Cisco Cookbook

Chapter 1. Router Configuration and File Management

1.0. Introduction

You can think of a Cisco router as a special-purpose computer. It has its own operating system, which is called the Internetwork Operating System (IOS), as well as files and filesystems. So we’ll start with a discussion of the basic system administration functions that a router engineer must perform. This includes managing your router’s filesystems, upgrading the operating system, doing backups, and restoring the system configuration.

Cisco routers use flash memory, rather than disks, for storing information. Flash storage media is significantly more expensive and slower than disk storage, but the amount of storage needed to run a router is relatively small compared to the amount needed to run a general-purpose computer. Flash also has the important benefit that it tends to be more reliable than disk storage.

Flash storage is similar to Random Access Memory (RAM), but it doesn’t need power to retain information, so it is called non-volatile. And, unlike Read Only Memory (ROM), you can erase and rewrite flash easily. There are other types of non-volatile solid state storage, such as Erasable Programmable Read Only Memory (EPROM) and Electronically Erasable Programmable Read Only Memory (EEPROM). EPROM is not suitable for routers because it generally requires an external device such as an ultraviolet light shone through a window on the chip to erase it. EEPROM, on the other hand, can be erased by simply sending an ...