The Internet

The Internet

The network of networks: Inter-network (Internet)

The Internet• The networks communicate with one another based on certain

protocols, such as the TCP/IP - Transmissin Control Protocol (TCP) and the Internet Protocol (IP).

• Tens of thousands of networks makes the Internet and these networks ranging from

– University networks to

– Corporate networks to

– ISP (Internet Service Provider) networks.

• Everytime you dial into your ISP, your own computer becomes part of the Internet.

Network Components

DATA COMMUNICATIONS NETWORKS

Data Communications

• Data CommunicationsThe movement of computer information from one point to

another by means of electrical or optical transmission systems.

Such systems are often called data communications networks.

• TelecommunicationsIncludes the transmission of voice and video as well as

data.

Components of a Network

• Server (or Host computer)Central computer in the network, storing data or software

that can be accessed by the clients.

• ClientThe input/output hardware device at the other end of a

communications circuit.

• CircuitThe pathway through which the messages travel.

Components of a Network

Components of a Network

• Peer-to-peer networksDo not need a server or host, but are designed to connect

similar computers which share their data and software with each other.

Microcomputer networks are connected by a hub and cables (circuit).

A router is used to connect two or more networks, enabling computers on one network to communicate with computers on other networks (e.g. the Internet).

Types of Networks

Networks can be classified in many different ways. One of the most common is by geographic scope:– Local Area Networks (LAN)– Backbone Networks (BNs)– Metropolitan Area Networks (MANs)– Wide Area Networks (WANs)

Types of Networks

Network

Local area network

(LAN)

Metropolitan area network

(MAN)

Wide area network

(WAN)

Local Area Network

Types of Networks

• Local Area Networks (LAN)A group of microcomputers of terminals located in the

same general area and connected by a common circuit.

Covers a clearly defined small area, such as within or between a few buildings,

Support data rates of 10 to 100 million bits per second (Mbps).

Local Area Network

Types of Networks

• Backbone Network (BN)A larger, central network connecting several LANs,

other BNs, metropolitan area networks, and wide area networks.

Typically span up to several miles.

Support data rates from 64 Kbps to 45 Mbps.

Metropolitan Area Network

Types of Networks

• Metropolitan Area Network (MAN)Connects LANs and BNs located in different

areas to each other and to wide area networks.

Typically span from 3 - 30 miles.

Supports data rates of 100 to 1000 Mbps.

Wide Area Network

Types of Networks

• Wide Area Network (WAN)Connects BNs and MANs and are usually leased

from inter-exchange carriers.

Typically span hundreds or thousands of miles.

Supports data rates of 28.8 Kbps to 2 Gbps.

The Internet

Also known as:

• Information Superhighway

• Cyberspace

The Internet is packet-switched

• The main difference between the Internet and the other networks (e.g., Telephone) is that it is packet-switched not circuit-switched.

• A packet switch network doesn't need to hold all channels in contrast to circuit switched thus maximize the use of network capacity.

Circuit switching holds all channels

Packet switching does not hold all channels

Packets

A single Packet

Ethernet Packet Header

History of the Internet

• What we call the internet today started in 1969 as the US military’s answer to the problem - possibilities of loosing centralized communication services during war.

• Decentralization was the solution and the result was ARPANET.

• ARPANET (Advanced Research Projects Agency NETwork) started with 4 nodes.

• It was the first operational packet-switched network. The Internet now connects millions of computers around the world into one huge network.

History of the Internet

• In the last 15 years the number of connections to the Internet has roughly doubled each year. Estimated number of users will be 45 million worldwide.

• For up-to-date statistics on the Internet see:– Georgia Institute of Technology's Survey:

http://www.cc.gatech.edu/gvu

– Network Wizards Internet Domain Survey:http://www.nw.com

– For the size of the Internet:http://info.isoc.org/guest/zakon/Internet/History/hit.html

History of the Internet• 1969

– ARPANET hosts start using Network Control Protocol (NCP).

• 1973 First international connections to the ARPANET:

University College of London (England) and Royal Radar Establishment (Norway)

• 1982

– DCA and ARPA establish the Transmission Control Protocol (TCP) and Internet Protocol (IP), as the protocol suite, commonly known as TCP/IP, for ARPANET.

This leads to one of the first definitions of an "Internet" as a connected set of networks, specifically those using TCP/IP, and "Internet" as connected TCP/IP Internets.

DoD declares TCP/IP suite to be standard for DoD

History of the Internet• 1984

– Domain Name System (DNS) introduced.

– Number of hosts breaks 1,000

• Canada begins a one-year effort to network its universities. The NetNorth Network is connected to BITNET in Ithaca from Toronto.

• 1986

– NSFNET created (backbone speed of 56Kbps)

• 1988

– DoD chooses to adopt OSI and sees use of TCP/IP as an interim.

– NSFNET backbone upgraded to T1 (1.544Mbps)

– Internet Relay Chat (IRC) developed by Jarkko Oikarinen

– First Canadian regionals join NSFNET: ONet via Cornell, RISQ via Princeton, BCnet via Univ. of Washington

History of the Internet• 1989

– Number of hosts breaks 100,000

• 1990

– ARPANET ceases to exist

– CA*net formed by 10 regional networks as national Canadian backbone with direct connection to NSFNET

• 1992

– Number of hosts breaks 1,000,000

• 1993

– InterNIC created by NSF to provide specific Internet services: directory and database services (AT&T) registration services (Network Solutions Inc.) information services (General Atomics/CERFnet)

• 1994

– Number of hosts breaks 4,000,000

• 1998

– Number of hosts breaks 30,000,000

Internet Address:• Internet addresses are strictly regulated; otherwise, someone could add a

computer to the Internet that had the same address as another computer.

• Each address has two parts:

- the computer name and

- the domain name

• The general format of an Internet Address is:

• computer.domain

• computer.3rdLevelDomain.2ndLevelDomain.TopLevelDomain

• Domain names provide a system of easy-to-remember Internet addresses, which can be translated by the Domain Name System (DNS) into the numeric addresses (Internet Protocol, IP numbers) used by the network.

• csplinux.saultc.on.ca

• 192.197.90.11

Domain• A subset of the total domain name space. A domain represents a

level of the hierarchy in the Domain Name Space, and is represented by a domain name. For example, the domain name saultc.on.ca represents the third level domain saultc which is a subset, or sub-domain, of the second level domain on which is a subset, or sub-domain, of the top level domain ca, which is in turn a larger subset of the total Domain Name Space.

– If you think of the Domain Name Space as a tree, a domain would be analogous to a limb and would encompass all of the branches of that limb.

• Each domain has an addressing board that assigns addresses for its domain. Mainly to avoid duplicates.

• e.g., top-level domain, second level domain, third level domain administrators, etc.

Top-Level Domains

• There are two types of top-level domains, generic and country code. Generic domains were created for use by the Internet public, while country code domains were created to be used by each individual country as they deemed necessary.

Generic Domains (.com, .org, .net, .edu, .gov, .mil, .int) Country Code Domains (.us, .ca, .jp, .uk, etc.)

Generic Domains

• com commercial

• org nonprofit organizations

• net organizations tied to Internet administrative bodies

• edu educational institutions, usually universities

• gov government department or agencies

• mil military unit

• int organizations established by international treaties between governments or Internet infrastructure databases

Country Code Domains

• us for United States of America

• ca for Canada

• jp for Japan

• uk for United Kingdom

A new set of 7 North American Generic Domains

• firm Business or firms

• store Business offering goods for purchase

• web entities emphasizing activities related to the Web

• arts entities emphasizing cultural and entertainment activities

• rec entities emphasizing recreation/entertainment activities

• info entities providing information services

• nom for those wishing individual or personal nomenclature

Internet Assigned Numbers Authority (IANA)

• A new non-profit organization with an international Board of Directors to oversee the operations of the necessary central coordinating functions of the Internet is being proposed.

• The United States government, as a custodian of the work started by the Defense Advanced Research Projects Agency and now supported by National Science Foundation funding that created the Internet and IANA (http://www.iana.org/).

The .ca domain

• The .ca domain maintains a web site with information, registration templates, and a domain search at: http://www.cdnnet.ca/

• The .ca domain is intended to be a useful, manageable means to refer to Canadian computing and communications resources within the worldwide Internet. The ca domain is registered with the Internet Assigned Numbers Authority (IANA) , the authority for top-level Internet domains.

• ca is the two-letter code for Canada according to the ISO 3166 standard (http://www.iana.org/country-codes.txt) used for country domains.

The .ca domain• The CA domain was registered with IANA in May, 1987.

The main goal was to use names that makes sense to people.

• The CA domain is structured according to Canadian political geography with entities registered at appropriate level.

– CA

- national organization

- province/territory

- provincial/territorial organization

- locality (e.g. city, town)

- residential person

- municipal organization 

Other registries

• Refer to the list of other registries or use the WHOIS database at rs.internic.net to determine which entity is the domain authority for a country by typing the country's ISO 3166 two-letter country code (listed in http://www.iana.org/country-codes.txt) followed by the suffix -DOM.

• For example: Whois: US-DOM

Whois

• A searchable database maintained by Network Solutions, which contains information about networks, networking organizations, domain names, and the contacts associated with them for the com, org, net, edu, and ISO 3166 country code top level domains. Also, the protocol, or set of rules, that describes the application used to access the database. Other organizations have implemented the Whois protocol and maintain separate and distinct Whois databases for their respective domains.

InterNIC

• InterNIC is project operated under a cooperative agreement with the National Science foundation (NSF). Under this agreement, Network Solutions, Inc. provides domain name registration services in com, net, org and edu.

How do I get access to the Internet?

• Either using Computers permanently connected to the network

• or connect your computer via MODEM to your ISP provider.

There are two other terms related to Internet are:

• Intranet - a LAN (Campus Network)

• Extranet - a restricted Internet (The Boeing Electronic Store, a closed site)