Enabling Portfast On A Trunk Port - Cisco WS-C2950SX-48-SI Configuration Manual

Chapter 8 Configuring Spanning Tree PortFast, BPDU Guard, BPDU Filter, UplinkFast, BackboneFast, and Loop Guard
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
Console> (enable) show spantree 4/1
Port
--------- ----
4/1
4/1
4/1
4/1
4/1
4/1
4/1
4/1
Console> (enable)

Enabling 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, like a switch, you might create network
loops.
To enable PortFast on a trunk port, perform this task in privileged mode:
Task
Step 1
Enable PortFast on a trunk port that is
connected to a single workstation, switch,
or server.
Step 2
Verify the PortFast setting on a trunk port.
This example shows how to enable PortFast on port 1 of module 4 of a trunk port, bring the trunk port
to a forwarding state, and verify the configuration (the PortFast status is shown in the "Fast-Start"
column):
Console> (enable) set spantree portfast 4/1 enable trunk
Warning:Connecting Layer 2 devices to a fast start port can cause
temporary spanning tree loops. Use with caution.
Spantree port
Console> (enable) show spantree 4/1
Port
Channel_id
------------------------ ---- ------------- --------- ---- ------------------
4/1
4/1
4/1
4/1
4/1
78-15486-01
4/1 fast start enabled.
Vlan Port-State
-------------
1 blocking
100 forwarding
521 blocking
522 blocking
523 blocking
524 blocking
1003 not-connected
1005 not-connected
4/1 fast start enabled.
Vlan Port-State
1
100
521
524
1003 not-connected
Catalyst 4500 Series, Catalyst 2948G, Catalyst 2980G Switches Software Configuration Guide
Cost Priority Fast-Start
----- -------- ----------
19 20 enabled
10 20 enabled
19 20 enabled
19 20 enabled
19 20 enabled
19 20 enabled
19 20 enabled
19 4 enabled
Command
set spantree portfast mod_num/port_num enable trunk
Note If you enter the set spantree portfast command
on a trunk port without entering the trunk
keyword, the trunk port stays in disable mode.
show spantree portfast [mod_num/port_num]
Cost
blocking 4
forwarding 4
blocking 4
blocking 4
4
Configuring PortFast
Group-method
------------
Prio Portfast
32 enabled 0
32 enabled 0
32 enabled 0
32 enabled 0
32 enabled 0
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Release 8.1
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