Monday, August 17, 2009


Well, we should all know a bit about this stuff already, but here's the just of it from the CBT videos. I will probably, like most of my other posts, have to post another wireless section as I read about it in the BCMSN Official Exam Certification Guide.
-WLAN (wireless local area network) shit sherlock, cummon
-Basic Service Set- one access point with associated access stations comprises a basic service set.
-Ext. Service Set- one or more BSS's that appear as one logical BSS to the link layer of connected devices
Image Source:,2845,1073,00.asp

The wireless "cell" is essentially the area of coverage that the AP provides, and host must form an association with an access point by matching both SSID and authentication measures.

There are essentially 2 types of wireless scanning:
  1. Active- Where the client sends probe request and waits for responses from AP's.
  2. Passive- hmmm, where the client passively listens for beacon frames pushed by AP's...
  1. Open System- essentially a wide open security measures
  2. Shared key- WEP, WPA(2)
  3. MAC authentication- not mentioned but important to remember, though it is easily spoofed.
RFC 3748 speaks on EAP, or extensible authentication protocol. Cisco proprietary cousin is LEAP. It provides two way authentication between the AP and client station, and users a radius server to do so. It uses dynamic keys propageted for each unique session.

The WIFI alliance created WPA and WPA2.

802.11a- 25MBPS- 54; 100ft indoors, 5 Ghz
802.11b- 6.5MBPS- 11; 100ft indoors, 2.4 Ghz
802.11g- 25MBPS- 54; 100ft indoors, 2.4 Ghz
802.11n- 200MBPS - 540; 160ft indoors, 2.4 or 5 Ghz

IrDA- Infrared Data Association
version 1. = 1 meter @ 115Kbps
version 1.1 = 1 meter @ 4Mbps

  1. Yagi-uda - uni-directions or "directional" antennas or peer 2 peer
  2. Omni- or all directions or peer to multi-peer
Wireless is half-duplex and uses carrier sense multiple access with collision avoidance

Aironet systems tray utilities color definitions:
red - low signal
yellow - fair signal
green - very good signal
lt gray - not EAP authenticated; connection present though
dark gray - no connection
white - adapter is disabled

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