Sybex CCNA Chapter 12: Wireless Networks

Chapter 12 Objectives The CCNA Topics Covered in this chapter include: What is a WLAN? IEEE Standards CSMA/CD (CA? – collision avoidance, not detection) ISM (medical) 2.4Ghz channels UNII (Unlicensed National Information Infrastructure) band BSS/ESS Wireless Security WEP, WPA 2

Wireless LAN’s Transmitting a signal using the typical specifications works a lot like it does with a basic Ethernet hub: They’re both two-way forms of communication, and they both use the same frequency to both transmit and receive, often referred to as half-duplex. Wireless LANs (WLANs) use radio frequencies (RFs) that are radiated into the air from an antenna that creates radio waves. 3

Unlicensed Frequencies 4 900MHz, 2.4GHz: Industrial, Scientific, and Medical (ISM) bands 5GHz: Unlicensed National Information Infrastructure (UNII) band.

Standards Here are the most popular standards in use today: b: 2.4Ghz, maximum bandwidth of 11Mbps g: 2.4Ghz, up to 54Mbps a: 5Ghz, up to 54Mbps 5

802.11b CSMA/CA 6 RTS: Request to Send CTS: Clear to Send You can’t observe a “collision” in the air or in the vacuum of space, so the only way to deal with collisions is to “avoid” them. Ask for clearance before you send anything.

ISM 2.4 Ghz Channels 7 14 different channels (each 22MHz) released by the FCC in the 2.4GHz range 3 non-overlapping channels

UNII 5Ghz Band 8 12 non-overlapping channels (each 20MHz) released by the FCC in the 5GHz range

Range Comparisons 9

BSS/ESS 10

Cisco Unified Wireless The Cisco Unified Wireless Network is an integrated end- to-end solution that addresses all layers of the WLAN, from client devices and access points, to the network infrastructure, to network management, to the delivery of advanced wireless services integration and award- winning, worldwide, 24-hour product support. It delivers the industry’s best wireless LAN security, innovation, and investment protection. It integrates innovative access point technology with an award-winning centralized management system, intelligent control, real-time location services and a wide array of interoperable Cisco Compatible client devices. It is the only solution that supports next-gen wireless solutions like n and enterprise wireless mesh that offer greater performance and extended reach for pervasive wireless connectivity.

Wireless Security All Wi-Fi Certified wireless LAN products are shipped in "open- access" mode, with their security features turned off. SSID (Service Set Identifiers), WEP (Wired Equivalency Protocol) and MAC authentication i WPA (Wi-Fi Protected Access) and WPA 2 The End 12