The SAP encapsulation type is an access property of the Ethernet port used for the service. It identifies the protocol that is used to provide the service.
The encapsulation ID for Ethernet ports is an optional suffix that is appended to a port-id to specify a logical sub-element for a SAP. For example, port-id:qtag1 represents a port that can be tagged to use IEEE 802.1Q encapsulation (referred to as dot1q), where each individual tag can identify with an individual service.