Give an example.....? FIOS The F in FIOS is fiber. FIOS uses a technology called PON. Passive Optical Network. Underwater cables that connect Europe to North America are fiber optic. 10Gbps, 40Gbps and 100Gbps Ethernet use fiber optics exclusively. Big data centers, like the one at Yahoo that all of this running over use 10G and 40G Ethernet between servers and network disk drives. There is a now largely defunct networking technology known as FDDI that used fiber optic exclusively. SONET is/was the technology used for carrying massive numbers of telephone calls (each call is 3Khz analog = 64Kbps digitized) You can pack a load of calls into a 10Gbps SONET circuit. You can't run copper Ethernet between separate buildings that have different power sources. The cooper needs to be isolated to prevent a ground loop. With standard 1000BaseT you don't get the protection from ground loops, because it isn't a design intent for it to be used this way. You connect separate buildings together with Ethernet over fiber optic (which won't conduct electricity) or you need to get an isolated "WAN" circuit from the telecommunications company - i.e a T1 line.
