switch mac address learning spanning tree

Then, the switch on the left will send the frame to the switch on the right, and vice versa. The switch will send the frame to all its clients, and to the two other switches as well. Imagine a computer connected to the top switch generates a broadcast frame. However, this inevitably creates loops, which are dangerous for broadcast frames. This way, in case one link stops working, we can have an alternative path. Now, we want to have multiple connections between switches for redundancy. If we have three switches forming a loop, like in the picture below, without Spanning Tree broadcast frames will loop.Įxample of Switching loop that might arise. This is common for broadcast frames, that a switch sends to all ports but the originating one. So, if a computer generates a frame and sends it to a switch, and the frame gets back to that switch at some point in the future, we have a loop. However, we haven’t explained what those loops are just yet.Ī loop is a series of switch connections that allow a frame to get back where it started. Introducing Spanning Tree The need for STPįrom the introduction, we already know that STP is out there to prevent loops. In case you don’t have any or need a refresh, you can check out our Data Link layer article. This article heavily relies on your switching knowledge. Having a solid knowledge of STP (IEEE 802.1D) is a mandatory requirement for any networker. In this article, we will learn how STP prevents loops, and how it handles the Layer 2 convergence.

The Spanning Tree Protocol (STP) prevents just that.

In fact, a wrong connection may cause a loop with frames duplicating across the network. Believe it or not, you could make an enterprise collapse by plugging a cable in the wrong place.

Switch mac address learning spanning tree