#NetworkWorksworksinsafemodeonly

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Network Works

Network Works Using HUB, SWITCH, ROUTER. All These Three Devices Are Similar But There Is A Difference In The Way They Handle Data. So Lets Understand About These Three.

HUB

The Purpose Of A Hub Is To Connect All Of Your Network Devices Together On A Internal Network. It Is A Device That Helps Multiple Ports That Accepts Ethernet Connection From Network Devices. A Hub Is Considered Not To Be Intelligent. Because It Does Not Filter Any Data Or Has Any Intelligence As To Where The Data Is To Be Sent. The Only Thing A Hub Knows Is If A Device Is Connected To One Of Its Ports So When A Data Packet Arrives To One Of Its Ports It Copies To All Of The Other Ports. So All The Devices On That HUB Sees That Data Packet. If The Data Packet Comes To Its One Port, The Data Packet Rebroadcasts That Data To Every Port The Device Connected To It.   If The Computer 1 Only Wants To Communicate With Computer 3, The Computer 3 And Computer 4 Receives The Data Same Data Sent To Computer 3. So When This Happens, It Not Only Creates Security Concerns, It Also Creates Unnecessary Traffic Which Wastes Bandwidth.  

SWITCH

SWITCH Is Very Similar To A HUB, It Is Also A Device Which Has Multiple Ports That Accepts Ethernet Connection From Network Devices But Unlike A HUB A SWITCH Is Intelligent. A SWITCH Can Actually Learn The Physical Addresses Of The Devices That Are Connected To It. And It Stores These Physical Addresses Called MAC Addresses In Its Table. So When A Data Packet Is Sent To A SWITCH, It Is Only Directed To The Intended Destination Port. Unlike A HUB Were HUB RebraodCast The Data To Every Port.   If Computer 1 Wants To Send Data Packet To Computer 3, The Data Packet Arrives At The SWITCH And Switch Will Look At Its Table  MAC Addresses And Matching Ports And Deliver The Data To The Correct Port And The Data Packet Will Go To That Computer. So That Is The Major Difference Between A HUB And A Switch. So As A Result SWITCH Is Far More Preferred Over HUBS Because They Reduce Any Unnecessary Traffic On The Network.  

Difference Between HUB And SWITCH

A HUB Only Detects A Device Is Physically Connected To It.SWITCH Can Detect Specific Devices Connected To It Because It Keeps A Record Of MAC Addresses Of Those Devices. HUBS And SWITCHES Are Used To Exchange Data Within A Local Area Network. For Example Such As Your Home Network Or In A Bussiness. They Are Not Used To Exchange Data Outside Their Own Network. Such As Out On The Internet. Because To Exchange Or Route Data Out Side Their Own Network To The Other Network Such As Out On The Internet. A Device Needs To Be Able To Read IP Addresses And HUBS And SWITCHES Do Not Read IP Addresses.So Thats Where Teh Router Comes In.

ROUTER

Router Does What Exactly What Its Name Implies.A Router Is A Device Which Routes And Forwards Data From One Network To Another Network Based On Their IP Address. When A Data Packet Is Received From The Router, The Router Inspects The Data's IP Address And Determines If The Packet Was Meant For Its Own Network Or If It Meant For Another Network. If The Router Determines That The Data Packet For Its Own Network, It Receives It. But If It is Not Meant For Its Own Network It Sends It Off To Another Network. So A Router Is Essentially A Gateway Of A Network.

If You Observe The Above Picture Two Computers(A Network) Connected To A Router And Router Receives Different Ip Addresses, The Different Colors(Yellow, Green, Orange, Red) Are IP Addresses. The Network Is Red, Router Only Receives Red Colored Packets And Sends To Two Computers(Network) From The Internet. All The Other Colors(IP Addresses) Are Rejected By The Router Because Those Are Not Intended For This Network, The IP Addresses Are Not Meant For This Network.  

If You See The Above Picture, There Are Four Routers Over The Internet. There Are Four Networks Each Network Receives Different Color Packets. Different Color Means Different IP Address. Each Network Is Exchanging Information Within Their Own Network. If The Red Color Receiving Computer Wants To Send Data To Green Color Receiving Computer, First It The Data Packet Reaches To It Own Router And Then Reaches To Router Of Blue Color And Then Sent To The Computer Or Blue Color. Hubs And Switches Are Used To Create Networks, Routers Are Used To Connect Networks.  

BRIDGE

BRIDGES Are Used To Divide A Network Into Separate Collision Domains. For Example, If You Observe The Below Network The Bridge Is Placed In Between And It Separated 3 Computers On Left And 4 Computers On The Right, To Reduce Unnecessary Traffic Between Two Segments(3 Computers And 4 Computers). By Filtering The Data Based On Their MAC Address, The Bridge Only Allows The Data To Cross Over If It Meets The Required MAC Address Of The Destination. Because The BRIDGE Keeps The Record Of All The MAC Addresses Which Are Connected To It. It Also blocks All Data From Crossing Over If It Fails To Meet This Requirement.

GATEWAYS

A Gateway Can Be Defined As A Device That Joins Two Networks Together. They Interconnect Networks With Different Or Incompatible Communication Protocols. A Gateway However Doesn't Change The Data,It Only Changes The Format Of The Data. So On Simple Terms, The Below Picture Is The Demonstration Show's How A Gateway Is Transforming A Simple Single Into Something Totally Different. The Circular Padder Represent One Network And It Goes Through The Gateway And Transforming Into A Wave Pattern Which Represents A Different Network.  

ARP,RARP,ICMP PROTOCOLS

 Address Resolution Protocol (ARP) This Is The Protocol That Is Use To Resolve IP Address To MAC Addresses. Whenever A Computer Needs Communicate With Another Computer On The Network.It Needs The MAC Address Of That Computer. Computers Use MAC Addresses For Communication Between Each Other.   If A Computer Wants To Communicate With Another Computer First It Looks At Its Internal List ARP Cache To See If The Targeted Computer's IP Address Already Has a Matching MAC Address In Its Table. If It Doesn't It Will Sent A Broadcast Message Out On The Network Asking Which Computer Has The IP Address. And The Computer That Has The Matching IP Address Will Respond Back Informing That It Has IP Address Its Looking For. Then The Original Computer Ask For The MAC Address And Then Once It Receives It, The Communication Will Takes Place Between TWO. See Below Picture

  REVERSE ADDRESS RESOLUTION PROTOCOL (RARP)

It Is Just Opposite Of ARP. RARP Is Used To Resolve MAC Address To IP Address.  

Internet Control Message Protocol(ICMP)

When Something Unexpected Occurs, The Event Is Reported By ICMP (Internet Control Message Protocol), Which Is Also Used To Test The Internet. About A Dozen Types Of ICMP Messages Are Defined. The Most Important Ones Are Listed Below.EachEach ICMP Message Type Is Encapsulated In An IP Packet. Message Type Description The DESTINATION UNREACHABLE Message Is Used When The Subnet Or A Router Cannot Locate The Destination Or When A Packet With The DF Bit Cannot Be Delivered Because A "small-packet" Network Stands In The Way. The TIME EXCEEDED Message Is Sent When A Packet Is Dropped Because Its Counter Has Reached Zero. The PARAMETER PROBLEM Message Indicates That An Illegal Value Has Been Detected In A Header Field.This Problem Indicates A Bug In The Sending Host's IP Software Or Possibly In The Software Of A Router Transited. The SOURCE QUENCH Message Was Formerly Used To Throttle Hosts That Were Sending Too Many Packets. When A Host Received This Message, It Was Expected To Slow Down. The REDIRECT Message Is Used When A Router Notices That A Packet Seems To Be Routed Wrong.It Is Used By The Router To Tell The Sending Host About The Problem Error. The ECHO And ECHO REPLY Messages Are Used To See If A Given Destination Is Reachable And Alive. Upon Receiving The ECHO Message, The Destination Is Expected To Send An ECHO REPLY Message Back. The TIMESTAMP REQUEST And TIMESTAMP REPLY Messages Are Similar, Except That The     Read the full article