PortFast:
setup Layer 2 LAN interface of the switch as an access port to enter the forwarding state immediately, bypassing the listening and learning states. Use PortFast only when connecting a single end station to a Layer 2 access port.
UplinkFast:
Provides from three to five seconds convergence after a direct link failure and achieves load balancing between redundant Layer 2 links using uplink groups.
BackboneFast:
Cuts convergence time by max_age for indirect failure.
BackboneFast is initiated when a root port or blocked port on a network device receives inferior bridge protocol data units (BPDU) from its designated bridge.
Loop guard:
Prevents an alternate or root port from becoming designated in the absence of BPDUs. Loop guard helps prevent bridging loops that could occur because of a unidirectional link failure on a point-to-point link.
Root guard:
Secures the root on a specific switch by preventing external switches from becoming roots.
BPDU guard:
When configured on a PortFast-enabled port, BPDU guard shuts down the port that receives a BPDU.
Unidirectional Link Detection (UDLD):
UDLD monitors the physical configuration of fiber-optic and copper connections and detects when a one-way connection exists. When a unidirectional link is detected, the interface is shut down and the system alerted.
