Computers and Networks















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Router Components


External router configuration sources

In this section, you will learn about the router components that play a key role in the configuration process. Knowing which components are involved in the configuration process gives you a better understanding of how the router stores and uses your configuration commands. Being aware of the steps that take place during router initialization will help
you determine what and where problems may occur when you start up your router.
You can configure a router from many external locations, including the following:

- from the console terminal (a computer connected to the router through a console port) during its installation
-via modem by using the auxiliary port
-from Virtual Terminals 0-4, after it has been installed on the network
-from a TFTP server on the network



Internal router's configuration components

The internal architecture of the Cisco router supports components that play an important role in the startup process. Internal router configuration components are as follows:
RAM/DRAM -- stores routing tables,ARP cache, fast-switching cache,packet buffering (shared RAM), and packet hold queues; RAM also provides temporary and/or running
memory for a router's configuration file while the router is powered; RAM content is lost during a power down or restart
NVRAM -- non-volatile RAM stores the router's backup/startup configuration file; NVRAM content is retained during power down or restart
Flash -- erasable, reprogrammable ROM that holds the operating system image and microcode; Flash memory enables software updates without removing and replacing processor chips; Flash content is retained during power down o restart; Flash memory can store multiple versions of IOS software
ROM -- contains power-on diagnostics, a bootstrap program, and operating system software;