Boot Sequence(s)

altdrugz

Hello everybody, Im reading Todd Lammles's study guide (already read Odom's) and I found a tricky part in the way that it describes the boot sequence. Chapter 7 page 280. Says:
Router Boot Sequence : 1. POST 2. Bootstrap(looks for and loads IOS...) 3. NVRAM (IOS searches for a valid conf file named startup config) 4. If it doesnt find it, router broadcasts out any inteface for a TFTP host blablabla... and if it fails it starts the setup mode.

After the 2 first step (POST and Bootstrap) it has a highlighted TIP "the default order of an IOS loading from a router is flash, TFTP server, ROM."

So correct me if I am wrong, we are talking about 2 different boot sequences... Router's boot sequence and IOS boot sequence right? And I guess that when it says that IOS goes for the valid startup configuration file to -> flash (if fails then)-> tftp(if fails then) -> ROM in the ROM is the setup mode ?

DANMOH009

Ye that's basically it

The easiest way I remember it is to say they are 2 separate sequences one for the IOS and one for a configuration file.

So basically.

Router Powered on,
Bootstrap in ROM loads POST
Bootstrap then checks config register to check where it can load IOS from (default is 0x2102).
It then does the sequence of 1. Flash (if not found) 2. TFTP server (if not found) 3. Mini IOS in ROM.
After the IOS is found it is load into RAM.

It then looks for the configuration file (so basically the second sequence)

So it will attempt firstly to find a configuration file in NVRAM and move it to RAM
if no luck it will look for a TFTP server
if no luck it will it will enter setup mode (Initial configuration mode).

When i was studying the books sometimes confused me, but as long as i remembered this method I found I was fine when facing questiuons about the process.

gbdavidx

talk about a complicated process