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Introduction to TCP/IP Protocol layers

Introduction to TCP/IP Protocol: In this post, we share knowledge TCP/IP Protocol and its layers and at the end, you will be able to describe IP addressing and discuss IPv4 addressing for more

Introduction to TCP/IP Protocol layers

TCP/IP is the communication protocol for the internet. It is a protocol suite which has two protocols:

  • Transmission control protocol:
  1. Assembles the message to be transmitted over the network into smaller data packets
  2. Reassembles the received packets into the original message
  • Internet Protocol:
  1. Manages the address of each data packet so that the data packet reaches the right destination. This is known as an IP address.

It is also known as the Internet protocol suite. TCP/IP is based on the client/server model of communication. The client computer sends requests to the server such as opening a web page. The server provides services such as connecting to the web page and giving access to that web page. Each client request in TCP/IP is an independent request, not related to the previous one. Hence it does not require a dedicated connection.

TCP/IP Model

The TCP/IP model is a set of protocols that defines how two or more computers can communicate with each other on the Internet. There are many protocols working within the TCP/IP model. These protocols provide various functionalities that are important for data transmission over the networks.

TCP/IP is composed of four layers, as shown in the following figure:

introduction to tcp ip protocol-TCP/IP addressing and IP addressing
introduction to tcp ip protocol-TCP/IP addressing and IP addressing

the description of TCP/IP layers:

Network Interface Layer/ Network Access Layer:

  • responsible for this placing or receiving of TCP/IP packets on or off the network medium.
  • includes ethernet, token ring, and WAN technologies.

Internet Layer:

  • responsible for IP addressing and routing functions

Transport Layer:

  • manages the rate of data flow
  • manages reliability of data

Application Layer:

  • provides the applications with access to services
  • defines the protocols that the applications will use for exchanging data

Layers of TCP/IP Protocol

There are four layers of TCP/IP protocol which are further classified on the basis of their functionalities as shown in the following image:

introduction to tcp ip protocol-TCP/IP addressing and IP addressing
introduction to tcp ip protocol-TCP/IP addressing and IP addressing

Application layer protocol

This layer provides the applications with access to services and defines the protocols that the applications will use for exchanging the data

Telnet

Telnet is a protocol used by the network users to communicate with and to access the network devices. To access telnet, the user must have installed telnet client software.

SSH

It is a network protocol that is used by the administrators to access a remote device in a secure way. Unlike telnet, SSH uses encryption, which means that all the data is transmitted securely over the network.

FTP

It is a standard protocol. It is responsible for the transfer of computer files to the client from a server using the server-client model architecture. FTP supports user authentication and sends all data in clear text.

TFTP

It is a utility internet software used to transfer simpler files between remote devices. Unlike FTP, TFTP is less capable of transferring heavy files and lacks advanced features of FTP.

HTTP

HTTP is an application protocol also known as a client-server protocol. It allows the client to request a web page from the web servers. It is the base for data communication of the World Wide Web (www).

DNS

DNS is an internet service protocol. It is responsible for translating domain names into their corresponding IP addresses. It is user-friendly because domain names are easier to remember than IP addresses.

Transport Layer Protocol

Transport layer protocol is also known as host to host protocol because it provides host to host services such as flow control, reliability and communication services. The two main layers of the transport protocol are described as follows:

TCP

It assembles the messages to be transmitted over the network into smaller data packets and reassembles the received packets into the original message. It is connection-oriented, which means before data is sent, a connection between the two hosts must be established.

UDP

UDP is a transport layer protocol and it is used with internet layer protocol for the transmission of data between applications running on a TCP/IP network.

UDP is also considered to be a connectionless protocol since no virtual circuit is established between the two endpoints before the data transfer takes place. Because it does not provide as many features as TCP, it uses lesser network resources than TCP.

Internet Layer Protocol

Internet layer protocol performs IP addressing as well as routing functions. It enables the packet to travel on its own to the destination. The pattern in which the packets are received is altered before they are dispatched.

IP Protocol

IP protocol is a set of internetworking methods in the IP suite. Its responsibility is to send packets from the host to the destination, as described by the IP address. This IP address is defined by the IP.

ICMP

ICMP is also known as error reporting protocol because it is used by the networking devices like a router to generate or send error messages such as an error in the delivery of IP datagrams (packets) or non-availability of requested service.

ARP

It is a communication protocol which is used to map an IP address to its corressponding physical or hardware address.

Network Access layer Protocol

It is responsible for the placing or receiving of TCP/IP packets on or off the network medium and includes Ethernet token ring and WAN technologies.

The protocols used at network access layer are as discussed:

Ethernet

It is a local area network (LAN) technology which describes how the networking devices format the data for transmission to other network devices. It is in connection with the first layer or the second layer of the OSI model.

Token Ring

It is another LAN technology where all the computers are linked together in the form of ring or star topology. In this, to prevent the data collision between two computers, a token scheme is used.

FDDI

FDDI is used for data transmission of information. It uses fiber-optic lines as its physical medium in a LAN. It works on a token ring scheme and its range can extend up to 200km.

Introduction to IP Addressing

An IP address is an exclusive identifier for a computer or any other device attached to the network. It is a 32-bit value. IP addresses are written in four decimal numbers, which are separated by dots. Each section ranges from 0to255. For example, 172.16.254.2 would be the IP address of a node. When the address is converted to binary, each section contains 8-bit, which is called an octet.

IP Terminology

  • Bit: It represents either 1 or 0.
  • Byte: A byte consists of 7 or 8 bits, depending on the parity digit.
  • Octet: An octet is made up of 8bits.
  • Network Address: It is the starting up the address of a network. It is the identity of that network.
  • Broadcast Address: It is the last IP address of a network and is used to send information to all the available nodes on the same network.

The following figure depicts the dotted decimal notation of the given IP address:

introduction to tcp ip protocol-TCP/IP addressing and IP addressing
introduction to tcp ip protocol-TCP/IP addressing and IP addressing

IP addresses are also known as host addresses.

In a TCP/IP network, the routers pass data packets between networks without knowing the exact location of the destined host. They only know the network of the host. They deliver a packet to the networks without knowing the exact location of the destined host. They only know the network of the host. They deliver a packet to the network and then using the information stored in the router, the packet is delivered to the host . For this purpose, the IP address contains two parts:

  • First part is the network address
  • The second part is the host address.

To locate devices in a distributed environment, which are different networks connected to each other, the nodes are assigned explicit addresses that identify the network in which the device is on and also identify the device in that particular network. When these two unique identifiers are combined, it is a globally unique address.

Example

IP address: 192.168.13.123

Network Address: 192.168.13.0

Host Address: 0.0.0.123

Types of IP Addresses

Based on their operational characteristics, the IP addresses are divided into three categories as shown in the following figure:

Unicast IP addressMulticast IP addressBroadcast IP address
1. It is an address of a single interface.
2. The IP addresses of this type are utilized for one-to-one communication.
3. Unicast IP addresses are utilized to send direct packets only to a specific host.
1. It is used for one-to-many communication.
2.IP multicast group addresses receive multicast messages from this IP address.
3. Only those hosts that need to receive the message will process the packets.
1. It is utilized to send data or information to all available targets in the broadcast domain(the one-to-everybody communication).
2 In this, the packets send by the host is accepted by every server in the broadcast domain.

IPv4 Addressing

IPv4 is a 32-bit address that is displayed in dotted decimal notation.

In this, the five classes of IP addresses, which are class A, B, C, D, and E, are defined by TCP/IP. Each class has a unique set of valid IP addresses.

The class is determined by the value of the first octet. The host address uses the first three classes of IP addresses(A, B and C). The remaining two classes are used for other purposes such as class D for multicast and class E for experimental purposes.

The following table represents different types of classes used in IPv4 addressing:

ClassLeading bitsNumber of NetworksAddress per Networkstart AddressEnd Address
Class A0128( 27) 16,777.216( 224) 0.0.0.0127.255.255.255
Class B1016,384(214 )65,536( 216) 128.0.0.0191.255.255.255
Class C11020,97,152( 221 )256( 28 )192.0.0.0223.255.255.255
Class D(multicast)1110Not definedNot defined224.0.0.0239.255.255.255
Class E (reserved)1111Not definedNot defined240.0.0.0255.255.255.255

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