Through The Internet

Through The Internet

Before proceeding, have a look at the video....

Traceroute:

Following are the steps which one can follow to get familiar with the traceroute program:

• If you are using Windows, open the command prompt.

• Type in the command tracert google.com

• You can type any destination address like 'yahoo.com' , 'blogger.com' etc. Also the command may vary depending upon which OS you are using.

• From here on the program will do the rest of the work.

• Here is a screenshot of the output.Lets try to understand it.

• As you can see after the command is typed in, the next row displays the server name (google.com) followed by its address [216.58.203.174]

• The next line indicates that the program will log records for maximum 30 nodes (routers or end systems).

• The main output has five columns, the first being the number of router along the route.Technically, they represent TTL (Time To Live) of the packets sent by traceroute program. TTL prevents the packets from being forwarded till the destination.

• The second column is the time elapsed from the instant packet is sent till the message arrives back to client PC (have a look at the video for better understanding) in milliseconds.

• Actually three packets are sent to each router instead of one and the round-trip time required for subsequent two packets is logged into the third and fourth column.

• The fifth column displays the address of the router.

• In above output we can see that there are 12 routers between our client and the server.

• At the 13th hop the destination address is reached.

• The second output displays ' Request Timed Out ' error which implies that the router has blocked ICMP (Internet Control Message Protocol) traffic and doesn't respond to requests for information.

• The traceroute program is used to measure the end-to-end delay.

• They are often used to diagnose speed issues in computer networking.

Now go on, experiment with the traceroute program yourself !

Internet Jargon

Internet Jargon

Internet:

           Internet is a global computer network which provides services to various                applications by using standardized protocols.

Internet

End Systems:

• End systems are devices like laptop,desktop,mobile etc which sit at the end of computer networks and run various applications like email,web browser program, web server programs etc.

• End systems are also referred to as hosts.

End Systems

• There are two types of hosts:clients and servers

• The clients can access data or services provided by the server.

Clients and Servers

Communication Links:

Communication links are physical media like optic fiber,coaxial cable or radio spectrum which connects two communicating devices.

Radio Spectrum for Communication

Network Cables

Transmission Rate:

• Transmission Rate is defined as number of bits transmitted in unit time.

• Its unit is Bits/Second.

Packets:

• When data is to be sent through a communication link from one end system to the other it is segmented into packets.

• Every packet has header bits which contain information about the destination where it is to be sent.

Packet Switch:

A packet switch takes packet arriving at one of its incoming communication link and sends it to one of its outbound link according to destination address.

Packet Switch

Route/Path:

Route or Path is the sequence of communication links and packet switches traversed by a packet from sending end system to receiving end system.

ISP(Internet Service Provider):

                      According to Wikipedia ISP(Internet Service Provider) is an organization that provides services for accessing, using, or participating in the Internet. 

   

Protocols:

• Protocols define the format and order of messages exchanged between two communicating devices.

• Internet standard protocols are developed by IETF(Internet Engineering Task Force).

• The standard documents are called RFCs (Requests For Comments).

Access Networks:

• An access network is a type of network which physically connects an end system to the immediate router (also known as the “edge router”) on a path from the end system to any other distant end system.

• Example of access networks are DSL(Digital Subscriber Link), FTTH(Fiber To The Home), HFC(Hybrid Fiber Coaxial Network) etc.

Evolution of Internet

EVOLUTION OF THE INTERNET

Evolution of the Internet

1964:

• Leonard Kleinrock was the first person to publish his work on packet  switching in 1964.

• Paul Baran in 1964 at Rand Institute used packet switching for voice over military network.

• Roger Scantlebury worked with Donald Davies on his pioneering packet switching concept at NPL i.e. National Physical Laboratory in England.

Leonard Kleinrock

Paul Barran

Rojer Scantlebury

Donald Davies

1969:

• For the first time in 1969, Lawrence Roberts published the complete plan for ARPAnet ,first packet switched computer network.

• On May 1 1969 i.e. Labor Day first packet switch was installed at (UCLA) University Of California, Los Angeles followed by (SRI) Stanford Research Institute and University Of Utah.

Lawrence Roberts

1972:

• ARPAnet had grown to 15 nodes and its demonstration was given by Robert Kahn.

• The first host-to-host protocol known as (NCP) Network Controlled Protocol was completed by 1972.

• Ray Tomlinson wrote e-mail program in 1972.

Robert Kahn

Ray Tomlinson

Other networks which used packet switching:

• ALOHAnet

• DARPA's packet satellite and packet-radio network

• Cyclades

• IBM's SNA

1980:

• Minitel was launched in France .

• The Minitel was a videotex online service accessible through telephone lines, and was the world's most successful online service prior to the World Wide Web.

•  It was invented in Cesson-Sévigné, near Rennes in Brittany, France.

• The service was rolled out experimentally in July 1980 in Saint-Malo, France, and from autumn 1980 in other areas, and introduced commercially throughout France in 1982 by the PTT (Postes, Télégraphes et Téléphones; divided since 1991 between France Télécom and La Poste).

1983:

• On January 1, 1983, in what is known as a "flag day", NCP was officially rendered obsolete when the ARPANET changed its core networking protocols from NCP to the more flexible and powerful TCP/IP protocol suite, marking the start of the modern Internet.

1989:

• The web was invented at CERN by Tim Berners-Lee in 1989.

• Berners-Lee proposed an information management system, on 12 March 1989, then implemented the first successful communication between a Hypertext Transfer Protocol (HTTP) client and server via the internet, in mid-November of the same year.

Tim Berners-Lee

1990: 

• ARPANET shuts down in 1990.

1991:

•  NSFNET lifted its restriction for use in commercial purposes in 1991.

• For much of the period from 1987 to 1995, following the opening up of the Internet through NSFNET and in particular after the creation of the for-profit ANS CO+RE in May 1991, some Internet stakeholders were concerned over the effects of privatization and the manner in which ANS, IBM, and MCI received a perceived competitive advantage in leveraging federal research money to gain ground in fields in which other companies allegedly were more competitive.

                                                      

2006:

• In 2006, Amazon launched its Elastic Compute Cloud (EC2) as a commercial web service that allows small companies and individuals to rent computers on which to run their own computer applications.

• Amazon announced a limited public beta test of EC2 on August 25, 2006, offering access on a first-come, first-served basis.
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THE INTERNET CONTINUES TO EVOLVE AND CHANGE OUR LIVES IN ALL ASPECTS UNIMAGINABLE!!

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