serial ppp link verification - PPP

This is a discussion on serial ppp link verification - PPP ; I use a serial null modem cable to connect 2 computers via ppp. If the connection is established and I unplug the cable no error occours. Is there a possibility to check if the link is still established (with a ...

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Thread: serial ppp link verification

  1. serial ppp link verification

    I use a serial null modem cable to connect 2 computers via ppp. If the
    connection is established and I unplug the cable no error occours. Is
    there a possibility to check if the link is still established (with a
    feature of the Protocol Layewr, like an LCP Request or something).

    Rgds
    Ruben


  2. Re: serial ppp link verification

    "Ruben" writes:
    > I use a serial null modem cable to connect 2 computers via ppp. If the
    > connection is established and I unplug the cable no error occours. Is
    > there a possibility to check if the link is still established (with a
    > feature of the Protocol Layewr, like an LCP Request or something).


    Yes. That's what LCP Echo-Request is for.

    However, before resorting to LCP echo messages (sometimes called
    "keepalive"), make sure that the physical layer is as robust as it can
    be. If this is a plain old async serial connection between two
    computers, then you should have DTR on one side connected to DCD on
    the other, and vice-versa. This will allow each side to detect the
    disconnect *immediately* on cable disconnect, rather than waiting for
    LCP to discover the problem.

    It's much more reliable to use the physical layer features if they're
    present. Cables that have this feature are usually called "null modem
    with full modem controls" or some such.

    You didn't mention any particular operating system or PPP
    implementation, so providing help is going to be difficult. If you
    want help, you might want to provide details. (Useful advice for any
    posting ...)

    --
    James Carlson, KISS Network
    Sun Microsystems / 1 Network Drive 71.234W Vox +1 781 442 2084
    MS UBUR02-212 / Burlington MA 01803-2757 42.497N Fax +1 781 442 1677

  3. Re: serial ppp link verification

    "Ruben" writes:

    >I use a serial null modem cable to connect 2 computers via ppp. If the
    >connection is established and I unplug the cable no error occours. Is
    >there a possibility to check if the link is still established (with a
    >feature of the Protocol Layewr, like an LCP Request or something).


    lcp-echo
    Look up man pppd


    >Rgds
    >Ruben



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