CWNA Guide to Wireless LANs, Second Edition [教程].pptVIP

Linux+ Guide to Linux Certification, Second Edition CWNA Guide to Wireless LANs, Second Edition CWNA Guide to Wireless LANs, Second Edition Chapter Two Wireless LAN Devices and Standards Objectives List WLAN devices and describe their basic functions Explain the different types of communication standards and why standards are important List the three major wireless standards and regulatory agencies and their functions Describe the different IEEE WLAN standards WLAN Devices: Wireless Network Interface Card Network interface card (NIC): Connects computer to network so that it can send and receive data Wireless NICs perform same function, but without wires When wireless NICs transmit: Change computer’s internal data from parallel to serial transmission Divide data into packets and attach sending and receiving computer’s address Determine when to send packet Transmit packet WLAN Devices: Wireless Network Interface Card (continued) WLAN Devices: Wireless Network Interface Card (continued) WLAN Devices: Wireless Network Interface Card (continued) WLAN Devices: Wireless Network Interface Card (continued) For smaller devices, several options: CardBus or Type II PC Card May require a sled CompactFlash (CF) card: Consists of small circuit board containing flash memory chips and dedicated controller chip Small and consume little power SDIO (Secure Digital I/O) or SDIO NOW! Card: Provides high-speed data input/output with low power consumption WLAN Devices: Wireless Network Interface Card (continued) A movement towards integrating wireless NICs Would eliminate need for external wireless NICs Software drivers necessary to allow wireless NIC and operating system (OS) to interface Windows XP and PDA OSs have built-in drivers WLAN Devices: Access Point Three major parts: Antenna and radio transmitter/receiver RJ-45 wired network interface Special bridging software To interface wireless devices to other devices Two basic function: Base station for wireless network Bridge between w