Cisco WS-C3550-12G Software Configuration Manual page 262

Understanding VLAN Trunks
Command
Step 8 show interfaces interface-id switchport Display the switchport configuration of the interface in the
Step 9
show interfaces interface-id trunk
Step 10
copy running-config startup-config
To return an interface to its default configuration, use the default interface interface-id interface
configuration command. To reset all trunking characteristics of a trunking interface to the defaults, use
the no switchport trunk interface configuration command. Use the no switchport mode and no
switchport access interface configuration commands to return to the default settings.
This example shows how to configure the Gigabit Ethernet interface 0/4 as an 802.1Q trunk. This
example assumes that the neighbor interface is configured to support 802.1Q trunking:
Switch# configure terminal
Enter configuration commands, one per line.
Switch(config)# interface gigabitethernet0/4
Switch(config-if)# switchport mode dynamic desirable
Switch(config-if)# switchport trunk encapsulation dot1q
Switch(config-if)# end
Switch#
These examples show how to verify the configuration:
Switch# show running-config interface gigabitethernet0/4
Building configuration...
Current configuration : 112 bytes
!
interface GigabitEthernet0/4
switchport trunk encapsulation dot1q
no ip address
snmp trap link-status
end
Switch# show interfaces gigabitethernet0/4 switchport
Name: Gi0/4
Switchport: Enabled
Administrative Mode: dynamic desirable
Operational Mode: down
Administrative Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Protected: false
Unknown unicast blocked: false
Unknown multicast blocked: false
Broadcast Suppression Level: 100
Multicast Suppression Level: 100
Unicast Suppression Level: 100
Catalyst 3550 Multilayer Switch Software Configuration Guide
9-26
Purpose
Administrative Mode and the Administrative Trunking Encapsulation
fields of the display.
Display the trunk configuration of the interface.
(Optional) Save your entries in the configuration file.
End with CNTL/Z.
Chapter 9 Creating and Maintaining VLANs
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