Networks require a Common Ground

by Johannes Helmig [Published on 11 Oct. 1997 / Last Updated on 11 Oct. 1997]

When systems in the same room are networked, it is usually easy, but most the time,networking connects systems over a much longer distance, and then an additional factor pops up: the "ground-level" of the power-line.

I have been confronted with situations, where there was a substantial difference between the ground-level of systems, because they were connected to a difference phase of the power-line or even on power-line segment, supplied from different transformers. If this difference of the ground-level gets too big, the systems cannot anymore read the Ethernet signal properly, on some installations the network become "slow" (caused by re-transmissions) or the communications breaks down completely.

In commercial installations, special converter box (or even "fiber glas ", segments are then installed to 'uncouple' the signal from the ground-level of the systems).
If you suspect in Home-installations such a problem, install temporary the systems next to each other in the SAME room, getting the power from the SAME power-outlet, but STILL use the same length of Ethernet-cable. If the problem now disappears, then it is likely such a ground-level problem.

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The Author — Johannes Helmig

Dr.Johannes Helmig is working as Director, Technical Knowledge Management in the Belgium office of Gerber Technology where he is involved in Customer Service and internal training, with special interest in Networking.


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