Co-existence of Different Authentication Models

1. Co-existence of Different Authentication Models Eleanor Hepworth, Siemens Roke Manor eleanor.hepworth@roke.co.uk Eleanor Hepworth, Siemens Roke Manor

2. Issues for Co-existence • Multiple ways to support authentication for Public Access WLAN access • Operator requirement for a smooth migration path / way to support both (co-existence) • Need some enhanced features in the hotspot e.g. capability advertisement • 802.11 flexibility allows this to be supported in multiple ways • interoperability problems? (analogous to those encountered for Virtual APs) Eleanor Hepworth, Siemens Roke Manor

3. Authentication Models • Two basic models for PWLAN • UAM: defined by WiFi Alliance • 802.11i: defined by IEEE • UAM is widely implemented in existing hotspots • Question now facing operators is whether and how to move towards 802.11i without annoying subscribers Eleanor Hepworth, Siemens Roke Manor

4. Operator Goals • Common user experience • Support for as many subscribers as possible (including roamed users) • Stepwise introduction of new components (avoid all or nothing upgrades) • Reuse of existing infrastructure where possible • Therefore, one option is to allow solutions to co-exist in the same network Eleanor Hepworth, Siemens Roke Manor

5. Hotspot Requirements • To support this, hotspot needs to provide • Operator Advertisement • Capability Advertisement • e.g. data rate/QoS, authentication model, cost • Possible solution in virtual APs • SSID provides clue as to capabilities of the virtual AP/access network Eleanor Hepworth, Siemens Roke Manor

6. Operator Advertisement • Can be implemented in two ways • The hotspot operator advertises their own identity but provides roamed information via some other mechanism e.g. EAP • I-D in IETF – requires support in APs. • Each roamed operator advertises their association with the hotspot via SSIDs in beacons and probe responses (i.e. multiple operators share the same hotspot infrastructure) • Information needs to be “meaningful”, especially for option 2 (SSIDs are not local anymore) • we need a standard naming convention, who is responsible for defining this? Eleanor Hepworth, Siemens Roke Manor

7. Capability Advertisement • May wish augment SSID with additional information • SSID is currently unstructured • A structure is needed, who defines this? • (Need a consistent way for a driver to interpret what information is being provided by the SSID) Eleanor Hepworth, Siemens Roke Manor

8. Virtual APs • Do Virtual APs provide the solution for all PWLAN requirements? • Scenario: if 5 operators are sharing a hotspot, each wanting to advertise UAM and WPA access, this leads to 10 VAPs per AP • There are scalability and administrative overhead concerns Eleanor Hepworth, Siemens Roke Manor

9. Conclusions • No clear impacts on 802.11 standard • BUT, there are interoperability issues • Many different external standardisation bodies are investigating the use of SSIDs for operator/capability advertisement • Who should provide guidance on these aspects? • Need to verify that Virtual APs provide the necessary support • Who is responsible for this? Eleanor Hepworth, Siemens Roke Manor