[PARPORT] help required with strange plip problem..

From: Julian Holley (julian@clares.globalnet.co.uk)
Date: Fri Mar 30 2001 - 10:30:28 EST

  • Next message: Gene Heskett: "Re: [PARPORT] help required with strange plip problem.."

    Hi everyone - For ages I've been backing up me laptop files to my
    desktop with plip - no problems. The laptop running 2.2.14 (redhat 6.0
    - with custom kernel) and the desktop running 2.0.35 (redhat 5.2 stock
    kernel). I recently upgraded my desktop to the same as the laptop ie
    kernel 2.2.14 (redhat 6.0 custom kernel) and the plip stopped working.

    The problem :- packets are successfully TXed and then RXed on both
    machines - no problems. _BUT_ the packets don't seem to get through to
    the networking sub-system in the kernel because when I ping no packet on
    either machine is returned even though it is received without error !?

    The Facts :- If I reboot my desktop back to the old kernel (not entire
    redhat system 5.2 but just kernel 2.0.35) the plip works again ! - same
    machines - same cable - same 2.2.14 on laptop.

    - The cable is correct (this I have checked with a meter and complies
    with pin outs in plip source).

    - IO and irqs are correct for both machines - (triple checked !)

    - I ping one machine and watch perfect packets arrive at the other
    machine but they are not returned
    (vice versa on each machine)

    - OK I thought - lets try another computer to see who's to blame - I got
    an old 486 out and installed stock redhat 6.0 (kernel 2.2.5-14) - I get
    exactly the same problem from old desktop to new desktop and new desktop
    to laptop !!

    - OK I thought lets dig out that SUSE 7.0 live CD and boot my laptop
    from that (kernel 2.4.0) and guess what !? - I get the exact same
    problem !?

    - If I ping each machine with its own host name I get the expected

    - I have checked /usr/src/linux/Documentation/Changes - and both
    machines comply.

    - my manually configured dial internet connection works fine.

    I think I am missing something big here - I'm not sure how plip passes
    packets on to the networking system I know that some sort of
    encapsulation within the ethernet system goes on - but I not sure how I
    can test to see where my the received packets are going - ie why they
    are not going to icmp system or why that system refuses to respond ?

    I'm pulling me hair here guys and I greatly appreciate any pointers.

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