WE3K 9 _ INTERNET INFRASTRUCTURE

WHATISINTERNETINFRASTRUCTURE? 

• With the growth of the Internet for personal use (e.g. Facebook, Amazon, Google, Gmail) and business purposes (i.e.file storage, web applications, collaboration and communication, VOIP) I thought it would be useful to talk about what actually powers all these things. I have a secondary reason for this too – when a non-technical person asks me what I do for a living, I have yet to come up with a short simple answer that actually explains it!

First of all, let me define what I mean by ‘Internet Infrastructure’. All the hardware and services required to make this web page appear in your browser, or an RSS feed download into your reader, or VOIP calls / emails get to your desktop. All the underlying technologies that are unseen, but ‘make the Internet go’.

-          I see Internet Infrastructure consisting of a ‘Top 5′ areas :

·         Data Centres

·         Network Connectivity

·         Computer Equipment

·         Storage Services

·         Server Applications

HIERARCHY OF NETWORKS :

-        -  From a single computer to LAN

-         - From LAN to ISP ( Internet Service Provider)

-         - From ISP to WWW. .... ( worldwide)

-             - Connect yourself :

• ·         Computer

• ·         Web browser

• ·         Internet access

-          - Policy and procedures to bring you to internet.

INTERNET PROTOCOL (IP )

-          The Internet Protocol (IP) is the method or protocol by which data is sent from one computer to another on the Internet. Each computer (known as a host) on the Internet has at least one IP address that uniquely identifies it from all other computers on the Internet. 

-          When you send or receive data (for example, an e-mail note or a Web page), the message gets divided into little chunks called packets. Each of these packets contains both the sender's Internet address and the receiver's address.

-          Any packet is sent first to a gateway computer that understands a small part of the Internet. The gateway computer reads the destination address and forwards the packet to an adjacent gateway that in turn reads the destination address and so forth across the Internet until one gateway recognizes the packet as belonging to a computer within its immediate neighborhood or domain. That gateway then forwards the packet directly to the computer whose address is specified.

-          Because a message is divided into a number of packets, each packet can, if necessary, be sent by a different route across the Internet. Packets can arrive in a different order than the order they were sent in. The Internet Protocol just delivers them. It's up to another protocol, the Transmission Control Protocol (TCP) to put them back in the right order.

IP ADDRESS :

 

Ø  A numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there.”

Ø  The designers of the Internet Protocol defined an IP address as a 32-bit number and this system, known as Internet Protocol Version 4 (IPv4),

-          IP CONSISTS 2 PART :

o   Identifying the node /host

o   Identifying network

§  The four numbers in an IP address are used in different ways to identify a particular network and a host on that network.:

Class A Network
~ binary address start with 0
~ no. can be anywhere from 1-126
~ first octet is the identify network
~ eg : 108.187.212.206

Class B Network

~ binary address start with 10
~ no. can be anywhere from 128-191
~ first two octets is the identify network
~ 127 is reserved for loopback
~ eg : 187.202.226.212

Class C Network

~ binary address start with 110
~ no. can be anywhere from 129-223
~ first three octets is the identify network
~ eg : 212.167.203.224

Class D Network

~ binary address start with 1110
~ no. can be anywhere from 224-239
~ used to support multicasting

Class E Network
~ binary address start with 1111
~ no. can be anywhere from 240-255
~ used for experiment and never been documented

 

ACCESS PROVIDERS (IAPS)

·         Main article: Internet access

·         ISPs employ a range of technologies to enable consumers to connect to their network.[citation needed]

·         For users and small businesses, traditional options include: dial-up, DSL (typically Asymmetric Digital Subscriber Line, ADSL), broadband wireless, cable modem, fiber to the premises (FTTH), and Integrated Services Digital Network (ISDN) (typically basic rate interface).[citation needed]

·         For customers with more demanding requirements, such as medium-to-large businesses, or other ISPs, DSL (often Single-Pair High-speed Digital Subscriber Line or ADSL), Ethernet, Metropolitan Ethernet, Gigabit Ethernet, Frame Relay, ISDN (B.R.I. or P.R.I.), ATM (Asynchronous Transfer Mode) and upload satellite Internet access. Sync-optical cabling (SONET) are more likely to be used.[citation needed]

·         Many access providers also provide hosting and email services.

DOMAIN NAME SYSTEM

• What is DNS?

 

What does actually stand behind that almighty 3-letter abbreviation - DNS? DNS refers to Domain Name System and represents a powerful Internet technology for converting domain names to IP addresses. Its special mission is to be a mediator between the IP addresses, the system-side names of the websites and their respective domains, and their user-side alpha-numeric titles. Another important function of the DNS is to control the delivery of email messages. 

 

Behind every site, there is an IP address. But, while it's easy to remember the name of a website, it's quite hard to remember the exact IP address. For example, everybody knows about Google.com, but if you had to remember "74.125.45.100", things would have been much harder. 

An example:

Clear/flush the DNS cache in Linux
/etc/rc.d/init.d/nscd restart
Clear/flush the DNS cache in Mac OS X Leopard
dscacheutil -flushcache
Clear/flush the DNS cache in Mac OS X (older versions)
sudo killall lookupd lookupd -flushcache
Clear/flush the DNS cache in Microsoft Windows XP
1. click on: Start -> Run -> type cmd
2. in command prompt, type ipconfig /flushdns

HIERARCHY DOMAIN NAME :

INTERNET SERVICE PROVIDER (ISP)

• ·         An Internet service provider (ISP) is an organization that provides access to the Internet.

• ·         Internet service providers can be either community-owned and non-profit, or privately owned and for-profit.

• ·         Access ISPs directly connect clients to the Internet using copper wires, wireless or fiber-optic connections. Hosting ISPs lease server space for smaller businesses and other people (colocation). Transit ISPs provide large amounts of bandwidth for connecting hosting ISPs to access ISPs.

 there are example for ISP ----------->

 HYPERTEXT TRANSFER PROTOCOL (HTTP)

     

•  Short for HyperText Transfer Protocol, the underlying protocol used by the World Wide Web. HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. For example, when you enter a URL in your browser, this actually sends an HTTP command to the Web server directing it to fetch and transmit the requested Web page.

·         The other main standard that controls how the World Wide Web works is HTML, which covers how Web pages are formatted and displayed.