1. Legacy STP (802.1d)
1.1. Port States
1.1.1. Disabled
1.1.2. Blocking
1.1.3. Listening
1.1.4. Learning
1.1.5. Forwarding
1.2. Port Roles
1.2.1. Root Port
1.2.2. Designated Port
1.3. Timers
1.3.1. Hello: 2 sec
1.3.2. Forward Delay: 15 sec
1.3.3. Max Age: 20 sec
1.4. TCN BPDU Content
1.4.1. Protocol ID: 0 (2 bytes)
1.4.2. Version: 0 (1 byte)
1.4.3. Message Type: 1 byte
1.5. Advanced Features
1.5.1. Convergence Optimizations
1.5.1.1. UplinkFast
1.5.1.1.1. Should be enabled on all switches
1.5.1.1.2. Bridge Priority increased to 49152
1.5.1.1.3. All Port costs increased by 3000
1.5.1.1.4. Switch "spoofs" the traffic from learned hosts at configurable rate (default 150 pps)
1.5.1.2. BackboneFast
1.5.1.2.1. Must be enables on all switches
1.5.1.2.2. Root Link Query (RLQ)
1.5.1.2.3. When Triggered:
1.5.1.3. PortFast
1.5.2. STP Filters
1.5.2.1. BPDUFilter
1.5.2.2. BPDUGuard
1.5.2.3. RootGuard
1.5.3. Loop Prevention
1.5.3.1. LoopGuard
1.5.3.2. Unidirectional Link Detection (UDLD)
2. Rapid STP (802.1w)
2.1. Port States
2.1.1. Discarding
2.1.2. Learning
2.1.3. Forwarding
2.2. Port Roles
2.2.1. Root Port
2.2.2. Designated Port
2.2.3. Alternate Port
2.2.4. Backup Designated Port
2.2.5. Edge Port
2.3. Timers
2.4. Link Types (Non-edge ports)
2.4.1. Point-to-point
2.4.2. Shared