The First Layer of OSI Model-Physical layer
The Physical layer is the first layer of the OSI Model. It provides the electrical and the mechanical interface of the network medium. It receives the frame from the Data link layer and transfers the bits over the cable to communicate in the network. The physical layer is consist of wire or the media on which the network signal is transfer from the source to the destination .Physical layer include wire, plugs , sockets, signal generator etc.
The Physical layer deals with the electrical and mechanical characteristic of the signal to be transferred .the following are the main work of the Physical layer-
1. It defines the physical characteristic of the interface between the devices that need to send or receive the data and the transmission media. It also defines the type of the transmission medium.
2. The physical layer represents the bits. The physical layer consists of stream of bits. The bits are converting into the electrical or optical form to be transmitted over the network from source to the destination.
3. The next is the Data rate that is also known as the transmission rate and the number of bits sends each second is also defined by the Physical layer.
4. At the physical layer the sender and the receiver clock must be synchronize.
5. The physical topology defines how devices are connected together to form a network.
6. The physical layer also defines the direction of the transmission between two devices. These are-simplex, half duplex and full duplex. In the simplex mode only one device can send and other device can receive the information. It is a one way communication. In the half duplex mode two devices can send and receive the data but not the same time. And in the full duplex mode two devices can send and receive the data at the same time.
The Physical layer sent bits and receive bits and this layer directly communicate with the various type of the communication media and this layer also make a difference between Data Terminal Equipment (DTE) and Data Communication Equipment (DCE).
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