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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.
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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
Router Components: RAM RAM stores following components: RAM (3) Command Executive Commands are loaded. (2) Internetwork Operating System (IOS) The IOS is located by the bootstrap program, it is loaded in to RAM • Programs • POST and bootstrap to test the equipment • and locate the IOS (4) Running Config. File the IOS loads active configuration file (usually from NVRAM) (5) Tables ARP and routing tables (6) Buffers used for routing incoming and outgoing packets
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
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
Show Commands R#show flash R#show version R#show interfaces RAM NVRAM Flash Internetwork Operating System Backup Configuration File Operating Systems Interfaces Programs Running Configuration Table and Buffers R#show process CPU R#show protocols R#show mem R#show stacks R#show buffers R#show startup-config R#show running-config R#write term
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
Chancing the Configuration Register Router(config)#config-register 0x101. • Recovering Passwords: pp. 356-359