- Layer 2 and 3 of the Open Systems Interconnection (OSI) Model. An explainer.
- Data Link Layer (Layer 2):
- Functionality: This layer is primarily concerned with the local delivery of frames between devices on the same network.
- Devices: Switches operate at Layer 2.
- Addressing: Devices on this layer are identified by MAC (Media Access Control) addresses.
- Data Unit: The frame is the basic data unit at Layer 2.
- Network Layer (Layer 3):
- Functionality: This layer is responsible for logical addressing, routing, and forwarding of packets between devices on different networks.
- Devices: Routers operate at Layer 3.
- Addressing: Devices on this layer are identified by IP (Internet Protocol) addresses.
- Data Unit: The packet is the basic data unit at Layer 3.
- VLAN Explainer
- VLANs (Virtual Local Area Network):
- Purpose: VLANs are used to logically segment a physical network into multiple broadcast domains. This segmentation helps improve network performance, security, and management.
- Functionality: Devices in the same VLAN can communicate with each other as if they are in the same physical network, even if they are not physically connected t the same switch.
- Implementation: VLANs are often implemented in switches, and devices within the same VLAN share the same VLAN ID.
- Isolation: VLANs provide isolation at Layer 2, meaning devices in different VLANs cannot communicate directly at the Data Link Layer.
- Subnets:
- Purpose: Subnets are used to divide an IP network into smaller, more manageable segments. Each subnet has its own range of IP addresses.
- Functionality: Devices within the same subnet can communicate with each other directly without the need for routing. Routing is required for communication between devices in different subnets.
- Implementation: Subnets are implemented at the Network Layer (Layer 3) and are associated with IP addresses.
- Isolation: Subnets provide isolation at Layer 3. Devices in different subnets require a route to communicate.