Layer Cooperation on the Source Host
Encapsulation in Layering
- Whenever a process at Layer N (the application, transport, internet, or data link layer) creates a message,
- That Layer N process passes the message down to the next-lower-layer process, the process at layer N-1
- The N-1 process encapsulates the Layer N message by placing it in the data field of a Layer N-1 message and adding headers and perhaps trailers to create the full Layer N-1 Message