VLAN Definition and Functions, Benefits and VLAN Examples

Currently the use of technology in computer networks as data communication is increasing. The higher the level of need and the increasing number of network users who want a form of network that can provide maximum results both in terms of efficiency or increased network security itself.

With the emergence of these desires, efforts to make improvements continue to be made by various parties.

By using various techniques, especially subnetting techniques and better use of hardware (such as switches), the concept of Virtual Local Area Network (VLAN) emerges, which is expected to provide better results than Local Area Networks (LANs).

Definition of VLAN

VLAN or virtual LAN is a network model that divides networks logically into several different lines but still passes through the same connecting device. VLANs do not have limitations on the physical condition of the network such as on a LAN . VLANs can be configured virtually without having to look at the condition of the equipment.

Therefore, VLANs have flexibility in network management and make it easy for network administrators to divide their networks according to the functions and network security requirements needed.

VLANs give the possibility to several IP networks and subnet masks or smaller networks on the same switched network. In order for computers to communicate with the same VLAN, each computer must have an IP address and subnet mask that matches the VLAN.

VLANs are grouped according to the method or type used to classify them, be they using MAC Addresses, ports, and so on. All information consisting of addressing or tagging a VLAN (tagging) is stored in a database, if the marking is based on the port used, the database will indicate the ports used by the VLAN.

To set it up, it is usually used an adjustable device called a switch. This switch or bridge has the responsibility to store all information and configuration of a VLAN and it is ensured that all switches have the same information.

The switch will determine where data or information will be forwarded and so on. Or you can also use a bridging software that has the function to record or mark a VLAN and workstations in it to connect between VLANs that require a router.

VLAN Cross Connect (CC) is a mechanism used to create Switched VLANs. CC VLANs use IEEE 802.1ad frames where the S Tag is used as a Label as in MPLS. IEEE approved the use of such a mechanism in nominal 6.11 of IEEE 802.1ad-2005.

In conclusion, VLANs allow us to control traffic patterns and react quickly to relocation. VLANs provide flexibility to adapt to changes in network requirements and allow for simplified administration.

VLAN Functions and Benefits

The function of a VLAN or Virtual Local Area Network on a computer network is to provide a method on a network that can divide a physical network into several broadcast domains. This broadcast domain is usually the boundary of an IP subnet. Each subnet mask has a VLAN.

VLANs allow multiple virtual LANs to co-exist in a physical LAN (switch). Just as there are two machines connected by one switch, they cannot send Ethernet frames to other machines even if they are on the same cable.

Benefits of VLAN 

VLANs besides having functions in computer networks, VLANs also have many benefits in the world of computer networks. Here are some of the benefits of VLAN:

  1. Security

Groups that have sensitive data are separated from the rest of the network to reduce the possibility of breach of confidential information or data. VLANs can restrict users who can access data or information, so VLANs can reduce the possibility of abuse of access rights.

  1. Cost reduction

In networks that use VLANs, you can create private networks even if you are not near your main network. This of course can minimize the costs needed to pull a LAN cable to a new location.

  1. Better performance

VLAN is able to divide flat layer 2 networks into several logical working groups (broadcast domains) to reduce unnecessary traffic on the network and make performance even more enhanced.

  1. Minimize broadcast domain

VLANs can divide networks so as to reduce the number of devices in the broadcast domain. As shown in the figure below, there are six computers on this network, but there are three broadcast domains: Faculty, Students, and Guest.

  1. Increasing the efficiency of IT staff

Every time the computer will move, usually the computer must be reset so that it can communicate with the network where the computer was moved. This makes the computer can not be directly used after being moved.

Now, using a VLAN network, you can minimize or even delete this step because basically the computer will still be on the same network. So as to improve efficiency of the performance of IT staff

  1. Simple project and application management

Aggregate VLAN users and network devices to support business or geographic requirements. VLANs have separate functions that make managing a project or working with specific applications easier. An example of such application is the e-learning development platform for universities.

Example VLAN

There are several types of VLANs in configuring it. Here are some types of VLAn:

  1. Static VLAN– manually configured switch port.
    First # config Terminal
    Enter configuration commands, one per line. End with CTRL / Z.
    Sw02 (config) #VLAN 10
    Sw02 (config-vlan) #name VLAN_Students
    Sw02 (config-vlan)
    #exit Sw02 (config) #Interface fastEthernet 0/2
    Sw02 (config-if) #switchport access mode
    Sw02 (config-if) #switchport access VLAN 10
  2. Dynamic VLAN
    This mode is widely used in large scale networks. Dynamic VLAN port membership is created using a special server called the VLAN Membership Policy Server (VMPS). By using VMPS, we can mark switch ports with VLANs dynamically based on the source MAC Address connected to the port.
  3. Voice VLAN– the port is configured in voice mode so that it can support the connected IP phone.
    Sw02 (config) #VLAN 120
    Sw02 (config-vlan) #name VLAN_Voice
    Sw02 (config-vlan)
    #exit Sw02 (config) #Interface fastEthernet 0/3
    Sw02 (config-if) #switchport voice VLAN 120

Here are a few commands to do basic VLAN configuration on the Cisco Catalyst switch:

Step 1 : Create a VLAN
(by default, there is only one VLAN, i.e. VLAN 1)

Switch # configure terminal
Switch (config) # vlan VLAN Number
Switch (config-vlan) #name VLAN name
example: to create a VLAN with ID number 10 marketing name.
# Configure terminal
switches Switch (config) # vlan 10
Switch (config-vlan) #name management
Switch (config-vlan) #end

Step 2 : Verify the VLAN has been created:
Command: Switch # sh vlan brief

Step 3 : Enter the Port to be a member of a VLAN
(by default all ports on the switch are members of VLAN 1)
Example: enter Port Fa0 / 1 as a member of VLAN 10:

# Configure terminal
switches Switch (config) # interface fa0 / 1
Switch (config-if) # switch mode access
switch (config-if) # switch access vlan 10
Switch (config-if) #end

If you want to enter several ports together to become a member of port 10, you can also use the interface range. For example, if you want to enter ports Fa0 / 1 through Fa0 / 6, then the order is:

# Configure terminal
switch Switch (config) # interface range fa0 / 1 – fa0 / 6
Switch (config-if-range) #switchport mode access
Switch (config-if-range) #switchport access vlan 10

Step 4 : Verify Port Settings Become a VLAN member:
Switch # sh vlan brief
VLAN Name Status Ports
—- ————————————————————————-
1 default active Fa0 / 7, Fa0 / 8, Fa0 / 9, Fa0 / 10
Fa0 / 11, Fa0 / 12, Fa0 / 13, Fa0 / 14
Fa0 / 15, Fa0 / 16, Fa0 / 17, Fa0 / 18
Fa0 / 19, Fa0 / 20, Fa0 / 21, Fa0 / 22
Fa0 / 23, Fa0 / 24, Gig1 / 1, Gig1 / 2
10 active marketing Fa0 / 1, Fa0 / 2, Fa0 / 3, Fa0 / 4
Fa0 / 5, Fa0 / 6
1002 fddi-default active
1003 token-ring-default active
1004 fddinet-default active
1005 trnet-default active

This time the article discusses the notion of VLANs, along with their functions and benefits, and also examples of VLANs. Hopefully this article can be useful for you. Thank you


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