Router

Router is a device to connect networks with each other.It blocks broadcasting & allows point to point communication there by reducing traffic on the network & works on the network layer.

A Router is a layer 3 network device that moves data between different network segments and can look into a packet header to determine the best path for the packet to travel. Routers can connect network segments that use different protocols.

They also allow all users in a network to share a single connection to the Internet or a WAN. It is used to improve network performance.Router Components (internal)ROM ROM is used to store the router's bootstrap startup program, operating system software, and power-on diagnostic tests programs. In order to perform ROM upgrades you remove and replace pluggable chips on the motherboard.Flash MemoryIt holds operating system image(s).

Flash memory is erasable, reprogrammable ROM.You can perform Cisco® IOS software upgrades without having to remove and replace chips. Flash content is retained when you switch off or restart the router.RAMRAM is used to store operational information such as routing tables, router's running configuration file. RAM also provides caching and packet buffering capabilities.

Its contents are lost when you switch off or restart the router.NVRAMNVRAM (nonvolatile RAM), is used to store the router's startup configuration file. It does not lose data when power is switched off. So the contents of the startup configuration file are maintained even when you switch off or restart the router.

Network InterfacesThe router's network interfaces are located on the motherboard or on separate interface modules. You configure Ethernet or Token Ring interfaces to allow connection to a LAN. The synchronous serial interfaces are configured to allow connection to WANs. You can also configure ISDN BRI interfaces to allow connection to an ISDN WAN..Router Components (External)A router can be configured over any of its network interfaces. You can supply configuration information to a router using:- TFTP servers : Trivial File Transfer Protocol; A simplified version of FTP that allows files to be transferred from one computer to another over a network