What is the function of the command switchport trunk native VLAN?
What is the function of the command switchport trunk native vlan 999 on a Cisco Catalyst switch? It creates a VLAN 999 interface. It designates VLAN 999 for untagged traffic. It blocks VLAN 999 traffic from passing on the trunk.
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.
What is native VLAN used for?
Conclusion. Finally, we can conclude that the basic purpose of native VLAN is to serve it as a common identifier on opposing ends of a trunk link. To carry untagged traffic which is generated by a computer device attached to a switch port, which is configured with the native VLAN.
How many VLANs does a trunk port have?
All VLAN IDs, 1 to 4094, are allowed on each trunk. However, you can remove VLANs from the allowed list, preventing traffic from those VLANs from passing over the trunk.
How can I see VLAN trunk?
To display the status of the trunk, determine the native VLAN used on that trunk link and verify trunk establishment using the show interfaces trunk command. The following output shows that the native VLAN on one side of the trunk link was changed to VLAN 2.
What is switchport mode trunk?
Switchport trunk means when you have a trunk link, all VLANs are allowed to pass through a trunk link. To configure a trunk on a switch FastEthernet port, use the switchport mode trunk command. This command puts the interface into permanent trunking mode and negotiates to convert the neighboring switch or links into trunk links.
What is trunk port in Cisco switches?
A port on a Cisco switch is either an access port or a trunk port. Access ports belong to a single VLAN and do not provide any identifying marks on the frames that are passed between switches. Access ports also carry traffic that comes from only the VLAN assigned to the port. A trunk port is by default a member of all the VLANs that exist on the switch and carry traffic for all those VLANs between the switches. To distinguish between the traffic flows, a trunk port must mark the frames with
What is a Cisco trunk port?
The term trunk port means different things to diffrent vendors. For example, in Cisco it is a port that uses multiple VLANs normally used to connect two switches together so all vlans traverse the network. It can be used for other devices like ip phones that need more than 1 vlan.
What is native VLAN?
Native VLAN is the untagged vlan on an 802.1q trunked switch port. Basically if a switch receives untagged frames on a trunk port, they are assumed to be part of the vlan that are designated on the switch port as the native vlan.