A router is a networking device which is used to forward data packets between computer networks, typically on the open internet or on private networks. The hardware and software of Cisco routers is tailored to the tasks of routing and forwarding information which is contained in IP basdd “packets”, the electronic medium by which information is transmitted over TCP/IP networks such as the internet. Routers typically connect two or more logical subnets, which do not necessarily map 1-to-1 with the physical interfaces of the Cisco router.Have a look at sell cisco routers for more info on this. The term “routing” often means the same thing as “Layer 3 Switching”.
Cisco routers can perform various functions, amongst them is Internet Protocol (IP) forwarding. Once an IP packet is forwarded by a Cisco router, the router should no longer retain statistical information about it. Rather, the sending and receiving endpoint devices on the IP network are responsible for keeping track of information about things such as dropped or missing packets.
One of the most important functions of router is to decide what to do when congestion occurs on a network. Much like with cars and traffic, congestion occurs when IP packets arrive at the router at a rate higher than the router can process. Three policies commonly used in the Internet are Tail drop, Random early detection, and Weighted random early detection. A Cisco router makes use of a routing table to decide where the packet should be sent so if the router cannot find the preferred address then it will look down the routing table and decide which is the next best address to send it to.