Networks are built from a variety of physical and virtual devices, each serving a specific purpose. Understanding these devices and how they are arranged in a network architecture is essential for designing reliable, scalable, and secure networks.
Core Network Devices
Hub (Legacy)
Operates at Layer 1 (Physical)
Receives a signal on one port and broadcasts it to all other ports
No intelligence — creates a single collision domain
Largely replaced by switches
Switch
Operates at Layer 2 (Data Link)
Forwards frames based on MAC addresses
Maintains a MAC address table for intelligent forwarding
Each port is its own collision domain
Managed switches offer VLANs, port security, monitoring, and QoS
Router
Operates at Layer 3 (Network)
Forwards packets between different networks based on IP addresses
Maintains a routing table with static and dynamic routes
Provides NAT, ACLs (Access Control Lists), and DHCP services
Connects your LAN to the Internet (WAN)
Layer 3 Switch (Multilayer Switch)
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