Have you ever wondered what exactly the native VLAN is and how it works? In this article, we will explore this concept in depth and provide you with a comprehensive understanding of its functionality. So, let’s dive in!
Contents
What is the Native VLAN?
Before we delve into the native VLAN, let’s quickly recap a few important terms. In the world of networking, there are access ports and trunk ports. Access ports are also known as untagged ports, while trunk ports are often referred to as tagged ports.
Ok, now that we have that covered, let’s focus on the native VLAN. Simply put, the native VLAN is the VLAN on a trunk port that does not have a VLAN tag. When traffic traverses a trunk port, a VLAN tag is added to distinguish which frames belong to which VLAN. However, the frames belonging to the native VLAN traverse the port without a VLAN tag.
Key Takeaways from an Illustration
To better understand the concept of the native VLAN, let’s walk through an example. In this scenario, we have two switches with multiple VLANs and computers connected to them. We can verify the configuration of the switches by using the “show VLAN brief” and “show interface trunk” commands.
Now, when we send pings between computers in different VLANs, we can observe the packets flowing through the trunk port. If we capture the packets using a tool like Wireshark, we can see that each successful ping consists of ICMP echo request and ICMP echo reply packets.
When traffic traverses a trunk port, a VLAN tag is added to the frame headers. This tag helps the receiving switch identify which VLAN the frames belong to. However, frames belonging to the native VLAN do not have a VLAN tag.
It is crucial to note that the native VLAN configuration is done per trunk port per switch. The sending switch will tag all frames sent across the trunk, except for frames belonging to the native VLAN. The receiving switch will accept all tagged traffic onto the VLAN indicated by the tag and all untagged traffic onto the VLAN configured locally as the native VLAN.
Changing the Native VLAN
If we want to change the native VLAN for a trunk port, we can do so by using the “switchport trunk native VLAN” command. After modifying the native VLAN, we can verify the configuration using the “show interface trunk” command.
FAQs
Q1: What is the purpose of the native VLAN?
A1: The native VLAN allows traffic to traverse a trunk port without a VLAN tag. It helps maintain compatibility between switches that may not support or understand VLAN tagging.
Q2: Can the native VLAN be different on each end of a trunk link?
A2: No, to ensure proper communication, both ends of the trunk link must be configured with the same native VLAN.
Q3: What happens if there is a native VLAN mismatch?
A3: A native VLAN mismatch can cause communication issues and potential security vulnerabilities. It is crucial to ensure both ends of the trunk link have the same native VLAN configured.
Conclusion
In conclusion, the native VLAN plays a significant role in trunk port communication. It allows traffic to traverse a trunk port without a VLAN tag, simplifying communication between switches. Understanding the native VLAN and its configuration is vital for maintaining a robust and secure network infrastructure.
If you want to explore further topics related to networking, be sure to check out the Techal website for more informative articles. Don’t forget to share this article with your friends and colleagues who might find it useful. Happy networking!
