Encapsulation is the process by which a lower-level protocol accepts a message from a higher-level protocol and places it in the data portion of the lower-level frame. As a result, datagrams transmitted through a physical network have a sequence of headers: the first header for the physical network (or data link layer) protocol, the second header for the network layer protocol (IP, for example), the third header for the transport protocol, and so on.
The following encapsulation protocols are supported on J-series Services Router physical interfaces: