WLAN network services - a survey of 802.11 network services

802.11 provides 9 WLAN network services. 3 of them are for data transfer, remaining 6 are for management operations. With services network can track stations and deliver frames accordingly.
They are divided into 2 main groups:

Station services - every product that uses WLAN must incorporate Station services.
They are provided by stations and access points.

Distribution system services connect access points to the distribution system. Access point job is to connect wireless and wired part of the network. This is done by Distribution system services.

Service	Station/distribution
Distribution	Distribution
Integration	Distribution
Association	Distribution
Reassociation	Distribution
Disassociation	Distribution
Authentication	Station
Deauthentication	Station
Privacy	Station
MDSU delivery	Station

Let’s see description of all 9 WLAN network services:

1) Distribution - mobile stations are using it, when they send data.
Access point uses distribution service to deliver frame to destination.
Any communication towards access point and between stations in same BSS, uses distribution service.

2) Integration - service that provide distribution system. It enables connection to wired networks.

3) Association - registration of mobile stations to access point. You can’t have any traffic with your station, if you aren’t associated to access point.
With association you are “plugged” in network.

4) Reassociation - switching station to other access point.
When a station moves within one extended service area, it needs to track signal strength. When signal strength, from associated access point, is to week, station reassociates to other access point with better signal strength.
When reassociation is finished, distribution system updates its location records.

5) Disassociation - termination of association. With disassociation, station is disconnected from network. Data about diassociated station has to be removed.

6) Authentication. Wireless network don’t have same level of physical security as wired networks. Wireless network must use additional authentication routines to be sure that stations using this network are authorized to do so.

Click here to find out more about wireless authentication.

7) Deauthentication - terminates authentication. Deauthentication is termination of association.

8) Privacy - WLAN networks use optional privacy service called Wired Equivalent Privacy (WEP). If you want to have physical access to network, you need to pass WEP. Unfortunately WEP doesn’t justify its name. It is very easy to crack WEP. It doesn't take more than 2 minutes.
WEP2 was also introduced, but attackers only need to spend more time for breaking it.
Don’t be afraid, I will show you much better options (802.1x and WPA) for security that are incomparably to WEP.

9) MSDU delivery - MAC Service Data Unit delivery service is responsible for delivery data to destination.

With WLAN network services you have better view of wireless processes.



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