Wi-Fi Topology — What does Extended Service Set Identifier (ESSID) mean? Your access point is configured as a root AP. In IEEE 802.11 terminology, what does the Extended Service Set Identifier (ESSID) represent in a multi-AP deployment?

Introduction / Context:
802.11 networks use identifiers to group basic service sets (BSS) into larger, seamless WLANs. The Extended Service Set (ESS) allows clients to roam between coverage cells while staying on the same logical network name (SSID). Understanding ESS/ESSID helps in designing multi-AP deployments with uniform user experience.

Given Data / Assumptions:

• There are multiple infrastructure APs.
• They share a wired (or wireless mesh) distribution system.
• They advertise the same network name (SSID), allowing roaming.

Concept / Approach:
An ESS is a set of one or more BSSs interconnected by a distribution system (for example, Ethernet). The ESS is identified to clients by an SSID (often called ESSID in some tools). When APs use the same SSID and security settings, clients can reassociate between APs as they move, maintaining connectivity within the same subnet/VLAN if designed accordingly.

Step-by-Step Solution:
Define BSS: a single AP plus its associated clients.Combine multiple BSSs via a distribution system → ESS.Recognize that the shared SSID represents this ESS to clients.Select the option describing multiple APs with the same SSID joined by a distribution system.

Verification / Alternative check:
Roaming tests show that devices retain the same network identity when moving between APs sharing SSID and security within the same L2 domain, confirming the ESS concept.

Why Other Options Are Wrong:

• B: Separate SSIDs create separate WLANs, not one ESS for roaming.
• C: Physical separation alone does not define an ESS.
• D: Repeater mode is a deployment detail, not the definition of ESS/ESSID.
• E: SSID/ESSID is standardized; it is not vendor-specific.

Common Pitfalls:
Assuming ESSID is different from SSID; many tools use ESSID synonymously for the SSID presented by an ESS of multiple APs.

Final Answer:
Multiple APs broadcasting the same SSID and connected by a common distribution system, forming one extended service set.