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Network and Classroom Management Thread, Network drop outs in Technical; I don't know how to word this Every now and then we get a whole site network dropout. It only ...
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    newpersn's Avatar
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    Network drop outs

    I don't know how to word this

    Every now and then we get a whole site network dropout.

    It only last for a few seconds but enough for the IP phones to restart. (Takes around a minute to start back up)

    We have vlans and I have walked round the site and done a quick look back checks and not seen anything.

    Where do we start? Kinda strange.

    If it was a switch it would only effect that vlan. (Unless it's the main switch)

    Help

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    jamesreedersmith's Avatar
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    is it a power blip affecting the cabinet and therefore the switches restarting - are they on a UPS?

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    newpersn's Avatar
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    Quote Originally Posted by jamesreedersmith View Post
    is it a power blip affecting the cabinet and therefore the switches restarting - are they on a UPS?
    We dont have any UPS. But if it was a network switch restarting it would take longer than a minute to restart.

    Computers reconnect within seconds of it happening.

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    Depends on the switches - some unmanaged/older switches will restart almost instantly.

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    newpersn's Avatar
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    Quote Originally Posted by jamesreedersmith View Post
    Depends on the switches - some unmanaged/older switches will restart almost instantly.
    None of our core switchs are unmanaged and there a only a few years old (3com/HP)

    The switchs that are connected to our VLAN are HP and are only 2/3 Years only

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    FN-GM's Avatar
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    The phones shouldn't power off, are they POE? Even if network connectivity is lost and the switch is still powered up the phones should remain powered. Is this all on 1 switch or 1 stack?

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    Quote Originally Posted by FN-GM View Post
    The phones shouldn't power off, are they POE? Even if network connectivity is lost and the switch is still powered up the phones should remain powered.
    This is why i think its a switch/es rebooting, seen it before.

    can you put them on a different/UPS'd supply for a while to see, or set a continuous ping to the switch and see what happens to this, can you enable a syslog/event log on the switch.

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    Quote Originally Posted by FN-GM View Post
    The phones shouldn't power off, are they POE? Even if network connectivity is lost and the switch is still powered up the phones should remain powered. Is this all on 1 switch or 1 stack?
    We have mix analog and poe phones. The POE phones display "DHCPSVR NOT FOUND" My deskphone is a analong phone which isnt connected to the network. Just runs straight to the phones.

    i cant say its 1 switch or stack as the phone are all over the site. (diffenent building connected by fibre)

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    We have this, where a particular cab with 2 or 3 switches loses power, this behaviour occurs when it powers back on. The cab contains a switch with trunked fibre connections to the core switch, and also the first link to the VOIP server.
    Not sure whether it's the order the switches boot up in (time taken), or something else, but it was the second time it happened that I managed to pin it down. Electricians were doing some work and killed the power to it both times. Really does seem to generate full network traffic bursts/outages for a minute or so until it settles.
    How often does it happen?

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    Quote Originally Posted by jamesreedersmith View Post
    This is why i think its a switch/es rebooting, seen it before.

    can you put them on a different/UPS'd supply for a while to see, or set a continuous ping to the switch and see what happens to this, can you enable a syslog/event log on the switch.
    The switchs are connected to the same supply that powers the servers. I would of thought it would trigger the servers to trip out if its a spike.

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    It could be the phone system or type of phones causing them to power off when they loose connection.

    Have you gone to have a look to see if you backbone has bandwidth? As they are only 3 year old I assume its a 10GB backbone? I managed to do similar (without the phones) in a test environment. SCCM was hogging the bandwidth.

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    If I were you I would buy a cheap APC ups for EVERY switch cabinet in the school. I did this in the school I worked in and it made a huge difference. We often had power cuts which were brief and this had no effect on the switches. A UPS will provide a constant reliable power source. A layer two edge switch (HP) uses very little power so a cheap 50 APC UPS will be more than adequate - just do the maths and work out the maximum power consumption and ensure the UPS can deliver more than needed. You will have to replace the batteries every three years but it will save a lot of problems.

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    Quote Originally Posted by FN-GM View Post
    It could be the phone system or type of phones causing them to power off when they loose connection.

    Have you gone to have a look to see if you backbone has bandwidth? As they are only 3 year old I assume its a 10GB backbone? I managed to do similar (without the phones) in a test environment. SCCM was hogging the bandwidth.
    Ok. We don't have a 10gb backbone.

    Just 1gb. But we never have any problems before now. Nothing changed. I'm playing with sccm but that's only on a hyper-v on my pc in the office.

    Moving away from the phone that's just part of the problem.

    Myself and the nm will start checking the logs on the switches. The dhcp/dns/ad are not showing any problems in the logs.

    I think it's a switch on its last leg.

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    You won't get any logs from DHCP DNS or AD to be honest.

  15. Thanks to FN-GM from:

    newpersn (17th June 2014)

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    It happened around 10 timed today. Started Around 845 this morning with few staff logged in.

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