Which Cisco component can be enabled on a switch port connected to a workstation to dramatically decrease the time a workstation must wait for spanning tree to converge?

A. PortFast

B. UplinkFast

C. EtherChannel

D. FastEthernet








 

Suggested Answer: A

When PortFast is enabled on a port, the attached end station can join the network almost immediately rather than waiting up to 50 seconds for spanning tree to converge. Instead of waiting for STP to cycle through the learning and blocking states, PortFast will place the port in the forwarding state immediately. PortFast does not disable Spanning Tree but instead causes it to skip some of the unnecessary steps. PortFast is also sometimes referred to as fast-start.
The following command enables PortFast:
switch(config-if)# spanning-tree portfast
You should only enable PortFast on a port that connects an end station. Enabling PortFast on a port that connects another switch could create a loop.
UplinkFast decreases convergence time to less than five seconds for inter-switch links. With UplinkFast enabled, the switch places the blocked port into the forwarding state once the switch detects a link failure. Without UplinkFast, all ports would stop forwarding during STP convergence.
EtherChannel and Gigabit EtherChannel provide the ability to combine up to eight physical links into one virtual link. When all links are up, traffic is load-balanced across all the links. However, if one link fails, the additional links can still provide connectivity. EtherChannel provides redundant links with bandwidths of from 200 to 800 Mbps. Recovery, in the event of link failure, typically takes place in a few microseconds or milliseconds and is transparent to users.
FastEthernet refers to a type of Ethernet (Fast Ethernet) and does not enhance STP convergence.
Objective:
Layer 2 Technologies -
Sub-Objective:
Configure and verify spanning tree
References:
Cisco > Cisco IOS Bridging Command Reference > rif through spanning-tree portfast (interface) > spanning-tree portfast (interface)

This question is in 300-115 Implementing Cisco IP Switched Networks (SWITCH) Exam
For getting Cisco Certified Network Professional (CCNP) Routing and Switching Certificate





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