Network connection riddle - Connectivity

This is a discussion on Network connection riddle - Connectivity ; Hi, Since very recent I have a networkingproblem, for which I have a workaround that shouldn't be working, considering the problem. Original situation: ADSL modem/router -> UTP cable -> 10/100MB LAN switch Problem: the cable-led on both the modem/router and ...

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Thread: Network connection riddle

  1. Network connection riddle

    Hi,

    Since very recent I have a networkingproblem, for which I have a
    workaround that shouldn't be working, considering the problem.

    Original situation:
    ADSL modem/router -> UTP cable -> 10/100MB LAN switch
    Problem: the cable-led on both the modem/router and the LAN switch blink
    very infrequently and are mostly off, so I have no connection. I tried
    other sockets on both the modem/router and LAN switch, replaced the
    modem/router and the UTP cable but nothing solves the problem. Can't
    replace the LAN switch as I only have 1.

    Work around:
    Modem/router -> Orignal UTP cable in original modem/router socket ->
    10MB hub -> UTP cable in original 10/100MB LAN switch socket. This works
    fine!

    Can someone give me a reason why this workaround does work and the
    original situation doesn't work anymore? Could it be that those LAN
    switch sockets suddenly can't differ between 10MB and 100MB? (I regard
    this as unlikely, since the other ports work fine).

    Thanks for helping out!

    Huub

  2. Re: Network connection riddle

    "Huub" <"v.niekerk at hccnet.nl"> wrote in message
    news:46877626$0$13935$e4fe514c@dreader12.news.xs4a ll.nl...
    > Hi,
    >
    > Since very recent I have a networkingproblem, for which I have a
    > workaround that shouldn't be working, considering the problem.
    >
    > Original situation:
    > ADSL modem/router -> UTP cable -> 10/100MB LAN switch
    > Problem: the cable-led on both the modem/router and the LAN switch blink
    > very infrequently and are mostly off, so I have no connection. I tried
    > other sockets on both the modem/router and LAN switch, replaced the
    > modem/router and the UTP cable but nothing solves the problem. Can't
    > replace the LAN switch as I only have 1.
    >
    > Work around:
    > Modem/router -> Orignal UTP cable in original modem/router socket -> 10MB
    > hub -> UTP cable in original 10/100MB LAN switch socket. This works fine!
    >
    > Can someone give me a reason why this workaround does work and the
    > original situation doesn't work anymore? Could it be that those LAN switch
    > sockets suddenly can't differ between 10MB and 100MB? (I regard this as
    > unlikely, since the other ports work fine).
    >
    > Thanks for helping out!
    >
    > Huub
    >


    My guess is you need a crossover ("null modem") cable between the
    modem/router and the switch. Each port - on the router and on the switch is
    probably wired DCE and expects to talk to a DTE device like a computer. A
    crossover cable has pins 1/2 swapped with pins 3/6 at one end so the
    transmit signal on one end goes to the receive pins on the other. No matter
    how loud you talk into the mouth at the other end it still can't hear you!

    Some switches have an "uplink" port that is wired DTE for just such things,
    but it sounds like yours doesn't.

    Mike




  3. Re: Network connection riddle

    "Huub" <"v.niekerk at hccnet.nl"> wrote in message
    news:46877626$0$13935$e4fe514c@dreader12.news.xs4a ll.nl...
    > Hi,
    >
    > Since very recent I have a networkingproblem, for which I have a
    > workaround that shouldn't be working, considering the problem.
    >
    > Original situation:
    > ADSL modem/router -> UTP cable -> 10/100MB LAN switch
    > Problem: the cable-led on both the modem/router and the LAN switch blink
    > very infrequently and are mostly off, so I have no connection. I tried
    > other sockets on both the modem/router and LAN switch, replaced the
    > modem/router and the UTP cable but nothing solves the problem. Can't
    > replace the LAN switch as I only have 1.
    >
    > Work around:
    > Modem/router -> Orignal UTP cable in original modem/router socket -> 10MB
    > hub -> UTP cable in original 10/100MB LAN switch socket. This works fine!
    >
    > Can someone give me a reason why this workaround does work and the
    > original situation doesn't work anymore? Could it be that those LAN switch
    > sockets suddenly can't differ between 10MB and 100MB? (I regard this as
    > unlikely, since the other ports work fine).
    >
    > Thanks for helping out!
    >
    > Huub
    >


    Something else - if the problem isn't with innies and outies, take a look at
    the port settings. Most modern equipment has multispeed ports set for
    auto-speed/auto-duplex. Occasionally auto/auto on both ends will fail to
    negotiate. In that case, try setting the switch port (more likely to have
    user settings than the router does) to 100/full. If still no-go you can drop
    back to 100/half, 10/full, or even 10/half to verify it connects at *some*
    setting.

    One last thought - the cable between them is at least cat 5, I hope? Cat 4
    is marginal for 100 mb and you can use cat 3 as an emergency replacement for
    a belt to hold your pants up but not for much else.

    Mike




  4. Re: Network connection riddle

    Hi Mike,

    Thanks for your reply. I suppose it had been better if I had added that
    the original situation has worked for about 3 to 4 years without any
    problem. No null-modem cable, just ordinary cat5 cable, as is the cable
    presently between the hub and the switch.
    Does this trigger new thoughts on the problem?

  5. Re: Network connection riddle

    "Huub" <"v.niekerk at hccnet.nl"> wrote in message
    news:468908d3$0$6856$e4fe514c@dreader13.news.xs4al l.nl...
    > Hi Mike,
    >
    > Thanks for your reply. I suppose it had been better if I had added that
    > the original situation has worked for about 3 to 4 years without any
    > problem. No null-modem cable, just ordinary cat5 cable, as is the cable
    > presently between the hub and the switch.
    > Does this trigger new thoughts on the problem?
    >

    Still focusing on the port config, then. The link light is usually lit by
    detecting the incoming carrier, so it sounds like the two ports haven't
    negotiated the speed (maybe the duplex, but I think the speed is the only
    part the light cares about). If you can manually set both ports to 100/full
    it really ought to work, but my grip on networking reality seems to weaken
    with my continued exposure ;-)

    Mike




  6. Re: Network connection riddle

    > Still focusing on the port config, then. The link light is usually lit by
    > detecting the incoming carrier, so it sounds like the two ports haven't
    > negotiated the speed (maybe the duplex, but I think the speed is the only
    > part the light cares about). If you can manually set both ports to 100/full
    > it really ought to work, but my grip on networking reality seems to weaken
    > with my continued exposure ;-)
    >


    The fact that the current work-around does work (with the 10MB hub in
    between) makes me suspect that the handling of 100MB speed of the switch
    might be problematic. Unfortunately, the switch is fully automatic and
    has no possibility of manual intervention. I guess I'm going to test the
    13 remaining untested switch sockets (didn't think of doing this
    earlier) and see if they all have the 100MB problem. If so, it's time
    for a new switch. If not, I hope someone can offer a new perspective.

  7. Re: Network connection riddle

    "Huub" <"v.niekerk at hccnet.nl"> wrote in message
    news:468b6472$0$21149$e4fe514c@dreader26.news.xs4a ll.nl...
    >> Still focusing on the port config, then. The link light is usually lit by
    >> detecting the incoming carrier, so it sounds like the two ports haven't
    >> negotiated the speed (maybe the duplex, but I think the speed is the only
    >> part the light cares about). If you can manually set both ports to
    >> 100/full it really ought to work, but my grip on networking reality seems
    >> to weaken with my continued exposure ;-)
    >>

    >
    > The fact that the current work-around does work (with the 10MB hub in
    > between) makes me suspect that the handling of 100MB speed of the switch
    > might be problematic. Unfortunately, the switch is fully automatic and has
    > no possibility of manual intervention. I guess I'm going to test the 13
    > remaining untested switch sockets (didn't think of doing this earlier) and
    > see if they all have the 100MB problem. If so, it's time for a new switch.
    > If not, I hope someone can offer a new perspective.
    >


    It's starting to sound that way. Good idea on testing the other ports. I
    presume the router doesn't offer any configuration, either :-(

    Mike




  8. Re: Network connection riddle

    >
    > It's starting to sound that way. Good idea on testing the other ports. I
    > presume the router doesn't offer any configuration, either :-(
    >


    Ok,it's time for a new switch. Tested 5 sockets: 4 adjacent are faulty,
    the 5th does well. Didn't test the rest, as I want them all be ok. My
    idea is for a new switch is 3Com OfficeConnect 16p 10/100.

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