9-9
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 9 Configuring Spanning-Tree PortFast, UplinkFast, BackboneFast, and Loop Guard
Configuring PortFast on the Switch
To enable PortFast on a switch port, perform this task in privileged mode:
This example shows how to enable PortFast on port 1 of module 4 and verify the configuration; the
PortFast status is shown in the “Fast-Start” column:
Console> (enable)
set spantree portfast 4/1 enable
Warning:Connecting Layer 2 devices 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)
Note
If the designation for a port is displayed as edge, that port is also a PortFast port. See the
“Edge Ports”
section on page 7-23
.
Enabling Spanning-Tree PortFast on a Trunk Port
Caution
You can use PortFast to connect a single end station or a switch port to a switch port. If you enable
PortFast on a port that is connected to another Layer 2 device, such as a switch, you might create network
loops.
To enable PortFast on a trunk port, perform this task in privileged mode:
Task
Command
Step 1
Enable PortFast on a switch port that is connected
to a single workstation, switch, or server.
set spantree portfast
mod_num
/
port_num
enable
|
disable
Step 2
Verify the PortFast setting on a switch port.
show spantree
[
mod_num/port_num
] [
vlan
]
Task
Command
Step 1
Enable PortFast on a trunk port that is connected
to a single workstation, switch, or server.
set spantree portfast
mod_num
/
port_num
enable
trunk
Note
If you enter the
set spantree portfast
command on a trunk port without using
the
trunk
keyword, the trunk port will
stay in disable mode.
Step 2
Verify the PortFast setting on a trunk port.
show spantree portfast
[
mod_num/port_num
]