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Doc.: IEEE 802.11-04/579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 1 Roaming Applications and Use Cases Michael Montemurro, Chantry.

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Presentation on theme: "Doc.: IEEE 802.11-04/579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 1 Roaming Applications and Use Cases Michael Montemurro, Chantry."— Presentation transcript:

1 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 1 Roaming Applications and Use Cases Michael Montemurro, Chantry Networks Chris Durand, Spectralink Jim Wendt, HP Stephano Faccin, Nokia Keith Amann, Spectralink

2 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 2 Purpose Define Applications that drive BSS- transition requirements Define Conditions for BSS-Transition (use cases)

3 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 3 Roaming Applications Summary ClassApplicationsTrafficLatency Delay Packet Loss Sensitivity Guar. BW ConversationalVoIP Video Phone ?Internet Game Bidirectional Small Pkts (VoIP, Gaming) Large Pkts (Video Phone) Strict&Low <50ms HighYes RT Streaming?Unidirectional Large Pkts / Multicast Bounded <1s HighYes Non-RT Streaming VOD Cable TV Unidirectional Large Pkts / Multicast Bounded <5s LowYes Fast InteractiveVideo GamingBidirectional / Asymetric Variable Pkts Tolerable <100ms HighYes InteractiveWeb Telnet Bidirectional / Asymetric Variable Pkts Tolerable <1s LowNo BackgroundFTP Bidirectional / Asymetric Variable Pkts Unbounded <5-10s LowNo

4 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 4 Basic Roaming Use Case Conditions AP’s on different channels, single ESS AP’s connected via a switch Traffic (characterized by application) Both AP’s remain powered up during roam

5 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 5 Overlay Conditions To Roaming Use Cases Enhanced Security Enhanced QoS – no admission control Enhanced QoS – admission control Roaming Coverage Zone –Cell overlap distance vs STA velocity (walking, slow vehicle, automotive) –Are these use case conditions or network engineering constraints?

6 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 6 Roaming Topology Switch AP Network Switch AP MU AP and MU Share Link State MAC, DS, Security, QoS MU Roaming Determination Link Quality, Scan Results, Service Availability, Velocity ESS Authentication Server

7 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 7 STA Considerations for Roaming TGe and TGk provid metrics for a roaming decision Depends on roaming time versus velocity of the client –When is roaming calculated versus when does it roam? Depends on service availability on new AP? –Is there bandwidth available? –Will the connection be secure?

8 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 8 State Transition Considerations Needs to be secure Do AP’s need to communicate? –Over the air? Over the wired network? –Could we leverage IAPP? CAPWAP? AP-AP communications needs to be secure Should the AP’s share state information?

9 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 9 What about? (Scope / Use Case / Reqmt / Constraint / Punt / Other?) L3 Roaming Tunnel DS –Two APs with same SSID / but on diff subnets –Client IP address is unchanged on L2 roam –How does L2 handoff (security/QoS/etc) relate to L3 cross-subnet roaming/tunneling? Roaming Load –Frequency and distribution of roam events Roaming control packet delivery guarantees –DS Capacity/QoS for roaming control packets –Is this a network engineering constraints? VLANs

10 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 10 Next Steps Expand the use case descriptions Identify the scenarios in more details Define the process flow Address Mesh Network BSS Transition

11 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 11 Backup

12 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 12 Snarfed Table ClassApplicationsTrafficLatency Delay JitterGuar. BW BER ConversationalVoIP Internet Game Strict&LowYes10(-3) StreamingVOD Cable TV BoundedYes10(-5) InteractiveWeb Telnet TolerableNo10(-8) BackgroundFTP UnboundedNo10(-9)

13 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 13 Terminology (needs work) System Attributes –Distinct characteristics of FRFH environments E.g. PHYs, Channels, Security mechanisms, QoS Scope –Environments in which FRFH is applicable – as defined by the fixed system attributes E.g MACs only –Assumptions regarding surrounding components in the FRFH environment E.g. Upstream L2 bridge table Requirements –Range of system attribute values that must be supported by FRFH Use Case –Specific example scenarios that are supported by FRFH - as defined by collections of specific values for system attributes Constraint (on network design) –A design constraint placed on a network design E.g. AP cell overlap for maximum intended STA velocity must allow for 100ms of co- coverage

14 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 14 FRFH Scope IS Client IP address doesn’t change Roam is between cells/APs APs have same: –ESS (SSID) –Others TBD APs may have: –Different PHYs (a/b/g/n) –Different channels –Others TBD DS may be: –L2 infrastructure (bridging table) –AP Mesh –? L3 infrastructure with non-changing client IP addresses Should/Must support or address: –TGi –TGe / BW reservation issues –? Extensible state transferal IS NOT Client IP address changes on roam Roam is between and other PHYs / mediums – / / Cellular AP Failure

15 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 15 Basic Roaming Use Case AP’s on different channels AP’s connected via a L2 switch Both AP’s remain powered up during roam Downlink traffic only Assumes (based on FRFH scope) –Single ESS / same SSID

16 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 16 Additional Use Case Conditions Enhanced Security (TGi) Enhanced QoS (TGe) –no admission control –admission control Roaming Coverage Zone –Cell overlap distance vs STA velocity (walking, slow vehicle, automotive) –Are these use case conditions or network engineering constraints? Mesh Network

17 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 17 Roaming Transition Process Roaming Determination –Could include pre-authentication –Could include network interaction Connection Process –Authentication/Re-association –Key Derivation/Exchange –Flow negotiation Re-establish Data Communications NOTE: PROCESS STEPS DON’T NEED TO BE SERIALIZED

18 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 18 The Elements of Roaming How to determine when/where to roam? How to minimize the time it takes to move state from one AP to another or establish state at the new?

19 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 19 When/Where to Roam? IEEE standards –States that the STA/MU can be only connected to one BSS/AP at any point in time –MU has to decide when and where to roam Cellular standards –Roaming is network driven –MU moves within the network –The Network hands off the connection from cell to cell

20 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 20 Minimizing Roaming Time What can a STA or AP do to minimize re- connection time? Need to moving connection state for the STA from the current AP to the new AP Need to update the DS with the new link state

21 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 21 State Transitions for Roaming Two options: 1.Transition connection state from one AP to another ( requires AP to AP communications) 2.Derive a new connection state between one MU and the AP (MU to AP communications only) State transition could occur before or during the roaming event

22 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 22 MU/AP Connection State MAC/PHY – link state, radio parameters, rate, etc. Security – PMK, PTK, etc. QoS – TSPEC’s DS – physical port map (MAC – Port Number)

23 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 23 Other considerations Does the process start before the MU roams? (i.e. like Pre-authentication) Should the MU reserve resources before it moves? Should the DS reserve resources before the MU moves?

24 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 24 Recap Reported Roaming Measurements Based on 11-04/377 without IAPP or IP interactions (DHCP, etc.): PMK cached/Active Scanning: –Using Passive Scanning: 14 ms – 1034 ms –Using Active Scanning: 34 ms – 380 ms PMK not cached (w/ 802.1x Fast Resume –Using Passive Scanning: 154 ms – 1304 ms –Using Active Scanning: 170 ms – 620 ms

25 doc.: IEEE /579r0 Submission May 2004 Michael Montemurro, Chantry NetworksSlide 25 Conclusions The two elements to fast roaming are: –Determination of when/where to roam Need to consider service availability –Minimize the time it takes to establish a new connection state at the new Needs to be secure Minimize roaming time


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