NETWORKING

FOR THE SHARING OF DATA AND PERIPHERALS.

THREE MAIN TYPES OF COMPUTER NETWORKS.

1) PEER TO PEER :

A TYPE OF NETWORK THAT INCLUDES TWO OR MORE PCs CONNECTED TO SHARE DATA, PRINTERS, AND OTHER RESOURCES.IN WHICH EACH WORKSTATION HAS EQUIVALENT CAPABILITIES AND RESPONSIBILITIES.

2) LOCAL AREA NETWORK : ( LAN )

THE CONNECTING OF TWO TO ABOUT 500 NODES .USING PERMANENTLY INSTALLED CABLING OR A WIRELESS TECHNOLOGY.THIS IS THE MOST COMMON TYPE OF NETWORK BECAUSE ITS CHEAP AND SIMPLE. USED BY COMPANIES, UNIVERSITIES, CORPORATIONS AND ETC.

3) WIDE AREA NETWORKS ( WAN ) :

NETWORK THAT SPANS A RELATIVELY LARGE GEOGRAPHICAL AREA.MOST COMMONLY CONSISTING OF TWO OR MORE LANs.THEY ARE CONNECTED THROUGH PUBLIC NETWORKS ( TELEPHONE ),LEASED LINES, OR SATELLITIES.THE MOST POPULAR WAN IS THE INTERNET.

TOPOLOGIES OF NETWORKING

HOW NODES ARE CONNECTED AND COMMUNICATE TO EACHOTHER.

1) BUS TOPOLOGY :

ALL DEVICES ARE CONNECTED TO A CENTRAL CABLE. BUS TOPOLOGY NETWORKS ARE CHEAP AND EASY TO INSTALL FOR SMALL NETWORKS.ALL ETHERNET SYSTEMS USE THIS TYPE OF TOPOLOGY. CONNECTING TO A HUB OR A SWITCH THAT IS CONNECTED TO THE BUS.

2) FDDI TOPOLOGY :
FIBER DISTRIBUTED DATA INTERFACE :

CONSIST OF A LASER OR DIODE TRANSCEIVER THAT CONVERTS ITS DIGITAL DATA INTO LIGHT TO BE TRANSMITTED ON A FIBER OPTIC NETWORK AND/OR BACK TO A DIGITAL SIGNAL FROM INCOMING LIGHT IMPULSES FOR USE BY A COMPUTER.

3) RING TOPOLOGY :

USES COPPER AND FIBER OPTIC CABLING SUPPORTING UP TO ABOUT 260 NODES. ALL DEVICES ARE CONNECTED TO ONE ANOTHER IN THE SHAPE OF A CLOSED LOOP ( RING ) SO EACH DEVICE IS CONNECTED DIRECTLY TO TWO OTHER DEVICES. ONE ON EITHER SIDE OF THE RING. THEY OFFER HIGH BANDWIDTH AND CAN SPAN LONG DISTANCES. CONSIDERED TO BE THE TOUGHEST TO TROUBLESHOOT.

4) STAR TOPOLOGY :

ALL DEVICES ARE CONNECTED TO A CENTRAL HUB. THEY ARE RELATIVELY EASY TO INSTALL AND MANAGE,BUT BOTTLENECKS CAN OCCUR THROUGH THE HUB. EVERY NODE IN A STAR NETWORK IS DIRECTLY CONNECTED TO A CENTRAL SERVER, GIVING IT A STARBURST LOOK.

NETWORK ARCHITECTURE

1) PEER TO PEER :

WHEN ALL NODES ON A NETWORK ARE EQUAL AND RESOURCES ARE SHARED EQUALLY.

2) CLIENT / SERVER :

WHEN ONE COMPUTER IS DESIGNED TO HOST PROGRAMS OR FILES FOR THE REST OF THE NETWORK, IT IS A SERVER, AND THE OTHER NODES ARE CLIENTS.

TYPES OF NETWORKING SWITCHES :

1) BRIDGE :

USED TO INTERCONNECT TWO OR MORE LANs OR LAN SEGMENTS.

2) ROUTER :

A VERY SMART DEVICE THAT EXAMINES THE SOURCE AND DESTINATION ADDRESSES OF NETWORK TRAFFIC AND DECIDES WHERE THE MESSAGE NEEDS TO BE ROUTED. ITS JOB IS TO DETERMINE THE BEST POSSIBLE WAY TO SEND THE MESSAGE TO ITS DESTINATION.

3) REPEATERS :

A AMPLIFIER THAT IS NEEDED AT REGULAR INTERVALS TO RESTORE THE POWER OF AN ANALOG SIGNAL. REPEATERS REGENERATE DIGITAL SIGNALS WHILE REMOVING UNWANTED NOISE. THE REGENERATING AND RETIMING ENSURE THAT THE SIGNAL IS CLEARLY TRANSMITTED.THEY SIMPLY PROAGATE SIGNALS FROM ONE CABLE TO ANOTHER CABLE..

TWO TYPES OF REPEATERS :

1) AMPLIFIER REPEATER :

PICKS UP THE INCOMING SIGNAL AND WITHOUT MAKING ANY MODIFICATIONS TO IT AT ALL,AMPLIFIES IT AND SENDS IT ON ITS WAY. GOOD, BAD,OR NOISY.

2) SIGNAL REGENERATING REPEATER :

IT SENDS OUT A CLEANED UP SIGNAL BY MAKING A FRESH AND EXACT COPY OF JUST THE GOOD PART OF THE INCOMING SIGNAL AND SENDING OUT THE COPY.

4) GATEWAY :

A DEDICATED COMPUTER THAT CONNECTS TO TWO OR MORE NETWORKS AND THAT ROUTES INFORMATION BETWEEN THEM. NETWORKS CONNECTED TO A GATEWAY MAY BE RUNNING DIFFERENT PROTOCOLS, AND THE GATEWAY CONVERTS BETWEEN PROTOCOLS OPERATING IN THE TOP THREE LAYERS OF THE OSI. THE TERM GATEWAY HAS GENERALLY BEEN REPLACED BY THE WORD ROUTER.

OSI --- OPEN SYSTEM INTERCONNECT

AN INTERNATIONAL STANDARD OF PROTOCOLS DEFINED BY THE INTERNATIONAL ORGANIZATION FOR STANDARDIZATION THAT IMPLEMENTS THE OSI REFERENCE MODEL FOR NETWORK COMMUNICATIONS BETWEEN COMPUTERS

OSI SEVEN LAYERS

LAYER 1 -- PHYSICAL LAYER

DEFINES HARDWARE CONNECTIONS AND TURNS BINARY INTO PHYSICAL PULSES. CAT 1-5, FDDI, COAXIAL CABLES, ATM, ADSL, ISDN.

LAYER 2 -- DATA LINK LAYER

PROVIDES DATA DELIVERY ACROSS THE PHYSICAL CONNECTION. SLIP,PPP,ETHERNET, SNAP

LAYER 3 -- NETWORK LAYER

MOVES PACKETS BETWEEN COMPUTERS ON DIFFERENT NETWORKS.
INTERNET PROTOCOL

LAYER 4 -- TRANSPORT LAYER

BREAKS DATA DOWN INTO MANAGEABLE PIECES. TCP, UDF

LAYER 5 -- SESSION LAYER

MANAGES SESSIONS BETWEEN APPLICATIONS.NETBIOS AND SOCKETS

LAYER 6 -- PRESENTATION LAYER

STANDARDISES DATA PRESENTED TO THE APPLICATIONS. POP/SMTP, USENET, HTTP, FTP, TELNET, DNS, NFS

LAYER 7 -- APPLICATION LAYER

PROVIDES TOOLS FOR PROGRAMS TO ACCESS THE NETWORK. E-MAIL, NEWSGROUPS, WEB APPLICATION, FILE TRANSFER, HOST SESSIONS, DIRECTORY SERVICES, NETWORK MANAGEMENT, FILE SERVICES

HELPFUL NETWORK TERMINOLOGY :

COAXIAL CABLE :

JUST ABOUT LIKE THE CABLE USED TO CONNECT YOUR TV TO CABLE TELEVISION SYSTEMS.

TWO TYPES OF COAXIAL CABLE

1) THICKNET : ( ALSO CALLED 10BASE5 OR THICKWIRE )

REAL THICK COAXIAL CABLE, SUPPORTS UP TO 100 DEVICES HOOKED TO ONE SEGMENT. MAXIUM LENGHT OF ONE SEGMENT IS 500 METERS

2) THINNET : ( ALSO CALLED 10BASE2 AND THINWIRE )

THIN COAXIAL CABLE, CHEAP AND EASY TO WORK WITH. SUPPORTS 30 DEVICES PER SEGMENT AT NO MORE THAN 185 METERS LONG. CONNECTED BY WAY OF THE BNC CONNECTOR ATTACHED TO A T CONNECTOR.

DATA PACKETS :

DATA, MESSAGES, AND TOKENS THAT ARE TRANSMITTED ON ANY NETWORK .

DNS : DOMAIN NAME SYSTEM :

USED TO TRANSLATE INTERNET NAMES TO THEIR IP ADDRESS EQUIVALENTS.

FIBER OPTIC CABLE :( ALSO CALLED 10BASEF OR 100BASEF )

FAST HIGH SPEED WAY OF TRANSMITTING DATA. MADE OF GLASS OR POLYMER SEALED WITHIN A TUBE TO CARRY LIGHT TO REPRESENT DIGITAL DATA SIGNALS.

FTP : FILE TRANSFER PROTOCOL :

USED TO SEND AND RECEIVE FILES IN CLIENT/SERVER MODE TO OR FROM A REMOTE HOST.

HTTP : HYPERTEXT TRANSFER PROTOCOL :

USED TO SEND W.W.W. DOCUMENTS.

HUB :

A CENTRAL DEVICE THAT CONNECTS SEVERAL COMPUTERS TOGETHER OR SEVERAL NETWORKS TOGETHER. IT RECEIVES A SIGNAL FROM ONE PORT AND PASSES IT ON TO ALL OF ITS OTHER PORTS.

IPX/SPX :

INTERNETWORK PACKET EXCHANGE / SEQUENCED PACKET EXCHANGE : STANDARD PROTOCOL OF NOVELL

MAC : ( MEDIA ACCESS CONTROL ) ADDRESS :

THE UNIQUE IDENTIFYING ADDRESS THAT IS BUILT IN TO EVERY NIC ( NETWORK INTERFACE CARD ) IN THE WORLD. WHICH IS USED TO LOCATE IT ON THE NETWORK. THIS ADDRESS IS 48 BITS LONG.

NETBEUI : NETBIOS EXTENDED USER INTERFACE :

USED ONLY BY WINDOWS SYSTEMS FOR LANS WITH NO EXTERNAL CONNECTIONS.

NODE :

ANY ADDRESSABLE NETWORK POINT,INCLUDING WORKSTATIONS AND OTHER NETWORK DEVICES.

PPP : POINT TO POINT PROTOCOL :

USED TO CONNECT AND MANAGE NETWORK COMMUNICATIONS OVER A MODEM.

PROTOCOL :

THE ESTABLISHED SET OF RULES THAT GOVERNS THE OPERATION OF ANY COMMUNICATIONS BASED SYSTEM.

SEGMENT :

THE CABLE IN WHICH THE PC IS CONNECTED.

SERVER :

A NETWORK COMPUTER FROM WHICH WORKSTATIONS ACCESS SHARED FILES, PRINTERS, COMMUNICATIONS, AND ANY OTHER TYPE OF SERVICES AVAILABLE.

SHIELDED TWISTED PAIR : ( STP )

CONSIST OF METALLIC SHIELDING TO PROTECT THE WIRES FROM INTERFERENCE.

SMTP : SIMPLE MAIL TRANSFER PROTOCOL :

USED TO SEND E-MAIL ACROSS A NETWORK.

SWITCH :

A DEVICE WHICH CAN SEND PACKETS DIRECTLY TO A PORT ASSOCIATED WITH A GIVEN NETWORK ADDRESS.

TCP/IP :

TRANSMISSION CONTROL PROTOCOL / INTERNET PROTOCOL : A SET OF COMMUNICATIONS PROTOCOLS.

TOPOLOGY :

THE GEOMETRIC ARRANGEMENT OF ANY NETWORK.

UNSHIELDED TWISTED PAIR : ( UTP )

MOST POPULAR CABLING FOR NETWORKS TECHNOLOGIES. HAS NO SHIELDING LIKE STP DOES. INSTEAD IT TWIST PAIRS OF WIRES AROUND EACHOTHER AT CERTAIN INTERVALS TO REDUCE INTERFERENCE.FOUND IN CERTAIN CATEGORIES.
A) CATEGORY 1,CAT 1 = PHONE LINES
B) CATEGORY 2,CAT 2 = SPEEDS OF 4 MEGABITS PER SECOND.
C) CATEGORY 3,CAT 3 = SPEEDS OF 16 MEGABITS PER SECOND.
D) CATEGORY 4,CAT 4 = SPEEDS OF 20 MEGABITS PER SECOND.
E) CATEGORY 5,CAT 5 = SPEEDS OF 100 MEGABITS PER SECOND.

WINS :

WINDOWS INTERNET NAMING SERVICE : CONVERTS NETBIOS NAMES TO IP ADDRESSES

WWW :

WORLD WIDE WEB