What Is The Purpose Of The Native VLAN?

What Is The Purpose Of The Native VLAN?

With network complexity outstripping the capacity of the standard local area networks, organizations are now adjusting to using the virtual local area networks (VLANs) to increase their security measures. 

If you don’t know, a VLAN is a logical grouping of different hosts, including servers and network devices, in a similar broadcast domain. This type of LAN performs several different functions; one of which is its ability to help mitigate security risks as the number of hosts connected on a broadcast domain reduces.

There are several different types of virtual local area networks available out there. One of them is the native VLANs, a VLAN that’s associated with all untagged packets on a tagged port.

The main function of a native VLAN is that it allows the interface to accept untagged packets. The VLAN helps to support and carry untagged traffic on a tagged/trunk port. Besides, it also helps to reduce workload, provide more flexibility, and eliminate the need for expensive routers.

The native VLAN is just one of the many types of virtual local area networks available out there. In the rest of this article, I’ll further discuss everything you need to know about the VLAN, including its purpose as well as how it functions.

What Is a Virtual Local Area Network?

Before going ahead to discuss native virtual local area networks, I’ll start by talking about VLANs. Doing that will give us better insight into the topic of today.

So, what exactly is a virtual local area network and what does it include?

As earlier stated, virtual LANs are a logical grouping of different hosts in a similar broadcast domain. They are primarily designed on the Layer-2 switch to help reduce the number of hosts connected to the broadcast domain. Furthermore, one of the benefits of virtual LANs is that they help to improve network performance by decreasing larger broadcast domains into smaller ones.

Main types of virtual LANs

The virtual local area network is grouped into five different types, depending on the network they carry.

First, there’s a Default VLAN, a virtual LAN that has all of the ports on a device, especially when it is switched on. Furthermore, you need to understand that this type of VLAN can’t be renamed or deleted. However, it’s capable of allowing any network device attached to a switch port to connect easily with other devices attached to other switch ports.

Another type of virtual LAN is the Data VLAN or User VLAN. The virtual local area network is specifically created for user-generated data. So, it means it’s impossible to use it to carry management traffic or voice traffic.

The third VLAN on this list is the Management VLAN, which is specifically created and configured to gain access to a switch’s management capabilities, such as SNMP, monitoring, system logging, etc. One of the benefits of this virtual LAN is that it ensures that the management bandwidth is readily available even when there’s high user traffic.

Another type of virtual LAN is the Voice VLAN. It’s specifically created and configured to carry only the voice traffic. Out of all virtual LANs, the voice VLANs have an edge over others in terms of transmission. They have a very high transmission capability.

Lastly, we have the native VLAN, which is our main focus for this article. Unlike the rest of the network traffic, the native VLANs are specifically created and configured to support and carry untagged traffic on a tagged port. Furthermore, they are capable of identifying the traffic that comes from each side of a trunk link.

What You Need to Know About the Native VLANs

So far, I’ve been able to talk about VLAN and the different types that we have. Now, let’s talk about the native VLANs; what are they, how do they function, and most especially – what are their purposes?

The Native VLAN is a type of VLAN that traverses a Trunk port without necessarily using a VLAN tag. Here’s a brief illustration of how it works:

Let’s assume we have one hub and two switches; Switch 1 and Switch 2. Connected to them are several different personal computers. Furthermore, Switch 1 is connected to Switch 2, and the Hub gets connected to Switch 2. The link between both Switch 1 and Switch 2 is the trunk link.

Now, we need to connect to the hub and we have a trunk link. Any traffic coming from switch 1, before moving to the truck link, will get a frame tag that’ll enable switch 2 to understand the VLAN that owns the frame.

Most times, when you’re receiving frames via the hub, they tend to come without tags – here’s where the native VLAN comes into the scene. In this case, the switch will assume that the untagged frame belongs to the native VLAN, as a result, it’ll send it directly to the network traffic.

The bottom line is that any specific untagged frame received by the switch will go to the native VLAN by assumption. That’s so because the trunk link only carries tagged frames; this makes it pretty much easy for the switch on the other end to read and determine which VLAN owns the frame.

What Is the Purpose and Benefit of the Native VLAN?

From the illustration above, it’s safe to say that the primary purpose of the native virtual LAN is – it makes it easy for the interface to accept untagged frames. 

Simply put, the native VLAN is specifically created and configured to offer support and carry untagged packets on the tagged/trunk port. Furthermore, the native VLAN makes it possible for the switch to forward all layer2 frames, both tagged or untagged, on a trunk port to the appropriate VLAN.

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