Routers components and sequence Description

Router Components

Basically, there are four components in a router which are listed below:

• ROM
• RAM
• NVRAM
• FLASH

ROM: ROM stands for Read Only Memory. It is a non-volatile memory which means your memory will be saved permanently even when the router is powered off. In the older versions of routers it is used to store IOS memory which is not the case in the new routers so ROM is used for POST(Power On Self Test) and Bootstrap program. When we switch on the router, the ROM performs POST sequence which makes sure that all the components of the router is functioning correctly. The bootstrap helps to locate the IOS when the router is turned on.

RAM: RAM stands for Random Access memory.It is a volatile memory which means when the data will be lost when the router is powered off. There are two parts of RAM named as Main memory and shared I/O memory.The main memory is used to store routing table, ARP Table  and runnig configuration of the router. Shared I/O memory is used as buffer location for storing packets temporarily.

NVRAM: NVRAM stands for NON volatile Random Access memory. It is used to store the startup configuration of the router. When you made changes in the router Running configuration ,changes are saved in NVRAM so that they are not lost when the router shuts down.

FLASH: The flash memory is used for running and storing the Cisco IOS which is the Operating System(OS) of the router. The contents of the Flash memory is in read only mode when the router is running.

TFTP SERVER

 

TFTP sends Trivial File Transfer Protocol which is a backup server for router.

Routing Sequence of a Router

ROM --------> POST

NVRAM -------> Config-Register

FLASH -------->IOS

NVRAM --------> Startup-Config

RAM ---------> Running-Config

Note: Config-register only helps in finding the location of the router.