The intelligent Router and its components

As described in the previous post, the Router is an intelligent device and we can simply call a special type of computer. It has the basic components as a standard desktop PC. However, routers are designed to perform some very specific functions. Just as computers need operating systems to runs software applications, routers need the Internetwork Operating System (IOS) to run configuration files, these configuration files contain the instructions and parameters that control the flow of traffic in and out of the router.

Router Components

IOS

The IOS is the Operating System of the Router. The core function of IOS is to enable data communications between network nodes. In addition to routing and switching, IOS offers dozens of additional services that an administrator can use to improve the performance and security of network traffic.

RAM

Random Access Memory also called dynamic RAM (DRAM). The following are the characteristics and functions of the dynamic RAM.

·        Store routing table

·        Holds ARP cache

·        Holds fast-switching cache

·        Perform packet buffering (shared RAM)

·        Maintains packet-hold queues

·        Provide temp memory for the configuration file of the router while the router is powered on

NVRAM

NVRAM is non-volatile RAM. By "non-volatile", we mean that the contents of NVRAM are not lost when the router is powered down or reloaded. Where RAM holds the running the configuration file, NVRAM holds the startup configuration file. If NVRAM is empty when the router reloads, you will be prompted to enter setup mode.

Characteristics and Functions:

·        Provides storage for the startup configuration file

·        Retains content when the router is powered down or restarted

Flash

The flash and NVRAM are similar but they do different functions. The IOS has held the flash memory. Flash is erasable and reprogrammable ROM. Its content is retained by the router on power-down or reload.

Characteristics and Functions:

·        Holds the operating system image (IOS)

·        Allows software to be updated without removing and replacing chips on the processor

·        Retains content when the router is powered down or restarted

·        Can store multiple versions of IOS software

ROM

ROM stands for Read-Only Memory. ROM stores the routers bootstrap startup program, operating system software, and power-on diagnostic test programs (the POST).

Characteristics and Functions

·        Maintains instructions for power-on-self-test (POST) diagnostics

·        Stores bootstrap program and basic operating system software

·        Requires replacing pluggable chips on the motherboard for the software upgrades

Interfaces

The router has different interfaces for doing special connections. The following are the common types.

·        Ethernet

·        Fast Ethernet

·        Serial

·        Token ring

·        ISDN BRI

·        Loopback

·        Console

·        Aux

Characteristics and Functions:

·      Connect the router to the network for frame entry and exit

·      Can be on the motherboard or on a separate module

Topic Conclusion

In this article, we have covered about the router and its components. The next article will explain the booting process of the Router and the functions.