STP

When you bundle multiple physical links into an EtherChannel, STP treats the entire port-channel as a single logical interface. This article covers STP cost calculation for port-channels, member link failure handling, and the misconfiguration pitfalls that cause spanning tree loops.

MST consolidates multiple VLAN spanning trees into fewer protocol instances, reducing CPU overhead and simplifying management on switches with 50+ VLANs.

Root Guard blocks unauthorized root bridges on designated ports. Loop Guard prevents loops from unidirectional links on blocking ports. Both are essential for large campus networks.

BPDU Guard immediately error-disables ports that receive BPDUs, preventing rogue switches from corrupting your spanning tree. This article covers configuration, monitoring, and recovery.

BPDU Filter stops sending and receiving BPDUs on a port. Unlike other STP protection features, it's inherently dangerous and rarely used in production networks.

PortFast (edge port in RSTP) skips listening and learning phases, allowing hosts to reach the network in milliseconds instead of 30 seconds. This article covers per-interface configuration, global defaults, trunk ports, and critical use cases.