9-8
Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
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Chapter 9 Configuring Spanning Tree PortFast, UplinkFast, BackboneFast, and Loop Guard
Configuring PortFast
Enabling PortFast
Caution
Use PortFast only when you connect a single end station to a switch port; otherwise, you might create
a network loop.
To enable PortFast on a switch port, perform this task in privileged mode:
This example shows how to enable PortFast on a port and verify the configuration (the PortFast status
is shown in the “Fast-Start” column):
Console> (enable)
set spantree portfast 4/1 enable
Warning: Spantree port fast start should only be enabled on ports connected
to a single host. Connecting hubs, concentrators, switches, bridges, etc. to
a fast start port can cause temporary spanning tree loops. Use with caution.
Spantree port 4/1 fast start enabled.
Console> (enable)
show spantree 4/1
Port Vlan Port-State Cost Priority Fast-Start Group-method
--------- ---- ------------- ----- -------- ---------- ------------
4/1 1 blocking 19 20 enabled
4/1 100 forwarding 10 20 enabled
4/1 521 blocking 19 20 enabled
4/1 522 blocking 19 20 enabled
4/1 523 blocking 19 20 enabled
4/1 524 blocking 19 20 enabled
4/1 1003 not-connected 19 20 enabled
4/1 1005 not-connected 19 4 enabled
Console> (enable)
Disabling PortFast
To disable PortFast on a switch port, perform this task in privileged mode:
This example shows how to disable PortFast on a port:
Console> (enable)
set spantree portfast 4/1 disable
Spantree port 4/1 fast start disabled.
Console> (enable)
Task
Command
Step 1
Enable PortFast on a switch port connected to a
single workstation or server.
set spantree portfast
mod
/
port
enable
Step 2
Verify the PortFast setting.
show spantree
mod/port
Task
Command
Step 1
Disable PortFast on a switch port.
set spantree portfast
mod
/
port
disable
Step 2
Verify the PortFast setting.
show spantree
mod/port