain.

    what am i missing? is anything wrong?
    ready to post ne other required details,
    just ne suggestions are welcome.
    thnx in advance

    - uday

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  2. Re: ISDN external TA - getting only 64k of 128k

    Uday wrote:
    >
    > We have a D-Link 128K external TA connected to a P-IV system running
    > RedHat Linux 8.0 (kernel 2.4) using serial comms port (16550 UART). At
    > present i connect to the inet by manually dialling the TA using
    > minicom and then running pppd -detach /dev/ttys0. Whatsoever i've
    > done, i m unable to get 128K Rx speed. The average Rx is just around
    > 52k - 60kbps (6-7KBps).
    >
    > The TA supports 128K for which i've to use AT%A2=6 (MLPPP), also the
    > portspeed is set to 230400bps in the pppd options, which the TA
    > supports.


    [snip]

    > I've tried using a shell script "pppd connect 'chat -v ......" for
    > connection. but all in vain.
    >
    > what am i missing? is anything wrong?


    It sounds like you're missing multi-link support (i.e., only one channel
    is being used). Are you passing the "mp" or "multilink" options to pppd
    when you try to connect? Have you read the "MULTILINK" section in 'man
    8 pppd'? (AIUI, you need to connect twice with two instances of pppd so
    that multilink will bind the two channels together.) Does your kernel
    include "Multilink PPP" support?

  3. Re: ISDN external TA - getting only 64k of 128k

    Problem may also be at your ISP ... Some ISPs do not support multilink
    especially on unmetered dialup numbers .. This is as you are tying up two
    lines and they are having to pay for two freephone lines instead of one ..

    Regards,

    Phil.
    "John-Paul Stewart" wrote in message
    news:3F48D6D7.17941B6E@sympatico.ca...
    > Uday wrote:
    > >
    > > We have a D-Link 128K external TA connected to a P-IV system running
    > > RedHat Linux 8.0 (kernel 2.4) using serial comms port (16550 UART). At
    > > present i connect to the inet by manually dialling the TA using
    > > minicom and then running pppd -detach /dev/ttys0. Whatsoever i've
    > > done, i m unable to get 128K Rx speed. The average Rx is just around
    > > 52k - 60kbps (6-7KBps).
    > >
    > > The TA supports 128K for which i've to use AT%A2=6 (MLPPP), also the
    > > portspeed is set to 230400bps in the pppd options, which the TA
    > > supports.

    >
    > [snip]
    >
    > > I've tried using a shell script "pppd connect 'chat -v ......" for
    > > connection. but all in vain.
    > >
    > > what am i missing? is anything wrong?

    >
    > It sounds like you're missing multi-link support (i.e., only one channel
    > is being used). Are you passing the "mp" or "multilink" options to pppd
    > when you try to connect? Have you read the "MULTILINK" section in 'man
    > 8 pppd'? (AIUI, you need to connect twice with two instances of pppd so
    > that multilink will bind the two channels together.) Does your kernel
    > include "Multilink PPP" support?




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