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Doc.: IEEE 802.11-04-614-01-frfh Submission July 2004 Jon Edney, NokiaSlide 1 What is an ESS? Jon Edney, Nokia.

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Presentation on theme: "Doc.: IEEE 802.11-04-614-01-frfh Submission July 2004 Jon Edney, NokiaSlide 1 What is an ESS? Jon Edney, Nokia."— Presentation transcript:

1 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 1 What is an ESS? Jon Edney, Nokia

2 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 2 Anecdotal Definitions for ESS (I have heard people use) Any group of APs having: –the same SSID and connected via a Layer 2 network –the same SSID and connected by any network –the same SSID

3 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 3 The Distribution System (DS) AP Distribution System

4 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 4 DS The BSS AP STA

5 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 5 ESS AP Distribution System STA

6 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 6 ESS AP Distribution System STA THIS IS ALL NO NON terminations allowed MSDU

7 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 7 What does the standard say? 3.25 extended service set (ESS): A set of one or more interconnected basic service sets (BSSs) and integrated local area networks (LANs) that appears as a single BSS to the logical link control layer at any station associated with one of those BSSs.

8 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 8 More ( ) The key concept is that the ESS network appears the same to an LLC layer as an IBSS network. Stations within an ESS may communicate and mobile stations may move from one BSS to another (within the same ESS) transparently to LLC.

9 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 9 Portal 3.39 portal: The logical point at which medium access control (MAC) service data units (MSDUs) from a non-IEEE local area network (LAN) enter the distribution system (DS) of an extended service set (ESS).

10 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 10 Portal AP Distribution System STA network HOSTRouter

11 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 11 SSID The SSID element indicates the identity of an ESS or IBSS There is no such thing as ESSID

12 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 12 Summary SSID does not define ESS Any network technology can be used for DS but… –The only terminations allowed are APs or portals –DS must provide a tunnel for MSDUs – effectively this means layer 2 delivery Connections through portal do not change when you roam within ESS If STA is required to change IP address when it roams then it cannot be intra-ESS roaming. For real networks, ESS is not a useful concept

13 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 13 What to do? If ESS is not a useful definition was should it be replaced with? Need to define a group of APs where: –Fast transition possible between them (TGr) –Characteristics are compatible (TGk+TGr) –Same network services are accessible through any AP in the group (Wien?) => same authentication requirements The original definition of ESS which make transitions transparent to the link layer achieve some of this. –But it is not enough any more.

14 doc.: IEEE frfh Submission July 2004 Jon Edney, NokiaSlide 14 Ideas Define new extended identifier that includes a service directory and is accessible through probe responses. Have special class of SSID that is centrally allocated with well known capabilities and service support Have a shared token that could be used in probe response to validate another AP as member the same group. Tie group definition information into


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