July 2004 doc IEEE 802 11 04 614

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh What is an ESS? Jon Edney, Nokia Submission 1 Jon Edney, Nokia

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh 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 Submission 2 Jon Edney, Nokia

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh The Distribution System (DS) Distribution System AP Submission AP 3 AP Jon Edney, Nokia

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh The BSS DS AP STA Submission STA 4 Jon Edney, Nokia

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh ESS Distribution System AP AP STA Submission AP 5 Jon Edney, Nokia

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh ESS Distribution System AP AP AP MSDU STA THIS IS ALL 802. 11 NO NON 802. 11 terminations allowed Submission 6 Jon Edney, Nokia

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh 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. Submission 7 Jon Edney, Nokia

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh More (5. 2. 2. 1) 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. Submission 8 Jon Edney, Nokia

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh Portal 3. 39 portal: The logical point at which medium access control (MAC) service data units (MSDUs) from a non-IEEE 802. 11 local area network (LAN) enter the distribution system (DS) of an extended service set (ESS). Submission 9 Jon Edney, Nokia

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh Portal HOST Router 802. 3 network Distribution System AP AP AP STA Submission 10 Jon Edney, Nokia

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh SSID • 7. 3. 2. 1 “The SSID element indicates the identity of an ESS or IBSS” • There is no such thing as “ESSID” Submission 11 Jon Edney, Nokia

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh 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 Submission 12 Jon Edney, Nokia

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh 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. Submission 13 Jon Edney, Nokia

July 2004 doc. : IEEE 802. 11 -04 -614 -01 -frfh 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 802. 21 Submission 14 Jon Edney, Nokia