Figure 4: A Cisco Router; source: www.cisco.com
A router is a device that works at layer 3 of the OSI model, and hence routes IP packets between different subnets. The hardware architecture at a block level would be similar to that of a switch, with the difference that the switch processor is replaced by a route processor. Since the router operates at a higher OSI layer than that of a switch, all the functions of a layer 2 switch would also be inbuilt into the router.
The route processor is the brain of the router. The routing tables are built by the route processor by running various routing protocols that we will discuss in the next ...
