VLAN (Virtual Local Area Networks)—What Are The Different Types of VLANs? How Does VLAN Work?

In the ever-evolving world of networking, Virtual LANs (VLANs) have emerged as a crucial tool for achieving efficient and secure communication within networks. As networks continue to grow in complexity, understanding VLANs and their benefits becomes essential for network administrators.

What is VLAN?

A VLAN, also referred to as a Virtual LAN, is a digital collection of devices that belong to a physical network. It provides the ability for network administrators to divide and separate devices into distinct broadcast domains, regardless of their physical connection to the network infrastructure. The purpose of VLAN is to improve network flexibility, safeguard security, and optimize performance.

What Are Some Common Types of VLANs?

There are different approaches to implementing VLANs, each suited to specific network requirements. Network devices, such as computers, servers, and network switches, are assigned to specific VLANs. There are a few types of common VLAN designations, as outlined below.

Port-based VLAN

Port-based VLANs assign devices to specific VLANs based on the physical switch port they are connected to. This method is widely used and offers a simple and effective way to segregate network traffic and improve network security. By assigning devices to VLANs based on their physical port, network administrators can control and manage network traffic more easily.

MAC-based VLAN

MAC-based VLANs assign devices to VLANs based on their Media Access Control (MAC) addresses. This type of VLAN provides granular control over device assignment and is useful in environments with frequent device mobility.

Protocol-based VLAN

Protocol-based VLANs classify traffic based on network protocols. This type of VLAN is often used to separate traffic for different applications or services, such as voice and video traffic or specific protocols like Internet Protocol Security (IPSec).

Take a look at an example of a VLAN network topology.

How Does VLAN Work?

Virtual LANs work by logically segmenting a physical network into multiple virtual networks. Instead of relying solely on physical connections, VLANs use software-based configurations and network switches to define and enforce network boundaries. Here’s a breakdown of how VLANs work:

VLAN Identification

Each VLAN is assigned a unique identifier called a VLAN ID or VLAN tag. Common VLAN ID ranges from 1 to 4094, although some switches reserve certain IDs for specific purposes.

The VLAN ID is embedded in the Ethernet frame as it travels through the network, allowing switches to identify which VLAN the frame belongs to.

VLAN Membership

Network devices, such as computers, servers, and network switches, are assigned to specific VLANs. VLAN membership is typically determined by one of the following methods:
Port-Based VLAN, MAC-Based VLAN, Protocol-Based VLAN.

VLAN Communication

Devices within the same VLAN can communicate with each other as if they were connected directly, regardless of their physical location on the network.

When a device sends an Ethernet frame, the frame is tagged with the appropriate VLAN ID before leaving the device.

Network switches use VLAN tags to forward frames only to the ports associated with the corresponding VLAN. Frames within a VLAN do not cross VLAN boundaries, preventing unwanted communication between different VLANs.

Inter-VLAN Communication

In some cases, it may be necessary for devices in different VLANs to communicate with each other. Inter-VLAN communication can be achieved through various methods, including:

Router: A router with multiple network interfaces can be used to connect different VLANs. The router acts as a gateway, allowing traffic to flow between VLANs while enforcing security policies and controlling access.

Layer 3 Switch: Some network switches have Layer 3 capabilities, allowing them to perform routing functions between VLANs without the need for a separate router.

VLAN Trunking: Trunk ports on network switches can carry traffic for multiple VLANs simultaneously. These trunk links enable VLAN communication by tagging Ethernet frames with the appropriate VLAN IDs.

By using VLANs, network administrators can effectively isolate and secure network traffic, enhance performance by reducing broadcast traffic, and simplify network management by grouping devices logically rather than physically. VLANs provide flexibility, scalability, and increased control over network resources, enabling organizations to optimize their network infrastructure according to their specific needs.

What is VLAN Tagging?

VLAN tagging is a technique employed to distinguish and classify Ethernet frames related to different VLANs while they move through a network structure.

VLAN Tag Structure

A VLAN tag consists of four bytes (32 bits) added to the Ethernet frame’s original header. The VLAN tag structure includes the following fields:

Tag Protocol Identifier (TPID): A two-byte field set to a specific value (usually 0x8100) that indicates the presence of a VLAN tag.

Priority Code Point (PCP): A three-bit field used for Quality of Service (QoS) prioritization. It defines the priority level of the frame.

Canonical Format Indicator (CFI): A one-bit field that was used in older VLAN implementations but is no longer significant.

VLAN Identifier (VID): A 12-bit field that represents the VLAN ID or VLAN tag number. It identifies the specific VLAN to which the frame belongs.

VLAN Tagging Methods

There are two common methods for VLAN tagging.

IEEE 802.1Q Tagging: This is the most widely used standard for VLAN tagging. It is often used in Ethernet networks. It inserts the VLAN tag between the source MAC address and the EtherType/length fields of the Ethernet frame. The VLAN tag structure is as described above.

IEEE 802.1ad QinQ Tagging (also known as Provider Bridging or Stacked VLANs): This method allows for multiple levels of VLAN tagging. It adds an additional VLAN tag, known as the service provider tag or outer tag, to the Ethernet frame. The original VLAN tag becomes the inner tag. QinQ tagging enables service providers to maintain VLAN segregation across their networks.

VLAN Tagging and Switches

Switches are the primary devices that handle VLAN tagging.

When a switch receives an Ethernet frame with a VLAN tag, it examines the VLAN tag’s VID field to determine the VLAN to which the frame belongs. Based on the VLAN information, the switch forwards the frame only to the ports associated with that VLAN or performs additional actions, such as applying VLAN-specific policies or QoS settings. Switches also remove the VLAN tag from frames when forwarding them out of access ports connected to devices that do not support VLAN tagging, such as end-user devices.

What Do Tags Have To Do With VLAN Trunking

VLAN tagging is particularly important when dealing with VLAN trunking.

Trunk ports are used to carry traffic for multiple VLANs simultaneously between switches or between switches and routers. Trunk links preserve the VLAN tag as frames traverse the network, ensuring that frames reach the correct VLANs on the receiving switch or router.  Trunking protocols like IEEE 802.1Q enable switches to identify and process VLAN tags on trunk ports.

VLAN tagging plays a crucial role in maintaining VLAN integrity, ensuring proper VLAN membership recognition, and facilitating VLAN communication across network infrastructure. It allows for the differentiation and proper handling of frames belonging to different VLANs, enabling the implementation of VLAN-based security, QoS prioritization, and network segmentation.

What Are The Key Differences Between Tagged And Untagged Ports?

It’s important to configure the correct port mode (untagged or tagged) to ensure proper VLAN communication and avoid misconfigurations that could result in communication issues or security vulnerabilities within the network.

What Are The Benefits And Advantages Of Virtual Local Area Networks?

VLAN connections offer several advantages that contribute to improved network efficiency, security, and manageability.

Enhanced Network Security

Isolation of Sensitive Data: VLANs allow for the segregation of sensitive data within separate VLANs, ensuring that critical information remains isolated from other parts of the network. This isolation adds an extra layer of security, preventing unauthorized access and limiting the potential impact of security breaches.

Segmentation of Network Traffic

VLANs divide the network into separate broadcast domains, effectively segregating traffic. This segmentation prevents unauthorized users or malicious activities in one VLAN from affecting devices or data in other VLANs, improving overall network security.

Improved Network Performance

Reduced Broadcast Traffic: VLANs limit the scope of broadcast traffic, ensuring that broadcasts are confined within the VLAN where they originated. This reduction in broadcast traffic helps to minimize network congestion, optimize bandwidth utilization, and improve network performance.

Enhanced Bandwidth Allocation: VLANs enable administrators to allocate network resources more effectively by separating devices based on their network requirements. High-bandwidth devices or applications can be assigned to their dedicated VLANs, preventing them from consuming excessive resources and impacting the performance of other devices or applications.

Simplified Network Management

Easy Reconfiguration and Scalability: VLANs simplify network reconfiguration and scalability. By assigning devices to VLANs based on their logical attributes rather than a physical location, administrators can easily add, remove, or relocate devices without the need for physical rewiring. This flexibility streamlines network management and reduces operational costs.

Centralized Control and Monitoring: VLANs enable centralized management and monitoring of network activity. Administrators can apply VLAN-specific policies, such as access controls and quality of service settings, from a central location. This centralized control simplifies network management tasks, improves troubleshooting efficiency, and enhances overall network visibility.

Optimized Resource Utilization

VLAN connections optimize the utilization of network resources. By logically grouping devices based on their network requirements, VLANs ensure that resources such as bandwidth, server capacity, and network services are allocated efficiently. This optimization results in improved network performance, reduced bottlenecks, and a better user experience.

Flexibility and Adaptability

VLANs offer flexibility in network design and adaptability to changing organizational needs. Administrators can easily create, modify, or remove VLANs to accommodate evolving network requirements, departmental changes, or new applications without significant disruption to the overall network infrastructure.

Static VLANs and dynamic VLANs are two different approaches to configuring Virtual LANs (VLANs) in a network. Each has its advantages and use cases. Let’s explore the differences between static and dynamic VLANs:

What Is Static VLAN?

Definition: In a static VLAN configuration, network administrators manually assign devices to specific VLANs based on criteria such as switch ports, MAC addresses, or network protocols. The VLAN assignments remain fixed unless manually changed by the administrator.

Configuration: Administrators must explicitly configure each switch port and the devices connected to them to be members of specific VLANs. This is typically done through the switch’s configuration interface.

What Are The Advantages of Static VLAN?

Simplicity

Static VLANs are easy to configure and manage, making them a straightforward choice for smaller networks or environments with stable device configurations.

Security

Static VLANs provide granular control over VLAN membership, reducing the risk of unauthorized access and potential VLAN hopping attacks.

Predictability

The VLAN assignments do not change unless explicitly modified, ensuring predictable network behavior.

What Are The Disadvantages of Static VLAN?

Manual Configuration: The manual assignment of devices to VLANs can be time-consuming and cumbersome, especially in larger networks or in environments where devices frequently move or change.

Scalability: As the network grows, the management overhead of static VLANs can become challenging, and changes may require a significant amount of manual effort.

What Is Dynamic VLAN?

Definition: Dynamic VLANs, also known as VLAN membership policy-based VLANs, use protocols such as IEEE 802.1x or Cisco’s Dynamic Host Configuration Protocol (DHCP) snooping to dynamically assign devices to VLANs based on authentication or other criteria.

Dynamic VLANs automatically assign devices to VLANs based on the rules set by the network administrator or the authentication mechanism used.

What Are The Advantages of Dynamic VLAN?

Automation

Dynamic VLANs automate the process of assigning devices to VLANs, making them more efficient and scalable for large networks or environments with frequent changes in device connections.

Flexibility

Devices can be dynamically assigned to VLANs based on user credentials, device characteristics, or other attributes, providing more dynamic network access control.

Reduced Administrative Overhead

Dynamic VLANs simplify network management and reduce the need for manual VLAN configuration.

What Are The Disadvantages of Dynamic VLAN?

Complexity

Setting up and configuring dynamic VLANs may require more advanced knowledge and additional infrastructure, such as an authentication server for IEEE 802.1x.

Potential Security Risks

If the authentication mechanisms are not properly configured or secured, there is a risk of unauthorized devices gaining access to VLANs they should not be part of.

How Can Businesses Use a VLAN Connection To Improve Internal Connections?

In large organizations, departmental segregation is crucial for maintaining data privacy, network security, and efficient collaboration. VLANs provide an effective solution for separating different departments within an organization.

Finance Department

The finance department deals with sensitive financial information, including payroll, budgeting, and financial records. By implementing a dedicated VLAN for finance, organizations can ensure the isolation of sensitive financial data from other departments. This separation protects critical information from unauthorized access and potential security breaches, providing peace of mind to finance teams.

IT Department

The IT department is responsible for managing and maintaining the network infrastructure and devices. By assigning IT devices, such as servers, switches, and routers, to a dedicated VLAN, IT administrators can streamline their network management tasks. This separation allows for more efficient troubleshooting, configuration, and maintenance activities specific to IT infrastructure, without interfering with other departments’ operations.

Marketing Department

The marketing department often handles proprietary campaign strategies, creative assets, and market research data. By implementing a marketing VLAN, organizations can facilitate secure collaboration within the marketing team while preventing non-marketing users from accessing their sensitive data. The VLAN ensures that marketing activities can proceed smoothly while maintaining the confidentiality and integrity of their projects.

How Can VLAN Help Clients Improve Their Online Experience?

The hospitality industry, including hotels, resorts, and conference centers, often provides guest networks for visitors. VLANs play a crucial role in creating secure and efficient guest network environments.

Secure Isolation of Guest Traffic

VLANs allow for the creation of a separate guest network that is isolated from the organization’s internal network. By assigning guest devices to a dedicated VLAN, organizations can ensure the security of their internal resources. This isolation prevents unauthorized access and potential attacks from compromising sensitive data and resources.

Seamless Connectivity for Visitors

VLANs provide a seamless connectivity experience for visitors, allowing them to connect to the guest network without disrupting the organization’s primary network infrastructure. By implementing VLANs, organizations can provide controlled and secure connectivity to guests, enabling them to access the internet and necessary services while maintaining network security and performance.

How Can VLAN Help Your Business Improve Internal Communication?

Voice over Internet Protocol (VoIP) systems have become increasingly popular for business communication. VLANs offer significant benefits when it comes to separating voice and data traffic within these systems.

Quality of Service Prioritization

VLANs enable the segregation of voice and data traffic, allowing organizations to prioritize voice traffic and ensure high-quality communication. By assigning voice devices to a dedicated VLAN, network administrators can prioritize voice packets, reducing latency, packet loss, and ensuring a reliable communication experience for users.

Efficient Resource Utilization

Separating voice and data traffic through VLANs enables organizations to allocate network resources more efficiently. By prioritizing critical voice traffic over regular data traffic, VLANs help ensure that voice communication remains smooth and uninterrupted, even during periods of heavy network utilization. This resource allocation optimization leads to an overall improvement in network performance and user satisfaction.

Scope and Physical Infrastructure

A local area network (LAN) is a network that connects devices within a small area, like an office, school, or house. It usually includes switches, routers, and connected devices that all use the same physical infrastructure.

On the other hand, a virtual LAN (VLAN) is a group of devices within a LAN that are logically organized together. It gives network administrators the ability to create virtual networks that spread throughout the physical LAN infrastructure, allowing for logical division and separation of network traffic.

Traffic Segmentation and Isolation

In a conventional local area network (LAN), all devices that are interconnected share the identical broadcast domain. Consequently, any broadcast traffic, like requests for Address Resolution Protocol (ARP) or packets for network discovery, will be received by all devices within the LAN.

On the other hand, virtual local area networks allow for the segmentation and separation of network traffic. Devices that belong to the same VLAN can communicate with each other as if they were directly connected, regardless of their physical placement across various switches or network segments. VLANs establish logical boundaries that limit the reach of broadcast and communication, thereby improving security and network performance.

VLAN Tagging and Logical Separation

In a local area network (LAN), devices communicate using Ethernet frames and there is no built-in distinction or recognition of traffic associated with various groups or departments.

Virtual LANs (VLANs) utilize VLAN tagging, which includes adding extra information, tags, to Ethernet frames in order to identify the specific VLAN they are a part of. These VLAN tags indicate the frame’s membership in a VLAN and enable switches to process and forward the frames based on their assigned VLAN.

Flexibility and Scalability

Flexibility and scalability are key factors to consider when implementing a LAN or VLAN network. While a LAN is typically set up using a specific physical infrastructure, with devices connected via network switches and routers, making changes to expand or reconfigure the LAN often involves physical alterations, like adding more switches or extending network cabling.

On the other hand, VLANs offer a higher level of flexibility and scalability. They allow for the creation, modification, or removal of virtual networks without the need for any physical adjustments to the underlying LAN infrastructure. Devices can be logically assigned to VLANs based on their specific network requirements, allowing for more dynamic network management.

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What Are The Potential Disadvantages of Using VLANs?

While VLANs offer numerous advantages, they also have potential disadvantages that should be considered when implementing them in a network.

Complexity and Configuration

VLANs can introduce complexity, especially in larger networks or those with intricate VLAN setups. Configuring and managing VLANs require careful planning and coordination among network administrators.

Misconfigurations or inconsistencies in VLAN configurations can result in connectivity issues, security vulnerabilities, or unintended traffic leakage.

Spanning and Scalability

In some cases, spanning VLANs across multiple switches or large network infrastructures can be challenging. Ensuring consistent VLAN configurations and maintaining proper VLAN trunking protocols can become more complex as the network scales.

As the number of VLANs and devices increases, VLAN management and coordination can become more time-consuming and prone to human error.

Increased Network Overhead

VLANs introduce additional overhead due to VLAN tagging. The VLAN tags added to Ethernet frames increase the frame size, which can slightly impact overall network throughput and latency. In certain scenarios with high VLAN density or extensive use of VLAN trunking, the increased overhead from VLAN tagging can become more noticeable.

Security Risks

Misconfigured VLANs can lead to security vulnerabilities. If VLANs are not properly configured or access controls are not adequately implemented, there is a risk of unauthorized access, also known as VLAN hopping.

VLANs can provide a false sense of security if other essential security measures, such as firewall rules, access controls, and encryption, are not properly implemented across the network.

Limited Broadcast Domain Isolation

While VLANs effectively isolate broadcast traffic within a VLAN, they do not provide complete isolation of broadcast domains. Broadcast traffic generated within a VLAN can still impact network performance and potentially consume excessive resources.

Inter-VLAN Communication Challenges

Enabling communication between different VLANs requires additional configuration and devices, such as routers or Layer 3 switches. Configuring and managing inter-VLAN routing can be complex, especially in larger networks.

Cost

Implementing VLANs may require investment in network switches with VLAN support, especially if existing infrastructure lacks the necessary capabilities. This cost should be considered when planning VLAN deployments.

While these potential disadvantages exist, they can be mitigated through proper planning, configuration, and ongoing management. It is important to thoroughly assess network requirements, consider the scalability of VLAN implementations, and regularly review and update VLAN configurations to maintain a secure and efficient network environment.

Can You Configure A VLAN Connection On An Asus FlashRouter?

Yes! Select Asus router support VLAN connections. Check out our post on setting VLAN router to learn how to do it!

Can You Configure A VLAN Connection On An ExpressVPN FlashRouter?

At the moment, no. ExpressVPN-configured FlashRouters do not support VLAN Connection.

Can You Configure A VLAN Connection On A DD-WRT FlashRouter?

Indeed! We even have a specific post about setting up VLAN on your DD-WRT network!

Can You Configure A VLAN Connection On A Privacy Hero?

At the moment, no. The Privacy Hert does not support VLAN tagging.

Have any questions about VLANs? Feel free to reach out!