Specifications

CHAPTER 9
Wireless LANs in a Campus Network
The Cisco Compatible Extensions Program tests other vendors’ devices for compatibility with Cisco wireless products.
Using products certified by this program ensures full functionality of Cisco enhancements and proprietary extensions.
Characteristics of Wireless LANs
WLANs function similarly to Ethernet LANs with the access point providing connectivity to the rest of the network as
would a switch. The physical layer is radio waves, rather than wires. IEEE 802.11standard defines the physical and data
link specifications, including the use of MAC addresses. The same protocols (such as IP) and applications (such as IPsec)
can run over both wired and wireless LANs.
The following lists some characteristics of wireless LANs and the data transmitted over wireless networks.
n WLANs use Carrier Sense Multi-Access/Collision Avoidance (CSMA/CA).
n Wireless data is half-duplex. CSMA/CA uses Request to Send (RTS) and Clear to Send (CTS) messages to avoid
collisions.
n Radio waves have unique potential issues. They are susceptible to interference, multipath distortion, and noise. Their
coverage area can be blocked by building features, such as elevators. The signal might reach outside the building and
lead to privacy issues.
n WLAN hosts have no physical network connection. They are often mobile and often battery-powered. The wireless
network design must accommodate this.
n WLANs must adhere to each country’s RF standards.
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CCNP SWITCH 642-813 Quick Reference by Denise Donohue