Protocol Data Units
Network Fundamentals
Overview
Encapsulation adds headers as application data descends through transport, internet and link layers. TCP data is called a segment, UDP a datagram, IP a packet and Ethernet a frame. These names describe different wrapping levels, not interchangeable physical objects.
Protocol stages
- 1Application data
- 2Transport segment / datagram
- 3IP packet
- 4Link frame
- 5Bits
Interactive exercise
Knowledge check
An Ethernet payload contains an IPv4 payload containing TCP. What wraps the IP packet on this link?
Educational model — not real hardware, traffic or official certification.