IST 228\Ch7: Managing Cisco... 1

Router Components: ROM• Read-only memory (ROM)• Stores:

– the bootstrap program, also called the ROM Monitor, that initializes the router’s basic hardware components.

– POST (power-on self test), that checks the basic functionality of the router hardware and determines interfaces.

– Mini-IOS, which is used to bring up an interface.

• ROM monitor mode– Router mode that allows to configure your

router in the event that there is no valid IOS file on your flash memory

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Router Components: RAM

RAM(1)Programs

POST and bootstrap to

test the equipment

and locate the IOS

(2) Internetwork Operating System (IOS)

The IOS is located by the bootstrap program, it is loaded in to RAM

(3) Command Executive

Commands are loaded.

(4) Running Config. Filethe IOS loads

active configuration file

(usually from

NVRAM)

(5) Tables

ARP and routing tables

(6) Buffers

used for routing

incoming and

outgoing packets

RAM stores following components:

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Router Components: NVRAM

• Nonvolatile random access memory (NVRAM)– Special type of RAM– Not cleared when the router is rebooted– Startup configuration for the router is

stored in NVRAM by default– Stores all the user-defined configuration

information for the router

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Router Components: Flash Memory• Erasable, programmable, read-only

memory (EPROM)– Not typically modified during normal

operations– Can be upgraded or erased when

necessary– Content of flash memory is maintained

even when the router is rebooted

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Show Commands

Internetwork Operating System

ProgramsRunning

Configuration

Table and

Buffers

Backup Configuration

File

OperatingSystems

Interfaces

RAM NVRAM Flash

R#show process CPUR#show protocols

R#show running-configR#write term

R#show memR#show stacksR#show buffers

R#show startup-config

R#show version R#show flash R#show interfaces

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Startup

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Managing Configuration Registers• 16-bit software register, which is

written into NVRAM. • By default, it is set to load IOS from

flash memory and look for startup-configuration from NVRAM.

• ..\Calc\config_register.exe

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Checking Current Configuration

IST 228\Ch7: Managing Cisco... 9

Chancing the Configuration RegisterRouter(config)#config-register 0x101.

Recovering Passwords: pp. 356-359