Networking Devices (Routers, Switches, Hubs)

Networking Devices

To connect computers together and allow them to communicate, we use various specialized hardware devices. Each device operates at a specific layer of the OSI model and has a specific level of 'intelligence'.

1. Hub (Layer 1 - Physical)

• What it does: A Hub is a 'dumb' device. When it receives a data signal on one port, it blindly copies and broadcasts that signal to all other ports.
• Problem: Because it broadcasts everything, it causes massive data collisions and wastes bandwidth. It does not understand MAC or IP addresses.
• Usage: Obsolete. Rarely used today.

2. Repeater (Layer 1 - Physical)

• What it does: Signals degrade and lose strength over long distances (Attenuation). A Repeater receives a weak signal, regenerates/amplifies it, and sends it further down the line.

3. Bridge (Layer 2 - Data Link)

• What it does: A Bridge connects two different LANs. Unlike a Hub, it is 'smart'. It reads the MAC address of the incoming frame and only forwards it to the other side if the destination computer is actually on the other side.
• Pros: It filters traffic and reduces collisions.

4. Switch (Layer 2 - Data Link)

• What it does: A Switch is a multi-port bridge. It is the core of modern local networks (LANs).
• How it works: It learns the MAC addresses of all computers connected to its ports and stores them in a MAC Table. When Data A wants to go to Computer B, the Switch looks at its table and sends the data only to Computer B's port.
• Pros: No collisions, highly efficient. Full bandwidth is available to every connection.

5. Router (Layer 3 - Network)

• What it does: While a Switch connects computers within the same network, a Router connects different networks together (e.g., your home LAN to the Internet).
• How it works: It reads the IP Address of a packet and uses its Routing Table to determine the best path to send the packet closer to its final destination.

6. Gateway (Layer 4 to 7)

• What it does: A Gateway is a protocol converter. It connects two networks that operate on completely different rules (protocols). For example, a Gateway can connect a modern IP network to an old legacy IBM network, translating the data structure so they can understand each other.