STP – Spanning Tree Protocol

Original STP – IEEE 802.1D
Supports redundancy in a layer 2 network
Keeping a loop-free topology.
It’s turn On by default in Cisco.

Types of STP
CST: Common Spanning-Tree
PVST: Per-VLAN Spanning-Tree
PVST+: Per-VLAN Spanning-Tree Plus
Rapid-PVST: Rapid Spanning-Tree

Root Bridge Election Process:
The bridge with lowest MAC address will be the the Root Bridge.

To see the Root Bridge information, type:
# sh spanning-tree
Setting the root bridge by setting its priority, example:
(config)# spanning-tree vlan 1,10,20 priority 0
include all the vlans

Enable rapid-pvst
(config)# spanning-tree mode rapid-pvst