Chap 5 Startup and Setup Andres, Wen-Yuan Liao Department of Computer Science and Engineering De Lin...

Chap 5Startup and Setup

Andres, Wen-Yuan Liao

Department of Computer Science and Engineering

De Lin Institute of Technology

andres@dlit.edu.tw

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