OSI Physical Layer Network Fundamentals – Chapter 8 Version 4.0 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 1 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. © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 2 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. © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 3 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. © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 4 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 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 5 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. © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 6 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-tomultipoint 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. © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 7 Wireless Media © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 8 Summary © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 9 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 10