07-05-2014, 12:15 PM
Router Components
Router Components.ppt (Size: 248 KB / Downloads: 10)
Bootstrap – stored in ROM microcode – brings router up during initialisation, boots router and loads the IOS.
POST – Power On Self Test - stored in ROM microcode – checks for basic functionality of router hardware and determines which interfaces are present
ROM Monitor – stored in ROM microcode – used for manufacturing, testing and troubleshooting
Mini-IOS – a.k.a RXBOOT/boot loader by Cisco – small IOS ROM used to bring up an interface and load a Cisco IOS into flash memory from a TFTP server; can also do a few other maintenance operations
Config-Register
controls how router boots; value can be seen with “show version” command; is typically 0x2102, which tells the router to load the IOS from flash memory and the startup-config file from NVRAM
System Startup
POST – loaded from ROM and runs diagnostics on all router hardware
Bootstrap – locates and loads the IOS image; default setting is to load the IOS from flash memory
IOS – locates and loads a valid configuration from NVRAM; files is called startup-config; only exists if you copy running-config to NVRAM
Startup-config – if found, router loads it and runs embedded configuration; if not found, router enters setup mode
Overview
Router configuration controls the operation of the router’s:
Interface IP address and netmask
Routing information (static, dynamic or default)
Boot and startup information
Security (passwords)
Router Access Modes
User EXEC mode - limited examination of router
Router>
Privileged EXEC mode - detailed examination of router, debugging, testing, file manipulation
Router#
ROM Monitor - useful for password recovery & new IOS upload session
Setup Mode – available when router has no startup-config file