What is router?
Routers are internetworking devices use to connect the multiple network. Router provide connectivity inside the enterprises, between enterprise and the internet and inside ISPs.The large router interconnect ISPs,inside ISPs or may be used very large enterprise network. The small routers provide the connectivity for home and small office. Routers connect two or more logical subnets. These are more sophisticated and access to network layer address. The Routers contain the software that enables them to determine the best in the several possible paths to the destination. Routers operate in the physical layer, data link layer and the network layer of the OSI model. Routers relay packets among multiple interconnected networks. They route the packet from one network to the other network
The Router is the center of the network and responsible for the delivery of the packets across different networks. The destination of the IP packet can be web server in other country or an e-mail server on the local area network. It is the router’s responsibility to deliver that packet in a timely manner. It is the router that forwards the packet from the network to network, from sending host to the destination host.
A router is a computer and has many of the common hardware components like the other computer. A router also includes an operating system. The primarily responsibility is to forward packets destined for local and remote network by-
1. Determining the best path to send the packet.
2. Forward the packet towards the destination.
A router receive a packet, encapsulated in one type of data-link layer frame such as an Ethernet frame and when forwarding the packet, encapsulate it in a different type of data link frame such as point-to-point protocol(PPP).The data link encapsulate depends on the type of interface on the router and the type of medium to which it connects. Router operates in two different planes-
The first one is Control plane-In this plane the router learns the outgoing interface for the forwarding the packet to the destination and the second one is Forwarding plane-it is responsible for sending the packet received on the logical interface to outbound logical interface.