Same-layer interaction is communication between corresponding layers of the TCP/IP model on different computers. Each layer on the sending host communicates conceptually with the same layer on the destination host. section 4.3.2
Data is encapsulated as it moves down the sending host’s layers: application data becomes a segment, packet, and frame. The receiving host inspects and removes those headers and trailers during de-encapsulation, delivering the data to the application. section 4.3.2
Practical example
A Layer 4 header is inspected by Layer 4 on the destination host, a Layer 3 header by Layer 3, and a Layer 2 header and trailer by Layer 2 at the next hop. section 4.3.2
