Understanding How Portfast Works - Cisco WS-C4003 - Catalyst 4000 Chassis Switch Software Configuration Manual

Configuring Spanning Tree PortFast, UplinkFast,
and BackboneFast, and Loop Guard
This chapter describes how to configure the PortFast, UplinkFast, and BackboneFast, and loop guard
spanning tree enhancements on the Catalyst enterprise LAN switches.
Note For information on configuring spanning tree, see
For complete syntax and usage information for the commands used in this chapter, refer to the Command
Note
Reference—Catalyst 4000 Family, Catalyst 2948G, and Catalyst 2980G Switches.
This chapter consists of these sections:
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Understanding How PortFast Works

Spanning tree PortFast causes a port to enter the spanning tree forwarding state immediately, bypassing
the listening and learning states. You can use PortFast on switch ports connected to a single workstation
or server to allow those devices to connect to the network immediately, instead of waiting for the port to
transition from the listening and learning states to the forwarding state.
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Understanding How PortFast Works, page 8-1
Configuring PortFast, page 8-2
Understanding How PortFast BPDU Guard Works, page 8-3
Configuring PortFast BPDU Guard, page 8-3
Understanding How PortFast BPDU Filtering Works, page 8-6
Configuring PortFast BPDU Filtering, page 8-6
Understanding How UplinkFast Works, page 8-8
Configuring UplinkFast, page 8-9
Understanding How BackboneFast Works, page 8-11
Configuring BackboneFast, page 8-13
Understanding How Loop Guard Works, page 8-15
Configuring Loop Guard, page 8-17
Software Configuration Guide—Catalyst 4000 Family, Catalyst 2948G, Catalyst 2980G, Releases 6.3 and 6.4
C H A P T E R
Chapter 7, "Configuring Spanning Tree."
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