Understanding how a Wi-Fi transmitter chooses a BSSID for Virtual Access Points I'm trying to understand if there is a certain protocol that a Wi-Fi transmitter must follow when creating a BSSID for virtual access points. In my university building, there are a bunch of CISCO routers and each provide 2 virtual access points: "eduroam" and "wifi guest". The BSSIDs for one Wi-Fi transmitter are **58:97:bd:4a:d6:70** and **58:97:bd:4a:d6:76**. Based on this example, it looks like only the last 2 characters of the BSSID are unique, and I presume that the first 10 are part of the original MAC address of the Wi-Fi transmitter. Does anyone know if there is a certain protocol which must be followed when creating a virtual access point? Or does the CISCO Wi-Fi transmitter have it's own unique methodology of creating these? Specifically, I'm looking for a citable source for this.

The OUI (Organizationally Unique Identifier) for a MAC address is assigned by the IEEE. The rest of the MAC address is assigned by the company to which the OUI is assigned, and it is completely up to the OUI owner for how to assign them.

In your example, the OUI is `58:97:bd`, assigned to Cisco Systems. The rest of the MAC addresses are assigned by Cisco in whatever fashion Cisco wants to assign them.