What is Spanning Tree? Why do we need it?

Your Network's Safety Net

A Visual Guide to the Spanning Tree Protocol (STP)

The Problem: A Network Loop

In networking, we love redundancy. Having multiple paths means if one link fails, another can take over. But this creates a problem: without a smart protocol, data packets can get caught in an endless loop.

This is called a "broadcast storm." A single broadcast frame (sent to everyone) gets duplicated and forwarded by switches forever. The network becomes so congested with looping traffic that legitimate data can't get through, causing a total network failure.

The Solution: Spanning Tree

This is where Spanning Tree Protocol (STP) comes in. It's a protocol that runs on switches to prevent these destructive loops. STP's job is to ensure there is only one active logical path between any two destinations on the network at any given time.

It does this by intelligently identifying redundant links and putting one of the ports connected to that link into a "blocking" state. The physical link is still there and ready to be used, but the switch won't forward any data through that blocked port, effectively breaking the loop.

If the primary link fails, STP is smart enough to automatically unblock the port and re-activate the redundant path, restoring connectivity within seconds.