This is a string that uniquely identifies the device acting as the EAP access point, sent along with the EAP session notification. Administrators or management stations use this identifier, in conjunction with ubpNotifyDeviceIdentifierType, to determine exactly which access device generated a given EAP session start or end event. For example, this attribute might carry the device's management IP address or SNMP engine ID as the value uniquely identifying the switch that sent the notification.