router configuration

Operating System: The Cisco IOS (Internetwork Operating System) is copied into RAM during bootup. • Running Configuration File: This is the configuration file that stores the configuration commands that the router IOS is currently using. With few exceptions, all commands configured on the router are stored in the running configuration file, known as running-config. • IP Routing Table: This file stores information about directly connected and remote networks. It is used to determine the best path to forward the packet. • ARP Cache: This cache contains the IPv4 address to MAC address mappings, similar to the ARP cache on a PC. The ARP cache is used on routers that have LAN interfaces such as Ethernet interfaces. • Packet Buffer: Packets are temporarily stored in a buffer when received on an interface or before they exit an interface.
RAM is volatile memory and loses its content when the router is powered down or restarted. However, the router also contains permanent storage areas, such as ROM, flash and NVRAM.