CHAPTER-2 : TCP/IP Internet Technology and Protocol

Internet Protocol

Protocol means that the set of rules or to enable computers to be connected with one another and to exchange information with very little error

The most commonly used Internet Protocol

1) Internet Protocol (IP)
2) Internet control message protocol (ICMP)
3) transmission control protocol (TCP)
4) User datagram protocol (UDP)
5) Address resolution protocol (ARP)

1) Internet Protocol (IP)

- Internet protocol is the primary network protocol

- IP supports the unique addressing for computers on a network.

- It contains addressing information and some control information that enables packets to be routed.

2) Internet Control Message Protocol (ICMP)

- It is a message control and error-reporting protocol

- between protocol a host server and a gateway to the internet

3) Transmission Control Protocol (TCP)

- TCP is a set of the rule used along with the IP protocol 

- which means that TCP works with the IP protocol 

- Used to send data in the form of message units between different computers over the internet.

- The TCP protocol is responsible for ensuring that a message is divided into the packets.

- IP protocol is responsible for re-assembling the message packets back into the complete message at the other end.

- In the OSI communication model, TCP is worked in layer 4

4) User Datagram Protocol (UDP)

- UDP is a connectionless protocol that works at the transport layer.

- UDP transport datagrams but does not acknowledge their receipt.

- If UDP detects some error while transmitting a datagram, it simply drops the datagram and doesn't inform the sender about the same.

5) Address Resolution Protocol (ARP)

- ARP is used for mapping an IP address into a physical machine address that is recognized by the local network.

- When the incoming packets destined for a host machine (the computer which connects to the internet) on a particular local area network arrives at a gateway.

- the gateway asks the ARP Protocol to find a machine address that matches the IP address.

Packet Switching Technology

- Long messages are broken into smaller units called packets, packets are sent continually as long as there is a message to be sent.

- When data is sent from one computer to another, it is broken into pieces called packets using the TCP protocol.

- Each Packet has the address of the sender and also the destination address called IP address.

- These packets are sent from one network to another till they all reach their destination, At the destination, the TCP re-assembles the packets into the complete message.

- A large message may be divided into thousands of individual packets. The beginning of a packet is called "header" and contains the following records 

  a) source address
  b) destination address
  c) length  

OPEN SYSTEM INTERCONNECTION (OSI)

The open system interconnection (OSI) model defines a networking framework to implement protocols in seven layers. 

Use this handy guide to compare the different layers of the OSI model and understand how they interact with each other.

Application layer: This layer provide the user interface using the application software.

Presentation layer: It converts the data into suitable formate. It does like encryption and decryption.

Session layer: This layer manages connections between different application layers.

Transport layer: This layer convert the data into segments and re-assembles the data stream. TCP and UDP are the protocols used in the layer.

Network layer: This layer decided the best path for data for transmission.
The router works in this layer.

Data-link layer: It adds source and destination address to packets and converts them into frames. This layer provides error-free transmission.

Physical layer: In this layer, data is carried from one device to another using wired or wireless. 

TCP/IP MODEL

- TCP/IP is an industry-standard protocol suite for WAN

- This model developed in the 1970s and 1980s by the US department.

- TCP/IP is a routable protocol that is suitable for connecting the dis-similar system.

e.g  Linux ----- window

       Unix -----  window

- The four DOD model layers and the OSI layers make it TCP/IP model

First Layer (Application)

- The process of application layer corresponds to the OSI session, presentation at the application layer.

- Protocols at this layer provide application services on the network

- Examples of Protocols at this layer are ;
   telnet (terminal emulator)
   FTP (file transfer protocol)

Second Layer (Host to Host Layer)


 - The host to the host layer corresponds to the transport layer.


- Protocol at this layer communicate with peer processes is another host of network devices an example of the host to host protocol is TCP (Transmission Control Protocol).

Third Layer (Internet Layer)

- The Internet layer corresponds to the OSI network layer. 

- Protocols at these layers are corner with transporting the packet through the Internetwork. 


- The main internet protocol is IP.

Fourth Layer (Network Layer)

The Network Access layer corresponds to the physical and data link layer of the OSI model.

Note: Internet (DOD) model and TCP/IP model both are same.

ROUTER

- Routers are the Network device.

- It is a combination of hardware and software.

- that help in determining the best path out of the available path, for a particular transmission.

- They accomplish this connection by organising the large network into logical network segments or sub-networks. 

- Routers are used logical and physical addressing to connect two or more logically separate networks.

Internet Addressing Scheme

The internet has more than a million computers attached to it.

In order to communicate every computer connected to the internet has a unique address whose format is define by the IP addressing system.

Note: An IP address is a number that represents a single unique computer on the internet.

1) Letter Addressing system

In this addressing system, the last three letters of the address are important because they provide information about the kind of organization to which the address belongs.

.edu                       Educational Institution

.com                      Commercial organization

.org                        Non-profit organization

.gov                       government department

.co                         company

The letter addressing system also uses country codes comparing two letters.

ca                          for Canada

jp                          for Japan

in                          for India

uk                         for united kingdom 

2) Number Addressing System

A numeric address called IP address is made up of four numbers, each less than 256, join together by a period such as;

192.12.248.73.  or   131.58.97.254

Note: IP address is the identifier for a particular machine (computer) on a specified network.

E-mail Addresses

An Email programme enables us to send, receive and manage our messages.

Email address commonly take this form

                               username@hostname

e.g abhisharma1923008@gmail.com

Resource Addresses

Uniform resource locator refers to the address on the internet. Billions of document multimedia files can be excesses on the internet using their URL.

The URL contains the following information;

- The internet name of the site containing resources (domain name).

- The type of service the resource is served (HTTP, FTP, etc).

- The internet port number (e.g http used port number 80, https used port number 443).

- The location of a resource in the directory structure of the server.

Type of URL

i) Absolute URL

- It is the complete path including the domain

e.g  

https://abhisharmaofficial.blogspot.com/2020/04/chapter-1-introuction-to-internet.html

- An absolute URL is a fully qualified URL that specified the location of a resource that resides on internet.

ii) Relative URL

- A partially qualified URL is the one that specified only the location of the resource on the internet and known as relative URL.

e.g abhisharmaofficial.blogspot.com

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