Wireless Communications (IEEE 802.11 standards, Wi-Fi)
Another new concept on the CCNA exam is the wireless network. The IEEE 802.11 standard also known as Wi-Fi, specifies the standards for communication between your wireless devices. Since this is the future, you know Cisco will be increasing this topic on the future CCNA exams. But right now there is not too much information covered on the current basic CCNA exam. So they have recently come out with a CCNA Wireless certification that goes much more in depth than what you need to know for this exam.
Advantages to wireless are the elimination of cables and the freedom of movement. Disadvantages include lack of range, reliability and security. But rest assured, they are improving each and every day on the short falls of wireless.
Current technologies can reach a wireless distance of 300 ft.
Only one device can transmit at a time.
Access Point (AP) devices are used to route or bridge traffic from the wireless LAN to the wired LAN. The following are some of the wireless technologies and their bandwidth:
802.11b support 11 Mbps at 2.4 GHz frequency
802.11a support 54 Mbps at 5 GHz frequency
802.11g support 54 Mbps at 2.4 GHz frequency
BSS
BSS is a single access point which provides network connectivity for its clients.
ESS
In ESS, each access point still defines a BSS, but a group of access points and their BSSes form an ESS. This way they can overlap coverage areas so you will not lose network connectivity.
Security Standards
WEP is the Wired Equivalent Privacy standard which is a part of the 802.11 standard and is one of the WLAN security standards.
WPA is the Wi-Fi Protected Access security standard that is a hybrid of proprietary and standards based protocols.
WPA2 is the second version of the Wi-Fi standard. It is called 802.11i and is not backward compatible with the older standard.
Line-of-Sight: Direct line between the wireless device and the receiver where there are no matters in between (i.e. cell phones do not require Line-of-Sight but TV remotes do.)
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