SSID

What Is SSID?

In the world of wireless networking, the Service Set Identifier (SSID) plays a vital role in identifying and distinguishing wireless local area networks (WLANs). It serves as a unique identifier for WLANs, enabling users to connect to the correct network. This article delves into the concept of SSID, its classification, and the benefits it offers in terms of network segmentation, authentication, and overall WLAN performance.

SSID is a character string that uniquely identifies a WLAN. It serves as the network name that wireless devices use to identify and connect to a specific WLAN. Think of the SSID as a label that differentiates one wireless network from another within range.

BSSID and ESSID

BSSID

SSID can be classified into two types: BSSID (Basic Service Set Identifier) and ESSID (Extended Service Set Identifier). The BSSID is used for network management and maintenance purposes and is not typically perceived by users. On the other hand, the ESSID is what users commonly refer to as the SSID when selecting and connecting to a wireless network.

BSSID is a unique identifier assigned to each wireless access point or wireless router within a wireless network. It represents the MAC (Media Access Control) address of the AP. BSSID is primarily used for network management purposes, such as identifying and distinguishing between different APs in a network. It is not typically perceived or used directly by end-users when connecting to a wireless network.

ESSID

ESSID is commonly referred to as the SSID. It is the network name that end-users see and select when connecting their wireless devices to a specific WLAN (Wireless Local Area Network). ESSID is a string of characters that identifies a particular WLAN and is typically set by the network administrator. When users want to connect to a specific wireless network, they select the corresponding ESSID from the available networks displayed on their devices.

To summarize, BSSID is a distinctive identifier assigned to each access point within a wireless network, primarily employed for network management purposes. On the other hand, ESSID (or SSID) functions as the visible network name that end-users select to connect their devices to a specific WLAN.

Application of SSID

Dividing a Network into Subnets Based on Multiple SSIDs

The application of SSID can be seen in various scenarios within wireless networking. Two key applications include dividing a network into subnets based on multiple SSIDs and enabling roaming capability based on an SSID.

Traditionally, early 802.11 chips in Access Points (APs) supported only a single SSID, limiting the provision of a single WLAN for all users. However, as WLAN usage grew, the need arose to cater to the requirements of users with different identities. Modern APs now support the multi-SSID function, allowing the creation of multiple Virtual Access Points (VAPs) on a single AP. Each VAP is associated with a specific user group and has a unique SSID, along with customized configurations for security policies, access authentication, rate limiting, access control, multi-user multiple-input multiple-output (MU-MIMO), and orthogonal frequency division multiple access (OFDMA). Consequently, a WLAN can be divided into numerous subnets, each with its own SSID, offering tailored services to its respective user group. For instance, an enterprise network can be divided into two subnets: "employee" and "guest." The "employee" SSID may be hidden and require authentication for access, while the "guest" SSID may be visible and allow unrestricted access without authentication.

Roaming Capability Based on an SSID

To facilitate seamless user mobility between multiple APs, an enterprise can configure the same SSID across these APs. The coverage areas of these APs overlap to ensure uninterrupted communication during roaming. For example, consider the roaming process of an employee's mobile phone within an enterprise network. Initially, the employee finds a wireless network named "employee" in the lobby and connects to it. The ESSID remains "employee," and the BSSID corresponds to the MAC address of the VAP on the AP in the lobby. As the employee moves towards the office, the mobile phone enters the coverage area of the office AP. When the signal strength meets the required threshold, the mobile phone automatically roams to the "employee" network of the office AP based on the SSID, enabling a smooth transition of services. The ESSID remains "employee," but the BSSID changes to the MAC address of the VAP on the AP in the office.