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Catalyst2950 and Catalyst2955 Switch Software Configuration Guide
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Chapter17 Configuring VLANs Configuring VLAN Trunks
To return to the default pruning-eligible list of all VLANs, use the no switchport trunk pruning vlan
interface configuration command.
Configuring the Native VLAN for Untagged Traffic
A trunk port configured with 802.1Q tagging can receive both tagged and untagged traffic. By default,
the switch forwards untagged traffic in the native VLAN configured for the port. The native VLAN is
VLAN 1 by default.
Note The native VLAN can be assigned any VLAN ID; it is not dependent on the management VLAN.
For information about 802.1Q configuration issues, see the 802.1Q Configuration Considerations
section on page 17-16.
Beginning in privileged EXEC mode, follow these steps to configure the native VLAN on an 8 02. 1Q
trunk:
To return to the default native VLAN, VLAN 1, use the no switchport trunk native vlan interface
configuration command.
If a packet has a VLAN ID that is the same as the outgoing port native VLAN ID, the packet is sent
untagged; otherwise, the switch sends the packet with a tag.
Step4 end Return to privileged EXEC mode.
Step5 show interfaces interface-id switchport Verify your entries in the Pruning VLANs Enabled field of the display.
Step6 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Enter interface configuration mode, and define the interface that is
configured as the 802.1Q trunk.
Step3 switchport trunk native vlan vlan-id Configure the VLAN that is sending and receiving untagged traffic
on the trunk port.
For vlan-id, the range is 1 to 4094 when the EI is installed, and 1 to
1005 when the SI is installed.
Step4 end Return to privileged EXEC mode.
Step5 show interfaces interface-id switchport Verify your entries in the Trunking Native Mode VLAN field.
Step6 copy running-config startup-config (Optional) Save your entries in the configuration file.