What is LAN? Overview of LAN and LAN cables

1.1 What is a LAN?

A computer network allows computers to connect and exchange data through various transmission media. There are three main types of networks based on coverage area:

• LAN (Local Area Network): Covers a small area
• MAN (Metropolitan Area Network): Covers a wider area than a LAN
• WAN (Wide Area Network): Covers the largest area

A LAN (Local Area Network) is a group of devices connected within a specific physical area such as a building, office, or home. LANs can range from small networks with a single user to large enterprise networks with thousands of users and devices across offices or schools.

1.2 How does a LAN work?

A LAN connects multiple devices in a small area like a home, office, or school, allowing them to communicate and share resources efficiently. Here's how a LAN operates:

• Device connections: Devices such as computers, printers, and smartphones connect to the LAN using Ethernet cables or wirelessly via Wi-Fi. Each device uses a Network Interface Card (NIC) to connect to the network.
• Data transmission: When a device sends data (e.g., a file), it is transmitted across the network. In a wired LAN, the data travels through Ethernet cables; in a wireless LAN, it is transmitted via radio waves.
• Switches and routers: A switch directs data to the correct device within the LAN. If a device needs Internet access, a router connects the LAN to the Internet.
• Resource sharing: Once connected, devices can share resources such as files, printers, and Internet connections, enabling efficient teamwork and communication.

2.2 Components of a LAN

A typical LAN consists of several key components working together to form a high-speed and reliable network:

• Devices (Nodes): Computers, smartphones, printers, and other electronics.
• Switches: Manage and route data to the correct devices, preventing data collisions.
• Routers: Connect the LAN to the Internet.
• Cables or wireless connections: Devices connect using Ethernet cables or wireless Wi-Fi.
• NICs (Network Interface Cards): Hardware installed in each device to enable network communication.

2.3 Common LAN topologies

Network topology refers to the layout or structure of device connections in a LAN. Each topology has its own advantages:

• Bus topology: All devices connect to a single central cable. It's simple and cost-effective but prone to failure if the main cable is damaged.
• Ring topology: Devices form a closed loop; data travels in one direction. A failure in one device can disrupt the entire network.
• Star topology: All devices connect to a central hub or switch. It's stable and easy to maintain - if one device fails, others remain unaffected.

A LAN cable, or network cable, is a specialized cable used to connect devices within a limited area, such as a home, school, or office. It transmits data signals and enables communication between devices like computers, printers, and networking hardware.

LAN cables use twisted copper wire pairs to carry electrical signals, minimizing electromagnetic interference (EMI) and crosstalk. Some cables include shielding to enhance noise resistance. They enable fast and secure data transfer when connecting devices to switches, routers, or directly to one another.

4.2 Twisted pair cables

Twisted pair cables use two insulated copper wires twisted together to reduce interference. They come in two types:

• UTP (Unshielded Twisted Pair): Most common in modern Ethernet networks. Suitable for LANs, telephones, and general networking.
• STP (Shielded Twisted Pair): Includes shielding for better EMI resistance. Ideal for high-speed or interference-prone environments.

4.3 Fibre optic cables

Fibre optic cables consist of core made of glass fibers to carry light signals and cladding typically made from PVC or Teflon for protection. Advantages:

• Speed: Transmits data at nearly the speed of light
• Distance: Supports long-distance transmission with minimal signal loss

Two types of fiber optic cables:

• Single-mode (OS1, OS2): For long-distance, high-speed transmission using one light beam
• Multimode (OM1–OM5): Uses multiple light beams, ideal for short to medium distances

5.1 Coaxial cables

• Standard RG cables: RG 217, RG 218, RG 223 U, RG 316 B/U, RG 302 B/U, RG 58 C/U, RG 59 B/U TWIN, RG 62 A/U
• Halogen-free, flame-retardant RG cables: RG-H 11 A/U, RG-H 58 C/U, RG-H 59 B/U, RG-H 62 A/U, RG-H 71 B/U, RG-H 213 U, RG-H 214 U
• Other types: SAT, SKT, CATV coaxial cables

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