Spare links keep a network running when a cable or switch fails. But they also create switching loops, which can stop the whole network in seconds. Spanning Tree Protocol (STP) keeps the spare links and removes the loops. It blocks just the right ports, and unblocks them when something breaks.
- 1. One active path. Traffic follows the tree through the root bridge, SW1.
- 2. One backup path, blocked. The SW2–SW3 link is ready to use, but blocked, so there is no loop.
About this course
First you'll learn the main idea: why STP is needed and what it does. Then you'll see how it works in the original Common Spanning Tree (CST): the steps it follows, port roles, states, timers and topology changes. Next comes Cisco's Per-VLAN Spanning Tree (PVST+) and how to tune it. After that you'll learn Rapid Spanning Tree (RSTP) and the guard features that protect the tree. Every lesson has animated diagrams, commands where needed, and practice questions. Two final labs bring it all together.
What you'll learn
Why STP exists
How spare links create loops between switches, and how STP stops the loops but keeps the spare links.
How STP operates
How switches choose a root bridge, port roles and port states, and how STP decides which paths stay open.
Configure and tune STP
Per-VLAN roots, cost and priority tuning, PortFast, UplinkFast and BackboneFast.
Protect the tree
BPDU Guard, Root Guard, BPDU Filter, Loop Guard and UDLD keep the network stable and safe.
Skills you'll gain
- Spanning Tree Protocol
- STP troubleshooting
- PVST+ & RSTP
- STP optimisation
- Network redundancy
- Layer 2 design
- Loop prevention
- Cisco STP configuration
Who is this for?
CCNA and CCNP students, and anyone working with Cisco switches. If you understand VLANs and basic switching, you're ready.