Layer 1 - Physical Layer: Think of this as the actual, tangible stuff—wires, cables, and switches. This layer deals with the physical connection between devices. It's concerned with things like voltage levels and the physical data rates (how fast bits travel).
Layer 2 - Data Link Layer: Imagine this as a small neighborhood road. It helps nearby devices (like computers in your home) talk to each other. Switches operate at this level, using MAC addresses to deliver data frames to the right local device.
Layer 3 - Network Layer: This is like the city's road network. It connects different neighborhoods or even cities together. Routers work here, using IP addresses to route data packets between different networks (like your home network and the Internet).
Layer 4 - Transport Layer: Picture this as the rules for different types of vehicles on the road—trucks, cars, bikes, etc. This layer sorts out how data is sent—either as a continuous stream or in individual chunks. It's where you'll find protocols like TCP and UDP.
Layer 5 - Session Layer: Think of this as setting up and taking down campsites (sessions) for travelers (data) to rest. It establishes, maintains, and ends communication "sessions" between applications on different devices.
Layer 6 - Presentation Layer: This is like a translation service. If two people speak different languages, they need a translator to understand each other. Similarly, this layer translates between different data formats or encryption methods, making sure the data is readable at both ends.
Layer 7 - Application Layer: Imagine this as different destinations you can go to—malls, hospitals, schools, etc. This layer is all about the applications that need network communication, like your web browser or email client. Protocols like HTTP and FTP operate here.
Layer 1 - Physical Layer:
Devices: Hubs, Repeaters, Network Cables
What it Does: Deals with the physical connection like wires and cables. Sends raw bits over the physical medium.
Layer 2 - Data Link Layer:
Devices: Network Switches, Bridges, Network Interface Cards (NIC)
What it Does: Helps local devices communicate within the same network. Uses MAC addresses to deliver data frames to the right local device.
Layer 3 - Network Layer:
Devices: Routers
What it Does: Connects different networks together, like your home network to the Internet. Uses IP addresses to route data packets.
Layer 4 - Transport Layer:
Devices: Firewalls (Layer 4 firewalls), Load Balancers (when operating at Layer 4)
What it Does: Sorts out how data is sent—either continuously (stream) or in individual chunks. Protocols like TCP and UDP operate here.
Layer 5 - Session Layer:
Devices: Some advanced Firewalls, Intrusion Detection Systems (IDS)
What it Does: Establishes, maintains, and terminates communication sessions between applications.
Layer 6 - Presentation Layer:
Devices: Rare, but Encryption Gateways might work here
What it Does: Translates between different data formats or encryption methods.
Layer 7 - Application Layer:
Devices: Proxies, Web Application Firewalls, Content Delivery Networks (CDNs), Load Balancers (when operating at Layer 7)
What it Does: Focuses on application-level protocols like HTTP, FTP, and email protocols. Helps applications on different devices communicate.