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Chapter 12 Cisco’s Wireless Technologies. WLAN Frequencies. 900MHz and 2.4GHz bands are referred to as the Industrial, Scientific, and Medical (ISM) bands. 5.7GHz band is known as the Unlicensed National Information Infrastructure (UNII) band. The 802.11 Standards.
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WLAN Frequencies • 900MHz and 2.4GHz bands are referred to as the Industrial, Scientific, and Medical (ISM) bands. • 5.7GHz band is known as the Unlicensed National Information Infrastructure (UNII) band.
2.4GHz (802.11b): (11, 5.5, 2, and 1Mbps), Direct Sequence Spread Spectrum (DSSS) • 2.4GHz (802.11g): 54Mbps, Orthogonal Frequency Division Multiplexing (OFDM) • 5GHz (802.11a ): (54, 48, 36, 24, 18, 12, and 6Mbps) • 5GHz (802.11h): Dynamic Frequency Selection (DFS), Transmit Power Control (TPC) & additional 11 channels • 2.4GHz/5GHz (802.11n): Using MIMO • 5GHz affecting with interference is less than that of 2.4GHz, reasons for interference are: • Cordless phones • Metal cabinets • Microwaves ovens • Antenna type & direction • Bluetooth devices
CSMA/CA Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is also called a Request To Send, Clear To Send (RTS/CTS)
Classification of Wireless Networks
Connecting APs (Cisco’s Unified Wireless Solution) • If the APs weren’t root, they could only connect to a root device as a repeater. Nonroot devices include clients, bridges, repeater access points, and work group bridges. • Cisco WLAN controllers (come with gigabit interfaces). • Controllers decide the packet’s destiny based on the Lightweight Access Point Protocol (LWAPP) information that’s encapsulated on it. • Split-MAC Architecture is the splitting the processing of the 802.11 protocol between two devices, the AP and a centralized Cisco WLAN controller. • The controller is managed either through the controller web interface, from the controller itself, or from Cisco’s Wireless Control System (WCS)
APs Functions • The frame exchange handshake between a client and AP when transferring a frame over the air • Transmitting beacon frames • Buffering and transmitting frames for clients in power save operations • Responding to probe request frames from clients • Forwarding notification of received probe requests to the controller • Providing real-time signal quality information to the controller with every received frame • Monitoring each of the radio channels for noise, interference, and other WLANs • Monitoring for the presence of other APs • Encryption and decryption except in the case of VPN/IPSec clients Controller Functions • 802.11 authentication • 802.11 association and reassociation (mobility) • 802.11 frame translation and bridging • Cisco Wireless Controller can do its job with more facilities using the GUI Wirelss Control System (WCS)
MESH, LWAPP, and AWPP • Root Access Points (RAPs) • Mesh Access Points (MAPs): 32 MAPs over a 5GHz • Adaptive Wireless Path Protocol (AWPP) runs on all APs
Wireless Security • Open Access • Service Set Identifier (SSID): Open authentication and shared-key authentication • Wired Equivalency Protocol (WEP): 40 or 128 bits • Media Access Control (MAC) authentication • Wi-Fi Protected Access (WPA) & (WPA2) Pre-Shared Key (PSK) (using password or passphrase) Cisco Unified Wireless Network Security • Secure Connectivity for WLANs: using strong dynamic encryption keys (WPA) & (WPA2) • Trust and Identity for WLANs: using IEEE 802.1X:EAP, RADIUS, & AAA server • Threat Defense for WLANs: using intrusion Prevention System (IPS), WLAN NAC, and advanced location services
Configuring WLAN Router(config)#int dot11radio 0/3/0 Router(config-if)#ip address 10.1.8.1 255.255.255.0 Router(config-if)#description Admin WLAN Router(config-if)#ssid ADMIN Router(config-if-ssid)#guest-mode Router(config-if-ssid)#authentication open Router(config-if-ssid)#infrastructure-ssid Router(config-if-ssid)#no shut