STP

networking

Stands for: Spanning Tree Protocol

STP stands for two different things: Spanning Tree Protocol, and Shielded Twisted Pair.

Two different things share these letters: Spanning Tree Protocol, and Shielded Twisted Pair. The two diagnoses have nothing in common.

Two entirely different things share these three letters, and confusing them is common enough to be worth a moment.

Spanning Tree Protocol is a Layer 2 protocol that prevents switching loops by computing a loop-free tree and blocking the redundant links. It is what this glossary means by STP everywhere else, and it has its own detailed entry.

Shielded Twisted Pair is a cable construction: twisted pairs wrapped in a conductive shield, in contrast to the unshielded pairs of ordinary UTP. Its variants have their own confusable notation - F/UTP has foil around all four pairs, S/FTP shields each pair individually inside a braided overall screen, and so on - and its practical catch is that the shield only helps if it is bonded to ground correctly at the right number of points. A shield grounded at both ends in a building with a ground potential difference becomes an antenna carrying current, which is worse than no shield at all.

The disambiguation matters in practice because both live in the same sentence surprisingly often. "We had an STP problem in the data centre" is genuinely ambiguous, and the two diagnoses have nothing in common.

Also known as: stp

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