A router is a computer networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. A data packet is typically forwarded from one router to another through the networks that constitute an internetwork (e.g., the Internet) until it reaches its destination node. A router is connected to two or more data lines from different networks and makes forwarding decisions based on network conditions, routing protocols, and static routing tables.
Routers may connect electronic communications networks such as local area networks (LANs), wide area networks (WANs), virtual private networks (VPNs), cellular telephone networks, and integrated services digital network s(ISDNs). Large corporations, e-commerce sites, Internet service providers (ISPs), and other organizations with extensive internets use routers to control or direct traffic within their domain. Small home office and residential users generally do not need routers unless multiple computers are being used on the same broadband connection or for some reason require access to more than one LAN . In these cases, an inexpensive broadband router may be all that is needed. The most common type of residential broadband router uses a technology called “NAT” which allows multiple computers on a LAN share a single public IP address .
A NAT router has three main components:
•A WAN interface that connects the NAT router to an ISP;
•One or more internal Ethernet interfaces that connect the NAT router to PCs or other devices on the local area network;
•And software that controls how traffic flows between these interfaces.
To understand how a NAT router works, it is helpful to think about what happens when you surf the web from your home computer. When you enter a URL into your web browser , your computer sends a request out over your home’s LAN asking for this website . This request first goes to your NAT router because all of your home computers are connected behind it. The NAT software in your router sees this request and looks up its own table of websites that it knows about. If it finds the website you requested in its table, it will send back the IP address of where this website lives on the Internet so that your computer can go fetch it . Your computer then sends another request directly to this IP address asking for the actual website . Once it receives this website , it displays it in your web browser window . So basically, when you want to view a website , three things have to happen:
1) Your computer must send a request out over the LAN asking for this site by name; 2) The NAT software in yourrouter looks up this site in its table and convertsit into an IP address ; 3) Yourcomputer sends anotherrequest directlytothisIPaddressaskingforactualwebsiteanddisplaysitinyourwebbrowserwindowonceite receive sitbackfromtheserverwhereitisstored..
There are several benefits associated with using NAT routers:
-Increased security : By hiding all ofthecomputersonyourLANbehindasingleIPaddress ,itispossibletorestrictoutsideaccess toyournetworktojustthosecomputersonwhichyouhaveopenedupthe necessaryportsfortrafficinandoutofthenetwork .Thisincreasesthe overallsecurityofyournetworkbecauseintruders would needto knowthe specificportnumberstouseinordertogainaccesstoyourLANdevices , whichispracticallyimpossibleunlesstheyhavebeenfortunateto stumbleuponthisfinformation somehow .Inaddition ,mostNATrouters alsoofferfirewall protectionthatcan further increasethe securityofyournetworkbypreventingunauthorized outsideusersfrom accessinginternaldataandresourcesonyournetwork .
-Easeofuse : Formosthomeuserswhodonot haveextensive knowledgeaboutcomputernetworking technologies ,configuringaNATroutercanbesimplerenoughthatno outsidehelpisneededinordertogetthenetworkingupandrunning quicklyandsmoothly .Becausethese typesofroutersaremeantforconsumer useratherthanbusinessorenterpriseuse ,theyaregenerally very user-friendly right outoftheboxwithlittletono configurationrequiredonthepartoftheenduserinorderto getthenetworkingoperationalquicklyandsuccessfullywithout anyhasslesorproblemsarising later downroad ..
-Betterperformance : Whenmanycomputersareconnecteddirectlytooneanotherviaan Ethernet switchorhub withoutanytypeofrouteringdeviceinthemiddlemanagingand regulatingtrafficflowbetweenthenetworkeddevices ,itispossible foreachdevicetonattempttocommunicatewithallotherdevicesatthesametime resultingsignificantamountsofcollisionsandretransmissions whichultimatelyleadtolowerdatatransferratesoveralleffectivelyslowing downthenetworkspeedforallusersconnectedtothis typeofsetup .. HavingaNATrouterbetween thenetzonedevicespreventsthisdegradationinspeedbecausethe routermanagesallintercommunicationbetweenthedevicesonthenetework behalfoffreesingletime slotsfromeachendsystemtopreventcollisions therebyincreasingperformanceratesforthoseusingthenative applicationsprogramminginterface(API)providedbytheoperatingsystem runningonthewired/wirelessclientdevicesconnectedbehindtherouter ..