Native Vlan

Introduction:

VLANs or Virtual Local Area Networks allow network administrators to segment the network into smaller logical networks, improving network security, performance, and manageability. A native VLAN, on the other hand, is the VLAN that is untagged and carries untagged traffic over a trunk link. In this article, we will explore Native VLANs in detail, including their configuration, verification, and use cases.

What are Native VLANs?

A Native VLAN is the VLAN that is untagged over a trunk link. It carries untagged traffic and is used for management traffic and untagged frames. By default, VLAN1 is the Native VLAN on Cisco switches, but it is good practice to change the Native VLAN to improve network security.

Native VLAN Configuration:

Assuming you want to configure VLAN 10 as the Native VLAN, and the switchport you want to configure is "GigabitEthernet0/1", you can follow these steps:

Switch# configure terminal
Switch(config)# interface GigabitEthernet0/1
Switch(config-if)# switchport mode trunk
Switch(config-if)# switchport trunk native vlan 10
Switch(config-if)# end

In this example, we've configured interface "GigabitEthernet0/1" as a trunk port, and specified VLAN 10 as the Native VLAN. This will ensure that all untagged traffic on the port is carried on VLAN 10.

It's important to note that you should choose a Native VLAN that is not currently in use on your network. It's also recommended to use a VLAN other than VLAN 1 as the Native VLAN, as VLAN 1 is often targeted by attackers.

Native VLAN Verification:

To verify the Native VLAN configuration, use the "show interface [interface name/number] switchport" command. or use the "show interfaces trunk" This commands displays the current information of the interface and includes the Native VLAN information.

Example Use Case:

One of the main benefits of using Native VLANs is the ability to improve network security. By separating untagged management traffic from data traffic, Native VLANs make it more difficult for attackers to intercept and manipulate management traffic.

For example, suppose an attacker gains access to a switch port and connects their own device to the port. If the switch port is not properly configured with a Native VLAN, the attacker can potentially intercept and manipulate management traffic. This could allow the attacker to execute a variety of attacks, such as ARP spoofing or MAC flooding, which can disrupt network traffic or compromise network security.

However, by configuring a Native VLAN for management traffic, network administrators can separate management traffic from data traffic, making it more difficult for an attacker to intercept and manipulate management traffic. This can help prevent a variety of attacks and improve network security overall.

In addition to improving security, using Native VLANs can also improve network performance by reducing the amount of unnecessary traffic on the network. This can lead to faster network speeds and better overall performance.

Conclusion:

In conclusion, Native VLANs play a critical role in VLAN configuration and can improve network security and performance. By designating a specific VLAN as the Native VLAN, network administrators can separate management traffic and untagged frames from data traffic, improving network performance and security.