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Chap 5Startup and Setup
Andres, Wen-Yuan Liao
Department of Computer Science and Engineering
De Lin Institute of Technology
http://www.cse.dlit.edu.tw/~andres
Overview
Start a router for the first time by using the correct commands
Startup sequence to do an initial configuration of a router
Router Boot Sequence and Setup Mode
Router startup routine
Router startup sequence
Commands related to router startup
Router startup routine
A router initializes by Hardware testLoad the bootstrapLoad the OSLoad a configuration file
Cisco router powers up
POST: Power-on self test
Executes diagnostics from ROM Verify the basic operation of the CPU, memory, and network interface ports
Router startup sequence: Step 1
The generic bootstrap loader, in ROM, executes on the CPU cardPreset operation to load
instructions that in turn cause other instructions to be loaded into memory, or cause entry into other configuration modes
Router startup sequence: Step 2
The IOS location is disclosed in the boot field of the conf. register
If the boot field indicates a Flash, or network load, boot system commands in the conf. file indicate the exact location of the image
OSI is loadedWhen it is loaded and operational, the OS locates the hardware and software components and lists the results on the console terminal
Router startup sequence: Step 3
The conf. file (NVRAM) is loaded into main memory and executed one line at a time
These conf. commands start routing processes, supply addresses for interfaces, set media characteristics, and so on
Router startup sequence: Step 4
If no valid conf. file exists in NVRAM, the OSI executes a question-driven initial configuration routine
Minimal configuration
Router startup sequence: Step 5
The Startup Order
Bootstrap from ROM
IOS from flash
IOS from tftp
IOS from ROM
Config from NVRAM
Config from tftp
Config from setup
Commands related to router startup
show startup-configDisplay the backup conf. files
show running-configDisplay active conf. files
erase startup-configDeletes the backup conf. file in NVR
AM
Commands related to router startup
reload (reboot)Cause it to run through the entire startup process
setup: enter setup mode from the privileged EXEC prompt
System Configuration Dialog
Using the setup command
Setting up global parameters
Setting up interface parameters
Setting up script review and use
Using the setup command
The main purpose of the setup mode is to bring up, quickly, a minimal configuration for any router that cannot find its configuration
Using the setup command
Default answers appear in square brackets [ ]
During the setup process, you can press Control+C at any time to terminate the process and start over
Setting up global parameters
The router host name
An enable password The "enable password" is used when no "enable secret word" exists
Setting up global parameters
Enable secret wordA one-way cryptographic secret word that is used instead of the "enable password" when it exists
Setting up script review and use
When you complete the conf. process Display the configurations
Ask if you want to use this conf.Yes: the conf. will be executed
and saved to NVRAM
Summary
The router initializes by loading a bootstrap, the OS, and a configuration file
If no configuration file exists, the router enters setup mode
