Networking

Functions of the OSI Layers There are the seven OSI layers. Each layer has different functions. A list of seven layers is given below: 1_Physical Layer : The main functionality of the physical layer is to transmit the individual bits from one node to another node. It is the lowest layer of the OSI model. It establishes, maintains and deactivates the physical connection. It specifies the mechanical, electrical and procedural network interface specifications. Functions of a Physical layer: Line Configuration: It defines the way how two or more devices can be connected physically. Data Transmission: It defines the transmission mode whether it is simplex, half-duplex or full-duplex mode between the two devices on the network. Topology: It defines the way how network devices are arranged. Signals: It determines the type of the signal used for transmitting the information. 2_Data-Link Layer : This layer is responsible for the error-free transfer of data frames. It defines the format of t

What are Switches ? Sitches are devices capable of creating temporary connections between two or more devices linked to the switch. Switching at Physical Layer : At the physical layer, we can have only circuit switching. There are no packets exchanged at the physical layer. The switches at the physical layer allow signals to travel in one path or another. Switching at Data-Link Layer At the data-link layer, we can have packet switching. However, the term packet in this case means frames or cells.  Packet switching at the data-link layer is normally done using a virtual-circuit approach.  Switching at Network Layer At the network layer, we can have packet switching. In this case, either a virtual-circuit approach or a datagram approach can be used. Currently the Internet uses a datagram approach, as we see in Chapter 18, but the tendency is to move to a virtual-circuit approach.  What is network? Connected Devices? what is network criteria in data communication?