IT+Infrastructures

8/8/2019 IT+Infrastructures

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IT Infrastructures

Computer Communication Networks IT Infrastructure is a combination of Software,

hardware and other equipments that support theactivities of an organization.

Basic Concept of Network

Network Architecture

Different Layers

Work group technologies

Intranet

Extranet

Internet





Basic Concept of network

A computer network is a data communication

system where two or more computers are

linked in order to exchange data(documents,

sheets etc.) and share resources (CD-ROM ,

printers, etc).

The computers on the network can be linked

through Cables, telephone

lines,satellites,radio waves etc.



Classification of Networks

PAN-A personal area network (PAN) is a computer network used forcommunication among computer devices (including telephones and personaldigital assistants ) close to one person.

Local Area Network(LAN)-A local-area network is a computer network covering asmall geographic area, like a home, office, or group of buildings e.g. a school

CAN-Campus Area Network- A 'campus area network'('CAN') is a computernetwork made up of an interconnection of local area network (LANs) within alimited geographical area. Ex- academic departments, the university library andstudent hostels.

Metropolitan network(MAN)-Metropolitan area networks, or MANs, are largecomputer networks usually spanning a city. They typically use wireless infrastructure oroptical fiber connections to link their sites.

Wide Area Network(WAN)-Wide Area Network (WAN) is a computer network

that covers a broad area(i.e., any network whose communications links crossmetropolitan, regional, or national boundaries ). Or, less formally, a network thatuses routers and public communication links. Ex-Internet



Disadvantages-LAN

LAN-

Difficulty in sharing-slow down network

Virus threat-spread more easilySecurity issues-if user and password known

Common server-if server break down, data lost

Complex Architecture-require maintenance



Components of a Network

Network Interface Card(NIC) This is a Networkinterface controller allows a computer to communicateover a network.

Cable: A network cable is a physical medium throughwhich two network devices communicate with eachother for data transfer.

Hub: A Hub is a central connecting point for all thenetwork devices via network cables.

Protocol: A protocol is a set of rules regardingcommunication that ensures that all the computers inthe network communicate in the same form.







Classification of Networks

Point-to-Point Network

Broad Cast Networks



Typical range of allocation

10 m Room LAN

100m Building LAN

1 km Site LAN

10 km City MAN

100 km Country WAN

1000 km Continent WAN

10000 km Planet Interconnection of WANs





Network Architecture

Client /Server

3- tier Client Server

Middle wire

Peer to peer

Mainframe

Distributed



Client/Server Architecture

2-tier architecture is used to describe client/server

systems where the client requests resources and the

server responds directly to the request, using its own

resources. This means that the server does not call on

another application in order to provide part of the service.



2-tier and 3-tier

In 3-tier architecture, there is an intermediary level, meaning the architecture is

generally split up between:

A client, i.e. the computer, which requests the resources, equipped with a user

interface (usually a webrowser) for presentation purposes

The application server (also called middleware), whose task it is to provide the

requested resources, but by calling on another server

The data server, which provides the application server with the data it requires



Multi Tier



Peer to peer

In contrast to client-server networks there is no

dedicated server in peer-to-peer architecture .

Thus each computer in such a network is part server

and part client.

This means that each computer on the network is

free to share its own resources. A computer which is

connected to a printer may even share the printer so

that all other computers may access it over the

network.









Network Models

The TCP/IP Model - This model is sometimescalled the DOD model since it was designed forthe department of defense It is also called the

internet model because TCP/IP is the protocolused on the internet.

OSI Network Model - The International StandardsOrganization (ISO) has defined a standard called

the Open Systems Interconnection (OSI)reference model. This is a seven layerarchitecture listed in the next section



What does TCP does?

TCP Breaks information in to small chunks calleddata packets and manages the transfer of thosepackets from computer to computer.

IP defines how a data packet must be formed andto where a router must forward each packet.

Packets travel independently to destinations. Thedestination computer reassembles all the packetsdepending on their identification sequencinginformation.

A packet data that confirms to the IP specificationis called IP datagram.



How does TCP/IP works?

Every Computer and router connected to internetis assigned with an unique IP address.

When an organization connects to internet, it

obtains a set of IP addresses that can assigns toits computers.

TCP helps IP guarantee to delivery of datagram byperforming three tasks- checks datagram that

may lost, collects incoming datagram and putsthem in order, finally discards and duplicatescopies of datagrams that create by hardware.







Network layer

The OSI Network Model Standard

Physical Layer -The actual hardware

Data Link Layers.

± Logical Link control (LLC) - Maintains the Link between two computersby establishing Service Access Points (SAPs) which are a series of interface points.

± Media Access Control (MAC) - Used to coordinate the sending of databetween computers. The 802.3, 4, 5, and 12 standards apply to thislayer. If you hear someone talking about the MAC address of anetwork card, they are referring to the hardware address of the card.

Network Layer - IP network protocol. Routes messages using the

best path available. Transport Layer TCP Ensures properly sequenced and error free

transmission.



Network Layer

Session Layer - The user's interface to the network. Determines when thesession is begun or opened, how long it is used, and when it is closed.Controls the transmission of data during the session. Supports securityand name lookup enabling computers to locate each other.

Presentation Layer ASCII((American Standard Code for Information

Interchange (ASCII) . Makes the type of data transparent to the layersaround it. Used to translate date to computer specific format such as byte

ordering. It may include compression. It prepares the data, either for thenetwork or the application depending on the direction it is going.

Application Layer - Provides services software applications need. Providesthe ability for user applications to interact with the network. - SMTP -Simple Mail Transfer Protocol

Many protocol stacks overlap the borders of the seven layer model byoperating at multiple layers of the model. File Transport Protocol (FTP)and telnet both work at the application, presentation, and the sessionlayers.



Network Layer

The Internet, TCP/IP, DODModel

This model is sometimes called the DOD model since it wasdesigned for the department of defense It is also called the TCP/IPfour layer protocol, or the internet protocol. It has the followinglayers:

Link - Device driver and interface card which maps to the data linkand physical layer of the OSI model.

Network - Corresponds to the network layer of the OSI model andincludes the IP, ICMP, and IGMP protocols.

Transport - Corresponds to the transport layer and includes the TCP

and UDP protocols. Application - Corresponds to the OSI Session, Presentation and

Application layers and includes FTP, Telnet, ping, Rlogin, rsh, TFTP,SMTP, SNMP, DNS, your program, etc.



Protocols

Protocols are sets of standards that define

operations and how they will be done.

Without protocols there would be much

confusion and there would be no standard to

allow computers to communicate.



Protocol Standards

The protocol stacks include:

± TCP/IP

± IPX/SPX Internetwork package

exchange/Sequenced Packet Exchange (Novell)

± Microsoft

± AppleTalk

± SNA system Network Architecture(IBM)

± Other - Includes OSI, DLC and SNAP



Functions of protocol

The function of the network protocols include:

± Packaging (IP)

± Transport (TCP,UDP-User datagram protocol)

± Network Management (ICMP, SNMP, ARP)

± Host Management (RARP, BOOTP, DHCP)

± Network Routing (BGP, EGP, IGP, RIP, OSPF)

±

Mail (SMTP) ± Multicasting (IGMP)

± Application (FTP, TFTP, NFS)



Protocol Terms

DLC - Data Link Control. This protocol operates at the data link layer and isdesigned for communications between Hewlett-Packard network printersand IBM mainframe computers. This protocol is not routable.

EAP - Extensible Authentication Protocol is used between a dial-in clientand server to determine what authentication protocol will be used.

EGP - Exterior Gateway Protocol is used between routers of differentsystems.

Ethernet - Ethernet is not really called a protocol. There are also manytypes of ethernet. The most common ethernet which is used to controlthe handling of data at the lowest layer of the network model is 802.3ethernet. 802.3 ethernet privides a means of encapsulating data frames tobe sent between computers. It specifies how network data collisions are

handled along with hardware addressing of network cards. FTP - File Transfer Protocol allows file transfer between two computers

with login required. Part of the TCP/IP suite of protocols.



Protocol Terms

HTTP - Hypertext Transfer Protocol is used to transport HTML pages fromweb servers to web browsers. Part of the TCP/IP suite of protocols.

ICMP - Internet control message protocol (ICMP) provides managementand error reporting to help manage the process of sending data betweencomputers. (Management). This protocol is used to report connection

status back to computers that are trying to connect other computers. Forexample, it may report that a destination host is not reachable. Part of theTCP/IP suite of protocols.

IGP - Interior Gateway Protocol. The name used to describe the fact thateach system on the internet can choose its own routing protocol. RIP andOSPF are interior gateway protocols.

IMAP4 - Internet Mail Access Protocol version 4 is the replacement for

POP3. IP - Internet Protocol. Except for ARP and RARP all protocols' data packets

will be packaged into an IP data packet. IP provides the mechanism to usesoftware to address and manage data packets being sent to computers.Part of the TCP/IP suite of protocols.



Protocol Terms

SAP - Service Advertising Protocol packets are used by file and print

servers to periodically advertise the address of the server and the services

available. It works at the application, presentation, and session levels. Part

of the IPX/SPX suite of protocols.

SMTP - Simple Mail Transfer Protocol is used to transport mail. SimpleMail Transport Protocol is used on the internet, it is not a transport layer

protocol but is an application layer protocol. Part of the TCP/IP suite of

protocols.

SNAP - Sub Network Access Protocol.

S

NMP - Simple Network Management Protocol is used to manage all typesof network elements based on various data sent and received. Part of the

TCP/IP suite of protocols



Some other Terms

Modem

Repeater

Bridge

Multiplexer Routers

Brouters

Chanel Service Units

Gateway

Packet switching



Some Other Concepts

Intranet

Extranet

Internet

The Internet is not considered to

be a part of the intranet or

extranet, although it may serve as a

portal for access to portions of an

extranet

An intranet is the internal network of a company .The

administrative entity closes the intranet to the rest of the

world, and allows only specific users

a company's customers may be given access to some part

of its intranet creating in this way an extranet



WWW

How it works?

The server-name portion of the URL is resolved into an IPaddress using the global, distributed Internet databaseknown as the domain name system, or DNS. This IP address

is necessary to contact and send data packets to the Webserver.

The browser then requests the resource by sending anHTTP request to the Web server at that particular address.

Then a typical Web page, the HTML text of the page is

requested first and parsed immediately by the Webbrowser. Having received the required files from the Webserver, the browser then renders the page onto the screenas specified by its HTML, and other Web languages.



DNS/Web server and IP Address

A DNS stores other information such as thelist of mail servers that accept email for agiven domain.

An Internet Protocol (IP) address is anumerical identification (logical address) thatis assigned to devices participating in acomputer network utilizing the InternetProtocol for communication between itsnodes



Internet

Started in 1960s- DARPA( Defense Advanced

Research Projects Agency)-Called it ARPANET

ARPANET combined with other network likeNSF( National Science Foundation) initiated

the NSFNET

Other part of world also get connected, like

BITNET,CSNET,NSINET,ESNET and NORDUNET



Internet/www

www is a system of internet servers that supportshypertext to access several internet protocols ona single interface.

www uses its own protocol called http. Web contains a complex virtual web of

connections among a vast number of documents,graphics,videos and sounds.

Producing hypertext for the web is accomplishedby creating documents with a language calledHTML.

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