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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
IST 228\Ch7: Managing Cisco... 2
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:
IST 228\Ch7: Managing Cisco... 3
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
IST 228\Ch7: Managing Cisco... 4
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
IST 228\Ch7: Managing Cisco... 5
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
IST 228\Ch7: Managing Cisco... 6
Startup
IST 228\Ch7: Managing Cisco... 7
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
IST 228\Ch7: Managing Cisco... 8
Checking Current Configuration
IST 228\Ch7: Managing Cisco... 9
Chancing the Configuration RegisterRouter(config)#config-register 0x101.
Recovering Passwords: pp. 356-359