OSI / TCP-IP models
Two layering models — OSI's 7 layers (Physical → Application) and the simpler TCP/IP 4-layer model. Every byte your network handles ascends and descends this stack. The animation shows the chip moving through each layer with the layer label highlighted as it passes.
Animation
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Engineering pitfalls
Layer 8 — the people layer
The OSI model doesn't formally include a Layer 8 but most network troubleshooting time is spent there. Always check user/configuration before blaming the wire.
Encapsulation order matters
Each layer wraps the payload from above. Reversing the order on decode = corruption. Wireshark visualises this correctly; many homemade parsers do not.
OSI vs TCP/IP — don't conflate them
TCP/IP collapses OSI Session + Presentation + Application into one. Mapping protocols (e.g. TLS) to a specific OSI layer is approximate, not exact.
References
Primary sources
- ISO/IEC 7498-1 — Information processing systems — Open Systems Interconnection — Basic Reference Model.
- RFC 1122 — Requirements for Internet Hosts — Communication Layers.
- CompTIA Network+ N10-009 §1.1.