Protocols in computer network

As we all know that rules are very important and required for the smooth functioning of every institution. Similarly, in a computer system we have PROTOCOLS are nothing but the rules and regulations in the context of a computer system. They can be implemented by hardware, software or a combination of both.

WHAT EXACTLY IS A PROTOCOL?

Rules and conventions explaining how something must be done.

Used to describe how devices can communicate. Protocol also defines the format of data i.e. to be

exchanged....

TCP/IPIt is the most important protocol consisting of a set of

communication protocols. Transmission control protocol (TCP) and the Internet Protocol (IP) were the first networking protocol.

Its functionality is organized into four abstraction layers which are used to sort all related protocols according to the scope

of networking involved.

In computer networking, we have a process called Encapsulation which is used to provide abstraction of protocols

and services. It is a method of designing Modular Communication in which a system is divided into small parts called modes or logically separate functions in a network are

abstracted from their underlying structures by inclusion or information hiding.  In general, an application (the highest level of

the model) uses a set of protocols to send its data down the layers, being further encapsulated at each level.

The four abstract layers are arranged as follow:

APPLICATION LAYERIt is where applications create user data and communicate this data to other applications on another or the same host. This uses services provided by the lower layers, especially the Transport Layer. TRANSPORT LAYERIt performs host-to-host communications on either the same or different hosts and on either the local network or remote networks. INTERNET LAYERThe internet layer has the task of exchanging datagrams across network boundaries.

LINK LAYERIt defines the networking methods within the scope of the local network link on which hosts communicate without intervening routers. 

POP3 IMAP SMTP

POP3 stands for Post Office Protocol. POP3 allows an email client to download an email from an email server. The POP3 protocol is simple and does not offer many features except for download. Its design assumes that the email client downloads all available email from the server, deletes them from the server and then disconnects. POP3 normally uses port 110.

SMTP stands for Simple Mail Transfer

Protocol. SMTP is used when email is delivered from an

email client, such as Outlook Express, to an email server or

when email is delivered from one

email server to another. SMTP uses

port 25.

IMAP stands for Internet Message Access Protocol. IMAP shares many similar features with POP3. It, too, is a protocol that an email client can use

to download email from an email server. However, IMAP includes many more features than POP3. The IMAP protocol is designed to let users keep their email on the server. IMAP requires more disk space on the server and

more CPU resources than POP3, as all emails are stored on the server. IMAP normally uses port 143.

VoIP Voice over IP or VoIP is a methodology and group of technologies for the delivery of voice communications and multimedia sessions over IP networks. It has been implemented in various ways using both proprietary protocols and protocols based on open standards.

WORKING OF VoIPVoIP systems employ session control and signaling protocols to control the signaling, set up and teardown of calls. They transport audio streams over IP networks using special media delivery protocols that encode voice, audio, video with audio codecs, and video codecs as Digital audio by streaming media. Various codecs exist that optimize the media stream based on application requirements and network bandwidth; some implementations rely on narrowband and compressed sheet, while others support high fidelity stereo codecs.

PSTN (Public Switched Telephone network) is the world's collection of interconnected voice-oriented public telephone networks, both commercial and government-owned.

For option 2, no internet is provided because connectivity is dedicated to voice data which assures high quality calls.

RTSPThe Real Time Streaming Protocol (RTSP) is a network

control protocol designed for use in entertainment and communications systems to control streaming media servers. The protocol is used for

establishing and controlling media sessions between end points. Streaming media is multimedia that is constantly received by and presented to an end-user while being delivered by a provider. The

transmission of streaming data itself is not a task of RTSP. Most RTSP servers use the Real-time Transport Protocol (RTP) in conjunction with Real-time Control Protocol (RTCP) for media stream delivery.

However, some vendors implement proprietary transport protocols. While similar in some ways to HTTP, RTSP defines control sequences useful in controlling multimedia playback. While HTTP is stateless, RTSP has state; an identifier is used when needed to track concurrent sessions. Like HTTP, RTSP uses TCP to maintain an end-to-end connection and, while most RTSP

control messages are sent by the client to the server, some commands travel in the other direction (i.e. from server to client).

HTTPS

HTTPS, also known as HTTP secure is a protocol for secure communication over a computer network which is widely used on internet. The main motivation for HTTPS is authentication of the visited website and protection of the privacy and integrity of the exchanged data. HTTPS creates a secure channel over an insecure network. This ensures reasonable protection from eavesdroppers and man-in-the-middle attacks, provided that adequate cipher suites are used and that the server certificate is verified and trusted.

How does HTTPS work?

DMCPThe Dynamic Host Configuration Protocol (DHCP) is a standardized network protocol used on Internet Protocol (IP) networks.

 When a computer or other networked device connects to a network, the DHCP client software sends a broadcast query requesting necessary

information. Any DHCP server on the network may service the request. The DHCP server manages a pool of IP addresses and information about client

configuration parameters such as default gateway, domain name, the name servers, and time servers.

On receiving a request, the server may respond with specific information for each client, as previously configured by an administrator, or with a

specific address and any other information valid for the entire network and for the time period for which the allocation (lease) is valid. A client typically

queries for this information immediately after booting, and periodically thereafter before the expiration of the information. When a DHCP client

refreshes an assignment, it initially requests the same parameter values, but the DHCP server may assign a new address based on the assignment

policies set by administrators.

ICMPThe Internet Control Message Protocol (ICMP) is used by network devices, like routers, to send error messages. ICMP can also be used to relay query messages. It is assigned protocol number 1.  ICMP messages are typically used for diagnostic or control purposes or generated in response to errors in IP operations. ICMP errors are directed to the source IP address of the originating packet.

UDPUDP stands for User Datagram Protocol .In UDP, the receiver does not generate an acknowledgement of packet received and in turn, the sender does not wait for any acknowledgement of packet sent. UDP provides two services not provided by the IP layer. It provides port numbers to help distinguish different user requests and, optionally, a checksum capability to verify that the data arrived intact. UDP is unreliable and connectionless. FTPThe File Transfer Protocol (FTP) is used to transfer computer files between a client and server on a computer network. It is the simplest and most secure way to exchange files over the internet. FTP is built on client-server model architecture and uses separate control and data connections between the client and the server. FTP users may authenticate themselves with a clear-text sign-in protocol, normally in the form of a username and password, but can connect anonymously if the server is configured to allow it. FTP may run in active or passive mode, which determines how the data connection is established. In both cases, the client creates a TCP control connection from a random, usually an unprivileged, port N to the FTP server command port 21.

In active mode, the client starts listening for incoming data connections from the server on port M. It sends the FTP command PORT M to inform the server on which port it is listening. The server

then initiates a data channel to the client from its port 20, the FTP server data port.

In situations where the client is behind a firewall and unable to accept incoming TCP connections, passive mode may be used. In this mode, the client uses the control connection to send a PASV command to the server and then receives a server IP address and server port number from the server, which the client then uses to open a data connection from an arbitrary client port to the server IP address and server port number received.

ARPThe Address Resolution Protocol (ARP) is a protocol used by the Internet Protocol (IP)  to map IP network addresses to the hardware addresses used by a data link protocol. The protocol operates below the network layer as a part of the interface between the OSI network and OSI link layer. It is used the most commonly used link layer protocol for (LANs) is Ethernet and is used to support a range of network layer protocols, including IP.

The address is "resolved" using a protocol in which a piece of information is sent by a client process executing on the local computer to a server process executing on a remote computer. The information received by the server allows the server to uniquely identify the network system for which the address was required and therefore to provide the required address. This process ends when the client receives a response from the server containing the required address. Below is the Format of an ARP message used to resolve the remote MAC Hardware Address (HA):

It is basically a model that characterizes and standardizes the communication functions of a

telecommunication or computing system. Its main goal is to operate communication systems with standard protocols.  The model partitions a communication

system into abstraction layers that are somewhat similar to the ones we learned about earlier.

TELNETTelnet is an application layer protocol used on the Internet or local area networks to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. User data is interspersed in-band with Telnet control information in an 8-bit byte oriented data connection over the Transmission Control Protocol (TCP). It is also known as the first Internet.In the old days, you had to physically walk to a server in order to access its data. Even if the server had the hardware power to do multiple things at the same time, you were blocked from using it at its full and you had to wait for others to finish their work first. In many circumstances we couldn't even touch the actual server.

Telnet brought extraordinary change. Using it meant you could simultaneously connect multiple users to a single server. In order to connect to the server, people only needed access to a terminal, which could be the simplest and cheapest computer available. This computer didn't need to have powerful hardware, it only needed a network connection and a text based interface.

NAME - PRIYACLASS - 10-CROLL NO. – 26

COMPUTER PROJECT FILE

PROTOCOLSSUBMITTED TO –

MS. GEETU MA’AM