2.3 Given a scenario, select and configure wireless devices and technologies
Service Set Identifiers
📘CompTIA Network+ (N10-009)
ESSID (Extended Service Set Identifier)
1. What is an ESSID?
- ESSID stands for Extended Service Set Identifier.
- It is basically the name of a wireless network that multiple Access Points (APs) use to create a larger, seamless network.
- Think of it as a common network name that devices use to connect across multiple APs in the same wireless network.
Key Point: Unlike a single AP’s network (BSSID), an ESSID can cover multiple APs, allowing devices to move around without losing the connection.
2. ESSID vs SSID vs BSSID
To understand ESSID, we need to compare it with SSID and BSSID:
| Term | What it is | Scope | Example in IT environment |
|---|---|---|---|
| SSID | Service Set Identifier, a wireless network name | Used by one AP or multiple APs | “OfficeWiFi” |
| BSSID | Basic Service Set Identifier, a unique MAC address of an AP | Single AP only | “00:1A:2B:3C:4D:5E” |
| ESSID | Extended SSID, the name for a network of multiple APs | Multiple APs combined into one network | “OfficeWiFi” across all floors of a building |
✅ Important: All APs in an ESS share the same ESSID but each AP has its own unique BSSID.
3. Why ESSID is important
- Roaming: Devices can move between APs in a large network without needing to reconnect manually.
- Example: Laptops in a company building can move from floor 1 to floor 2 while staying connected to “OfficeWiFi”.
- Network management: IT can manage one ESSID instead of managing multiple SSIDs for each AP.
- Consistent security: Same encryption and authentication settings can be applied across all APs in the ESS.
4. How ESSID works in a network
- An Extended Service Set (ESS) is a group of APs that are connected through a wired backbone (LAN).
- Each AP broadcasts the same ESSID.
- Devices (like laptops, phones, printers) see only one network name even though multiple APs exist.
- The device automatically connects to the strongest AP signal, making the connection seamless.
IT Example:
- Imagine a company has APs on every floor. Each AP has a different BSSID, but all broadcast the ESSID “CompanyWiFi”. A laptop moving across floors will automatically switch APs while staying connected to “CompanyWiFi”.
5. ESSID and Security
- ESSID is often hidden to increase security.
- If hidden, the network does not show up in the list of available Wi-Fi networks, but devices that know the ESSID can still connect.
- Even with a visible ESSID, encryption (WPA2/WPA3) is needed for security.
6. ESSID and the Exam
For the CompTIA Network+ (N10-009) exam, you need to know:
- Definition: ESSID = network name for multiple APs.
- Purpose: Enables seamless roaming in a wireless network.
- Relationship: ESSID = multiple APs, each with its own BSSID.
- Security: Can be hidden, but encryption is needed.
- IT Use Case: Large offices, campuses, or buildings where multiple APs provide a single network experience.
✅ Tip for remembering:
- Think of ESSID as the brand name of your network. Multiple APs are like stores under that brand; each store has its own unique address (BSSID), but the brand name (ESSID) is the same everywhere.
