04 Try it yourself Interactive

Push the GET down the stack, then pull it back up

The same 38-byte request from section 02, the same two addresses, the same byte counts. Encapsulate walks down the sender’s stack: each step adds a header, and the block that was added on that step turns green in the byte layout. Decapsulate walks up the receiver’s stack: the header the current layer is about to check and discard turns rose, and the field list becomes a list of what this layer verified before it stripped anything. The four counters are computed from the byte sizes on screen, so the overhead figure is arithmetic and not an assertion. Nothing plays on its own: Next, Back and Reset, or the arrow keys.

Encapsulate · down the sender
38 bytes of HTTP, about to be wrapped
Indigo is the application payload and it never changes size. Green is a header or trailer that was just added. Rose is one that is about to be checked and thrown away. Block widths follow their byte counts, with a floor so the 4-byte FCS stays readable.
Press Next to begin. Each press moves the request one layer.


      
Payload bytes
Header + trailer
Total bytes
Overhead
step 0 / 0