Distribution system (DS) concepts

 Distribution system (DS) concepts

.1 Overview
PHY limitations determine the direct station-to-station distance that may be supported. For some networks
this distance is sufficient; for other networks, increased coverage is required.
Instead of existing independently, an infrastructure BSS may also form a component of an extended form of
network that is built with multiple BSSs. The architectural component used to interconnect infrastructure
BSSs is the DS.


IEEE Std 802.11 logically separates the WM from the distribution system medium (DSM). Each logical
medium is used for different purposes, by a different component of the architecture. The IEEE 802.11
definitions neither preclude, nor demand, that the multiple media be either the same or different.
Recognizing that the multiple media are logically different is key to understanding the flexibility of the
architecture. 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.
An access point (AP) is any entity that has STA functionality and enables access to the DS, via the WM for
associated STAs.


Data move between a BSS and the DS via an AP. Note that all APs are also STAs; thus they are addressable
entities. The addresses used by an AP for communication on the WM and on the DSM are not necessarily
the same.
Data sent to the AP’s STA address by one of the STAs associated with it are always received at the
uncontrolled port for processing by the IEEE 802.1X port access entity. In addition, if the controlled port is
authorized, these frames conceptually transit the DS.