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 Question by Ralph Shumway posted 19 May 2002
Well, we decided tov drop the 802.11b connection from the shop to the house, we couldnt get a strong enough signal. So I ran cat5e cable from the shop to the house and when we connect I get a link light but the avtivity light is pulsating. The OS sees the NIC as connected but there is no protocol running successfully. When you look at he activity light on our Linksys gateway, it just pulsates.

What could be causing this? Could it be the fact that the drop runs behind the electric service?
 Answer by Dmitri Abaimov posted 27 May 2002
Dear Ralph,

It's very unlikely that EMI from the power line causes that. That’s especially true if the light blinks at regular intervals. More likely it's the NIC trying to establish a connection to a DHCP server or other resource in the network that's unavailable due to network mis-configuration.

Unless the CAT5E cable is running in parallel to a power circuit that feeds really powerful equipment that goes constantly on and off (like AC unit), it's very unlikely that EMI will cause any disturbance to Ethernet equipment because the frequency range of the noise and the LAN equipment is extremely different. Even in the case of AC unit, the disturbance will (probably) be present for a matter of milliseconds, and will not be noticeable anyway.

Dmitri Abaimov, RCDD

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