An extended service set (ESS) expands wireless coverage beyond one access point by linking multiple basic service sets through a distribution system. Each BSS has a unique BSSID, while all share one SSID, making the ESS appear as a single wireless network. section 18.3.3
An ESS provides these operational characteristics:
- Clients can move between AP coverage areas without manually reconnecting; this handoff between BSSs is called roaming. section 18.3.3
- Each BSS normally uses a different non-overlapping channel, such as the 1–6–11 pattern, to reduce interference. section 18.3.3
- Overlapping neighboring cells by roughly 10–15 percent, with some recommendations reaching 20 percent, supports seamless roaming. section 18.3.3
Enterprise office coverage
An office with three APs can form one ESS named “Jeremy’s Wi-Fi.” Each AP provides a BSS with its own BSSID and channel, while a client moves between them as signal strength changes. section 18.3.3
Figure 18.17 An ESS consisting of three BSSs. Each BSS shares the same SSID, but has a unique BSSID. A client can roam seamlessly between BSSs.
Use the topology figure to compare the shared SSID, unique BSSIDs, and roaming path across three BSSs. section 18.3.3
