Editing Ethernet over twisted pair (section)

=== Shared cable ===
{{See also|Category 5 cable#Shared cable}}

10BASE-T and 100BASE-TX require only two pairs (pins 1–2, 3–6) to operate. Since common Category 5 cable has four pairs, it is possible to use the spare pairs (pins 4–5, 7–8) in 10- and 100-Mbit/s configurations for other purposes. The spare pairs may be used for [[power over Ethernet]] (PoE), for two [[plain old telephone service]] (POTS) lines, or for a second 10BASE-T or 100BASE-TX connection. In practice, great care must be taken to separate these pairs as 10/100-Mbit/s Ethernet equipment [[Electrical termination|electrically terminates]] the unused pins ("Bob Smith Termination").<ref>{{cite web|url=https://resources.altium.com/p/bob-smith-termination-it-correct-ethernet |title=Bob Smith Termination: Is it Correct for Ethernet? |last=Peterson |first=Zachariah |date=2020-10-28 |website=altium.com |access-date=2022-05-14}}</ref> Shared cable is not an option for Gigabit Ethernet as 1000BASE-T requires all four pairs to operate.