Do trunks need a native VLAN?
Untagged traffic received on a trunk interface can only be mapped to a single VLAN – hence, only one VLAN can be specified as the native VLAN for a trunk interface. By default, the native VLAN for a trunk interface on a Cisco IOS device is the default VLAN on Cisco IOS devices – VLAN 1.
Is native VLAN tagged on a trunk?
In Cisco LAN switch environments the native VLAN is typically untagged on 802.1Q trunk ports. The packet will be routed at layer-3 between the two VLANs by Switched Virtual Interfaces (SVIs) configured on the layer-2/3 switch.
Why might you want to change the native VLAN on a trunk?
Changing the native VLAN is mostly related to preventing VLAN hopping attacks. If this is of a concern you should use a different native VLAN on trunk ports between switches. For safety, this should be a VLAN not in use in the network. You want every valid VLAN to be tagged between switches.
How do I enable VLAN on trunk port?
To add a VLAN to the trunk, issue the switchport trunk allowed vlan add vlan-list command. This example shows how to remove VLANs 5 through 10 and 12. Add VLAN 7 back and verify the allowed VLANs on the trunk link.
What is the difference between native VLAN and default VLAN?
The default VLAN is always VLAN 1, and it can’t be changed. By default, Native VLAN is VLAN 1, but it can be changed to any VLAN. Traffic will be sent when both Default and Native VLAN are the same. Traffic can be sent irrespective of Default and Native VLAN being the same or different.
Do I need a native VLAN?
In order to configure native VLAN, switch port trunk native VLAN command is used. Native VLANs are recognized if they are not tagged to any trunks. It is not necessary to have native VLAN on the trunk.
Why should the native VLAN be changed?
What is the native VLAN Cisco?
Native VLAN: The native VLAN is the one into which untagged traffic will be put when it’s received on a trunk port. This makes it possible for your VLAN to support legacy devices or devices that don’t tag their traffic like some wireless access points and simply network attached devices.
What is VLAN dot1Q tag native?
The global command “vlan dot1Q tag native” is a common command found on ciscos devices which makes the native vlan on trunk ports require a tag or its dropped (essentially drops all untagged traffic on trunk ports).
How to configure VLAN trunk?
Configure IP for port 1
What is difference between default VLAN and native VLAN?
What is the default VLAN on a switch?
Which VLANs are allowed on this trunk?
When a trunk link is established, all of the configured VLANs are allowed to send and receive traffic across the link. VLANs 1 through 1005 are allowed on each trunk by default. However, VLAN traffic can be removed from the allowed list. This keeps traffic from the VLANs from passing over the trunk link.
What is a Cisco trunk?
By David Hucaby,Stephen McQuerry .