Roaming Applications and Use Cases

1. Roaming Applications and Use Cases Michael Montemurro, Chantry Networks Chris Durand, Spectralink Jim Wendt, HP Stephano Faccin, Nokia Keith Amann, Spectralink Michael Montemurro, Chantry Networks

2. Purpose • Define Applications that drive BSS-transition requirements • Define Conditions for BSS-Transition (use cases) Michael Montemurro, Chantry Networks

3. Roaming Applications Summary Michael Montemurro, Chantry Networks

4. Basic Roaming Use CaseConditions • 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 Michael Montemurro, Chantry Networks

5. Overlay Conditions ToRoaming 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? Michael Montemurro, Chantry Networks

6. Roaming Topology Network Switch Switch AP AP Authentication Server ESS AP and MU Share Link State MAC, DS, Security, QoS MU MU Roaming Determination Link Quality, Scan Results, Service Availability, Velocity Michael Montemurro, Chantry Networks

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? Michael Montemurro, Chantry Networks

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? Michael Montemurro, Chantry Networks

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 Michael Montemurro, Chantry Networks

10. Next Steps • Expand the use case descriptions • Identify the scenarios in more details • Define the process flow • Address Mesh Network BSS Transition Michael Montemurro, Chantry Networks

11. Backup Michael Montemurro, Chantry Networks

12. Snarfed Table Michael Montemurro, Chantry Networks

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. 802.11 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 Michael Montemurro, Chantry Networks

14. IS Client IP address doesn’t change Roam is between 802.11 cells/APs APs have same: ESS (SSID) Others TBD APs may have: Different 802.11 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 802.11 and other PHYs / mediums 802.16 / 802.3 / Cellular AP Failure FRFH Scope Michael Montemurro, Chantry Networks

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 Michael Montemurro, Chantry Networks

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 Michael Montemurro, Chantry Networks

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 Michael Montemurro, Chantry Networks

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? Michael Montemurro, Chantry Networks

19. When/Where to Roam? • IEEE 802.11 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 Michael Montemurro, Chantry Networks

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 Michael Montemurro, Chantry Networks

21. State Transitions for Roaming Two options: • Transition connection state from one AP to another ( requires AP to AP communications) • 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 Michael Montemurro, Chantry Networks

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) Michael Montemurro, Chantry Networks

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? Michael Montemurro, Chantry Networks

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 Michael Montemurro, Chantry Networks

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 Michael Montemurro, Chantry Networks