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Roaming Improvements to TGe. Mark Bilstad, Cisco Systems. Motivations. Resolve several comments related to roaming performance, including comment numbers 860, 861, 862, 863 Alternate resolution to 181, 182, 186, 187, 189, 369, 864, 865, 880
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Roaming Improvements to TGe Mark Bilstad, Cisco Systems M. Bilstad, Cisco Systems
Motivations • Resolve several comments related to roaming performance, including comment numbers 860, 861, 862, 863 • Alternate resolution to 181, 182, 186, 187, 189, 369, 864, 865, 880 • Respond to general mandate from task group to maintain and improve roaming performance in light of QoS application needs M. Bilstad, Cisco Systems
Probe Requests … Probe Response Pre-authentication Exchange Re-association Exchange ADDTS, 4-way crypto handshakes Existing Handoff Process STA APs Discovery Other APs New AP IAPP Commit M. Bilstad, Cisco Systems
Design Considerations • Discovery phase: QoS must be part of new AP selection • Client needs some confidence that its TSPECs will be accepted by the new AP while in the discovery phase • But, AP needs to be able to respond to probe requests quickly (must not require a query to admissions control) • Commit phase: QoS handshakes must not slow this down • TSPEC information should be allowed to be piggybacked on existing messages rather than sent in discrete action frames • Allow grouping of multiple TSPEC elements, regardless of frame M. Bilstad, Cisco Systems
AP Authenticator Ideally, compress roaming to: Client Supplicant Probe Request Probe Response: available admission capacity (predictor) Reassociate Request: TSPEC(2), TCLAS Reassociate Response: status,TSPEC(2) M. Bilstad, Cisco Systems
Changes Required • Define a new “Available Admission Capacity” field in the QBSS Load element • Define a new “QoS Management Action Header” element to allow ADDTS (and other) actions to be attached to (re)association requests and responses • A “transport” alternative; semantics are preserved • Create a “bidirectional” TSPEC direction code • Two TSPECs collapse into one: good reduction of message size M. Bilstad, Cisco Systems
Mapping between action frame andelement sequence in (re)association Existing action frame example Action Category = QoS Mgmt Action Code = ADDTS Dialog Token Status TSPEC Element TCLAS Element Element ID = QoS Mgmt Action Header Element Length = 3 Action Code = ADDTS Dialog Token Status TSPEC Element TCLAS Element Corresponding element sequence M. Bilstad, Cisco Systems