Multiple logical address spaces

4.6 Multiple logical address spaces

Just as the IEEE 802.11 architecture allows for the possibility that the WM, DSM, and an integrated wired
LAN may all be different physical media, it also allows for the possibility that each of these components
may be operating within different address spaces. IEEE Std 802.11 only uses and specifies the use of the
WM address space.
Each IEEE 802.11 PHY operates in a single medium—the WM. The IEEE 802.11 MAC operates in a single
address space. MAC addresses are used on the WM in the IEEE 802.11 architecture. Therefore, it is
unnecessary for the standard to explicitly specify that its addresses are “WM addresses.” This is assumed
throughout this standard.
IEEE Std 802.11 has chosen to use the IEEE 802 48-bit address space (see 8.2.4.3.2). Thus IEEE 802.11
addresses are compatible with the address space used by the IEEE 802 LAN family.
The IEEE 802.11 choice of address space implies that for many instantiations of the IEEE 802.11
architecture, the wired LAN MAC address space and the IEEE 802.11 MAC address space may be the same.
In those situations where a DS that uses MAC level IEEE 802 addressing is appropriate, all three of the
logical address spaces used within a system could be identical. While this is a common case, it is not the
only combination allowed by the architecture. The IEEE 802.11 architecture allows for all three logical
address spaces to be distinct.
A multiple address space example is one in which the DS implementation uses network layer addressing. In
this case, the WM address space and the DS address space would be different.
Note that IEEE 802.11 STAs within a single ESS share the same address space, fulfilling the transparency
requirement from the definition of the DS. The DSS uses this same address space, even in the case where the
DSM uses a different address space.
The ability of the architecture to handle multiple logical media and address spaces is key to the ability of
IEEE Std 802.11 to be independent of the DS implementation and to interface cleanly with network layer
mobility approaches. The implementation of the DS is unspecified and is beyond the scope of this standard.