802.11 WLAN Architectural Considerations for IETF CAPWAP Apr-19 802.11 WLAN Architectural Considerations for IETF CAPWAP L. Lily Yang Editor of IETF CAPWAP Architecture Design Team lily.l.yang@intel.com Lily Yang, IETF CAPWAP Design Team Editor

Overview Introduction: IETF CAPWAP and IEEE Month 2002 doc.: IEEE 802.11 Apr-19 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 Lily Yang, IETF CAPWAP Design Team Editor John Doe, His Company

Introduction IETF CAPWAP (Control and Provisioning of Wireless APs): Apr-19 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 First WG meeting in March 2004 at Seoul Architecture Design Team (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 Lily Yang, IETF CAPWAP Design Team Editor

WLAN Architecture Defined by 802.11 today Apr-19 WLAN Architecture Defined by 802.11 today MAC Services defined by .11: 4 Station Services 5 Distribution Privacy Other AP functions: AP Load balancing Dynamic RF mgmt & control Station Mobility support Better network security STA1 STA2 AP STA3 STA4 AP Distribution System (DS) STA5 STA6 AP Portal External Network Implementation of DS is not specified in 802.11 standard, for good reason: flexibility. Lily Yang, IETF CAPWAP Design Team Editor

Autonomous AP Architecture Month 2002 doc.: IEEE 802.11 Apr-19 Autonomous AP Architecture STA 5 STA 1 STA2 STA 3 STA 4 AP AP AP External Network Autonomous (standalone) AP: “fat” and self-contained AP No explicit infrastructure support Each AP provides most of the WLAN functions including “distribution”, “integration” and other L3 services within itself. Traditional WLAN Architecture Lily Yang, IETF CAPWAP Design Team Editor John Doe, His Company

Problems in Large WLAN Deployment Apr-19 Problems in Large WLAN Deployment Network administration burden: Management Monitoring Control Maintaining Consistent Configuration Effective RF Dynamic Provisioning: needs coordination among APs Security: Access to the network (e.g., physical security of APs) Rogue AP detection One Solution: Hierarchical Architecture Lily Yang, IETF CAPWAP Design Team Editor

Hierarchical Architecture: “AP + AC” (Access Controller) Month 2002 doc.: IEEE 802.11 Apr-19 Hierarchical Architecture: “AP + AC” (Access Controller) STA 5 STA 1 STA2 STA 3 STA 4 AP AP AP Access Controller (AC) External Network “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 Lily Yang, IETF CAPWAP Design Team Editor John Doe, His Company

“Split” Architecture Examples Apr-19 “Split” Architecture Examples AP Functional Stack Fat AP AP MAC PHY L3 & above Split AP AC AP MAC PHY L3 & above Split MAC AP AC Real Time MAC PHY Non RT MAC L3 & above Antenna AP MAC PHY L3 & above AP AC “Split” Continuum Lily Yang, IETF CAPWAP Design Team Editor

Split Implications on 802.11 MAC & PHY Month 2002 doc.: IEEE 802.11 Apr-19 Split Implications on 802.11 MAC & PHY Split MAC AP AC Real Time MAC PHY Non RT MAC L3 & above Antenna AP MAC PHY L3 & above AP AC Performance implications ? Timing constraints => separation constraints? Lily Yang, IETF CAPWAP Design Team Editor John Doe, His Company

Network Topology: How AP and AC are connected? Apr-19 Network Topology: How AP and AC are connected? Via L3 cloud Directly Connected Via L2 cloud AC AC AC (bridge) L2 L2 L3 Switch/bridge router AP AP AP AP AP AP AP AP AP Lily Yang, IETF CAPWAP Design Team Editor

Inter-dependency between split architecture and topology Apr-19 Inter-dependency between split architecture and topology topology L3 x ? ? L2 x x ? x x x Direct Split AP Split MAC Antenna AP Split architecture Continuum Lily Yang, IETF CAPWAP Design Team Editor

Security in CAPWAP AP STA Authentication Server STA AP AC Apr-19 Security in CAPWAP AP STA Authentication Server OTA security Current 802.11 Security Standard CAPWAP Security Issues Mutual authentication of AP and AC Secure the CAPWAP segment of AP-AC STA AP AC OTA security CAPWAP segment Authentication Server Lily Yang, IETF CAPWAP Design Team Editor

Next Steps for CAPWAP WG Architecture Survey DT Architecture Taxonomy Apr-19 Next Steps for CAPWAP WG Architecture Survey DT Architecture Taxonomy IEEE & IETF Expert Review AP functional Definition IEEE ? 03/24 v01: April IESG ? IETF Protocol(s) Functional split of AP and AC Design considerations Network topological considerations Security threats Pros and cons Data analysis Categorization Tradeoff of Interoperability vs. flexibility Recommendations Aug 04 Interoperable Standard(s) ? Lily Yang, IETF CAPWAP Design Team Editor

Open Questions & Suggestions Apr-19 Open Questions & Suggestions WLAN architecture issues border on L2 & L3 => IEEE/IETF collaboration Issues to ponder: “Split” implications on 802.11 PHY and MAC? Clearer AP functional definitions? Expert review Future update in WNG from CAPWAP? Lily Yang, IETF CAPWAP Design Team Editor

Summary Autonomous AP Hierarchical “AP+AC” Update on CAPWAP WG Plan Apr-19 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 Lily Yang, IETF CAPWAP Design Team Editor