From the course: Cisco CCNA (200-301) Cert Prep: 1 Network Fundamentals and Access

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Spanning tree protocol

Spanning tree protocol

- In a layer two network, one of the major dangers for any administrator is a switching loop. This occurs when any frame is flooded into a switch network that contains redundant links with no protection. These packets will loop infinitely, and as they do so, will consume more and more resources on the switch, until they are completely exhausted. Just one frame can crash a modern switch network in a matter of seconds. A technology known as Spanning Tree Protocol was developed to prevent this exact behavior. There are several flavors of STP, but at their core, most seek to find redundant links, and stop forwarding of frames over them, thus preventing loops. STP starts by electing a route bridge. Imagine the structure of an STP instance as a tree, hence the name Spanning Tree. The root bridge is the very base of the tree, from which everything else grows. The root bridge, has all of its up interfaces forwarding traffic. Every subsequent switch connected at the tree from the root, will…

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