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Thread: network problems

  1. #1
    Member Kandar's Avatar
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    network problems

    Hi people. does anyone know if there is a recomended maximum number of machines that should be connected via unmanaged network switches.

  2. #2
    Mod w/ an attitude Sterling_Aug's Avatar
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    The max. is 252 devices or you run out of IP addresses. You can't use address 0, 127, or 255 on the last octet.

    It would depend on the manufacturer of your equipment.

    Details please?

  3. #3
    Member Kandar's Avatar
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    Sorry, I was a little vague there.
    We are experiencing major packet storm type network outages that very quickly bring down the entire network. It seems to be occurring randomly and tracing the fault is proving difficult as it sometimes seems to clear itself. Kids used to cause a packet storm by inserting a loop on the network but that doesnít happen that often now and we are pretty sure that itís not that.
    The school network was originally installed some years ago and was not designed with any consideration to future usage. A recent damming network audit highlighted just how poor the network is actually performing as a direct result of inappropriate installation of the cables. There is a high degree of packet loss and mains frequency harmonics are present in every network cable run. We are trying to convince the administration to address this with emphasis on replacing the tired old switches with either Cisco or Pro curve switches and replacing the cat5E uplinks to sub cabinets with fibre but this is not going to happen for a while even if they agree. Just recently the school installed interactive whiteboards and additional PCís in every room without giving any consideration to the networks ability to cope. We feel that this may have pushed the netgear switches over the edge as two of them seem to be sticking and require resetting regularly. Even with these faulty switches isolated from the network the problems are still occurring.

    I was just curious if anyone knew if there was any sort of limit or recommendation to the amount of connections a rack of unmanaged switches could be reasonably expected to handle.

  4. #4
    Member cyber_gubat's Avatar
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    can you give me the number of Nodes or workstations? is there any distance exceeding 70-100 meters? What switch does the school use? 10/100 or 10 baseT alone.? switching to cisco is quite expensive compared to HP procurve but in my personal opinion I prefer using foundry entry level switches. Also if you need cabling solutions I highly recommend R&M you can visit their site it's http://www.rdm.com

  5. #5
    Member Kandar's Avatar
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    There are 6 remote sub cabinets supplying over 500 fixed workstations plus staff alocated laptops can be used sporadically around the building. The bulk of the switches are 50 port Netgear FS750 10/100/1000 Modular Ethernet Switches and 24 port models from the same range. Most of the uplink runs are quite lengthy and some are known to be borderline in terms of distance. The newer install is correctly installed but the original stuff is run alongside mains cables.

  6. #6
    Mod w/ an attitude Sterling_Aug's Avatar
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    Running alongside of mains is your problem.

    Get the cables re-routed away from all interferences.

  7. #7
    Member Kandar's Avatar
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    If only life was so simple.
    I am well aware of how the lack of cable segregation throughout the site is effecting the networks overall performance however this is a new problem which I feel is directly related to hardware failure rather than harmonic interference as this site has been running in this condition for a number of years without suffering from these packet storm type outages.
    I wholeheartedly agree that a complete reinstall would be advantageous but this is simply not economically or practically a viable option at this stage.

  8. #8
    Mod w/ an attitude Sterling_Aug's Avatar
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    Then start dropping off devices or entire rooms to isolate which section of the school is causing the packet storms. You should be able to easily find the router, switch, or PC that is causing it.

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