802.11r Packet Formats
What is the packet format in 802.11r?
802.11r defines specialized frame formats to support fast transitions (FT) between access points while maintaining compatibility with legacy 802.11 frames.
How does 802.11r modify management frame formats?
It adds new information elements (IEs) and fields within management frames like Authentication and Reassociation to carry fast transition context.
What are Fast Transition (FT) Action frames?
FT Action frames are special management frames used to exchange FT authentication and reassociation messages quickly.
What new Information Elements (IEs) are introduced in 802.11r packets?
802.11r introduces FT Capabilities IE, FT Request IE, FT Response IE, and FT Reassociation Request/Response IEs.
How does the packet format support fast roaming?
By embedding key material and context information within frames to avoid full reauthentication at each AP.
Are the 802.11r packets backward compatible?
Yes, 802.11r packets maintain compatibility with legacy 802.11 devices by carefully adding new IEs without altering fundamental frame structures.
What type of frames carry the Fast Transition IEs?
Primarily Authentication, Reassociation Request, and Reassociation Response management frames carry FT IEs.
Does 802.11r modify data frame formats?
No, 802.11r mainly modifies management frames; data frame formats remain unchanged.
How are security parameters conveyed in 802.11r packet formats?
Security keys and context are included via Fast BSS Transition Key elements in management frames.
What is the significance of the Mobility Domain IE in 802.11r packets?
It identifies the mobility domain to coordinate fast transitions among authorized APs.
Are there special sequence numbers or flags in 802.11r packets?
Yes, FT frames include specific sequence numbers and flags to track and validate fast transition messages.
What role does the Reassociation Request frame play in 802.11r packet formats?
It carries FT-specific IEs that allow the client to quickly establish a connection with the new AP.
How is the FT Response frame structured?
It contains status codes, reassociation parameters, and key material to confirm the fast transition.
Are there special error or status codes in 802.11r packet formats?
Yes, FT-specific status codes indicate success or reasons for failure in fast transitions.
Do 802.11r packets include timers or timing information?
Yes, some frames include timing information to coordinate handoff and key establishment.
How does 802.11r ensure the integrity of packet formats?
Through cryptographic protection of IEs and use of robust authentication protocols embedded in the frames.
Are there differences in packet formats between over-the-air and backend communication?
802.11r packet formats focus on over-the-air frames; backend protocols like RADIUS handle key distribution separately.
How do 802.11r packet formats handle multi-AP coordination?
Mobility Domain and FT Capabilities IEs in packets help coordinate roaming between APs within the same domain.
Can packet formats vary based on device capabilities?
Yes, devices indicate supported features via FT Capabilities IE, which affects how packets are formatted and processed.
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