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12-21
Cisco Systems Intelligent Gigabit Ethernet Switch Modules for the IBM BladeCenter, Software Configuration Guide
24R9746
Chapter 12 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 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. The
native VLAN ID on the internal 100 Mbps management module interfaces (ports 15 and 16) changes
when the management VLAN changes. The native VLAN cannot be explicitly changed, it will only
change when the management VLAN of the switch changes. Changing the native VALN on management
module interfaces is not allowed. This ensures that the switch and the management module always have
an open communication path for ethernet traffic used to manage the switch.
For information about IEEE 802.1Q configuration issues, see the “IEEE 802.1Q Configuration
Considerations” section on page 12-16.
Beginning in privileged EXEC mode, follow these steps to configure the native VLAN on an IEEE
802.1Q trunk:
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 13-4).
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.
Command Purpose
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Enter interface configuration mode, and define the interface that is
configured as the IEEE 802.1Q trunk.
Step 3
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.
Step 4
end Return to privileged EXEC mode.