Switchport Trunk - Cisco IE-3000-8TC Command Reference Manual

switchport trunk

Defaults VLAN 1 is the default native VLAN ID on the port.
The default for all VLAN lists is to include all VLANs.
Command Modes
Interface configuration
Command History Release
12.2(44)EX
Usage Guidelines Native VLANs:
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Allowed VLAN:
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Trunk pruning:
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Examples
This example shows how to configure VLAN 3 as the default for the port to send all untagged traffic:
Switch(config)# interface gigabitethernet1/2
Switch(config-if)# switchport trunk native vlan 3
This example shows how to add VLANs 1, 2, 5, and 6 to the allowed list:
Switch(config)# interface gigabitethernet1/2
Switch(config-if)# switchport trunk allowed vlan add 1,2,5,6
This example shows how to remove VLANs 3 and 10 to 15 from the pruning-eligible list:
Switch(config)# interface gigabitethernet1/2
Switch(config-if)# switchport trunk pruning vlan remove 3,10-15
Cisco IE 3000 Switch Command Reference
2-580
Modification
This command was introduced.
All untagged traffic received on an IEEE 802.1Q trunk port is forwarded with the native VLAN
configured for the port.
If a packet has a VLAN ID that is the same as the sending-port native VLAN ID, the packet is sent
without a tag; otherwise, the switch sends the packet with a tag.
The no form of the native vlan command resets the native mode VLAN to the appropriate default
VLAN for the device.
To reduce the risk of spanning-tree loops or storms, you can disable VLAN 1 on any individual
VLAN trunk port by removing VLAN 1 from the allowed list. When you remove VLAN 1 from a
trunk port, the interface continues to send and receive management traffic, for example, Cisco
Discovery Protocol (CDP), Port Aggregation Protocol (PAgP), Link Aggregation Control Protocol
(LACP), Dynamic Trunking Protocol (DTP), and VLAN Trunking Protocol (VTP) in VLAN 1.
The no form of the allowed vlan command resets the list to the default list, which allows all VLANs.
The pruning-eligible list applies only to trunk ports.
Each trunk port has its own eligibility list.
If you do not want a VLAN to be pruned, remove it from the pruning-eligible list. VLANs that are
pruning-ineligible receive flooded traffic.
VLAN 1, VLANs 1002 to 1005, and extended-range VLANs (VLANs 1006 to 4094) cannot be
pruned.
Chapter 2 IE 3000 Switch Cisco IOS Commands
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