Most of us must be familiar with terminologies like switchers, routers, LAN, WAN, VAN, etc., and most of us might be in this domain trying to understand the network topology, switch designs, router usage, IP addresses, MAC addresses and others. Let us try to understand the basic terminologies used in Ethernet in this series of articles:
Before going to other terminologies, we have to understand the OSI layer stack. OSI is nothing but open system interconnect defines the system architecture. The 7 layers are Application, Presentation, Transport, Session, network, Data link and physical layer. If you are hardware engineer you must be familiar with physical layer which defines the electrical characteristics. Firmware engineers will be more familiar with the Data Link, network and other higher layers. The transmission happens in packets and protocol is defined by TCP/IP. The layer naming convention is as follows:
Layer 1: Physical Layer
Layer 2: Data Link
Layer 3: Network
Layer 4: Transport
Layer 5: Session
Layer 6: Presentation
Layer 7: Application
The layer 1 receives packet from the medium and hands it over to layer 2. In other words Layer N+1 requests data from Layer N and data flow happens in that sequence.
For example, Switch is basically a Layer 2 device and Router is basically a Layer 3 device.
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