Configuring Native 802.1Q Vlans - Cisco nexus 5000 series Configuration Manual

Configuring Access and Trunk Interfaces
This example shows how to add VLANs to the list of allowed VLANs on an Ethernet trunk port:
switch# configure terminal
switch(config)# interface ethernet 1/3
switch(config-if)# switchport trunk allow vlan 15-20

Configuring Native 802.1Q VLANs

Typically, you configure 802.1Q trunks with a native VLAN ID, which strips tagging from all packets on that
VLAN. This configuration allows all untagged traffic and control traffic to transit the Cisco Nexus device.
Packets that enter the switch with 802.1Q tags that match the native VLAN ID value are similarly stripped
of tagging.
To maintain the tagging on the native VLAN and drop untagged traffic, enter the vlan dot1q tag native
command. The switch will tag the traffic received on the native VLAN and admit only 802.1Q-tagged frames,
dropping any untagged traffic, including untagged traffic in the native VLAN.
Control traffic continues to be accepted untagged on the native VLAN on a trunked port, even when the vlan
dot1q tag native command is enabled.
The vlan dot1q tag native command is enabled on global basis.
Note
SUMMARY STEPS
1. switch# configure terminal
2. switch(config)# vlan dot1q tag native [tx-only]
3. (Optional) switch(config)# no vlan dot1q tag native [tx-only]
4. (Optional) switch# show vlan dot1q tag native
DETAILED STEPS
Command or Action
Step 1 switch# configure terminal
Step 2 switch(config)# vlan dot1q tag native [tx-only]
Step 3 switch(config)# no vlan dot1q tag native
[tx-only]
Step 4 switch# show vlan dot1q tag native
OL-25842-01
Purpose
Enters global configuration mode.
Enables dot1q (IEEE 802.1Q) tagging for all native VLANs on all
trunked ports on the Cisco Nexus device. By default, this feature
is disabled.
(Optional)
Disables dot1q (IEEE 802.1Q) tagging for all native VLANs on
all trunked ports on the switch.
(Optional)
Displays the status of tagging on the native VLANs.
Cisco Nexus 5000 Series NX-OS Layer 2 Switching Configuration Guide, Release 5.1(3)N1(1)
Configuring Native 802.1Q VLANs
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