RAVENNA Networking Guide
V1.0/3
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Appendices
The OSI Reference Model
The OSI Reference Model
The OSI (Open System Interconnection) Reference Model is a conceptual model that describes how different
devices on a data network communicate with each other. Within the data networking industry, you will often find
components described according to the "layers" of the model - for example, a Layer 2 switch or Layer 3 router.
The model is divided into seven layers:
Layer 1
is the
Physical
layer used for the connection - it describes the cable type (e.g. CAT 5 or fibre),
connector type (e.g. RJ45), transmission speed (e.g. 1000BASE-TX), etc.
Layer 2
is the
Data Link
layer which describes the protocols required to transfer data between devices within the
same LAN. For example, this would describe your computer's network interface card or a Network Switch. Layer
2 provides basic error correction and point-to-point communication, but is not yet IP. The most commonly used
Data Link layer protocol is Ethernet.
Layer 3
is the
Network
layer which provides the functions and procedures to transfer data from one source in
one network to a destination in different network. Network Routers operate at this layer and communicate via IP
(Internet protocol).
Layers 4
to
7
are the application and protocol-based layers.
The first three layers are the most important for Audio-over-IP.
