802.11r - Fast BSS Transition =========================================== .. toctree:: :maxdepth: 1 :hidden: :includehidden: 802_11r/802_11r 802_11r/mac_functions 802_11r/mac_timings 802_11r/packet_formats 802_11r/power_save 802_11r/interoperability 802_11r/physical_rates 802_11r/ppdu 802_11r/channels 802_11r/PHYs IEEE 802.11r is a Wi-Fi standard that enables fast and secure handoffs between access points to support seamless roaming, especially for real-time applications like voice and video. .. list-table:: :widths: 20 60 20 :header-rows: 1 * - Category - Description - Use Case * - MAC Functions - Introduces Fast BSS Transition (FT) to optimize handoff performance at the MAC layer using key caching and reduced negotiation overhead. - Enables seamless roaming for mobile clients between access points. * - MAC Timings - Reduces handoff latency by pre-authenticating with target APs and accelerating reassociation. - Maintains session continuity for latency-sensitive applications like VoIP. * - Packet Formats - Defines new FT authentication and reassociation frames with embedded mobility domain and key information. - Streamlines security context transfer during AP transitions. * - Power Save - Maintains standard power save modes; no specific enhancements under 802.11r. - Supports uninterrupted power management during roaming. * - Interoperability - Designed to interoperate with legacy and non-FT-aware devices through backward compatibility modes. - Allows gradual deployment of fast roaming in existing networks. * - Physical Rates - Inherits physical layer characteristics from the underlying 802.11 standard (e.g., a/g/n/ac). - Offers consistent data rates while enhancing mobility performance. * - PPDU - No changes to PPDU format; relies on base standard (e.g., 802.11a/n). - Keeps PHY transmission unchanged while optimizing MAC-layer handoffs. * - Channels - No channel-specific mechanisms; operates over any channel supported by base PHY. - Compatible with both 2.4 GHz and 5 GHz bands. * - PHY Overview - Uses existing PHY (e.g., OFDM in 802.11a/n) without modifications; enhancements are MAC-centric. - Focuses on roaming and session continuity rather than physical layer changes. .. tab-set:: .. tab-item:: 802.11r Basics **Standard:** IEEE 802.11r (2008) **Main Features:** - Introduces Fast BSS Transition (FT) for seamless and secure handoffs between APs - Minimizes handoff delay through key caching and pre-authentication - Enables real-time applications (VoIP, video) to maintain low latency during roaming - Adds new frame structures to support fast transition protocols - Supports both over-the-air and over-the-DS (distribution system) transitions - Enhances mobility support in enterprise and public Wi-Fi networks **Use Cases:** - High-mobility Wi-Fi environments such as warehouses, hospitals, and campuses - Real-time applications requiring low-latency roaming (e.g., VoIP, video conferencing) - Enterprise-grade wireless LANs supporting seamless handoffs - Environments where consistent connectivity during AP transitions is essential **Related Concepts:** - Fast BSS Transition (FT) - Pre-authentication and key hierarchy - Mobility domain identifiers (MDIE) - Over-the-air vs. over-the-DS transitions - Reduced handoff latency .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the foundational concepts of 802.11r:** * :ref:`Learnings in this section <802_11r_step1>` * :ref:`Terminology <802_11r_step2>` * :ref:`Version Info <802_11r_step3>` * :ref:`802_11r Version&IEEE Details <802_11r_step4>` * :ref:`802_11r Basic Setup on Ubuntu using IPv4 <802_11r_step5>` * :ref:`802_11r Basic Setup on Ubuntu using IPv6 <802_11r_step6>` * :ref:`Reference links <802_11r_step16>` .. button-link:: ./802_11r/802_11r.html :color: primary :shadow: :expand: Jump to "802.11r Basics" .. tab-set:: .. tab-item:: 802.11r MAC Functions **Standard:** IEEE 802.11r (2008) **Main Features:** - Introduces Fast BSS Transition (FT) procedures at the MAC layer - Enables secure and fast handoffs between access points with minimal delay - Implements key caching and pre-authentication mechanisms for seamless roaming - Supports both over-the-air and over-the-DS roaming transitions - Coordinates with mobility domain definitions to manage transition decisions - Integrates with existing MAC operations for backward compatibility **Use Cases:** - Reducing handoff latency in high-mobility environments - Ensuring uninterrupted service for real-time applications like VoIP and video - Enhancing roaming performance in enterprise and large-scale networks - Enabling seamless connectivity across access points without user-perceived drop **Related Functions:** - Fast Transition (FT) state machines and handshake sequences - Key hierarchy and PMK-R0/PMK-R1 caching logic - Mobility domain information element (MDIE) signaling - Compatibility functions with legacy MAC operations and security policies .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11r MAC Functions:** * :ref:`Reference links <802_11r_mac_functions_step17>` .. button-link:: ./802_11r/mac_functions.html :color: primary :shadow: :expand: Jump to "802.11r MAC Functions" .. tab-set:: .. tab-item:: 802.11r MAC Timings **Standard:** IEEE 802.11r (2008) **Main Features:** - Defines timing parameters for fast BSS transitions (handoffs) - Minimizes latency during roaming through optimized timing coordination - Supports key caching and pre-authentication timing mechanisms - Integrates with MAC timing to ensure seamless packet delivery during handoffs - Coordinates over-the-air and over-the-distribution system (DS) transition timings - Maintains backward compatibility with legacy MAC timing standards **Use Cases:** - Reducing roaming delays for real-time applications (VoIP, video) - Supporting seamless handoff in enterprise Wi-Fi networks - Optimizing timing for secure and fast mobility domain transitions **Related Timing Parameters:** - Fast BSS Transition handshake timers - Pre-authentication and re-association timing windows - Mobility domain key caching timers - Standard MAC interframe spaces adapted for fast roaming .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11r MAC Timings:** * :ref:`Reference links ` .. button-link:: ./802_11r/mac_timings.html :color: primary :shadow: :expand: Jump to "802.11r MAC Timings" .. tab-set:: .. tab-item:: 802.11r Packet Formats **Standard:** IEEE 802.11r (2008) **Main Features:** - Defines new management frame elements for Fast BSS Transition support - Includes Fast Transition Information Elements (FT IE) for roaming messages - Adds key hierarchy and mobility domain related fields in frames - Supports over-the-air and over-the-DS frame formats for seamless handoff - Maintains compatibility with legacy 802.11 frame structures - Enables secure and efficient signaling during fast handoff procedures **Use Cases:** - Ensuring fast and secure handoff signaling in enterprise Wi-Fi - Supporting real-time mobility with minimal packet loss - Facilitating communication of key caching and pre-authentication info **Related Frame Types:** - Fast BSS Transition Request and Response frames - Fast Transition Key Hierarchy elements - Mobility Domain Information Elements (MDIE) - Reassociation frames with FT extensions .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11r Packet Formats:** * :ref:`Reference links ` .. button-link:: ./802_11r/packet_formats.html :color: primary :shadow: :expand: Jump to "802.11r Packet Formats" .. tab-set:: .. tab-item:: 802.11r Power Saving Mechanisms **Standard:** IEEE 802.11r (2008) **Main Features:** - Optimizes power management during fast BSS transitions - Minimizes power usage impact while maintaining low-latency roaming - Works with key caching and pre-authentication to reduce active time - Supports power saving alongside mobility domain operations - Enhances battery life for mobile clients in high-mobility Wi-Fi environments - Balances seamless connectivity and energy efficiency for roaming devices **Use Cases:** - Battery-efficient roaming for mobile devices in enterprise Wi-Fi - Power-aware handling of fast handoffs in campus or hospital networks - Reducing power consumption during frequent transitions between APs **Related Mechanisms:** - Power management integration with fast BSS transition protocols - Key caching and pre-authentication timing for optimized power use - Mobility domain aware power saving strategies .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11r Power Saving mechanisms:** .. button-link:: ./802_11r/power_save.html :color: primary :shadow: :expand: Jump to "802.11r Power Saving" .. tab-set:: .. tab-item:: 802.11r Interoperability **Standard:** IEEE 802.11r (2008) **Main Features:** - Ensures backward compatibility with legacy 802.11 devices during fast roaming - Supports coexistence with non-802.11r devices in mixed Wi-Fi environments - Facilitates smooth transitions even when some APs or clients lack 802.11r support - Implements fallbacks for handoff and security mechanisms in heterogeneous deployments - Enables interoperability with standard security protocols and roaming architectures - Maintains seamless connectivity across legacy and FT-enabled networks **Use Cases:** - Mixed enterprise networks with both 802.11r-capable and legacy devices - Gradual deployment of 802.11r in existing Wi-Fi infrastructure - Ensuring uninterrupted roaming during partial migration to FT-enabled networks **Related Mechanisms:** - Fast Transition fallback procedures for legacy device compatibility - Key caching interoperability strategies - Standard security and roaming protocol support across device types .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11r Interoperability mechanisms:** * :ref:`Reference links ` .. button-link:: ./802_11r/interoperability.html :color: primary :shadow: :expand: Jump to "802.11r Interoperability" .. tab-set:: .. tab-item:: 802.11r Physical Rates **Standard:** IEEE 802.11r (2008) **Main Features:** - Defines physical layer data rates optimized for fast BSS transitions - Supports seamless rate adaptation during roaming between APs - Ensures minimal latency and packet loss during rate switching - Utilizes OFDM modulation consistent with 802.11a PHY enhancements for FT - Enables dynamic rate control in mobility domain environments - Maintains reliable throughput in high-mobility Wi-Fi networks **Use Cases:** - Fast, reliable data rates during handoffs in enterprise and campus WLANs - Optimizing throughput while preserving low-latency roaming for real-time apps - Mobile device connectivity with minimal disruption during AP transitions **Related Concepts:** - Rate adaptation mechanisms supporting Fast BSS Transition (FT) - OFDM PHY modulation with 802.11r enhancements - Mobility-aware physical layer rate adjustments .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11r Physical Rates:** * :ref:`Physical Rates in 802.11r ` * :ref:`Reference links ` .. button-link:: ./802_11r/physical_rates.html :color: primary :shadow: :expand: Jump to "802.11r Physical Rates" .. tab-set:: .. tab-item:: 802.11r PPDU **Standard:** IEEE 802.11r (2008) **Main Features:** - Defines PPDU structure adapted for fast BSS transition support - Supports OFDM PHY format with enhancements for seamless roaming - Integrates signaling mechanisms to reduce handoff latency at PHY layer - Ensures compatibility with legacy 802.11a PPDU formats where needed - Optimizes frame timing and security context exchange during transition - Enables robust, low-latency data transmission in mobility domains **Use Cases:** - Fast handoffs with minimal packet loss and delay in enterprise Wi-Fi - Supporting real-time applications during roaming at the PHY level - Reliable PHY layer operation optimized for FT-enabled devices **Related Concepts:** - OFDM PHY modulation with FT enhancements - PPDU timing coordination for handoff acceleration - Mobility domain signaling embedded in PHY frames .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11r PPDU:** * :ref:`Reference links ` .. button-link:: ./802_11r/ppdu.html :color: primary :shadow: :expand: Jump to "802.11r PPDU" .. tab-set:: .. tab-item:: 802.11r Channels **Standard:** IEEE 802.11r (2008) **Main Features:** - Manages channel usage optimized for fast BSS transitions and roaming - Supports seamless channel switching during handoffs to minimize latency - Enables dynamic channel selection to maintain optimal connectivity - Coordinates with mobility domain to ensure stable frequency use during FT - Utilizes signaling to prepare clients for channel changes during roaming - Ensures efficient use of available spectrum while minimizing disruptions **Use Cases:** - Fast and reliable channel changes during roaming in enterprise WLANs - Maintaining connectivity and performance in high-mobility environments - Optimizing channel usage within mobility domains for seamless transitions **Related Concepts:** - Mobility domain channel management - Fast BSS Transition (FT) channel switching mechanisms - Channel switch signaling for roaming devices .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11r Channels:** * :ref:`List of channels ` * :ref:`List of channel widths ` * :ref:`List of Bands ` * :ref:`Reference links ` .. button-link:: ./802_11r/channels.html :color: primary :shadow: :expand: Jump to "802.11r Channels" .. tab-set:: .. tab-item:: 802.11r PHY **Standard:** IEEE 802.11r (2008) **Main Features:** - Uses OFDM PHY based on 802.11a with enhancements for fast BSS transitions - Supports low-latency physical layer signaling to accelerate handoff processes - Integrates mobility domain parameters to optimize PHY operation during roaming - Maintains compatibility with legacy OFDM PHY for seamless device support - Enables robust modulation and coding schemes suitable for mobile environments - Supports timing and synchronization improvements for fast secure transitions **Use Cases:** - Fast and reliable PHY layer performance during handoffs in enterprise networks - Reducing latency and packet loss during physical layer transitions - Enhancing roaming efficiency for mobile clients in Wi-Fi networks **Related Concepts:** - OFDM PHY enhancements for FT - PHY layer signaling supporting mobility domain - Timing and synchronization in fast BSS transitions .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: What You Will Learn in This Section **Explore the details of 802.11r PHY:** * :ref:`Reference links ` .. button-link:: ./802_11r/PHYs.html :color: primary :shadow: :expand: Jump to "802.11r PHY"