IEEE 802.11i, IEEE 802.11r, IEEE 802.11k and IEEE 802.11w
IEEE 802.11i
The Group Key Handshake
The GTK used in the network may need to be updated due to the expiry of a preset timer. When a device leaves the network, the GTK also needs to be updated. This is to prevent the device from receiving any more multicast or broadcast messages from the AP.
IEEE 802.11r
The non-802.11r BSS transition goes through six stages:
- Scanning – active or passive for other APs in the area.
- Exchanging 802.11 Authentication messages (first from the client, then from the AP) with the target access point.
- Exchanging Reassociation messages to establish connection at target AP.
At this point in an 802.1X BSS, the AP and Station have a connection, but are not allowed to exchange data frames, as they have not established a key.
- 802.1X master key (PMK) negotiation
- Key (PTK) derivation – 802.11i 4-way handshake of session keys, creating a unique encryption key for the association based on the master key established from the previous step.
- QoS admission control to re-establish QoS streams
A fast BSS transition performs the same operations except for the 802.1X negotiation, but piggybacks the PTK and QoS admission control exchanges with the 802.11 Authentication and Reassociation messages.
IEEE 802.11k
802.11k is intended to improve the way traffic is distributed within a network. In a wireless LAN, each device normally connects to the access point (AP) that provides the strongest signal. In a network conforming to 802.11k, if the AP having the strongest signal is loaded to its full capacity, a wireless device is connected to one of the underutilized APs. Even though the signal may be weaker, the overall throughput is greater because more efficient use is made of the network resources.
IEEE 802.11w
Wireless LANs send system management information in unprotected frames, which makes them vulnerable. This standard will protect against network disruption caused by malicious systems that forge disassociation requests that appear to be sent by valid equipment.
