Winot Overview Proposal Tgu Network Selection Requirements Cluster

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Transcript of Winot Overview Proposal Tgu Network Selection Requirements Cluster

  • 1. WiNOT Consortium: Proposal For TGu Network Selection Requirements Cluster
    • Date:2006-01-15

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 IEEEs name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEEs 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 < http:// ieee802.org/guides/bylaws/sb-bylaws.pdf >, 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 < [email_address] > 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 < [email_address] >. Authors: 2. WiNOT consortium

  • This presentation is made on behalf of the WiNOT (Wireless NetwOrking Technology), comprising:
    • Intel
    • Nokia
    • Siemens
    • Panasonic
    • STMicroeletronics
    • Cingular
    • BenQ
    • T-Mobile

3. Proposal Overview

  • Optimized Discovery of Network Features and Roaming Rights, support of multiple SSPNs, identification of interworking services
    • Passive information discovery
      • ESSID
      • Optimized Information Delivery
    • Active information discovery:
      • Optimized Power Saving Querying Mechanism
    • Optimized Information Delivery
      • Layered Beacons
      • Content Differentiation And Adaptive Advertising
  • Advertisement of usage charges
    • Based on above solution, with simplified alternative provided
  • Addresses N1, N3, N4 and N5

4. Requirement N3

  • Define functionality to support authentication with multiple SSPNs through a single AP.
  • There are two issue with this requirement
    • Advertising the availability of the SSPNs
    • Directing authentication and subsequent data to the correct SSPN
    • Issue (1) requires a scalable mechanism to provide information to the STA prior to connection
    • Issue (2) requires additional state information connected to STA association so that messages can be directed to the appropriate SSPN

5. Advertising capabilities

  • Most schemes require modification to beacons
  • There are lots of problems with SSID apart from inability to advertise SSPN (see 11-05-0971 Redefining SSID)
  • If we are to add the capability to meet N3 requirement then there is the opportunity to improve the operation of SSID in general
  • Therefore we propose tomeet the N3 requirement through the definition of ESSID as previously presented to TGu

Requirement N3 6. Advertising SSPN through ESSID

  • In the ESSID proposal the SSPN supported is identified by a 16 bit Path Selector
  • The Path selector value can be computed by hashing the public name of the SSPN with the ESSID value
    • the purpose of the Path Selector is to enable the STA to identify a particular service provided by the AP and ESS
    • Now the AP can advertise a reasonable number of services efficiently
  • Thus STA can compute the target hash and (with high confidence) whether the AP supports the required SSPN simply by observing the Path Selector in the beacon
  • STA will confirm full name SSPN in SSID field during association.

Requirement N3 7. New ESS-ID Element

  • New ESS-ID element to be carried in beacon and probe requests.
  • ESS-ID element to be included also in 802.11r to provide post-authentication verification that it was not modified or forged.

Requirement N3 8. Passive versus Active Discovery

  • Thanks to the additional (optional) SSPN/services IE, 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).
  • Active discovery in following slides for support of requirement N1
  • Passive discovery when the ESSID and path selectors are used is also described in the support for N1
  • Passive discovery is also applicable to TGr when deciding where to perform the fast transition
    • When STA wants to transition to different AP is scans for AP which:
      • have the same SSID
      • have the same ESSID-Value
      • ESSID includes the same path selector as currently in use
    • This gives assurance that the AP will support connectivity to SSPN upon transition.

Requirement N3 9. Security analysis based on G2

  • If a rogue AP copies the ESSID from a genuine AP it will appear to be valid
  • However rogue AP cannot simply accept any and all SSPN requests - it must advertise a limited set
  • Full name of SSPN must be submitted at association
  • Real Authentication occurs using EAPOL as currently defined in the standard

Requirement N3 10. Addressing N3 Requirement

  • This approach provides solution for N3
    • Mechanism provided for the AP to advertise the SSPN compatible with requirement N1
    • Connection procedure allows STA to confirm required SSPN
    • AP filters traffic to SSPN according to local policy
  • Use of ESSID provides a mechanism to efficiently advertise and specify SSPN
  • Use of ESSID enabled assurance the transition target AP will support required SSPN

11. N1: Optimized Discovery of Network Features and Roaming Rights

  • N1: Define functionality by which a STA can determine whether its subscription to an SSPN would allow it to access a particular 802.11AN before actually joining a BSS within that 802.11 AN. Proposals must describe their consideration of scalability.
    • Its not acceptable for a STA to be required to attempt IEEE 802.1X authentication with all available networks until it finds one that works.Equally a solution is not practical if it requires every possible credential supplier to be listed in a beacon (due to scalability problems).

12. Analysis of Issues

  • Issues are twofold
    • Need a mechanism to enable an STA to discover in an optimized manner whether it has roaming rights, and potentially information related to the network
    • Need an optimized way for network to provide information to stations
  • Proposal has two components:
    • Part I: Optimized Discovery for STA
    • Part II: Optimized Information Delivery
    • Support or either Part I or Part II or both is advertised to the stations, e.g. in beacons and possibly in Neighbor Reports (2 bits are sufficient)

Requirement N1 13. Part I: Optimized Discovery for STA

  • Currently the burden is on the STAs to know information on the network a-priori (e.g. list of all SSIDs for which the STA has a roaming agreement) in order to identify whether the STA has roaming in a given network and therefore perform network selection