INTERNET PROTOCOLS

INTERNET PROTOCOLS

Transmission Control Protocol (TCP)

TCP is a connection oriented protocol and offers end-to-end packet delivery. It acts as back bone for connection.It exhibits the following key features:

Transmission Control Protocol (TCP) corresponds to the Transport Layer of OSI Model.
TCP is a reliable and connection oriented protocol.
TCP benefits:
Stream Data Transfer.
Efficient Flow Control
Full-duplex operation.
TCP offers connection oriented end-to-end packet delivery.
TCP ensures reliability by sequencing bytes with a forwarding acknowledgement number that indicates to the destination the next byte the source expect to receive.
It retransmits the bytes not acknowledged with in specified time period.
TCP Services

TCP offers following services to the processes at the application layer:

Stream Delivery Service
Sending and Receiving Buffers
Bytes and Segments
Full Duplex Service
Connection Oriented Service
Reliable Service
Internet Protocol (IP)

Internet Protocol is connectionless and unreliable protocol. It ensures no guarantee of successfully transmission of data.

In order to make it reliable, it must be paired with reliable protocol such as TCP at the transport layer.



The length of datagram is variable.
The Datagram is divided into two parts: headerand
The length of header is 20 to 60 bytes.
The header contains information for routing and delivery of the packet.
User Datagram Protocol (UDP)

Like IP, UDP is connectionless and unreliable protocol. It doesn’t require making a connection with the host to exchange data. Since UDP is unreliable protocol, there is no mechanism for ensuring that data sent is received.



UDP is used by the application that typically transmit small amount of data at one time.
UDP provides protocol port used i.e. UDP message contains both source and destination port number, that makes it possible for UDP software at the destination to deliver the message to correct application program.
File Transfer Protocol (FTP)

FTP is used to copy files from one host to another. FTP creates two processes such as Control Process and Data Transfer Process at both ends i.e. at client as well as at server.

FTP establishes two different connections: one is for data transfer and other is for control information.
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FTP uses port 21for the control connection and Port 20 for the data connection.
Trivial File Transfer Protocol (TFTP)

Trivial File Transfer Protocol is also used to transfer the files but it transfers the files without authentication. Unlike FTP, TFTP does not separate control and data information. Since there is no authentication exists, TFTP lacks in security features therefore it is not recommended to use TFTP.

Key points

TFTP makes use of UDP for data transport. Each TFTP message is carried in separate UDP datagram.
The first two bytes of a TFTP message specify the type of message.
The TFTP session is initiated when a TFTP client sends a request to upload or download a file.
The request is sent from an ephemeral UDP port to the UDP port 69 of an TFTP server.
Telnet

Telnet is a protocol used to log in to remote computer on the internet. There are a number of Telnet clients having user friendly user interface.

Hyper Text Transfer Protocol (HTTP)

HTTP is a communication protocol. It defines mechanism for communication between browser and the web server. It is also called request and response protocol because the communication between browser and server takes place in request and response pairs.

HTTP Request

HTTP request comprises of lines which contains:

Request line
Header Fields
Message body
Key Points

The first line i.e. the Request linespecifies the request method i.e.Get or
The second line specifies the header which indicates the domain name of the server from where index.htm is retrieved.
HTTP Response

Like HTTP request, HTTP response also has certain structure. HTTP response contains:

Status line
Headers
Message body