Describing Components

A Cisco router or switch uses an operating system and a number of configuration files to perform its tasks. These components are stored in various locations on the device. Some components can even be located on a different device in the network and accessed as required across the network. The device also requires some general memory to use as a working space, as any computing device does.

This section presents the various types of storage that exist on a router or switch, with a particular emphasis on the type of information that is stored in these locations. This section also covers the ability of each type to retain information and the operations required to harness these capabilities.

Defining the Contents of RAM

All Cisco routers and switches have random access memory (RAM). This very fast memory is used in the same fashion as RAM in a computer or server. This type of memory requires power to the device to retain its information. When the router or switch boots up, it will place some information in RAM, specifically the IOS tables, and it will dedicate some of this RAM to be used as buffers. This is not unlike the operating system on a computer, which will “load” itself into memory from the hard drive at bootup and operate from that location.