What are VLANs? Meanings of VLANs

Rusq.org Explains What VLAN Means

  • Welcome to Rusq.org, which specializes in aggregating all questions and answers what is the definition, discussing and answering what the abbreviation stands for among young people, today we will learn a new concept that is what is VLAN? Meanings of VLANs. What are VLANs? 2 basic types of VLANs should know! What are VLANs? How to configure a VLAN on a Cisco Switch? What are VLANs? Is it necessary to use it? How to create VLANs?
What are VLANs? How to configure a VLAN on a Cisco Switch? - Website Rusq Website
What are VLANs? How to configure a VLAN on a Cisco Switch? – Rusq website

What is VLAN definition?

  • Before delving into what is the term VLAN, we must know what is LAN? LAN is an abbreviation of the phrase Local Area Network. This is the term used to refer to a local area network. The above term is also defined as all the computers operating in the same broadcast domain. At this point you need to remember that, while the Router or router has the effect of blocking the broadcast, the Switch – The switch forwards the data.
  • Based on the definition of LAN, we continue to have another definition of VLAN. According to industry experts, VLAN is a virtual LAN. But technically speaking, VLAN is also understood as a broadcast domain created by the switches themselves. If for normal networks, the Router will play the role of creating the broadcast domain, but in the VLAN Switch is still capable of performing the same function.
  • Usually, VLAN configuration will be done when the user’s computer network is too large and the traffic is too much. Sometimes people use VLANs for the simple reason that the computer network they are working on already uses VLANs.

Benefits of VLANs

  1. Saving network bandwidth: VLAN divides LAN into many small segments, each segment is a broadcast domain. When there is a broadcast packet, it will be transmitted only in the corresponding VLAN. Therefore, dividing VLANs helps to save network bandwidth.
  2. Increased security: Because devices in different VLANs cannot access each other (unless we use routers connecting between VLANs). As in the example above, computers in the accounting VLAN (Accounting) can only communicate with each other. The machine in the accounting VLAN cannot connect to the computer in the engineering VLAN.
  3. Easily add or remove computers to VLAN: Adding a computer to a VLAN is very simple, just configure the port for that machine to enter the desired VLAN.
  4. Make the network highly flexible: VLANs can easily move devices. Suppose in the above example, after a period of use the company decided to put each division on a separate floor. With VLANs, we just need to reconfigure the switch ports and put them in the required VLANs. VLANs can be configured statically or dynamically. In the static configuration, the network administrator must configure each port of each switch. Then assign it to a certain VLAN. In dynamic configuration, each port of the switch can configure its own VLAN based on the MAC address of the device it is connected to.

There is an important thing that I need to emphasize, that you do not need to configure a virtual LAN unless your computer network is too large and has too much traffic. Many times people use VLANs simply because the computer network they are working on already uses them.

Another important issue is that on Cisco switches, VLANs are enabled by default and all computers are in one VLAN. That VLAN is VLAN 1. So by default, you can use all ports on the switch and all computers are able to communicate with each other.

When do you need a VLAN?

You need to consider using VLANs in the following cases:

  1. You have more than 200 computers on your LAN
  2. Broadcast traffic in your LAN is too large
  3. Workgroups that need increased security or are slowed down by too many broadcasts.
  4. The workgroups need to be on the same broadcast domain because they are sharing the same applications. For example, a company uses VoIP phones. Some people who want to use the phone may be on a different VLAN network, not with regular users.
  5. Or just to convert a single switch into multiple virtual switches.

Why not split the subnet?

  • A frequently asked question is why not split the subnet instead of using VLANs? Each VLAN should be in its own subnet. VLANs have an advantage over subnets in that computers in different physical locations (not back to the same router) can be on the same network. The drawback of sharing a subnet with a router is that all computers on that subnet must be connected to the same switch and that switch must be connected to a port on the router.
  • With VLANs, one computer can be connected to this switch while another computer can connect to the other switch and all computers remain on the common VLAN (broadcast domain).
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How can computers on different VLANs communicate with each other?

  • Computers on different VLANs can communicate with a router or a Layer 3 switch. Since each VLAN is its own subnet, a Layer 3 router or switch must be used to route between the subnets.

VLAN classification

To understand how to classify VLANs, we need to base on the structure of each VLAN network. Rather, the way to create VLANs will help users classify virtual computer networks. Up to now, there are two popular VLAN networks: Static VLAN or static VLAN and Dynamic VLAN or dynamic VLAN.

Dynamic VLAN (Dynamic VLAN)

  • Unlike Static VLAN, Dynamic VLAN is constructed in a different way. So what is Dynamic VLAN? How is this type of VLAN created?
  • It is known that Dynamic VLAN is a type of VLAN that is created using typical software such as Ciscowork 2000. At this time, users will use the VLAN Management Policy Server (VMPS) to register Switch ports connected to VLANs automatically. The connection is made based on the source MAC address of the device type connected to the port.
  • Similar to the network device model, Dynamic VLAN works to query a database based on the VMPS of the remaining member VLANs.

Static VLAN (VLAN tĩnh)

  • Static VLAN is a type of VLAN created by attaching switch ports to a VLAN. This is similar to a device connected to the network and it recognizes itself as the VLAN of that port.
  • In case the user needs to change the ports and needs to access a common VLAN, the administrator must declare the port for the VLAN in the next connection.

Trunk line in VLAN

  • The concept of VLAN trunking is understood as a technique to build trunks in VLANs. In which, Trunk is a path that allows the transmission of data streams belonging to many different VLANs. Thanks to the convenient Trunk, users do not need to use communication wires for VLANs.

Currently, VLAN trunking has two types of standards, 802.1Q and ISL. More specific:

  • 802.1Q is an international standard used for devices from many different brands.
  • ISL is a proprietary standard for devices belonging to a single company, Cisco.

Usually 802.1Q Trunking is more commonly used, because many of the user’s devices are not Cisco products.

It is known that in order for VLAN data to be transmitted correctly, VLAN trunking will add an information field inside the header of frames. These frames will be in the Data Link layer, also known as the Tag (the tag contains the sequence number of the VLAN or VLAN ID).

Another point to note about trunks in VLANs is that the Native VLAN feature is equipped. This is a feature that supports data transmission without adding tags. Smart features are often used to configure VLANs that are fast-paced and have high processing capacity.

Conclude

Thank you for reading Rusq.org’s article, hopefully the answer is what is VLAN ? The meanings of VLAN will help readers add useful knowledge. If readers have any comments or questions related to the definition of what VLAN is? Please leave comments below this article. Rusq.org is always ready to exchange and receive new information and knowledge from readers

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