Access & Privacy Services
There are two characteristics of a wired LAN that not inherent in a wireless LAN.
- In order to transmit over a wired LAN, a station must physically connect to the LAN. On the other hand, with a wireless LAN, any station within radio range of the other devices on the LAN can transmit. In a sense, there a form of authentication with a wired LAN, in that it requires some positive and presumably observable action to connect a station to a wired LAN.
- Similarly, in order to receive a transmission from a station that part of a wired LAN, the receiving station must also attach to the wired LAN. On the other hand, with a wireless LAN, any station within radio range can receive. Thus, a wired LAN provides a degree of privacy, limiting reception of data to stations connected to the LAN.
- IEEE 802.11 defines three services that provide a wireless LAN with these two features:
Authentication of Access & Privacy Services
- Used to establish the identity of stations to each other. In a wired LAN, it generally assumed that access to a physical connection conveys authority to connect to the LAN.
- This not a valid assumption for a wireless LAN, in which connectivity achieved simply by having an attached antenna that properly tuned.
- The authentication service used by stations to establish their identity with stations they wish to communicate with IEEE 802.11 supports several authentication schemes and allows for expansion of the functionality of these schemes.
- The standard does not mandate any particular authentication scheme. Which could range from relatively unsecured handshaking to public key encryption schemes.
- However, IEEE 802.11 requires mutually acceptable, successful authentication before a station can establish an association with an AP.
- This service invoked whenever an existing authentication to terminate.
- Used to prevent the contents of messages from reading by other than the intended recipient. The standard provides for the optional use of encryption to assure privacy.