An administrator observes that workstations connected to switch port GigabitEthernet0/12 experience a 30-second delay before successfully acquiring an IP address from a DHCP server upon initial link up. The switch is running classic 802.1D Spanning Tree Protocol (STP). Which interface configuration command directly resolves this delay, and what is its operational effect on the port?
- Enable `spanning-tree portfast`; it allows the access port to immediately transition from blocking to forwarding state upon link up, bypassing listening and learning states.Cevap
- BEnable `spanning-tree portfast trunk`; it should be configured on inter-switch trunk connections to eliminate convergence delays across the switch fabric.
- CConfigure `spanning-tree vlan 1 priority 4095`; it reduces the port transition timers by adjusting the local bridge priority value.
- DEnable `spanning-tree portfast`; it completely disables BPDU transmission and reception on the interface to stop STP from monitoring the link.
Cevap
The command `spanning-tree portfast` resolves the issue because it allows an access interface connected to an end-user host to bypass the 15-second Listening and 15-second Learning states, transitioning directly to Forwarding state upon link up.
Enabling `spanning-tree portfast` on an access port connected to a workstation bypasses the standard 802.1D Listening (15 seconds) and Learning (15 seconds) STP states. The interface immediately enters the Forwarding state upon link up, allowing the host to successfully send DHCP requests without timing out.
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STP PortFast Benefits and Operation