1. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 1 TGu Proposal: Network Selection 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: 2006-05-015 Authors:

2. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 2 Abstract This proposal addresses all mandatory requirements in the network selection cluster (R9N1, R9N2, R9N3 and R9N4). The slides are related to following documents –802.11-06/0648r00 –802.11-06/0649r00

3. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 3 Motivation To enable the STA to identify the availability of a desired network service and indicate a desire to use it. –Requirement identified by deployment issues associated with public access hotspots, but could be extended for use in Enterprise Currently networks selected based on SSID and guesswork –If unsuccessful, other networks are associated with on a trial and error basis The aim of this proposal is to improve user interactions with the network, for example, by providing roaming agreement information to user devices.

4. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 4 Proposed Solution Framework The proposal is divided into two parts –Passive Discovery: which provides information to the STA in beacon/probe responses –Active Discovery: which supports a query/response exchange between STA and AP, allowing the STA to request additional information from the network Finally, associating with the Network: providing a means for the STA to indicate which SSPN it is interested in accessing.

5. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 5 Passive Discovery: ESSID The scheme is based on –an expanded definition of SSID and the introduction of a new IE called ESSID, to be carried in beacon, probe responses and neighbour reports –the station asserting the selected ESSID at association The ESSID contains three types of data: –An identifying name (ESS Name) human readable name to identify the group of APs, can be the same as the SSID USED to inform the user about which ESS they are connecting to –A unique identifier (ESS Address) It ensures there will not be a collision between the ESSID values of two groups of APs set to the BSSID value of one of the APs in the group; the use of the BSSID guarantees that the ESSID as a whole is globally unique –One or more External Network Identifiers used to enable the station to select between multiple possible back-end networks each External Network Identifier is advertised by adding a SSPN id for each

6. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 6 ESSID Use of ESSID removes some of the observed weaknesses of SSID: –Deprecates SSID to be general network identifier –It encourages the assignment of a unique identifier to groups of APs –It has a method to ensure uniqueness of each AP as manufactured –It provides discrimination between access point groups in cases where SSID has been overloaded with the service provider’s identity The scheme introduces a new feature not previously available: –The ability to discriminate between multiple networks behind the AP E.g. Handle forwarding of EAP to specific SSPN –A station can use the ESSID to gather more accurate information about the connectivity and compatibility of an access point before an association/ transition Format is left to the implementers or other organizations –Formatted NAI as in 3GPP, NAI with domain name etc.

7. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 7 Passive Discovery Techniques to reduce beacon bloating Layered Beacon –Include ESSID related IE to current beacons under low load conditions –Implementation decides what to do when load increases Hashing –Basic: External Network Identifier value can be hashed and truncated whose length can be varied based on load conditions –Diverse: An AP with diverse hashing capability chooses one of the truncations from the calculated hash value to reduce hash collision

8. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 8 Passive versus Active Discovery Thanks to the additional Unadvertised Service IDs bit, the STA knows whether the whole list of services is advertised in the beacon or not In case the STA does not discover the desired service advertised in the beacon (passive discovery), it can perform an active discovery (e.g. through a query). Passive discovery is also applicable to TGr when deciding where to perform the fast transition, in order to give assurance that the AP will support connectivity to the selected SSPN/service upon transition.

9. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 9 Active Discovery Active discovery allows the STA to query the network to find out whether particular services are available Supported through the definition of two new Action Frame formats –Service Request: indicates the external network identity (SSPN) the STA would like to discover. The information is sent as a string of up to 256 bytes. –Service Response: includes an indication as to whether the requested service is supported, and the SSID and a Supported ESSID IE containing the information to be used to connect to the network the ESSID (and the SSPN id, if provided) will be verified when the user attempts to connect to the network. In addition, the Query ID and ComeBackDelay IEs may be included to support the ComeBack mechanism to enable power saving advantages.

10. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 10 Active Service Query STAAP Backend Service Request (IE1, IE2, IE3) “Come-back” Service Request ([QueryID]) Service Response (resp-IE2, resp-IE3) “Come-back” Service Response (resp-IE1, [QueryID], [ComeBackDelay]) AP cannot provide response to IE2 and IE3 Retrieve info for IE2 and IE3 Resp-IE2, Resp-IE3 Typically >> 5ms < 5ms Delay = ComeBackDelay [X] : optional IE Not defined in TGu

11. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 11 Data-frame based Solution Relies on providing a transparent protocol solution using 802.11 data frames with a defined Ethertype Argument for media independence, but –Essentially this is a WLAN network selection –Speculation that this can be extended to other 802 technologies AP or 802.11 MAC is not involved in this solution (except for capability adv) –Protocol defined elsewhere –dependency on other protocols for WLAN network selection Data-frame solution considerations –Power management issues –Security issues are same as active discovery mechanisms e.g. DoS attacks

12. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 12 Summary and Assessment R9G1: Minimize battery consumption (not applicable to data frame solution) –Extended passive discovery is not expected to impact battery consumption. –Active discovery battery concerns have been addressed by the ComeBack mechanism. –Association modifications only affect the contents of the message, so only have a trivial impact on battery life. –The improved selectivity of the passive discovery process reduces the number of failed association attempts, thereby improving battery life even further.

13. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 13 Summary and Assessment R9G2: Security Impacts –Additional information included for passive discovery is treated in the same way as existing information; it is not believed that new threats are introduced. –Finer granularity of information may mitigate rogue AP attacks. –Active discovery introduces some new DoS attacks. R9G3: Legacy STAs –Legacy STAs are still able to use existing SSID IE and can ignore ESSID information.

14. doc.: IEEE 802.11-05/0499r1 Submission May 2006 Srinivas SreemanthulaSlide 14 Supporting Parties