Why is network communication organised into layers, and what are the advantages of doing so?
The concept of a layered model for network protocols, the role of layers, and the advantages of using a layered approach.
An Eduqas GCSE Computer Science answer on the layered model of network protocols: what a layer is, how the layers work together, the four-layer TCP/IP stack, and the advantages of a layered approach.
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What this dot point is asking
Eduqas wants you to explain what a layered model of network protocols is, how the layers work together, and the advantages of organising communication into layers. You do not need to memorise every layer of a specific model in depth, but you should know the idea, recognise the four-layer TCP/IP stack, and be able to give real advantages.
What a layered model is
The TCP/IP layers
The advantages of layering
Try this
Q1. State what each layer in a layered model provides to the layer above it. [1 mark]
- Cue. A service (the layer above uses it through a fixed interface).
Q2. Give one advantage of using a layered model. [1 mark]
- Cue. A layer can be changed without rewriting the others (or it isolates faults, or lets different manufacturers' equipment work together).
Q3. Name the TCP/IP layer that handles addressing and routing. [1 mark]
- Cue. The internet layer (where IP works).
Exam-style practice questions
Practice questions written in the style of WJEC Eduqas exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Eduqas Component 1, 20224 marksExplain what is meant by a layered model of network protocols and give two advantages of using layers.Show worked answer →
What it is (up to 2 marks): communication is divided into separate layers, each responsible for a specific part of the job (such as addressing, or transferring the data). Each layer provides a service to the layer above it and uses the service of the layer below, and the layers work together to move data.
Advantages (1 mark each, up to two): a layer can be changed or updated without affecting the others, as long as the interface between them stays the same; it breaks a complex task into manageable parts; it lets different manufacturers' equipment work together through standard interfaces; and it makes faults easier to find because problems can be isolated to one layer.
Markers reward the "each layer has one job and provides a service to the next" idea plus two genuine advantages.
Eduqas Component 1, 20233 marksA networking protocol at one layer is replaced with a faster one. Explain why this does not require the other layers to be rewritten.Show worked answer →
In a layered model each layer only needs to know how to talk to the layer directly above and below it through a fixed interface; it does not need to know how those layers work inside (up to 2 marks).
So as long as the new protocol keeps the same interface (the same services in and out), the layers above and below carry on unchanged; only the internals of that one layer change (1 mark).
Markers reward the idea of self-contained layers with fixed interfaces, which is exactly the benefit a layered model is designed to give.
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Sources & how we know this
- WJEC Eduqas GCSE Computer Science specification (from 2016) — Eduqas (2020)