Local-Area Networks and LAN Switching - CCIE Routing and Switching Exam Certification Guide - page 127

WLAN Modes
WLAN architecture has three modes of operation. The first mode is the Basic Service Set (BSS) .
In BSS mode, all stations communicate with the Access Point (AP). The AP provides commu-
nication between clients and connects the WLAN network with the wired LAN. As shown in
Figure 4-13, in BSS mode, clients do not communicate directly with each other; all communi-
cation is through the AP. BSS is also referred to as infrastructure mode .

BSS (Infrastructure) Mode

Figure 4-13

Wired LAN

Access point

AP

WLAN clients

The second mode is the Independent Basic Service Set (IBSS) . In IBSS mode, stations
communicate directly with each other without using an AP. IBSS is also known as Ad hoc mode .
Figure 4-14 displays IBSS (Ad-hoc) mode.

Figure 4-14

IBSS (Ad-hoc) Mode

WLAN stations

WLAN stations