16 September 2011

NETWORKING BASICS

I'll be giving y ou all  Tutorials on NETWORKING basics & their working

NETWORKS - A COMPUTER NETWORK IS A GROUP OF COMPUTERS CONNECTED TO SHARE RESOURCES SUCH AS FILES PRINTERS AND EMAIL . NO TWO NETWORK S ARE ALIKE IN SIZE OR CONFIGURATION . HOWEVER EACH NETWORK INCLUDES COMMON NETWORK THAT PROVIDE RESOURCE AND COMMUNICATIONS
CHANNELS NECESSARY FOR A NETWORK TO OPERATE
NETWORK COMPONENTS


DEVICE - ANY PIECE OF HARDWARE SUCH AS A COMPUTER , SERVER , PRINTER OR FAX MACHINE
 
MEDIA -- WHICH CONNECTS DEVICES IN A NETWORK and carries data between them
 
NETWORK OPERATING SYSTEMS -- SOFTWARE THAT CONTROLS NETWORK TRAFFIC , ACCESS TO RESOURCES , AND AUTHORIZATION
 
PROTOCOL -- CONTROLS NETWORK COMMUNICATION USING A SET OF RULES

SERVERS

A SERVER IS A NETWORK COMPUTER THAT SHARES RESOURCES WITH AND RESPONDS TO REQUESTS FROM OTHER NETWORK COMPUTERS , INCLUDING OTHER SERVERS
SERVERS PROVIDE CENTRALIZED ACCESS AND STORAGE FOR RESOURCES THAT CAN INCLUDE APPLICATIONS, FILES, PRINTERS OR OTHER HARDWARE AND SPECIALIZED SERVICES SUCH AS EMAIL . A SERVER CAN BE OPTIMIZED AND DEDICATED TO A SPECIFIC FUNCTION , OR IT CAN SERVE GENERAL NEEDS . MULTIPLE SERVERS OF VARIOUS TYPES CAN EXIST ON A SINGLE NETWORK .


CLIENTS
A CLIENT IS A NETWORK COMPUTER THAT UTILIZES THE RESOURCES OF OTHER NETWORK COMPUTERS , INCLUDING OTHER CLIENTS . THE CLIENT COMPUTER HAS ITS OWN PROCESSOR , MEMORY AND STORAGE , AND CAN MAINTAIN SOME OF ITS OWN RESOURCES AND PERFORM ITS OWN TASK AND PROCESSING . ANY TYPE OF COMPUTER ON A NETWORK CAN FUNCTION AS A CLIENT OF ANOTHER COMPUTER FROM TIME TO TIME

PEERS

A PEER IS A SELF SUFFICIENT COMPUTER THAT ACTS AS A SERVER AND A CLIENT TO OTHER SIMILAR COMPUTERS ON THE NETWORK . PEER COMPUTING IS OFTEN USED IN SMALLER NETWORKS WITH NO DEDICATED SERVERS BUT BOTH SERVERS AND CLIENTS IN OTHER TYPES OF NETWORKS CAN ALSO SHARE RESOURCES WITH THEIR PEER COMPUTERS

HOST COMPUTERS/SERVERS

A HOST COMPUTER IS A POWERFUL , CENTRALIZED COMPUTER SYSTEM SUCH AS A MAINFRAME COMPUTER THAT PERFORMS DATA STORAGE AND PROCESSING TASKS ON BEHALF OF CLIENTS AND OTHER NETWORK DEVICES . ON A HOST BASED NETWORK , THE HOST DOES ALL THE COMPUTING TASKS AND RETURNS THE RESULTANT DATA TO THE END USER'S COMPUTER

TCP/IP HOSTS

IN THE EARLY DAYS OF COMPUTER NETWORK , ALL COMPUTER WERE HOST COMPUTERS THAT CONTROLLED THE ACTIVITIES OF NETWORK TERMINAL DEVICES . THE HOSTS WERE JOINED TOGETHER TO COMMUNICATE IN THE EARLY RESEARCH NETWORKS THAT LAID THE FOUNDATION FOR THE INTERNET

AS THE TCP/IP PROTOCOL WAS ADOPTED AND BECAME UBIQUITOUS AND AS PERSONAL COMPUTERS JOINED THE NETWORK THE TERM HOST WAS GENERALIZED AND IS NOW USED TO REFER TO VIRTUALLY AND INDEPENDENT SYSTEMS ON A TCP/IP NETWORK

TERMINALS

A TERMINAL IS A SPECIALIZED NETWORK DEVICE ON A HOST BASED NETWORK THAT TRANSMITS THE DATA ENTERED BY THE USER TO THE HOST FOR PROCESSING AND DISPLAYS THE RESULTS . TERMINALS ARE OFTEN CALLED ' DUMB ' BECAUSE THEY HAVE NO PROCESSOR OR MEMORY OF THEIR OWN .
STANDARD CLIENT COMPUTERS THAT NEED TO INTERACT WITH HOST COMPUTERS CAN RUN A SOFTWARE CALLED TERMINAL EMULATOR SO THAT THEY APPEAR TO THE HOST AS DEDICATED TERMINALS

AUTHENTICATION

DEFINITION :- AUTHENTICATION IS A NETWORK SECURITY MEASURE IN WHICH A COMPUTER USER OR SOME OTHER NETWORK COMPONENTS PROVES ITS IDENTITY IN ORDER TO GAIN ACCESS TO NETWORK RESOURCES . THERE ARE MANY POSSIBLE AUTHENTICATION METHODS , WITH THE MOST COMMON BEING A COMBINATION OF USER NAME AND PASSWORD .

TCP/IP HOSTS

IN THE EARLY DAYS OF COMPUTER NETWORK , ALL COMPUTER WERE HOST COMPUTERS THAT CONTROLLED THE ACTIVITIES OF NETWORK TERMINAL DEVICES . THE HOSTS WERE JOINED TOGETHER TO COMMUNICATE IN THE EARLY RESEARCH NETWORKS THAT LAID THE FOUNDATION FOR THE INTERNET

AS THE TCP/IP PROTOCOL WAS ADOPTED AND BECAME UBIQUITOUS AND AS PERSONAL COMPUTERS JOINED THE NETWORK THE TERM HOST WAS GENERALIZED AND IS NOW USED TO REFER TO VIRTUALLY AND INDEPENDENT SYSTEMS ON A TCP/IP NETWORK

TERMINALS

A TERMINAL IS A SPECIALIZED NETWORK DEVICE ON A HOST BASED NETWORK THAT TRANSMITS THE DATA ENTERED BY THE USER TO THE HOST FOR PROCESSING AND DISPLAYS THE RESULTS . TERMINALS ARE OFTEN CALLED ' DUMB ' BECAUSE THEY HAVE NO PROCESSOR OR MEMORY OF THEIR OWN .
STANDARD CLIENT COMPUTERS THAT NEED TO INTERACT WITH HOST COMPUTERS CAN RUN A SOFTWARE CALLED TERMINAL EMULATOR SO THAT THEY APPEAR TO THE HOST AS DEDICATED TERMINALS


NETWORK DIRECTORY SERVICES

A NETWORK DIRECTORY IS A CENTRALIZED HIERARCHICAL DATABASE THAT STORES AND ORGANIZES DATA ABOUT NETWORK USERS AND NETWORK RESOURCES . EACH PIECE OF DATA IS AN OBJECT HAS A SET OF ATTRIBUTES ASSOCIATED WITH IT . OBJECTS STORED IN A DIRECTORY INCLUDE USERS GROUPS PASSWORDS SHARED FOLDERS COMPUTERS AND SERVERS AMONG OTHERS

THE DIRECTORY MAY BE STORED ON ONE SERVER OR MAY BE REPLICATED ON MANY SERVERS ON THE NETWORK . NETWORK DIRECTORIES PROVIDE CENTRAL ADMINISTRATION AND CENTRALIZED AUTHENTICATION WHICH OFFER ADMINISTRATORS GREATER CONTROL OVER NETWORK


STANDARD NETWORK MODELS

A NETWORK MODEL IS A DESIGN SPECIFICATION FOR HOW THE NODES ON A NETWORK INTERACT AND COMMUNICATE. THE NETWORK MODEL DETERMINES THE DEGREETO WHICH COMMUNICATIONS AND PROCESSING ARE CENTRALIZED OR DISTRIBUTED


THREE PRIMARY NETWORK MODELS INCLUDE
* CENTRALIZED OR HIERARCHIAL
* CLIENT/SERVER
* PEER-TO-PEER

SOME NETWORKS CAN EVEN HAVE A MIXTURE OF THE ABOVE MODELS
I.E A NETWORK WITH PEER-TO-PEER NETWORK AS WELL AS CLIENT/SERVER MODEL


CENTRALIZED COMPUTING NETWORKS -- A CENTRALIZED NETWORK IS A NETWORK IN WHICH A CENTRAL HOST COMPUTER CONTROLS ALL NETWORK COMMUNICATION AND PERFORMS DATA PROCESSING AND STORAGE ON BEHALF OF CLIENTS. USERS CONNECT THROUGH A DEDICATED TERMINAL OR TERMINAL EMULATOR . CENTRALIZED NETWORKS PROVIDE HIGH PERFORMANCE AND CENTRALIZED MANAGEMENT ,BUT ALSO EXPENSIVE TO IMPLEMENT


CLIENT/SERVER NETWORKS
A CLIENT SERVER NETWORK IS A NETWORK IN WHICH SERVERS PROVIDE RESOURCES TO CLIENTS. TYPICALLY THERE IS ATLEAST ONE SERVER PROVIDING CENTRAL AUTHENTICATION SERVICES. SERVERS ALSO PROVIDE ACCESS TO SHARED FILES, PRINTERS HARDWARE AND APPS. IN CLIENT SERVER NETWORK PROCESSING POWER MANAGEMENT SERVICES AND ADMINISTRATIVE FUNCTIONS CAN BE CONCENTRATED WHERE NEEDED, WHILE CLIENTS CAN STILL PERFORM MANY BASIC END USER TASKS ON THEIR OWN

PEER - TO - PEER NETWORKS
A PEER TO PEER NETWORK IS A NETWORK IN WHICH RESOURCE SHARING ,PROCESSING AND COMMUNICATION CONTROL ARE COMPLETELY DECENTRALIZED . ALL CLIENTS IN THE NETWORK IS EQUAL IN TERMS ON SHARING AND RECEIVING RESOURCES AND USERS ARE AUTHENTICATED BY EACH INDIVIDUAL WORKSTATIONS . PEER TO PEER NETWORKS ARE THE MOST EASY RELIABLE AND INEXPENSIVE TO IMPLEMENT. HOWEVER THEY ARE ONLY PRACTICAL IN A VERY SMALL ORGANIZATION . DUE TO LACK OF ADMINISTRATION AND DATA STORAGE. A PEER TO PEER NETWORK IS ALSO REFERRED AS A WORKGROUP

EG: A BEST AWESOME EXAMPLE IS THE TORRENTS U USE TO DOWNLOAD FILES . THE APP WORKS ON THIS BASIS . IN THIS CASE SUPPOSE U R THE CLIENT U DONT GET THE FILE FROM THE OFFICIAL SERVER BUT FROM A PEER REMOTELY CURRENTLY DOWNLOADING THE SAME FILE .

SECONDLY COMES UR MINI LAB . WHERE U IMPLEMENT A NETWORK OF TWO OR MORE SERVER FOR THE PURPOSE OF GAMING OR FILE TRANSFER



PHYSICAL NETWORK TOPOLOGIES
A TOPOLOGY IS A NETWORK SPECIFICATION THAT DETERMINES THE NETWORKS OVERALL LAYOUT AND THE NETWORKS DATA FLOWING AND SIGNALLING PATTERNS , A TOPOLOGY CAN BE A PHYSICAL TOPOLOGY WHICH DESCRIBES PHYSICAL WIRING LAYOUT AND DIAGRAMS OR IT CAN BE A LOGICAL TOPOLOGY , WHICH DESCRIBES THE PATHS THROUGH WHICH THE DATA MOVES . THE PHYSICAL AND LOGICAL TOPOLOGIES DO NOT HAVE TO DO THE SAME . COMMON PHYISAL PATTERNS INCLUDE A STAR TOPOLOGY , TREE PATERN BUS OR A STRAIGHT LINE PATERN

NOTE:PHYSICAL BUS,TREE AND RING HAS BEEN DELETED OUT DUE ITS OUTDATED TECHNOLOGY AND NONRELIABLE NATURE

SO LETS START WITH PHYSICAL STAR TOPOLOGY

A PHYSICAL STAR TOPOLOGY IS A TYPE THAT USES A CENTRAL CONNECTIVITY DEVICE (ROUTER , SWITCHES , HUBS) WITH SEPERATE PHYSICAL CONNECTION TO EACH NODE(TERMINALS, SERVERS , PCS) THE INDIVIDUAL NODE FIRST SENDS DATA TO THE CENTRAL DEVICE AND THEN THE DEVICE FORWARDS THE DATA TO THE DESTINATION ADDRESS. STAR TOPLOGIES ARE INEXPENSIVE AND EASY TO MAINTAIN AND CONFIGURE ALSO TO IMPLEMENT. THE ONLY DRAWBACK IS IF THE CENTRAL DEVICE (SWITCH OR ROUTER ) GETS FAILED THEN THE WHOLE NETWORK IS ABNDONED AS ALL NODES ARE CONNECTED TO IT FOR DATA TRANSFER AND RESOURCE SHARING. STAR TOPLOGY IS THE MOST COMMERCIALLY USED TYPE OF NETWORK TOPOLOGIES EG: IN SCHOOLS, CYBERCAFES, SMALL ORGANIZATIONS , BANKS ETC ETC


PHYSICAL MESH TOPOLOGY
A PHYSICAL MESH TOPOLOGY IS A TYPE IN WHICH EACH NODE HAS A DIRECT CONNECTION TO EVERY OTHER NODE SIMILAR TO POINT TO POINT TOPOLOGY
. IN THIS CASE SUPPOSE THERE ARE 10 COMPUTERS EVERY NODE IS CONNECTED TO THE REMAINING 9 COMPUTERS VIA NIC CARDS (NETWORK INTERFACE CARDS)
OVERALL THIS TYPE OF NETWORK TOPOLGY IS THE MOST RELIABLE AND THE MOST MODERN . THE MOST SECURE AND MOST POWERFUL AND A FAULT TOLERENCE ONE AS NO TERMINAL NEEDS TO DEPEND ON OTHER END POINTS OR SERVERS


DRAWBACKS ARE ITS THE MOST EXPENSIVE ONE , THE MOST DIFFICULT ONE TO CONFIGURE AND IMPLEMENT . AND IS ALMOST A MESSY SITUATION WHEN IT COMES TO MAINTENANCE (AS THE NAME INDICATES MESH)

EG: COMPANIES AND ORGANIZATION WHICH WANTS THEIR NETWORKS TO BE MISSION CRITICAL AND FAULT TOLERANT IMPLEMENTS THIS NETWORK TOPOLOGY


FOR CURRENTLY I LL B NOT EXPLAINING LOGICAL TOPOLOGY
BECAUSE ITS OF NO USE ITS A THING JUST TO BE KEPT IN MIND
AND IS NOTHIN TO DO WITH PRACTICAL IMPLEMENTATION


HOWEVER IF ANYONE WANTS TO KNOW ABOUT IT
PLEASE LET ME KNOW AND I SHALL START POSTING

FOR NOW I LL B CONTINUING FROM LAN NETWORKS




LOCAL AREA NETWORKS


A LOCAL AREA NETWORK IS A SELF CONTAINED NETWORK THAT SPANS A SMALL AREA SUCH AS A SINGLE BUILDING , FLOOR OR ROOM , IN A LAN , ALL NODES AND SEGMENTS ARE DIRECTLY CONNECTED WITH CABLES OR SHORT RANGE WIRELESS TECHNOLOGIES
ALSO KNOWN AS WIRELESS LAN ( WLAN) .

WIDE AREA NETWORKS (WAN)
A WIDE AREA NETWORK IS A NETWORK THAT SPANS MULTIPLE GEOGRAPHIC LOCATIONS INCLUDING A METROPOLITAN AREA GEOGRAPHIC REASONS OR ENTIRE NATION . WANS TYPICALLY CONNECT MULTIPLE LANS AND OTHER NETWORKS USING LONG RANGE TRANSMISSION MEDIA. THE RESULT IS THAT USER AND COMPUTERS IN ONE LOCATION CAN COMMUNICATE WITH USERS AND COMPUTERS IN OTHER LOCATION(SIMILAR TO INTERNET) WANS ARE MOSTLY IMPLEMENTED BY LARGE PRIVATE COMPANIES OR BY INTERNET SERVICE PROVIDERS

Network Types:--
Peer to peer:

In a peer to peer network, the host provides and consumes network services, and each host has the same O.S
*.....Advantages of peer to peer network include:--
1)Easy implementation
2)Inexpensive

*.....Dis-Advantages of peer to peer network include:-
1)Difficult to expand (Not scalable)
2)Difficult to support
3)Lack centralized control
4)No centralize storage.

Client/server:

In a client/server network, hosts have specific rules. For example, some hosts are assigned server roles which allow then to provide network resources to other hosts.
Other hosts are assigned client roles which allow them to consume network resources. Unlike peer to peer network, host in a client/server network have difficult O.S.

*.....Advantages:-
1)Easily expanded (scalable)
2)Easy support
3)Centralized services
4)Easy to backup

*....Dis-Advantages:-

1)Servers O.S are expensive.
2)Requires extensive advanced planning.


Geographical types of network:-
1) LAN (Local area network)
2) MAN (Metropolitan area network)
3) CAN (Campus area network)
4) WAN (Wide area network)LAN:-
LANs reside in a smack geographic area, like in an office. A series of connected LANS, or a LAN connected across several building or offices is called an internetwork.Examples includes, home and organization (small business, corporate institute and govt.) network.

WAN: -
A WAN is a group of LANs that are geographically isolated but connected to form a large internetwork.
Example: INTERNET

CAN

A campus network is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area.The networking equipments (switches, routers) and trasmission media (optical fiber, copper plant, Cat5 cabling etc) are almost entirely owned (by the campus tenant / owner: an enterprise, university, government etc

MAN (Metropolitan Area Network )

A MAN is optimized for a larger geographical area than a LAN, ranging from several blocks of buildings to entire cities. MANs can also depend on communications channels of moderate-to-high data rates. A MAN might be owned and operated by a single organization, but it usually will be used by many individuals and organizations. MANs might also be owned and operated as public utilities. They will often provide means for internetworking of local networks.

Maximum Arear Covered

LAN 1 Kms
MAN: 100 KMS
Can: 5 Kms
Wan: Unlimited

Signaling
Baseband And BroadbandBaseband:Baseband signaling allows one signal at a time on network medium (cabling).

Broadband:Broadband signaling divides the network medium into multiple channels, allowing several signals to transverse the medium at the same time.

Topology

Topology is the term used to describe how devices are connected and how massages flow from device to device. There are 2 types of networking topologies.
1) The physical topology – Describes the physical way the network is wired.
2) The logical topology – Describes the way in which messages are sent.




1)Physical Topology Includes the following topologies

Bus topology
Star topology
Ring topology
Mesh topology
Hybrid topology

1)Bus topology: - A physical bus topology consists of a trunk cable with nodes either inserted directly into the trunk, or nodes tapping into the trunk using offshoot cables called drop cables.
*Signals travel from one mode to all other nodes on the bus.
*A device called a terminator is placed at both ends of the trunk cable.
*It absorbs signals and prevents them from reflecting back.
*This topology requires less cable than the star topology.
*Can be difficult to isolate cabling.
*100 Ohms of resistors are used at both the ends of the cable.

2)Ring topology: - A ring topology connects neighboring nodes until they form a ring .Signals travel in one direction around the ring .In ring topology, each device on the network acts as a repeater to send the signals to the next device.
With a ring:-
*Installation requires careful planning to create a continuous ring.
*Isolating problem can require going to several physical locations along the ring.
*A malfunctioning node or cable break can prevent signals reaching nodes further along on the ring.

3)Star Topology: - A star topology uses a hub or switch to concentrate all network connection to a single physical location. Today it is the most popular type of topology for a LAN. With the star:-
*All network connections are located in a single place, which makes it easy to troubleshoot and reconfigure.
*Hosts can be added or removed easily.
*Cabling problem only affect a single host.
*It requires more cable than any other topology.


4)Mesh Topology: - A mesh topology exists when there are multiple paths between any 2 nodes on a network. Mesh topologies are created using point to point connection. This increases the network’s fault tolerance because alternate paths can be used when one path fails.
Two vibrations of mesh topologies exist:-
*Partial mesh -> some redundant paths exists.
*Full mesh -> every node has a point to point connection with every other node.

Full mesh topologies are usually impractical because the number of connections increases dramatically with every new node added to the network. However a full mesh topology becomes more practical through the implementation of an ad-hoc wireless network. With this topology, every wireless network card can communicate directly with any other wireless network card on the network. A separate and dedicated network interface and cable for each host on the network is not required.

Advantages And Disadvantages
Advantages of bus topology :-
1) Installation of devices easy.
2) Requires less cable compared to star topology.
3) Less expensive and works better for smaller networks.

Dis- Advantages :-
1) If backbone breaks, entire networks get down.
2) Difficult to isolate.
3) Limited number of devices.

Advantages of star topology :-
1) Easy to install, configure, manage and expand.
2) Centralized management.
3) Addition or removal of device does not affect the whole network.

Dis-Advantages :-
1) Requires more cable
2) Failure of hub affects entire network.
3) More expensive.

Advantages of Ring topology :-
1) Data travels at greater speed.
2) No collisions.
3) Handles large volume of traffic.

Dis-Advantages:-
1) More cabling is required as compared to bus.
2) One faulty device affects the entire network.
3) Addition of devices affect network.

Advantages of Mesh topology :-
1) Improve Fault tolerance.
2) Failure of one link does not affect entire network.
3) Centralized management is not required.

Dis- Advantages:-
1) Difficult to install and manage.
2) Each link from one device to other requires individual Nic.
3) Very much expensive.

Advantages of Hybrid topology :-
1) Used for creating larger networks.
2) Handles large volume of traffic.
3) Fault detection is easy.

Dis-Advantages:-
1) Installation and configuration is difficult.
2) More expensive than other topologies.
3) More cabling is required.


SHARE THIS

0 comments: