1. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 1 Virtual AP Presentation Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at.http:// ieee802.org/guides/bylaws/sb-bylaws.pdfstuart.kerry@philips.compatcom@ieee.org Date: 2006-03-07Authors:

2. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 2 Abstract This Virtual AP solution uses a single beacon to efficiently advertise multiple BSSIDs and SSIDs. The Probe Request frame is augmented to probe for multiple SSIDs in a single frame. The Probe Response frame is extended to include the complete attributes of multiple SSIDs

3. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 3 Goals Support multiple virtual APs (BSSID/SSID combination) per physical AP –Avoid multiple beacon overhead –Minimize the beacon length Interoperate with legacy 802.11 clients Support hidden SSIDs in beacons Support multiple-SSID probe response Support multiple-SSID probe request

4. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 4 Approach Legacy beacon format remains unchanged –APs can still send multiple beacons to implement virtual APs Virtual AP information is carried in a separate Multiple BSSID Element –Multiple BSSID Element consists of one or more of Multiple BSSID profiles –A Multiple BSSID profile may partially or fully define a virtual AP –Not all valid Multiple BSSID profiles need to be present in all beacons –An AP may choose to send the complete multiple BSSID profiles only in probe responses Each Virtual AP may have its own privacy profile, power save profile, etc Support for multiple BSSID/SSID in probe responses and requests TIM is shared by all stations and BSSs

5. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 5 Multiple BSSID Element Element IDLength Max BSSID indicator Non-Transmitted BSSID Profile Octets:111variable More than one Multiple BSSID element may be sent in beacon Max BSSID indicator defines the maximum number of supported BSSIDs

6. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 6 Multiple BSSID Index Element Element ID Length BSSID Index DTIM PeriodDTIM Count Octets:111 1 1 Uniquely identifies each BSSID and associated power-save characteristics

7. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 7 Non-transmitted BSSID Profile Only two elements are mandatory –SSID and Multiple-BSSID Index Other elements are optional –If not present, inherited from the previously transmitted BSSID’s elements Simplified beacons –Probe response may include the full BSSID profile while a beacon does not have to Some elements are always inherited from the transmitted BSSID’s elements –Other optional elements may also be inherited

8. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 8 Non-transmitted BSSID AP_BSSID is the legacy BSSID from beacon’s MAC header Virtual AP BSSID(i) = (AP_BSSID n LSBs set to zero) | ((n LSBs of AP_BSSID) + i) mod 2 n ) The BSSID Index (i) is part of the Multiple BSSID Index IE

9. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 9 TIM Handling TIM is interpreted differently by stations associated with a Non-transmitted BSSID –DTIM Count and DTIM Period for the Non-transmitted BSSID are carried separately in the Multi-BSSID element The first 2 n bits of the TIM are reserved for broadcast/multicast for each BSS –Each BSS can have its own DTIM interval The rest of the AID space is shared by all BSSs –Including the transmitted BSSID and all non-transmitted BSSIDs

10. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 10 Beacon Frame Format OrderInformationNotes 22Multiple BSSID The Multiple BSSID element is present only within Beacon frames generated by APs which support multiple BSSIDs. 23Multiple BSSID- Index The Multiple BSSID-Index element is present only within Beacon frames generated by APs which support multiple BSSIDs. 25Vendor Specific One or more vendor specific information elements may appear in the frame.

11. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 11 Beacon size comparison Average beacon length of 128 bytes The worst case includes all optional elements Medium access and PHY (preamble/PLCP) overhead are not counted

12. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 12 Beacon size comparison data # VAPs Legacy beacon size (multiple beacons) Minimum beacon size with proposed solution Maximum beacon size with proposed solution 1 128 2 256152 209 3 384169 283 4 512186 357 5 640203 431 6 768220 505 7 896237 579 8 1024254 653 9 1152271 727 10 1280288 801 11 1408305 875 12 1536322 949 13 1664339 1023 14 1792356 1097 15 1920373 1171 16 2048390 1245

13. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 13 Probe Responses Includes Multiple BSSID element in the same format as in beacons The number of BSSIDs returned in a probe response could be different from the ones advertised in beacons

14. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 14 Probe Requests Ability to request responses from multiple BSSIDs using Multiple-SSID element –An STA may send a broadcast request with multiple SSIDs that may span multiple physical APs More than one Multiple-SSID element may be included in a probe request

15. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 15 Probe Request Format OrderInformationNotes 5Multiple SSIDThe Multiple SSID element is present when the STA requests information on multiple SSIDs. 6Vendor SpecificOne or more vendor specific information elements may appear in the frame.

16. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 16 Probe Response Format OrderInformationNotes 21Multiple BSSIDThe Multiple BSSID element is present only within Probe Response frames generated by APs supporting the Multiple BSSID capability. 22Vendor SpecificOne or more vendor specific information elements may appear in the frame.

17. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 17 Legacy Interoperability The beacon appears like a legacy beacon to legacy STAs –The new IE are ignored by legacy STAs APs can still send multiple “legacy” beacons to implement virtual APs –Mixed mode is also allowed (i.e., multiple beacons with multiple BSSIDs) All frames from the AP, except the beacon, should use the appropriate BSSID in the MAC header The TIM format is also legacy compatible –Only multiple BSSID aware stations interpret the TIM elements differently

18. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 18 Motion Motion: “Instruct the editor to include the substantive text in document 11-05-1120r4-Virtual AP Proposal into the TGv draft” Mover/Seconder: Result –Yes –No –Abstain

19. doc.: IEEE 802.11-05/1219r4 Submission March, 2006 S. Ponnuswamy (Aruba Networks)Slide 19 References