The physical layer is either the first or the seventh layer of the Open Systems Interconnection (OSI) Model

The physical layer is either the first or the seventh layer of the Open Systems Interconnection (OSI) Model depending on which end you decide to start your counting. It holds a significant role in the functioning of the OSI Model. As suggested by the name, it has a physical body that consists of circuits and technologies of the network.


Most of the times, the physical layer is installed in the form of a chip. This chip is called PHY (Chip), an abbreviation for 'Physical Layer.’ The role assigned to the Physical Layer is to deal with the physical connectivity of two different stations with interacting with hardware and mechanism of the signal, making it the only layer to be capable of doing so. All the Layers in the model work on the data or functions provided by the lower layer and provides its’ services to the layer above itself. Being the lowermost layer, the physical layer only provides the service to the data link layer in the form of raw bits or electrical pulses instead of data packages like some of the other layers.


The electrical pulses are representative of the binary data that can be sent over both the wireless and the wired network and media. Despite being named the physical layer, it does not deal with the actual physical mediums such as fiber and copper.


Below are the functions of the physical layer

1. Bit-by-bit or Symbol-by-Symbol delivery

2. Convention from one form to another of a signal so it could be interpreted and sent over communication to the other party.

3. It also functions in the process of error-correcting and channel coding.

4. Line coding allows the transmission of the data through a hardware device and physical layer to provide its' service in that matter as well.

5. When the signal is multiplexed digital, it functions as a controlled or the multiplex hardware control and switches circuit where need be.

6. The power of auto-negotiation to an extent is also provided to this layer.

7. It also deals with synchronization of the transmitter and receiver.

8. It holds the ability to control; start-stop flow control of the signal.

9. Whether a collision has happened or is about to happen has to be detected and the physical layer is responsible for that job as well.

What it really detects is the carrier availability and by doing so it can avoid the congestion caused by the packages that are now undeliverable.

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