802.11r MAC Functions
What is the role of the MAC layer in 802.11r?
The MAC layer manages fast transitions between access points by coordinating authentication and key management for seamless roaming.
How does MAC handle fast BSS transitions in 802.11r?
It uses Fast Transition (FT) protocols to pre-authenticate with target APs and cache keys to reduce handoff latency.
What MAC frames are introduced by 802.11r?
802.11r introduces FT Action frames used for exchanging mobility domain and fast transition information between stations and APs.
How does the MAC layer support key caching in 802.11r?
The MAC layer caches PMK (Pairwise Master Key) and PTK (Pairwise Transient Key) to quickly resume security contexts during roaming.
What is the Mobility Domain Identifier in MAC?
It is a unique identifier included in MAC frames to define a group of APs where fast transitions are allowed.
How does the MAC layer coordinate pre-authentication?
The MAC layer sends FT Action frames to the target AP for pre-authentication before the client roams.
What is the role of the MAC sublayer management entities in 802.11r?
They manage the fast transition state machine, triggering handoffs and managing security contexts during roaming.
Does 802.11r change the MAC authentication process?
Yes, it streamlines authentication by enabling fast reauthentication and key establishment via FT.
How are MAC timings affected by 802.11r?
802.11r reduces MAC timing delays during handoff by minimizing message exchanges needed for authentication.
What MAC frame exchanges are involved in FT?
Key exchanges include FT Authentication Request and Response frames carrying mobility and security parameters.
How does the MAC layer handle roaming decision signaling in 802.11r?
It uses FT Action frames to notify target APs and coordinate seamless transitions.
Are MAC layer encryption methods impacted by 802.11r?
No, 802.11r maintains standard encryption methods but optimizes key distribution for fast roaming.
How does the MAC layer ensure security during fast transitions?
It uses FT Key Hierarchy and secure FT message exchanges to protect against replay and man-in-the-middle attacks.
What is the MAC layer’s role in managing the PMK cache?
It stores and retrieves PMKs associated with APs in the mobility domain to speed up handoffs.
How does MAC interact with the PHY during fast transitions?
MAC coordinates with PHY to switch channels and maintain timing synchronization during roaming.
Does 802.11r affect the MAC’s management of power saving?
802.11r can impact power saving by requiring quick channel switches, but mechanisms exist to minimize power consumption.
How does the MAC layer handle coexistence with legacy devices in 802.11r?
It falls back to standard roaming for legacy devices while enabling fast roaming only for 802.11r-capable clients.
Are there any new MAC timing parameters introduced in 802.11r?
Yes, 802.11r defines specific timing requirements for FT message exchanges to ensure minimal handoff delays.
How does the MAC layer handle FT reassociation?
It uses FT Reassociation Request/Response frames to finalize the fast transition after pre-authentication.
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