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RULES OF LOGIC ---> INTERNET PROTOCOL

 RULES OF LOGIC---->INTERNET PROTOCOL FRIENDS, TODAY I AM GOING TO DISCUSS SOMETHING ABOUT IP ADDRESSING.  IP IS A LOGICAL ADDRESS FULLFORM INTERNET PROTOCOL.  IT PROVIDES LOGICAL ADDRESS TO NETWORKING DEVICES.   THESE ADDRESSES ARE USED TO DEFINE SOURCE AND DESTINATION OF DATA PACKETS IP HAS TWO VERSIONS 1. IP VERSION 4 2. IP VERSION 6 IP VERSION 4 IT IS 32 BIT ADDRESS WRITTEN IN DECIMAL NUMBER  FORMAT  192.168.1.1 THE NUMBERS IN THE DIGITS LIKE 192.68.1.1 HERE EVERY NUMBER BEFORE THE DOT IS AN OCTET. HERE IT IS SHOWN THAT EACH DIGIT IS PRECEDED BY DOT IS AN NUMBER BELONGING TO AN OCTET LIKE FIRST OCTET, SECOND OCTET , THIRD OCTET AND FOURTH OCTET. EACH OCTET IS AN NUMBER IN BINARY FORM WRITTEN IN 2^8=256 BINARY FORM HERE THE DIGIT SHOWS THAT A VARIABLE IS IN THE BY POWER OF 2, HERE I WANT TO SAY THAT AS COMPUTER UNDERSTANDS BINARY DIGIT IN WHICH THE VARIABLES ARE 0 AND 1.  AS THE COMPUTER UNDERSTANDS BINARY DIGIT SO IT HAS ONLY 2 VALUES. HENCE THE POWER IS WRITTEN IN 2. SO THE

NETWORKING DEVICES A GENERAL SUMMARY

 NETWORKING DEVICES USED IN INTERNET CONNECTION: A GENERAL SUMMARY

NETWORK DEVICES, OR NETWORKING HARDWARE, ARE PHYSICAL DEVICES THAT ARE REQUIRED FOR COMMUNICATION AND INTERACTION BETWEEN HARDWARE ON A COMPUTER NETWORK.


LAYER 4 -> FIREWALL

LAYER 3 -> ROUTER

LAYER 2 -> BRIDGE, SWITCH

LAYER 1 ->LAN CARD, REPEATER, HUB, MODEM, ACCESS-POINT.


NETWORK INTERFACE CARD(NIC) A LAN CARD


IT IS A LAYER 1 DEVICE.  IT IS USED TO CONNECT A PC, LAPTOP, WORK STATION AND A SERVER TO A NETWORK.

A LAN CARD IS BUILT INTO A MOTHERBOARD BUT WE CAN PURCHASE ADDITIONAL LAN CARD ATTACH IT IN A PCI OR USB SLOT.  EVERY LAN CARD HAS ITS OWN MAC ADDRESS.


REPEATER





REPEATER IS A LAYER ONE DEVICE. IT WORKS LIKE N AMPLIFIER, BUT REMEMBER APLIFIER WORKS IN ANALOG SIGNAL WHERE REPEATER WORKS IN DIGITAL SIGNAL.  IT IS USED TO FIX THE PROBLEM OF ATTENUATION.


HUB



IT IS ALSO A LAYER1 DEVICE IT WORKS LIKE A REPEATER BUT REMEMBER REPEATER CANNOT BE A HUB.  A HUB CONTAIN 4, 6, 8, 12, 16 PORTS.  HUB REGENERATE AND INCOMMING SIGNAL AND FORWARDS IT BY ALL OFF ITS ACTIVE PORT.  THIS TYPE OF COMMUNICATION IS KNOWN AS BROADCAST.

HUB WORKS IN HALF DUPLEX MODE.  WHEN TWO DEVICES TRIES TO COMMUNICATE WITH EACH OTHER AT A SAME POINT OF TIME.  THEIR DATA GETS COLLIDED.


COLLISION DOMAIN


IN A HALF DUPLEX NETWORK WHEN TWO OR MORE THAN TWO COMPUTERS TRIES TO COMMUNICATE WITH EACH OTHER AT THE SAME POINT OF TIME THEIR DATA PACKETS GET COLLIDED.  IT IS CALLED COLISION DOMAIN.


WHEN A COLLISION OCCURS A JAM SIGNAL IS GENERATED AND ALL OF THE DEVICES INSIDE A NETWORK STOPS FORWARDING DATA.


BROADCAST DOMAIN

WHEN IN A NETWORK, A PC GENERATES A BROADCAST FRAME; ALL OF THE DEVICES INSIDE THT NETWORK GETS A COPY OF THE FRAME.   IT IS CALLED A BROADCAST DOMAIN.


A HUB NETWORK RESIDES INSIDE A SINGLE BROADCAST AND COLLISION DOMAIN.



CSMA – CD(CARIER SENSE MULTIPLE ACCESS COLLISION DETECTION)


IN A MULTI ACCESS NETWORK THE CARRIER SENSE MECHANISM DETECTS IF THE CHANNEL IS FREE OR NOT.  IT CHECKS FOR VOLTAGE LEVEL IN COPPER WIRE AND LIGHT IN FIBRE OPTICS.


THE COLLISION DETECTION MECHANISM DETECTS THE JAM SIGNAL AND STOPS FORWARDING DATA.  THEN A BACK OF ALGORITHM IS CALCULATED AND AGAIN THOSE COLIDDED DEVICES START SENDING THE DATA WITH LITTLE TIME GAP.



SWITCH



IT IS A LAYER 2 DEVICE.  IT WORKS WITH MAC ADDRESS.  IT IS A HARDWARE DEVICE.  IT IS ALSO KNOWN AS MULTIPORT BRIDGE.  A SWITCH CONTAINS  4, 8, 12, 16, 24, 48, 64 PORTS. EACH PORT WORKS AT FULL DUPLEX MODE.  EACH SIGNLE PORT OF A SWITCH IS IN SEPARATE COLLISION DOMAIN.


SWITCH CANNOT BREAK BROADCAST DOMAIN.  A SWITCHED NETWORK RESIDES INSIDE A SINGLE BROADCAST DOMAIN.  SWITCH HAS A PROCESSOR NAMED ASIC (APPLICATION SPECIFIC INTEGRATED CIRCUIT) WHICH LEARNS THE MAC ADDRESS OF ALL CONNECTED DEVICES AND STORES IN A TABLE CALLED CAM (CONTENT ADDRESSABLE MEMORY).


SWITCH IS OFF TWO TYPES (1) MANAGED SWITCH AND (2) UNMANAGED SWITCH.  (1)MANAGED SWITCH – THIS SWITCH CAN BE MANUALLY CONFIGURE (2) UNMANAGED SWITCH - THIS SWITCH CAN NOT BE CONFIGURED MANUALLY.


NOW I WILL SOMETHING ABOUT SWITCHING METHODS.


(1) CUT THROUGH SWITCHING

THIS TYPE OF SWITCH STARTS FORWARDING DATA FRAME IMMEDIATELY AFTER LEARNING DESTINATION MAC ADDRESS OF THAT FRAME.

IT IS A FASTEST SWITCHING METHOD.  THE PROBLEM WITH THE SWITCHING METHOD IS THAT IT CAN FORWARD CORRUPT FRAME AND RUNT FRAME (FRAME SIZE LESS THAN 64 BYTE).


(2)STORE AND FORWARD SWITCHING

THIS SWITCHING METHOD STORES THE ENTIRE FRAME INTO ITS BUFFER MEMORY.  THEN RUNS CRC(CYCLIC REDUNDANCY CHECK) TO VERIFY CORRUPTED DATA IF THE DATA IS GOOD THEN STARTS FORWARDING.

IT IS THE SLOWEST METHOD OF SWITCHING BUT NO CORRUPTED FRAME IS FORWARDING.  IF A BAD FRAME IS FOUND WITH BAD FCS(FRAME CHECK SEQUENCE).  IT WILL DROP THAT FRAME.


(3)FRAGMENT FREE SWITCHING

IT IS AN ADVANCED VERSION OF AS CUT THROUGH SWITCHING.  A SWITCH RUNNING IN FRAGMENT FREE MODE LEARNS THE FIRST 64 BYTE OF A FRAME, THEN STARTS FORWARDING THAT FRAME.  THIS METHOD DOESN’T ALLOW ANY RUNT FRAME TO BE FORWARDED.


FIREWALL


IT IS LAYER 4 DEVICE.  IT WORKS WITH ALL TYPES OF NETWORK ADDRESES (MAC, IP, PORT NUMBER).  IT IS A SECURITY APPLIANCE.   IT IS USED TO SECURE OUR NETWORK FROM UNATHOURIZED ACCESS, SUCH AS HACKING, NETWORK ATTACKS, VIRUSES AND WORMS.


FIREWALL IS OF TWO TYPES

1> SOFTWARE FIREWALL

2> HARDWARE FIREWALL


LET US SEE SOFTWARE FIREWALL

 IT IS A SOFTWARE BASE PROGRAM WHICH PROTECTS OUR PCS, LAPTROPS , SERVERS EG:- ANTIVIRUS FIREWALL, WINDOWS FIREWALL, COMODO FIREWALL, WINDOWS DEFENDER.


LET US SEE HARDWARE FIREWALL

IT IS A HARDWARE COMPONENT WHICH WORKS WITH SOFTWARE COMPONENT. IT CONTAINS VARIOUS SECURITY PROTOCOLS WHICH HELPS TO PROTECT A WHOLE NETWORK.

FOR EXAMPLE ->CISCO ASA, PIX, A5BIG IP, CHECK POINT, TALO ALTO


MODES OF FIREWALL


1.INTRUSION DETECTION SYSTEM

IT IS A PASSIVE PROTECTION WHICH DOESNOT BLOCK ANY MALICIOUS NETWORK ACTIVITY.  IT  HELPS TO MONITOR AND DETECT THOSE ACTIVITIES.


2.INTRUSION PREVENTION SYSTEM

IT IS A AN ACTIVE PROTECTION WHICH BLOCKS ANY MALICIOUS NETWORK ACTIVITY.



MODEM

MODEM MEANS MODULATION AND DEMODULATION.  THIS DEVICE CONVERTS ANALOG SIGNAL INTO DIGITAL SIGNAL AND VICE VERSA.IT IS USED WITH BROADBAND CONNECTION PROVIDED BY PLAIN OLD TELEPHONE SYSTEM (POTS) AND TELCO NETWORK. FOR EXAMPLE BSNL LANDLINE


MODEM IS OFF TWO TYPES:-

1> ADSL 2 WHICH PROVIDES WIRED NETWORK.

2> ADSL 2+ WHICH PROVIDED BOTH WIRED AND WIRELESS NETWORK.


ADSL – ASSYNCHRONOUS DIALUP SUBSCRIBER LINK


ACCESS POINT

IT IS A LAYER 1 DEVICE.  IT IS USED TO CREATE A WIRELESS LAN.  IT USES WIFI TECHNOLOGY .  IT NEVER MAKES COLLISION BUT WORKS INSIDE A SAME BROADCAST DOMAIN.  DATA ACCESS MECHANISM CSMA\CA  (CARRIER SENSE MULTI ACCESS WITH COLLISION AVOIDANCE).


THE COLLISION IS AVOIDED BY EXCHANGING CTS AND RTS MESSAGE.  ACCESS POINT WITH LAYER 3 ENGINE CAN FORWARD I TRAFFIC FROM ONE NETOWK TO ANOTHER THEN IT IS CALLED A WIFI ROUTER.


THE WIFI STANARDS COMES UNDER IEEE (INSTITUTE OF ELECRICAL AND ELECTRONICS ENGINEERS) 802 PROJECT.  WIFI COMES UNDER 802.11 STAMDARD.  IT HAS 5 SUB STANDARD.802.11 A,  802.11B, 802.11G, 80211N, 802.11AC.


ROUTER



IT ISS A LAYER 3 DEVICE.  IT IS USED TO CONNECT MULTIPLE NETWORKS.  IT WORKS WITH IP ADDRESS.  A ROUTER FORWARDS DATA PACKETS FROM ONE NETWORK TO ANOTHER ACCORDING TO THE DESTINATION IP OF THE DATA PACKET.


IF A DESTINATION IP NETWORKIS UNKNOWN TO THE ROUTER IT WILL DROP THAT PACKET.  TO LEARN ABOUT THIS NETWORK INFORMATION VARIOUS ROUTING PROTOCOLS ARE IMPLEMENTED IN A ROUTER.


ROUTER STORES THE UNKNOWN NETWORK INFOMRATION IN A TABLE KNOWN AS ROUTING INFORMATION BASE(RIB) OR ROUTING TABLE.  ROUTER WORKS AT FULL DUPLEX MODE.  IT NEVER BROADCAST .  EACH SINGLE PORT OF A ROUTER IS IN SEPERATEDE BROADCAST DOMAIN AND COLLISION DOMAIN.


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