Network Topologies & Transmission Media

Network Topologies

1. Bus Topology

• All computers are connected to a single central cable called the 'Bus' or 'Backbone'.
• Pros: Easy to set up and cheap (requires less cable).
• Cons: If the main cable breaks, the entire network goes down. Data collisions are common.

2. Star Topology

• All computers are connected to a central device (like a Hub or Switch).
• Pros: If one cable breaks, only that specific computer loses connection; the rest of the network is unaffected.
• Cons: If the central switch fails, the entire network goes down. Requires more cabling than Bus.

3. Ring Topology

• Computers are connected in a closed-loop circle. Data travels in one direction (unidirectional).
• Pros: No data collisions because of the strict order of transmission (often using a 'Token').
• Cons: If one computer fails or a cable breaks, the entire ring is broken and the network stops.

4. Mesh Topology

• Every computer is connected to every other computer in the network.
• Pros: Extremely reliable. If one cable fails, data just takes another route.
• Cons: Very expensive and highly complex to install due to the massive amount of cabling required.

Transmission Media

1. Guided (Wired) Media

• Consists of pairs of copper wires twisted together to reduce electromagnetic interference (crosstalk).
• UTP (Unshielded Twisted Pair): Standard Ethernet cable (CAT5/CAT6). Cheap and easy to install.
• STP (Shielded Twisted Pair): Has a metal shield. Better for noisy environments. B. Coaxial Cable:
• Has an inner copper core surrounded by an insulator and a braided metal shield. Commonly used for Cable TV. C. Fiber Optic Cable:
• Uses extremely thin strands of glass to transmit data as pulses of light.
• Pros: Insanely high bandwidth, immune to electromagnetic interference, secure, and can travel long distances without losing signal.
• Cons: Expensive, fragile, and hard to splice.

2. Unguided (Wireless) Media

• Radio Waves: Omnidirectional (spread in all directions). Can pass through walls. Used for FM radio and standard Wi-Fi.
• Microwaves: Unidirectional (travels in a straight line). Requires line-of-sight between antennas. Used for satellite communication.
• Infrared: Used for very short-range communication (like TV remotes). Cannot pass through walls.