Introduction to Networking

Physical Layer

The physical layer is the last layer from the sender and the first layer from the receiving side in the OSI model.

Note: Generally we assume the numbering of OSI layers according to Receiver Side. 

  • It transmits the individual bits from one node to another node through a communication Medium.

  • It establishes, maintains, and terminates the physical connection of the network.

Functions Of the Physical Layer

  • Communication Channel: It defines how devices can be connected physically, i.e., coaxial cable, fiber optic, etc.
  • Data Rate: It tells the number of bits delivered in one second.
  • Hardware: Repeaters and Hubs are mostly used in the Physical layer.
  • Data Transmission: It defines the transmission mode, i.e., simplex, half-duplex, or full-duplex mode, between the two devices on the network.
  • Physical Topology: It defines the way network devices are arranged, i.e., star, bus, ring, etc.
  • Signals: It determines the type of signal (digital or analog) used for transmitting the information.
  • Encoding: It defines the encoding method where the bits are encoded into electrical signals before to transmission. There are various encoding methods used for this purpose.
  • Multiplexing & De-Multiplexing: Most layers use Multiplexing & De-Multiplexing. In the physical layer, it requires when multiple senders need to send data at a time over a single transmission Medium.