In a computer network, machines can communicate with each other by means of protocols.
This protocols ensures that computers can communicate with different hardware and software for their use. Largely different types of networks have these protocols on the Internet and each has its own purpose.
Do you know what the primary goal of networking is? Let us know about networking packets The primary goal of networking is to exchange information between computer networks, this information is carried by packets.
Packets
Packets are nothing but streams of bits used for data transmission over physical media as electric signals. Such media as a wire in a LAN ( local area network ) or the air in a WiFi network.
These electricals signals are then interpreted as bits ( zeros and ones ) that make up the information. Every packets in every protocol has the following structure.
The header has a protocol specific structure. This ensures that the receiving host can properly interpret the payload and handle the entire communication.
The header has a protocol specific structure. This ensures that the receiving host can properly interpret the payload and handle the entire communication.
This payload is the actual information so it could be something like part of an email messages what the content of a file during download of any messages.
Example The IP Header
For example, the internet protocol header is atleast 160 bits (20 bytes) long, and it includes information to interpret the content of the IP packets.
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The first four bits identify the Internet protocol (IP) version. Today they can be used to represent IP version 4 or 6.
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The 32 bits starting at position 96 represent the source address.
Also read - Master Local Area Network (LAN) Topologies In Just A Few Hours!
The following tour bytes represent the destination address.
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Using the information in header, the nodes involved in the communication can understand and use IP packets.
Also read - Network Monitoring Tools HelpSystems Intermapper
Protocol layers
There are many protocols out there, each for a specific purpose.
Purpose like -
# Transmitting data.
# identifying computers on a network.
# Exchanging emails, files or performing VoIP calls.
# Establishing a communication between the a server and a client.
Instead of using specific examples, let's focusing on the features that a protocol provides-
# Use the physical media to send packets.
# identify hosts
# Make an application ( email client, FTP, browsers, ....) work.
# transport data between processes ( the server and the client programs ).
Moreover, we can rewrite the list again as:
# Application Layer
# Transport Layer
# Network Layer
# Physical Layer
These layers work on top of one another and every layer has its own protocols.
For example -
A few examples of application layer protocols are the Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Post Office Protocol (POP), Simple Mail Transfer Protocol (SMTP), and Domain Name System (DNS).
The application layer does not need to know how to identify a process on a host, how to reach it and how to use the copper wire to establish a communication.
It's just uses its underlying layers.
The OSI Model
The OSI (Open Systems Interconnection) Model is a standardised model which we use to demonstrate the theory behind computer networking. In practice, it's actually the more compact TCP/IP model that real-world networking is based off; however the OSI model, in many ways, is easier to get an initial understanding from. The OSI Model: An Overview
There are many mnemonics floating around to help you learn the layers of the OSI model -- search around until you find one that you like.
Let's briefly take a look at each of these in turn:
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Also read - The TCP IP Model in Networking
Encapsulation
So let's know how the protocols work with each other. If each protocol has header and payload, then how can the protocol use these lower layers?
The entire upper protocol packet ( header and payload ) is the payload of the lower one, this is called encapsulation.
TCP is the real world implementation of a networking stack and is the protocol stack used on the internet.
The TCP/IP model is, in many ways, very similar to the OSI model. It's a few years older, and serves as the basis for real-world networking. The TCP/IP model consists of four layers: Application, Transport, Internet and Network Interface. Between them, these cover the same range of functions as the seven layers of the OSI Model. The TCP IP Model in Networking
You would be justified in asking why we bother with the OSI model if it's not actually used for anything in the real-world. The answer to that question is quite simply that the OSI model (due to being less condensed and more rigid than the TCP/IP model) tends to be easier for learning the initial theory of networking.
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