New Training: Explain Spanning-Tree Protocol

In this 9-video skill, CBT Nuggets trainer Jeff Kish unpacks the spanning-tree protocol as it relates to data center hardware and topologies. Watch this new Cisco training.

Learn Cisco with one of these courses:

• Data Center Networking with Cisco Nexus Switches

• Cisco CCNP Data Center

This training includes:

• 9 videos

• 56 minutes of training

You’ll learn these topics in this skill:

• Intro

• Traditional 802.1D STP

• Rapid Spanning-Tree Protocol

• STP Port Types

• Topology STP Extensions

• Loop-Prevention STP Extensions

• Bridge Assurance

• STP Design in the Data Center

• Review and Quiz

Why a Whole Protocol Was Developed to Prevent Bridge Loops

Spanning Tree Protocol (STP) is an old protocol — it was developed all the way back in 1985. It’s still around because it still accomplishes the central thing it was developed to do: build a topology that doesn’t have bridge loops. What Spanning Tree Protocol essentially does is probe a network and all its devices and compile the results of that probe to come up with a logical tree that explains how all the switches on a network are organized.

But when you’re sending information like that out throughout a network, you have to watch out for something: two switches connected through multiple ports, or two ports on the same switch connected to each other. These are usually configured to provide redundancy, but they can lead to bridge loops. That’s when requests for connections go to one switch and out its ports, to another switch and out its ports, but then back to the first switch and out its ports again, and on and on.

For humans, a bridge loop would be fairly easy to recognize. For devices, it’s much harder without STP. It might sound simple, but Spanning Tree Protocol is a complex, intricate and highly mathematical protocol that massive data centers still rely on to create and disseminate their topologies.