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OSI Physical Layer. Network Fundamentals – Chapter 8. Fiber Media. Copper uses electrical voltage to represent data. Fiber-optic cable uses light pulses conducted through special glass conductors to carry data .
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OSI Physical Layer Network Fundamentals – Chapter 8
Fiber Media • Copper uses electrical voltage to represent data. • Fiber-optic cable uses light pulses conducted through special glass conductors to carry data. • Fiber has greater bandwidth and can run much farther than cable without needing a signal enhanced, • but the higher cost of fiber-optic cable and connectors, + special training required for installing + handling fiber.
Fiber Media • Because fiber does not carry voltage and current = immune to the earth ground and lightning concerns. • Usually considered the best choice for backbone connections between floors and wiring closets in large buildings and for connections between buildings on a campus.
Fiber Media • Fiber-optic cable starts with a core strand of glass or special plastic on which the light signal travels. • Around the glass is cladding, a special material that reflects escaping light into the core. • Outer layers protect and strengthen the vulnerable center core from moisture and damage.
Fiber Media • There are two basic types of fiber-optic cable: • single-mode - most commonly used by telephone companies and in data installations as backbone cable. • multimode - usually the fiber-optic cable used with networking applications such as FDDI and ATM
Wireless Media • Wireless media carry electromagnetic radio signals that represent the binary data of the data-link frame. • Transmit and receive signals through the medium of the open atmosphere = open areas are best • Within buildings, interference occurs from physical objects such as • walls, metal air ducts, • and floors and • machinery. • + subject to degradation • microwave ovens, • fluorescent lighting, • phones and Bluetooth devices.
Wireless Media • Four common data communications standards that apply to wireless media: • ■ Standard IEEE 802.11: Commonly referred to as Wi-Fi, 802.11 is a wireless LAN (WLAN) technology that uses a contention or nondeterministic system with a carrier sense multiple access/collision avoid (CSMA/CA) media access process. • ■ Standard IEEE 802.15:Wireless Personal-Area Network (WPAN): Commonly known as Bluetooth, 802.15 uses a device-pairing process to communicate over distances from 1 to 100 meters. • ■ Standard IEEE 802.16: Commonly known as WiMAX (Worldwide Interoperability for Microwave Access), 802.16 uses a point-to-multipoint topology to provide wireless broadband access. • ■ Global System for Mobile Communication (GSM): Includes physical layer specifications that enable the implementation of the Layer 2 General Packet Radio Service (GPRS) protocol to provide data transfer over mobile cellular telephony networks.
