Two Company switches are connected via a trunk link. In this network， the original frame is encapsulated and an additional header is added before the frame is carried over a trunk link. At the receiving end， the header is removed and the frame is forwarded to the assigned VLAN. This describes which technology？（）
- A DISL
- B ISL
- C DTP
- D IEEE 802.1Q
- E MPLS
- F None of the other alternatives apply