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We have a 3COM 3C16980A Superstack3 switch in our office and it keeps dropping out broadband connection. Are setup is this:

Internet -> BT Box -> Wifi Router -> Switch -> cables run into the walls to all the sockets round the office.

Several times now our switch has stopped serving out data, mainly in the morning but once in the afternoon. The wifi still works and I have connected a computer directly to the wifi router and that works, so it's only the switch which is blocking the connection.

We end up fixing it by switching it on and off several times, leaving it off for a while, or just waiting, nothing consistently works. My thoughts are that the switch is faulty but it is out of warranty so wanted to get a second opinion before recommending we get a new switch as they are expensive.

Additional switch details: http://h20566.www2.hpe.com/portal/site/hpsc/public/psi/home/?sp4ts.oid=4236314&sp4ts.pn=JE854A&sp4ts.sn=7MMV6E5CF38 http://www.zdtronic.com/images/3C16980A.jpg http://www.mtmnet.com/PDF_FILES/3C16980A_Datasheet.pdf

Ross Coulbeck
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2 Answers2

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Your switch is old.

Replace the switch.

The device went End-of-Sale in 2004. That's 11 years ago. There's no reason to be running a critical device that old without support. Plus, it's 10/100 Megabit.

You could look at the front panel and see if there are any error lights. Switches like that can have fan failures. But it's not worth repairing.

A decent replacement switch from HP could be found as low as $350 in the HP 1820 switch series.

ewwhite
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  • Are you sure? I'm sure it was bought a lot more recently than that. This is it:http://www.zdtronic.com/images/3C16980A.jpg http://h20566.www2.hpe.com/portal/site/hpsc/public/psi/home/?sp4ts.oid=4236314&sp4ts.pn=JE854A&sp4ts.sn=7MMV6E5CF38 It's a 3COM Superstack 3 3300 series. – Ross Coulbeck Aug 05 '15 at 10:19
  • http://www.mtmnet.com/PDF_FILES/3C16980A_Datasheet.pdf – Ross Coulbeck Aug 05 '15 at 10:46
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    @RossCoulbeck if you bought that recently, and paid a lot of money, you probably got ripped off. Just buy a modern switch. – Grant Aug 05 '15 at 11:30
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    @RossCoulbeck Quick reference guide for 3C16980A dated september 2000: http://www.retrocomputing.net/parts/3com/3C16980A/docs/dqa1698-0aaa06.pdf – Håkan Lindqvist Aug 05 '15 at 12:37
  • Thank you, obviously we need to upgrade the switch. I will look at the model you linked @ewwhite – Ross Coulbeck Aug 05 '15 at 12:39
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    @RossCoulbeck In 2015 you should expect to pay $50 for this switch, not $650, though in 2015 it's also practically useless. – Michael Hampton Aug 05 '15 at 16:20
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Could it be that the switch is set up to use Spanning Tree Protocol (STP)?

3com has a broken implementation on some older models that will stop forwarding packets for two minutes whenever a link goes up. That bug is fixed in more recent firmware, but might explain why it happens often in the morning (when people turn on their computers), and seldom in the afternoon (when someone who was just leaving needs to look up something quickly and turns the computer back on).

Simon Richter
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