VLAN

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Zach

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What is a VLAN?

Imagine you’re in a big office building with different departments—HR, IT, Sales, and Finance. Everyone shares the same physical network (same Wi-Fi or Ethernet cables), but you don’t want just anyone accessing sensitive files or systems. This is where VLANs (Virtual Local Area Networks) come in!

🏢 Think of VLANs Like Virtual Office Spaces

A VLAN (Virtual Local Area Network) is like creating separate office spaces inside one big building without needing extra walls. It allows devices in the same VLAN to communicate as if they were on the same network, even if they are physically in different locations.

For example:

• HR (VLAN 10) can only talk to HR systems.
• IT (VLAN 20) has access to servers and networking tools.
• Sales (VLAN 30) can share files internally but not with Finance.

Even though all departments use the same physical network (switches, routers, Wi-Fi), VLANs virtually separate them for better security, organization, and performance.

🚦 Why Use VLANs?

1. Improves Security – Keeps sensitive data separate (e.g., Finance and Guests shouldn’t share a network).
2. Reduces Network Congestion – Traffic stays in its own VLAN instead of flooding the whole network.
3. Enhances Network Organization – Groups related devices together without extra cables or hardware.
4. Better Access Control – Only authorized devices can communicate within a VLAN.

📡 VLANs in Action

Let’s say a company uses one switch for all devices, but they set up VLANs like this:

• HR devices can only talk to HR systems.
• IT can access everything for troubleshooting.
• Guests get internet access but no access to company files.

Even though all devices connect to the same physical network, VLANs keep them separated and secure.

🏗️ How VLANs Work (A Bit More Technical)

VLANs are created on managed switches using VLAN IDs (like VLAN 10, VLAN 20, etc.). There are two types of VLAN connections:

1. Access Ports – Connects to end devices (PCs, printers, etc.) and assigns them to a VLAN.
2. Trunk Ports – Allows multiple VLANs to travel across switches using VLAN tagging (802.1Q).

A router or Layer 3 switch is needed for devices in different VLANs to communicate (if allowed).

🛠️ Example Use Case

A school wants students and teachers on separate networks but doesn’t want to install separate Wi-Fi routers. Instead, they create VLANs:

• VLAN 10 (Teachers) → Access to grading systems, private resources.
• VLAN 20 (Students) → Only access the internet and school files.
• VLAN 30 (Guests) → Only internet, no internal network access.

🔑 Final Takeaway

A VLAN divides one physical network into multiple virtual networks, improving security, performance, and organization. It’s like having invisible walls in your network, keeping departments, devices, and data separated but efficient. 🚀