Understanding OSI Layers: Where Do Routers, Switches, and Other Devices Belong?
The OSI model is a framework for understanding networking devices. It consists of seven layers, each with specific functions. Here’s where routers, switches, and other devices fit:
1. Routers – Layer 3 (Network Layer) 🚃
Routers direct data between networks using IP addresses, ensuring efficient communication across different subnets.
How to remember? 😊
Which layer does an IP address belong to? Layer 3
2. Switches – Layer 2 (Data Link Layer) & Layer 3 (Network Layer) 🔘
Layer 2 switches use MAC addresses for data forwarding within a network. Layer 3 switches can route packets between subnets.
3. Hubs – Layer 1 (Physical Layer) 🛜
Hubs broadcast signals to all devices without filtering, making them less efficient than switches.
4. Modems – Layer 1 & Layer 2☎️
Modems convert digital and analog signals for transmission, handling some error detection at Layer 2.
5. Firewalls – Layer 3 & Layer 4 ⚠️
Firewalls filter traffic based on IP addresses (Layer 3) and TCP/UDP ports (Layer 4), with advanced models inspecting data at Layer 7(eg. http traffic filters)
Summary
+------------+-----------------------------------+
| Device | OSI Layer |
+------------+-----------------------------------+
| Routers | Layer 3 (Network Layer) 🚃 |
| | |
| Switches | Layer 2 (Data Link Layer) 🔘 |
| | Layer 3 (Network Layer) 🌍 |
| | |
| Hubs | Layer 1 (Physical Layer) 🛜 |
| | |
| Modems | Layer 1 (Physical Layer) 📡 |
| | Layer 2 (Data Link Layer) 🛠 |
| | |
| Firewalls | Layer 3 (Network Layer) 🔐 |
| | Layer 4 (Transport Layer) 🚦 |
| | Layer 7 (Application Layer) 🌐 |
+------------+----------------------------------+Read “The Journey of Data: Encapsulation and De-encapsulation” to understand how these devices unwrap data units.