Data Encapsulation Workbench

Build and inspect protocol data units as application data moves down and back up the network stack

Interactive data encapsulation animation for learning protocol data units, header and trailer overhead, decapsulation, MTU pressure, and IoT header-compression tradeoffs.

Animation OSI and TCP/IP Header Overhead IoT Links

Data Encapsulation Workbench

Watch an application message become a transport segment, network packet, link frame, and physical bit stream. Then reverse the path to see what the receiver strips during decapsulation.

100 B Application payload

158 B Final frame bytes

63% Useful payload ratio

Frame Current PDU view

Learning Brief

Encapsulation means each lower layer treats the entire upper-layer unit as its payload and adds control information needed for its own job.

What changes? Ports, addresses, MAC fields, checksums, and frame trailers are added around the original message.

Why IoT cares Small radio frames make every byte expensive; compression and lightweight protocols preserve payload room.

Scenario

Controls

Payload Bytes: 100

Transport TCP base header, 20 B UDP header, 8 B

Network IPv4 minimum header, 20 B IPv6 base header, 40 B IPv6 with 6LoWPAN-style compression example

Link Ethernet II, 14 B header + 4 B FCS IEEE 802.15.4 example, 9 B header + 2 B FCS

Direction

Application Data

Stage 1 of 5

The sender starts with the application message before protocol headers are added.

Layer Path

Current Byte Layout

Diagnosis

Packet Trace

Quick Reference

PDU Names Application message, transport segment/datagram, IP packet, link frame, physical bits.

Common Header Sizes UDP 8 B, TCP base 20 B, IPv4 minimum 20 B, IPv6 base 40 B, Ethernet header 14 B plus 4 B FCS.

Payload Efficiency Useful payload ratio = application bytes divided by the final transmitted frame bytes.

MTU Pressure Large headers can force fragmentation or adaptation-layer work before the packet can cross a small radio link.

Decapsulation The receiver validates and removes each lower-layer wrapper before passing the remaining payload upward.

IoT Design Hint CoAP/UDP, header compression, and careful payload sizing are common ways to keep constrained traffic efficient.

How to Read the Workbench

Layer Path Green layers have already handled the PDU. The orange layer is the layer currently adding or removing its fields.

Byte Layout Each colored block is a protocol field group. The application data block should stay visible as headers accumulate around it.

Diagnosis Use the efficiency and MTU messages to decide whether the selected stack is sensible for a constrained IoT link.

Technical Accuracy Notes

IPv4 and TCP The workbench uses minimum IPv4 and TCP base headers. Options can increase both values.

IPv6 and Extension Headers The IPv6 base header is 40 B; extension headers are separate and are not included unless a scenario explicitly adds them.

6LoWPAN Example The compressed case is an educational example. Real compressed sizes depend on addressing mode, context, hop limit, ports, and mesh/security fields.

Link-Layer Variability IEEE 802.15.4 frame overhead changes with addressing and security fields. This page uses a small representative frame to show MTU pressure.

Ethernet Wire Detail The frame byte total includes Ethernet header and FCS. Preamble and inter-frame gap are physical-layer timing overhead and are kept out of the frame byte count.

Layer Models The display maps practical TCP/IP behavior onto OSI-style names so learners can connect both vocabularies.

Source Links

UDP Header RFC 768 - User Datagram Protocol

IPv4 Header RFC 791 - Internet Protocol

IPv6 Header RFC 8200 - IPv6 Specification

TCP Header RFC 9293 - Transmission Control Protocol

6LoWPAN Compression RFC 6282 - IPv6 Header Compression

IEEE 802.15.4 Overview IEEE 802.15.4-2020 standard page