This topic has been covered extensively by experts. What has not been covered in my opinion, is the underlying and fundamental change of transport infrastructure and specially power. The traditional WAN transport mechanisms are solid in terms of power normalization all through the last mile. With the new (or not so new) shift towards commercially available Internet connections (namely DSL and Cable), customers need to watch out for excessive power coming through those lines and the respective modems and into their edge devices. There are surge protectors out there with "ethernet in/out" ports which could be used to mitigate this problem. Happy conversation out there...
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