Networking devices connect end devices and forward, control, secure, or extend communication.
👉 Unlike end devices, they forward traffic.
A Gateway is a device that connects two different networks using different protocols.
🡪 It acts as a translator between networks.
• Converts data from one protocol to another
• Connects LAN to WAN / Internet
• Acts as an entry and exit point of a network
• Performs routing + protocol conversion
• Often includes firewall and NAT features
• Home Wi-Fi router = Gateway between your home network and ISP
• Email gateway → converts internal mail format to internet format
• Gateway works at multiple OSI layers
• Can combine router + firewall + NAT
A Router connects multiple networks and forwards data using IP addresses.
• Routes packets between networks
• Uses routing table
• Selects best path for data
• Connects LAN to WAN
• Supports static & dynamic routing
• Performs NAT (Network Address Translation)
• Can block or allow traffic using ACLs
• Internet router at home
• Office router connecting branches
• Works at OSI Layer 3 (Network Layer)
• Uses IP addresses
• Slower than switches but smarter
A Switch connects multiple devices within the same network and forwards data using MAC addresses.
• Connects devices in LAN
• Learns MAC addresses automatically
• Sends data only to intended device
• Reduces network congestion
• Supports VLANs
• Supports full-duplex communication
• Stores MAC Address + Port Number
• Office LAN switch
• College computer lab
• Works at OSI Layer 2 (some are Layer 3)
• Faster than hubs
• More secure than hubs
A Hub is a basic device that connects multiple devices and broadcasts data to all ports.
• Connects multiple devices
• Sends data to every device
• No intelligence
• No MAC table
• Works in half-duplex
• High collisions
• No security
• Slow performance
• Works at OSI Layer 1 (Physical)
• Almost obsolete
A Firewall is a security device that monitors and controls incoming and outgoing traffic.
• Allows or blocks traffic
• Protects from unauthorized access
• Filters traffic using rules
• Prevents attacks
• Logs network activity
• Supports VPN
• Hardware firewall
• Software firewall
• Network firewall
• Next-Generation Firewall (NGFW)
• Office security firewall
• Windows Firewall
• Works mainly at Layer 3 & 4
• Security device, not routing device
An Access Point allows wireless devices to connect to a wired network.
• Provides Wi-Fi connectivity
• Converts wired signal to wireless
• Extends network coverage
• Manages wireless clients
• Supports authentication & encryption
• College Wi-Fi AP
• Office ceiling-mounted AP
• Works at Layer 2
• Used in WLAN
A Modem converts digital data to analog and analog to digital.
(MO = Modulator, DEM = Demodulator)
• Connects ISP to customer network
• Signal conversion
• Enables internet connectivity
• Broadband modem
• Fiber ONT
• Used for ISP communication
• Required for internet access
A Bridge connects two LAN segments and filters traffic using MAC address.
• Reduces network traffic
• Divides LAN into segments
• Filters unnecessary traffic
• Improves performance
• Works at Layer 2
• Older technology (replaced by switches)
A Repeater regenerates and amplifies signals to extend network distance.
• Boosts weak signals
• Extends cable length
• Used in long-distance networks
• Wi-Fi repeater at home
• Signal booster
• Works at Layer 1
• No filtering or security
| Device | Layer | Role |
|---|---|---|
| Hub | L1 | Broadcast |
| Repeater | L1 | Signal Boost |
| Bridge | L2 | Segment LAN |
| Switch | L2 | Forward by MAC |
| Router | L3 | Route by IP |
| Firewall | L3/4 | Security |
| AP | L2 | Wireless |
| Modem | Physical | ISP |
| Gateway | Multiple | Protocol Translation |
If asked:
🡪 Difference between Router and Switch
Say:
A switch works within a network using MAC addresses, while a router connects different networks using IP addresses.
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