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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
78-11380-12
Chapter 16 Configuring VLANs
Configuring VLAN Trunks
This example shows how to remove VLAN 2 from the allowed VLAN list:
Switch(config)# interface fastethernet0/1
Switch(config-if)# switchport trunk allowed vlan remove 2
Switch(config-if)# end
Switch#
Changing the Pruning-Eligible List
The pruning-eligible list applies only to trunk ports. Each trunk port has its own eligibility list. VTP
pruning must be enabled for this procedure to take effect. The “Enabling VTP Pruning” section on
page 17-14 describes how to enable VTP pruning.
Beginning in privileged EXEC mode, follow these steps to remove VLANs from the pruning-eligible list
on a trunk port:
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 IEEE 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 IEEE 802.1Q configuration issues, see the “IEEE 802.1Q Configuration
Considerations” section on page 16-16.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Enter interface configuration mode, and select the trunk port for which
VLANs should be pruned.
Step 3
switchport trunk pruning vlan {add |
except | none | remove} vlan-list
[,vlan[,vlan[,,,]]
Configure the list of VLANs allowed to be pruned from the trunk. (See
the “VTP Pruning” section on page 17-4).
For explanations about using the add, except, none, and remove
keywords, see the command reference for this release.
Separate nonconsecutive VLAN IDs with a comma and no spaces; use a
hyphen to designate a range of IDs. Valid IDs are from 2 to 1001.
Extended-range VLANs (VLAN IDs 1006 to 4094) cannot be pruned.
VLANs that are pruning-ineligible receive flooded traffic.
The default list of VLANs allowed to be pruned contains VLANs 2 to
1001.
Step 4
end Return to privileged EXEC mode.
Step 5
show interfaces interface-id switchport Verify your entries in the Pruning VLANs Enabled field of the display.
Step 6
copy running-config startup-config (Optional) Save your entries in the configuration file.
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