Network Devices

🌐 NIC (Network Interface Card)

NIC (Network Interface Card) is a hardware component that allows a device to connect to a network and communicate with other devices.It also called an Ethernet card or network adapter.

The NIC handles the network interface’s transmission and reception of data. For Ethernet, it converts data between the computer’s internal representation and Ethernet frames/signals on the network medium & For Wi-Fi, the wireless NIC communicates using Wi-Fi radio signals.

📡 Repeater

A Repeater is a network device that receives a signal, regenerates/reshapes it, and retransmits it so the signal can travel farther.

As a signal travels through a cable or wireless medium, it can become weaker or distorted. A repeater receives that signal and sends a regenerated version onward.

🌐 Hub

A Hub is a basic networking device used to connect multiple devices in a network. When a hub receives data from one device, it broadcasts/repeats that incoming signal out of its other ports, rather than determining the specific destination port.

Working:

1. PC1 sends data to Hub
2. The signal enters the hub through one port.
3. It doesn’t inspect MAC addresses to make forwarding decisions.
4. Hub repeats the signal, The signal is repeated toward the other ports.
5. The intended recipient processes the frame; other devices generally discard it if the frame isn’t addressed to them.

Bridge

A Bridge is a networking device that connects two or more network segments and controls traffic between them.

Unlike a hub, a bridge can examine MAC addresses and decide whether an Ethernet frame should be forwarded to another segment.

Working

1. PC1 wants to send data to PC3.
2. PC1 sends an Ethernet frame
3. The frame contains information including:

Source MAC      → PC1
Destination MAC → PC3

4. The bridge examines which MAC addresses are reachable through which side/port.

5. The bridge forwards the frame to the appropriate segment.

Key Point

One important job of a bridge is filtering unnecessary traffic.

Suppose PC1 communicates with PC2:

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If the bridge knows both PC1 and PC2 are on the same segment, it can filter the frame instead of forwarding it to the other segment.

Switch

A switch is a device that connects multiple devices within a LAN (Local Area Network) and forwards Ethernet frames to the appropriate port using MAC addresses.

🌐 Router

A Router is a networking device that connects different IP networks and forwards packets between them.

Working

Suppose your computer wants to open a website. The data is divided into packets, and each packet contains information such as the source IP and destination IP.

1. Your PC sends the packet to its default gateway, usually your router.
2. The router looks at its routing table to determine where the packet should go.
3. If the destination doesn’t match a more specific route, the router can use the default route (0.0.0.0/0).
4. Routers generally use the longest-prefix match: among matching routes, the most specific route is preferred.
5. After selecting the route, the router sends the packet through the appropriate interface.
6. The router may use NAT/PAT to translate the private address to the network’s public IP when communicating with the Internet.
7. Packet is forwarded toward Internet.

🌐 Gateway

A gateway is a device or network point that allows communication between different networks or systems, especially when they use different network architectures or protocols.

Working

Suppose your PC wants to communicate with a server outside your local network.

1. Your PC compares the destination IP with its own network.
2. The PC sends the packet to its configured default gateway.
3. The gateway determines where the traffic needs to go and forwards it toward the destination.

📡 Modem

A modem is a device that connects your local network or router to an ISP (Internet Service Provider) by converting signals between the format used by your local equipment and the transmission technology used by the ISP.

Working

Suppose you open a website.

1. The laptop sends the network traffic to the router.
2. Router sends traffic to the modem.
3. The modem receives traffic that needs to go toward the ISP.
4. Modem converts the signal

📶 Access Point (AP)

Access Point (AP) allows wireless devices such as laptops, smartphones, and tablets to connect to a wired network using Wi-Fi.