STP

Spanning tree protocol (STP) is a layer 2 loop prevention, STP comes in different flavors.

STP Flavors

STP comes in different flavors coming from IEEE and Cisco but we will focus on Cisco STP flavors
1. CST (802.1D)
2. PVST+ (Cisco Prosperity)
3. RSTP (802.1W)
4. Rapid PVST+ (Cisco Prosperity)
5. MST (802.1S)

Why do we need STP?

The obvious reason is for our switch to prevent switching loops in our network. Lets look at the below example if we don't implement STP.

BPDU

Bridge Protocol Data Unit are frames that contains STP information

BPDU Frames contains the following:

Fast Knowledge

Firewall
ASA NAT
ASA Static Route
ASA Routing
ASA Initial Configs
Cisco IOS
IOS VS IOS XE
OSPF
Layer 2
STP
STP Features