Differences Between ESS and IBSS LANs

When the concept of the IBSS LAN was introduced, we noted that an IBSS is often used to support an ad hoc network. In an IBSS network, an STA communicates directly with one or more other STAs. Consider the full IEEE 802.11 architecture, as shown in Figure 5-7. An IBSS consists of STAs that are directly connected. Thus, there is, by definition, only one BSS. Further, since there is no physical DS, there cannot be a portal, an integrated wired LAN, or the DSSs. The logical picture reduces to Figure 5-8. Only the minimum two stations are shown, although an IBSS may have an arbitrary number of members. In an IBSS, only Class 1 and 2 frames are allowed since there is no DS in an IBSS. The services that apply to an IBSS are the SSs.

Figure 5-7: IEEE 802.11 architecture (again)

Figure 5-8: 802.11 IBSS