H3C Technologies H3C WA2600 Series WLAN Access Points - Manual (Page 72)

10-4
Authentication
To secure wireless links, a wireless client must be authenticated before accessing an AP, and only
wireless clients passing the authentication can be associated with the AP. 802.11 links define two
authentication mechanisms: open system authentication and shared key authentication.
z Open system authentication
z Shared key authentication
For more information about the two types of authentication, see WLAN Security in the WLAN
Configuration Guide.
Association
A client that wants to access a wireless network via an AP must be associated with that AP. Once the
client chooses a compatible network with a specified SSID and passes the link authentication to an AP,
it sends an association request frame to the AP. The AP detects the capability information carried in the
association request frame, determines the capability supported by the wireless client, and sends an
association response to the client to notify the client of the association result. Usually, a client can
associate with only one AP at a time, and an association process is always initiated by the client.
Other related frames
1) De-authentication
A de-authentication frame can be sent by either an AP or wireless client to break an existing link. In a
wireless system, de-authentication can occur due to many reasons, such as:
z Receiving an association/disassociation frame from a client which is unauthenticated.
z Receiving a data frame from a client which is unauthenticated.
z Receiving a PS-poll frame from a client which is unauthenticated.
z The validity timer for a client expires and the port is not secured.
2) Dissociation
A dissociation frame can be sent by an AP or a wireless client to break the current wireless link. In
wireless the system, dissociation can occur due to many reasons, such as:
z Receiving a data frame from a client which is authenticated and unassociated.
z Receiving a PS-Poll frame from a client which is authenticated and unassociated.
A dissociation frame is either unicast or broadcast.
802.11 Overview
The following functions are provided by Fat-AP WMAC:
z Beacon generation
z Handling Probe Request
z Handling Open System Authentication
z Handling (Re) Association
z Handling De-authentication
z Handling Disassociation
z Power Management
z Fragmentation and Defragmentation
z Dot11 to Ethernet Frame Conversion