Overcoming Collision and Broadcast Domain Issues with the VLAN Approach in Networking

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By Marilyn Royce

The VLAN approach is used in the computer networking system to address the collision and broadcast domain issues.

A logical group of end devices located in the same group of the broadcast domain makes up a virtual local area network, or VLAN. At the switch level, VLAN setup is carried out via several interfaces. Depending on the requirements of a network, separate switches may be configured with the same or a distinct VLAN.

Even though they are not physically connected, hosts connected to two or more distinct switches can still be connected within the same VLAN since VLAN functions like a virtual LAN network. As a result, hosts linked via various switches might share a single broadcast domain.

Let’s use the example of a sample network, where one network uses VLAN and the other does not, to better understand how VLAN is used.


The network topology shown below does not employ the VLAN technique:

Without VLAN, every network component will receive the broadcast message delivered from host 1 on the network.

Instead, a broadcast message from Host 1 will only reach Host 2 if VLAN is used and configured in both switches of the network by adding an interface card with the names fast Ethernet 0 and fast Ethernet 1, also known as Fa0/0.

During configuration, only Hosts 1 and 2 are defined as belonging to the same VLAN network, while the remaining components are members of other VLAN networks.

It is crucial to remember that layer-2 switches can only enable hosts devices to connect to hosts within the same VLAN. The Layer-3 switch or router is necessary to connect to the host device of another network.

Since any secret document or file can be transferred via two designated hosts of the same VLAN that are not physically connected, VLAN networks are extremely secure networks.

This also controls broadcast traffic since only the defined VLANs will receive and deliver the message, not the entire network.

Below is a diagram of a network employing VLANs:

Trunk and Access Ports

At Switch ports, several setups are carried out. We allot an access port to each individual VLAN network so that it can be accessed.

When we only need to configure host end devices to a certain VLAN network, access ports are employed.

The switch’s trunk port has been designated as the interface’s access point for multiple switches and various VLANs. The truck port is intelligent enough to handle traffic from multiple VLANs.

Setting up VLAN

  • Activate the switch’s IOS mode before configuring VLAN on it.
  • Switch(config)# VLAN 10 is the command to create a VLAN when in configuration mode.
  • An interface command can be used to assign the fast Ethernet port to a VLAN.
  • Now, we can declare that the interface is an access mode by using the switchport access command line.
  • Allocating VLAN NUMBER to the switch port access mode will be the subsequent command.

The following is an illustration of a succession of commands:

VLAN 10 switch configuration

#exit Switch(config-vlan)

Switch(config) #if switchport mode access Switch(config-if) #int fa0/1

Switchport access Vlan 10 (config-if)

It is evident from the above line of commands that VLAN 10 is created and the switch’s fa0/1 port is switched to VLAN 10.

  • Only one VLAN can be assigned to the switchport access mode command. Switchport trunk mode interface command is used to configure several VLANs since it can handle their traffic.


In conclusion, the VLAN approach provides a powerful solution to the challenges faced by computer networks, particularly in terms of collision and broadcast domain. VLANs allow the network administrator to segment the network into smaller, isolated broadcast domains and reduce the risk of collisions by controlling the flow of data traffic. This enhances the performance and security of the network and ensures that resources are utilized optimally. The use of VLANs in computer networks has become a standard practice, providing a flexible and scalable solution for businesses of all sizes. With its many advantages, the VLAN approach continues to play an important role in the modern computer networking landscape.