May 2004 doc IEEE 802 11 040629 r

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 The Nature of an ESS Darwin Engwer, Nortel Networks Bob O’Hara, Airespace dengwer@nortelnetworks. com bob@airespace. com Submission 1 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 Further thoughts on ESS (triggered by submission 11 -04 -0614 -00) • Doc 614 [1] cites a number quotes directly from the standard wrt the definition of an ESS. • Strictly interpreted these existing definitions constrain the implementation options as cited in doc 614 • However, other logical (abstract) views are possible, which have in fact allowed vendors to construct functional WLANs within the constraints imposed by existing definitions. • First, a diagram from doc 614. . . Submission 2 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 Slide 6 from [1] doc 11 -04 -614 -00 AP + DS + Portal HOST Router 802. 3 network Portal Distribution System AP AP AP STA Submission 3 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 • But real world implementations (to date) look like this. . . Submission 4 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 Real World AP Devices HOST Router 802. 3 network 802. 3 L 2 Hub or Switch AP Device Portal Integration Distribution System WM WM STA Submission STA 5 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 Real World AP Review • In that common real world AP and WLAN implementation, the mini-DSs and portals in each AP combined with the 802. 3 L 2 network can be considered as forming a single logical Distribution System and Portal, since those logical components meet all the criteria described in 802. 11 -1999 Clause 5. – “ 5. 2. 2 … The IEEE 802. 11 LAN architecture is specified independently of the physical characteristics of any specific implementation. ” – … The DS enables mobile device support by providing the logical services necessary to handle address to destination mapping and seamless integration of multiple BSSs. ” Submission 6 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 Logical DS and Portal HOST Router 802. 3 network Portal 802. 3 L 2 Hub or Switch AP Device Distribution System Portal AP Device Portal Integration Distribution System WM WM A single logical portal is indistinguishable from multiple physical portals. STA Submission STA 7 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 Logical DS and Portal • There is no disagreement between the Logical DS and Portal model and the formal definitions provided in 802. 11 -1999 Clause 5. – Consider: “ 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 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 L 2 Connectivity with a Logical DS and Portal HOST Router 802. 3 network Portal 802. 3 L 2 Hub or Switch AP Device Distribution System Portal Integration Distribution System WM WM STA AP Device STA L 2 link Submission 9 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 Extent of the ESS • Hence, the ESS can span all the APs in such a network. Submission 10 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 ESS with a Logical DS and Portal HOST Router 802. 3 network Portal 802. 3 L 2 Hub or Switch AP Device Distribution System Portal Distribution System WM WM Submission STA ESS L 2 link Portal Integration STA AP Device L 2 link ESS 11 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 What if the network includes a router? Submission 12 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 L 2 Connectivity with a Logical DS and Portal using a Router HOST Router 802. 3 network Portal 802. 3 L 2 Hub or Switch Distribution System AP Device Portal Integration Distribution System WM WM STA AP Device STA L 2 link Submission 13 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 L 2 Connectivity thru a Distribution System that includes a Router • At first look it appears as if the two STAs on opposite sides of the router do not have L 2 Connectivity. • However, the DS (or some other component in the network) can arrange this to be true. – e. g. the mini-DS in one AP can transport the MSDU to the mini. DS in the AP that is on the other side of the router. The second AP can then deliver the MSDU to the mobile STA. To the mobile STAs it appears as if they have L 2 connectivity. – e. g. A consistent VLAN can be set up on both sides of the router, so that packets on that VLAN are switched across the router. In fact, this is a common deployment scenario today. Again, to the mobile STAs it appears as if they have L 2 connectivity. Submission 14 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 ESS with a Logical DS and Portal using a Router • Hence, the ESS concept can apply to WLAN deployments that rely on a logical DS/ logical portal(s) construct, even when using a router. Submission 15 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 ESS with a Logical DS and Portal using a Router HOST Router 802. 3 network Portal 802. 3 L 2 Hub or Switch Distribution System AP Device Portal Distribution System WM WM Submission STA ESS L 2 link Portal Integration STA AP Device L 2 link ESS 16 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 ESS Summary • BSSs with the same SSID may be part of the same ESS. • No scenarios are [necessarily] excluded. • The 802. 11 -1999 definition of an ESS is somewhat broad and flexible. Therefore, TGr may need to specify and explicitly define the BSS-transition cases that are in -scope and out-of-scope. – i. e. If TGr wants something more precise than ESS, then need to specify that. Submission 17 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 References: – [1] 11 -04 -0614 -00 -frfh-what-ess. ppt – [2] 11 -04 -0500 -01 -0 mes-need-clarification-definition-ess-mesh. ppt Submission 18 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace

May 2004 doc. : IEEE 802. 11 -04/0629 r 1 The End Submission 19 Darwin Engwer, Nortel Networks; Bob O'Hara, Airespace