1. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 1 802.11 WLAN Architectural Considerations for IETF CAPWAP L. Lily Yang Editor of IETF CAPWAP Architecture Design Team lily.l.yang@intel.com

2. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 2 Overview Introduction: IETF CAPWAP and IEEE Current 802.11 standard on architecture Autonomous AP architecture Deployment problems Hierarchical “AP+AC” architecture CAPWAP architectural considerations –Functional split continuum –Topology –Security Open questions and suggestions Summary

3. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 3 Introduction IETF CAPWAP (Control and Provisioning of Wireless APs): –Newly chartered WG in Jan 2004 –Problem: interoperability –Co-chairs: Mani, Mahalingam & Dorothy Gellert Need close collaboration with IEEE –Liaison: Dorothy Stanley –Technical Advisor: Bob O’Hara First WG meeting in March 2004 at Seoul –Architecture Design Team (12 members, L. Yang Editor) –Task: 802.11 architecture taxonomy –Will be reviewed by experts from IEEE & IETF http://www.ietf.org/html.charters/capwap-charter.html

4. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 4 WLAN Architecture Defined by 802.11 today MAC Services defined by.11: –Station Services (4) –Distribution System Services (5) Other AP functions: –AP Load balancing –Dynamic RF mgmt & control –Station Mobility support –Better network security Distribution System (DS) STA3STA4 AP STA5 STA6 AP Portal STA1STA2 AP External Network Implementation of DS is not specified in 802.11 standard, for good reason: flexibility.

5. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 5 Autonomous AP Architecture STA 1STA2 AP STA 3STA 4 AP Autonomous (standalone) AP: “fat” and self-contained AP No explicit infrastructure support for “wireless” Each AP provides most of the WLAN functions including “distribution”, “integration” and other L3 services within itself. External Network AP STA 5 Traditional WLAN Architecture

6. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 6 Problems in Large WLAN Deployment Network administration burden: –Management –Monitoring –Control Effective RF Dynamic Provisioning: needs coordination among APs Maintaining Consistent Configuration Security: –Access to the network (e.g., physical security of APs) –Rogue AP detection One Solution: Hierarchical Architecture

7. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 7 Hierarchical Architecture: “AP + AC” (Access Controller) STA 1STA2 AP STA 3STA 4 AP External Network AP Access Controller (AC) STA 5 “AP + AC” together implements AP functions Advantages of AC: –centralized controller(s) => manageability for large networks –network wide visibility => better coordination across the network Challenges: –no standard way of splitting AP functions onto AP and AC No interoperability

8. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 8 AP Architecture Examples Local MAC (split AP) Split MAC Remote MAC (antenna AP) MACPHYControl & config WTP AC AP Functions WTP AC Real Time MACPHYNon RT MACControl & config Autonomous (fat AP) WTP MACPHYControl & config “Split” Continuum AC WTP MACPHYControl & config

9. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 9 Split Implications on 802.11 MAC & PHY Performance implications ? Timing constraints => separation constraints? Split MAC APAC Real Time MACPHYNon RT MACL3 & above Antenna AP MACPHYL3 & above APAC

10. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 10 Network Topology: How AP and AC are connected? AP AC Directly Connected Via L2 cloud Via L3 cloud AC Switch/bridge L2 AC router L3 AP

11. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 11 Inter-dependency between split architecture and topology L3 L2 topology Split architecture Continuum x x x x x x Direct Split APSplit MACAntenna AP ? ? ?

12. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 12 Security in CAPWAP APSTA Authentication Server OTA security AC APSTA Authentication Server OTA security Current 802.11 Security Standard CAPWAP segment CAPWAP security issues Mutual authentication of AP and AC Secure the CAPWAP segment of AP-AC Dependent on split architecture

13. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 13 Next Steps for CAPWAP Functional split of AP and AC Design considerations Network topological considerations Security threats Pros and cons Architecture Survey WG Architecture Taxonomy DT Expert Review IEEE & IETF Data analysis Categorization Tradeoff of Interoperability vs. flexibility Recommendations 03/24v01: April AP functional Definition Interoperability solution IEEE IEEE & IETF

14. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 14 Open Questions & Suggestions Issues for IEEE to ponder: –“Split” implications on 802.11 PHY and MAC –Clearer AP functional definitions Expert review Future update in WNG from CAPWAP WLAN architecture issues border on L2 & L3 Need IEEE/IETF collaboration

15. doc.: IEEE 802.11-04/250r2 Submission March 2004 Lily Yang, IETF CAPWAP Design Team EditorSlide 15 Summary Autonomous AP Hierarchical “AP+AC” –Functional split continuum –Topology Constraints –Security Issues Update on CAPWAP WG Plan Issues that need attention & feedback from IEEE Closer collaboration between IETF and IEEE