1. Layered protocol architecture

When it comes to communication between two entities, there are several possible ways of grouping the rules to be followed. They can be combined in a single protocol, grouping together all the functions required for communication. The drawback of this solution is that improvements cannot simply be introduced; the entire protocol must be modified to add or change a rule. The classic solution, found in many architectures, is to group rules into layered protocols that stack one on top of the other. The advantage is that you can modify a single layer of the architecture without having to touch the others, provided you respect the interfaces between layers.

The most classical architecture is the one described in the ISO reference model (see article [H 3 220] ); it contains seven protocol...