TCP/IP Model: The Physical Layer

To properly learn something, we have to start at the beginning. We will be learning one concept at a time, process it, and move to the next.

The goal is consistent learning and absorbing information while feeling engaged and not overwhelmed.

Goal of this article

I will be explaining the physical layer of the TCP/IP Five-layer network model.

The Physical Layer

  • The lowest layer of the TCP/IP Five-layer is the physical layer. It is responsible for the actual physical connection between the devices.
  • The physical layer contains information in the form of bits.

Responsibilities of the physical layer:

  • Encoding and Signaling: Ones and Zeros are sent across network cables through a modulation process called line coding. Modulation is a way of varying the voltage of this charge moving across the cable.
  • Data Transmission and Reception: After encoding the data, the physical layer transmits the data and receives it. The various transmission modes possible are Simplex, half-duplex, and full-duplex.
  • Topology and Physical Network Design: The physical layer is also considered the domain of many hardware-related network design issues, such as LAN and WAN topology.
  • Hardware Specifications: The details of the operation of cables, connectors, wireless radio transceivers, network interface cards, and other hardware devices are generally a function of the physical layer (although also partially the data link layer).

Twisted Pair Cabling and Duplexing

  • The most common type of cabling used for connecting computing devices is known as twisted-pair. It's called a twisted pair cable because it features pairs of copper wires that are twisted together.
  • These pairs act as a single conduit for information, and their twisted nature helps protect against electromagnetic interference and crosstalk from neighboring pairs.
  • Duplex communication is the concept that information can flow in both directions across the cable.
  • Simplex communication is unidirectional.
  • Full duplex communication ensure that duplex communication is possible is by reserving one or two pairs for communicating in one direction and the other one or two pairs for communicating in the other direction. So, devices on either side of a networking link can both communicate with each other at the same time.
  • Twisted pair network cables are terminated with a plug that takes the individual internal wires and exposes them. The most common plug is known as a Registered Jack 45(RJ45).

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