© 2007 Cisco Systems, Inc. All rights reserved.Cisco Public 1 Version 4.0 OSI Physical Layer Network Fundamentals – Chapter 8

2 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public 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.installing + handling

3 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public 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.

4 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public 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.

5 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public 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

6 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public 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.

7 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless Media  Four common data communications standards that apply to wireless media: ■ Standard IEEE : Commonly referred to as Wi-Fi, 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 :Wireless Personal-Area Network (WPAN): Commonly known as Bluetooth, uses a device-pairing process to communicate over distances from 1 to 100 meters. ■ Standard IEEE : Commonly known as WiMAX (Worldwide Interoperability for Microwave Access), 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.

8 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless Media

9 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Summary

10 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public