User's Manual

Appendix
BreezeNET PRO.11 Series 8-21 User’s Guide
Access Points are connected through some kind of backbone (called
Distribution System or DS). This backbone is typically Ethernet but, in
some cases, might be wireless itself.
The whole interconnected wireless LAN, including the different cells, their
respective Access Points and the Distribution System, is seen as a single 802
network to the upper layers of the OSI model and is known in the Standard
as the Extended Service Set (ESS).
The following diagram shows a typical 802.11 LAN including the
components described above:
Figure 9.14: Typical 802.11 LAN
The standard also defines the concept of a Portal. A portal is a device that
interconnects between an 802.11 and another 802 LAN. This concept is an
abstract description of part of the functionality of a “translation bridge”.
Even though the standard does not necessarily require it, typical installations
will have the AP and the Portal on a single physical entity. This is also the
case with BreezeCOM’s AP which provides both functions.
8.5.2. IEEE 802.11 Layers Description
As in any 802.x protocol, the 802.11 protocol covers the Media Access
Control Layer (MAC) and Physical Layer (PHY). The Standard currently
defines a single MAC which interacts with three PHYs (all of them running
at 1 or 2 Mbit/s) as follows: