Every school year, we work through a two to three week phase where whole building networks lock-up. These brief network outages are triggered by improperly connecting a 3COM phone or small desktop Ethernet switch to the room wall jacks. Either way, one little cable can induce a network storm capable of freezing phones, email, web services and just about anything else that runs over our district data networks.
Here is how it works: Both phones and mini-switches are designed to have only one jack connect back to the building network. The other jack(s) should link to another computer or series of classroom computers. If both jacks on a 3COM phone are plugged back into classroom wall jacks, a loop is created. Once looped, the network electronics begin to spew a flood a bad bits and datagrams. Think of it as a digital version of an epileptic seizure- a small loop in the network cascades to all other devices until every connected phone or computer either shuts down or behaves like an electric bull in a china shop.
So how can we avoid bad phone vibes? The best course of action is to double check with a member of the technology team before plugging in any 3COM phone or mini-switch. If you have any doubt as to which cable goes where, please ask. We’ll be happy to give you a hand with the phone and/or computer cable connections.