The TCP/IP Five-Layer Network Model

GH RAISONI COLLEGE OF ENGINEERING AND MANAGEMENT PUNE

Name:- Atharva S. Jadhao (TECA31)

In this blog we are going to have a little introduction to the Five-Layers of Networking Model.

But before diving in we will look at what is mean by Networking. So lets start.

What is Networking

The internet is just an interconnection of computers around the world, like a giant spider web that bring us all together. Internet is the physical connection of computers and wires around the world and web is the information on the internet that we use to access the internet through link like www.google.com. In this field managing, building, and designing network is known as networking.

The internet is composed of a massive network of satellites, cellular network, and physical cables buried under the ground. We don't actually connect to the internet directly. Instead, computers called servers connect directly to the internet. The machine that we use like mobile, laptops etc. are called clients. Clients request the content from server. Clients don't connect directly to the internet. Instead they connect to a network run by an Internet Service Provider or ISP. Computers on a network have an identifier called an IP address. Devices that can connect to a network have another unique identifier called MAC address. MAC address are generally permanent and hard-coded onto a device.

Five-Layer Network Model

Lets start at the bottom of our stack, where we have what's known as the Physical layer.

The Physical layer is a lot like what it sounds. It represents the physical devices that interconnect computers. This includes the specification for the networking cables and the connectors that join devices together along with specifications describing how signals are send over these connections.

The second layer we have is known as the Data Link layer. At this layer we introduce our first protocol. Data link layer is responsible for defining a common way of interpreting these signals, so network devices can communicate. Lots of protocol exists at the data link layer, but the most common is known as Ethernet. The Ethernet standards also define a protocol responsible for getting data to nodes on the same network or link.

The third layer, the Network layer is also sometime called the Internet layer. The network layer allows different network to communicate with each other through devices known as routers. Internetwork, a collection of networks connected together through routers, the most famous of these being the Internet.

Data link layer is responsible for getting data across a single link, and the Network layer is responsible for getting data delivered across  a collection of networks. The most common protocol used at this layer is known as IP or Internet Protocol. IP is the heart of the Internet and most smaller network around the world.

Next layer is Transport layer. Transport layer sorts out which client and server programs are supported to get that data. In transport layer, we have TCP or Transmission Control Protocol. Other transfer protocols also use IP to get around, including a protocol known as UDP or User Datagram Protocol. TCP provides mechanism to ensure that data is reliably delivered while UDP does not.

It is important to know that the network layer,  in our case IP, is responsible for getting data from one node to another. In transport layer, mostly TCP and UDP, is responsible for ensuring that data gets to the right application running on those nodes.

Fifth layer is known as the Application layer. There are lots of different protocol at this layer, and as you might have guessed from the name, they are application - specified. This layer is what deals with protocols such as FTP and Telnet that relate to the handling of IP traffic. Web browse, SNMP protocols and HTTP protocols or HTTP's successor HTTPS, are other examples of application layer system.

TCP/IP Five Layer Network Model Overview