The Need for Fast Roaming January 2004 The Need for Fast Roaming Keith Amann SpectraLink Corporation Keith Amann, SpectraLink

January 2002 doc.: IEEE 802.11-02/xxxr0 January 2004 Is there a problem? Question of great debate since March 2003, or possibly earlier Empirical data, does it exist or not? Some, but not well organized or distributed Can a client perform a “fast roam” today (or in the near future)? (Opinion) Not without some help Keith Amann, SpectraLink John Doe, His Company

Issues (Opinion) 802.11 being incorporated into more and more devices January 2004 Issues (Opinion) 802.11 being incorporated into more and more devices Many have limited resources (memory, processor) Increasing on air requirement for context transfer More time sensitive applications 802.11 becoming more and more complex! Keith Amann, SpectraLink

The “Debate” Mostly centered around 802.11i/Security Issues January 2002 doc.: IEEE 802.11-02/xxxr0 January 2004 The “Debate” Mostly centered around 802.11i/Security Issues One side claims the facilities exist within 802.11i to allow this to work Other side claims these facilities are inadequate, or don’t satisfy the needs of the applications Not enough data to substantiate claims one way or the other Little or no discussion regarding QoS, Radio Resources, etc. Largely an “emotional” debate Keith Amann, SpectraLink John Doe, His Company

What about existing 802 “enhancements”? January 2004 What about existing 802 “enhancements”? 802.11e Ability to send a Traffic Specification (either eDCA or HCCA) via (re)association Nothing else related to context transfer of “stream” 802.11f Not well deployed Lacks the necessary specifics 802.11k looking at providing assistance Not attempting to solve the problem 802.11i Several “mechanisms” defined Finding many interpretations of how to best use these mechanisms 802.1 Handoff Study Group Really oriented toward handoff between differing network technologies NOTHING TO TIE ALL OF THIS TOGETHER!! Keith Amann, SpectraLink

802.11e Enhancements Ability to send TSPEC in (re)association January 2004 802.11e Enhancements Ability to send TSPEC in (re)association Fails to address successful association with failed TSPEC request Requires a full context negotiation following the roam Keith Amann, SpectraLink

802.1 Handoff, 802.11f, 802.11k 802.1 Handoff Study Group January 2004 802.1 Handoff, 802.11f, 802.11k 802.1 Handoff Study Group Looking at addressing inter-technology handoff, not inner-technology handoff 802.11f Lacks sufficient deployment base Does not provide specifics about how to improve roaming efficiency, or how to use it for this situation 802.11k Only trying to help with identification of roaming candidates Not addressing roaming efficiency improvements Keith Amann, SpectraLink

802.11i Enhancements “Key Caching” January 2004 802.11i Enhancements “Key Caching” Allows the STA and AP to “cache” credentials for authentication Requires memory at both the AP and STA Requires some “loose” interpretation of 802.11i Doesn’t solve the “initial” roam problem “Pre-Authentication” Allows the STA to authenticate through an existing association Requires memory at the AP and STA Creates a “window of opportunity” for potential threats, and synchronization issues between AP and STA “Pre-Shared Key Mode” Reduces the overhead of authentication Designed to be used in the SOHO market Efficiency issues with current implementations Keith Amann, SpectraLink

Examples of the Problem January 2004 Examples of the Problem Discussions with Infrastructure Vendors Different thoughts on how to utilize 802.11i mechanisms Different signaling requirements/mechanisms Pre-Shared Key Testing 3 Different Manufacturers 2 traditional APs 1 “switch style” AP Embedded Client VoIP Phone Non-optimized encryption (no hardware assist) Keith Amann, SpectraLink

PSK Testing (times in milliseconds) January 2004 PSK Testing (times in milliseconds) Message AP1 AP2 AP3 Assoc Resp 4-Way Message 1 .876 992.02 472.182 4-Way Message 2 19.903 20.279 20.328 4-Way Message 3 1.409 2.621 2.032 4-Way Message 4 5.617 5.66 5.862 4-Way GTK 1 6.397 1.744 2.442 4-Way GTK 2 7.774 7.33 7.463 Total Time 41.976 1029.654 510.308 Keith Amann, SpectraLink

What does it all mean? Ongoing 802.11 efforts Proprietary Solutions January 2004 What does it all mean? Ongoing 802.11 efforts Problem is only going to become worse, not better Proprietary Solutions Difficult for client specific developers to implement because of diversity of solutions Requires client side changes in all cases No standard “expectation”, barrier to broad market acceptance Nothing tying all the pieces together 802.11f, 802.11e, 802.11i, 802.11k, 802.1 Handoff Keith Amann, SpectraLink

Summary The industry needs this effort, help support it! January 2004 Keith Amann, SpectraLink