Networking Essentials: Cables, Signals, and Devices

Twisted Pair Cable Subclassifications

Unshielded Twisted Pair (UTP)

• They do not have a conducting screen.
• Advantage: Very flexible.
• Disadvantage: Very sensitive to interference.

Shielded Twisted Pair (STP)

• Each pair is surrounded by a protective mesh.
• Disadvantage: Less flexible.
• Advantage: Improved immunity to noise, reducing interference.

Shielded/Foiled Twisted Pair (S/FTP)

• An overall screen is added to all cables.
• Advantage: Enhanced noise immunity (even better than STP).

Foiled Twisted Pair (FTP)

• They have an overall conducting screen in the form of a braid.
• Advantage: Reduces interference.
• Disadvantage: More expensive than STP.

Analog vs. Digital Signals

• Analog signals represent continuous functions and can take any value within a range.
• Digital signals represent discrete functions and take values only within a specific range.
• Digital signals are faster but require higher quality cables.

ADSL Network Technology

The ADSL network is based on the idea of using the telephone network to transmit information at high speed. (ATM allows the implementation of services that require high-speed transmission.)

Features

• It's an access technology for broadband Internet.
• Increased ability to transmit data.
• Faster transmission speeds.
• Uses a higher frequency band than conventional telephone conversations.

Routers: Network Traffic Directors

Features

• Operates at OSI Layer 3 (Network Layer).
• Directs received packets to their destination: When a packet is received, the router examines its destination address and, using its routing tables and algorithms, chooses the best route.
• Analyzes information such as the number of hops, destination addresses, and output link.

Advantage

• Provides security through firewalls (filtering packets to or from external networks).

Modems: Bridging Digital and Analog

A modem is a device that allows a computer to communicate with the Public Switched Telephone Network (PSTN) by converting digital electrical signals into analog signals for transmission and vice versa for reception.

Components

• Digital-to-analog and analog-to-digital converters.
• Modem control unit.

Switches: Enhancing LAN Performance

A switch interfaces two or more Local Area Networks (LANs) at the data link layer using the same protocols.

Features

• Operates at OSI Layer 2 (Data Link Layer).
• Facilitates the construction of virtual networks.
• Segments a network into multiple collision domains.
• Quick frame processing.
• Main difference from a bridge: higher speed operation.

Repeaters and Amplifiers: Signal Regeneration

Repeaters and amplifiers solve problems that arise in long-distance transmissions.

Features

• Regenerate the signal to its original strength and form.
• Repeaters handle digital signals.
• Amplifiers handle analog signals.
• They operate at the physical layer.
• Ports are bidirectional.

Limitations

• The length of cable sections between a repeater or amplifier has a maximum value.
• Signals cannot traverse multiple amplifications due to accumulated distortion.

Advantage

• Ease of operation (repeats the signal at high speed).

Disadvantage

• Does not isolate network problems (propagates errors).

Fiber Optic Cable: High-Speed Data

Fiber optic cable utilizes light waves to transmit binary data. A light source converts electrical signals into optical signals. The transmission medium is an ultra-thin glass fiber. A detector generates an electrical pulse when light is received.

Advantages

• Extremely high bandwidth and speed.

Disadvantages

• Fragile (cannot bend sharply).
• High cost.

Coaxial Cable: Robust Data Transmission

Features

• Features a solid copper wire in the center.
• Insulating material wraps the central conductor.
• A cylindrical mesh of braided copper (shield) surrounds the insulation, serving as the ground.
• An outer plastic jacket.
• Advantage: High bandwidth.
• Advantage: Excellent noise immunity.

Types

• Baseband: For digital transmission, cable lengths up to 1 KM, speeds up to 10 Mbps.
• Broadband: For analog transmission (e.g., cable television signals), supports distances up to 100 KM.