11r, to standardize
???fast roaming??? by reducing latency during handoffs between APs.
2.2.4 Establishing a Wireless Connection
Because the physical boundaries and connections within a radio cell are not fixed, there is
no guarantee that a radio source is who or what it claims to be. Security requires some
means of authentication. Because the physical arrangement and membership of any group
of WLAN stations is purposely fluid, stations must be able to manage their own
Guide to Wireless LAN Analysis 18
connections to one another. The WLAN standard refers to this logical connection between
two nodes as an association. Because radio signals are inherently public, confidentiality
requires the use of encryption.
These three functions - authentication, association, and confidentiality - are all a part
of making a connection in a WLAN. We add a fourth function, discovery (not explicitly
named in the standards), to construct a general picture of the process of creating a
connection in a WLAN.
2.2.4.1 Discovery
A station or access point discovers the presence of other stations by listening. Access
points (and their equivalents in ad hoc networks) can periodically send out management
packets called beacon packets containing information about their capabilities (data rates,
security policies, BSSID, SSID, and so forth).
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