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  • ADSL modem connected to a hub

    Hello,

    I have a very strange problem. I have two computers and an ADSL hub
    all connected to an Intel InBusiness 8 port 10/100 hub. Now, everthing
    works fine, but sometimes (usually a couple of times a day, sometime
    more) the LED of the port in the hub the modem is connected to starts
    flashing very fast, and I can't access my modem, I don't even have a
    ping. When this happens I disconnect the modem from the hub and
    immediatley connect it again and everything works again.

    Does anyone have any idea what can cause these disconnections?

    Thanks you!

  • #2
    Modem problems

    TheC Posted: Sat Jul 10, 2004 5:18 pm Post subject: ADSL modem connected to a hub

    --------------------------------------------------------------------------------


    I have a very strange problem. I have two computers and an ADSL hub
    all connected to an Intel InBusiness 8 port 10/100 hub. Now, everthing
    works fine, but sometimes (usually a couple of times a day, sometime
    more) the LED of the port in the hub the modem is connected to starts
    flashing very fast, and I can't access my modem, I don't even have a
    ping. When this happens I disconnect the modem from the hub and
    immediatley connect it again and everything works again.

    Yes first what i would do if i were you is go to the website of the manf that made your modem and Flash the bios. Be sure to have a good understanding of what this does before you proceed. Then after you have done that do the same with your router(if you use a switch then exclude this)After that if you still have problems what i would do is set your modem to bridge mode were encap is llc-based and emulation is rfc-1494<===this number is probably wrong but u get the general idea.
    then i would set up a new internet connection on both ure clients using a miniport Pppoe and have ure comp authenicate it self threw ure modem(or gateway)If all else fails what i would do is contact you isp and ask for a new modem.

    Comment


    • #3
      hi TheC,

      please check my thread in this forum right near yours with the name:

      "SpeedTouch Home->PRO + Switching Hub = random Switch crash"

      I've seen many guys experiencing these frustrating problems when connecting a Switch to the SpeedTouch Home, Pro and even 510 ... you sure you're using a Hub and not a Switch ?

      A desktop Switch (Switching Hub) in general has auto-negotiation and
      it can easily pick 10Mbps or 100Mbps even if the other side can't auto-negotiate - but auto-negotiation fails when picking the right duplex mode. The SpeedTouch Home and Pro work only at 10Mbps Half-Duplex with no auto-negotiation or configuration possible. So what happens in my case is that the Switch is working at 10Mbps Full-Duplex with the Router and while it seems that everything is working fine, now and then the Switch crashes in the way you explain (very fast blinking light). I've experienced the problem with 2 different Switches so far.

      That's why I am exchanging this Switch for a Hub (Repeating Hub) that works only at Half-Duplex so I am pretty sure problems will disappear.

      This is why i am asking if you sure you're using a Repeating Hub instead of a Switching Hub.

      Orionn.

      Comment


      • #4
        I have an Intel 8 port 10/100 Fast Hub.
        I tried to check if it's a repeating hub or a switching hub, but I don't know...

        A few days ago I tried to change all the computers to work at 100Mb Half Duplex, and since then it seems that the problem does occur, but it just hangs for a second and then the connection is reestablished, as opposed to before when it would take it a few minutes to reconnect (assuming I didn't manully disconnect the modem from the hub and reconnect it).

        My problem does seem very similar to yours, have you found a way to fix it?

        Comment


        • #5
          A few things you want to know:

          1. in which traffic conditions does the Hub crash/lock ? it's important to reproduce the problem.
          In my case I can easily crash the Switch with Streaming Video.

          2. what is your Modem ? is it a Alcatel SpeedTouch Home/Pro (510 has also problems) ? What are the
          specifications of the RJ45 Router port that you connect the Hub to ?
          The SpeedTouch has a 10Mbps Half-Duplex port not configurable.

          3. I don't think that changing the NICs to 100Mbps Full-Duplex would have any influence on the
          Modem-Hub link - in my case it didn't have any impact on the problem. You should focus on the
          Modem/Router-Hub link since that is the one that locks/crashes.

          4. I did not find a fix for my problem but i am pretty sure this is autonegotiation problems.
          I am trying to exchange this Switch for a Hub since i am convinced my problem is a Duplex autonegotiation
          mismatch (Switch working at Full-Duplex and SpeedTouch Home->Pro working at Half-Duplex).
          I am trying to avoid anything that says 'autonegotiation' or 'autosensing' since this is where problems
          can arise. Also if i had bought a cheap Switch with plenty of diagnostic LEDs (10/100 Half/Full Duplex)
          instead of the more expensive Linksys SD205-EU or DLink DES-1005D with only a single LED per
          link I would have found the problem much faster.

          5. I suggest that once you know how to crash/lock the Hub you connect your computer directly to the
          Modem/Router - then configure the NIC for 10Mbps Half-Duplex, 10Mbps Full-Duplex, 100Mbps Half-Duplex
          and 100Mbps Full-Duplex - if your Modem/Router is a SpeedTouch you'll see that you can't connect
          at 100Mbps, that you can connect at 10Mbps Full-Duplex but that the NIC (network card) will eventually
          Crash/Lock in the same traffic conditions that you crashed the Hub and finally that at 10Mbps Half-Duplex
          there are no problems since you're working like the SpeedTouch want you to.

          Hope this helps.

          Comment


          • #6
            I've tried to find what exactly causes the problem, but I couldn't...
            It may disconnect when both computers are connected and it may disconnect when only one computer is connected. I couldn't find any relation to the bandwidth usage, since there are times when I use the network quite heavily and it works fine... So I couldn't reproduce the problem...

            A few hours ago I configured my NIC to work at 10Mbs Half Duplex, and I want to see if the problem still occurs.

            As to your question, I have an Alcatel SpeedTouch Pro Modem.
            What do you mean by port specifications?

            Comment

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