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TechKnowSurge Catalog Videos DEMO: Boot Up Process
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DEMO: Boot Up Process

Covers the Cisco 2960 switch boot process, including POST, bootstrap loading, IOS initialization, and how to verify system information using the show version command.

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About this video

When a Cisco 2960 switch is reloaded, it follows a defined boot sequence that begins with the Power-On Self Test. After POST completes, the bootstrap program initializes the flash drive and searches for an IOS image. If a specific image is configured, that image loads; otherwise, the switch defaults to the first available IOS file it finds on flash. The selected image is then decompressed and loaded into RAM, where it runs during normal operation. The full boot process on a 2960 typically takes just over two minutes from reload to prompt. Once the switch is running, the show version command—executed from privileged EXEC mode—returns a detailed snapshot of the device's current state. This includes the IOS version and image filename, hardware details, MAC address, and the configuration register value. The configuration register, displayed in hexadecimal, determines boot behavior, including where the switch looks for its IOS during startup. Understanding how to read and interpret this output is foundational for managing and troubleshooting Cisco devices in a production environment.

What you'll learn

What's covered

Cisco Switch Boot Process

Aligned to

Cisco CCNA
1.1 Explain the role and function of network components
2.8 Describe network device management access
Cisco CCST Networking
4.5 Explain basic switching concepts
5.5 Run basic show commands on a Cisco network device
5.4 Differentiate between different ways to access and collect data about network devices

Key terms

Power-on Self-Test
POST
A diagnostic routine run by the BIOS or UEFI firmware immediately when a computer is powered on to verify that essential hardware components such as CPU, RAM, and storage are present and functioning correctly. If POST detects a critical failure it halts the boot process and signals an error.
Bootstrap
A small program stored in ROM on a Cisco device that initializes hardware and locates the IOS image to load during the boot sequence.
Flash Memory
A type of non-volatile solid-state memory that stores data on chips and retains information without power; it is the storage technology behind SSDs, USB drives, and SD cards.
Internetworking Operating System
IOS
Cisco's proprietary operating system running on most Cisco routers and switches, providing a command-line interface for device configuration, management, and monitoring. IOS is the foundation for Cisco's network equipment and has evolved into variants such as IOS XE, IOS XR, and NX-OS.
Configuration Register
A hexadecimal value on a Cisco device that instructs the bootstrap program how to behave at startup, including which IOS to load, whether to enter ROMmon mode, or whether to bypass the configuration file.
show version
A Cisco IOS command executed in privileged EXEC mode that displays the IOS image filename, software version, hardware information, and configuration register value.

Topics

Cisco Ios Cisco Catalyst 2960 Boot Process Show Version Post Networking

Transcript

Reloading the switch

We're going to take a look at the boot up process here and see what it looks like as you boot up. In this case right here it's a switch, it's a 2960.

In order for me to issue the command to restart this switch, which is the command reload, I have to be in privileged exec mode. Right now I'm in user exec mode. We'll talk about the different modes later, but for now I just know that I have to hit enable. I'm going to type in reload to reload this device. It's going to confirm that, and once I hit enter on here I'm going to actually start a timer so we can time it, because I'm going to fast forward through some of this.

The boot sequence

I've got the message coming up saying that a reload command has been issued. Then it goes into the POST, and that's where it's doing the power on self test. Once that's done, it is then loading the bootstrap, and the bootstrap starts initializing the drive, so we see it says initializing flash drives. Once it's done initializing the flash drive, then it's going to take a look and say, what IOS do I need to load? So right now it's looking for the IOS that it needs to load. If it's specified, it's going to load that. If it's not specified, it's going to take the first IOS that it comes across.

It looks like it's now found an IOS, so now what it's doing is unpacking that and loading it into the RAM, so it's going to function within RAM. This is going to take a while, so I'm going to fast forward through this. It's displaying information about this particular system, and we're going to look further into that here in a little bit.

Right around the two minute and twenty second mark is when it finished up. We see a press return to get started, so now I'm going to hit return, and it's going to go into the switch. It discovered that there was a configuration file, so it's not prompting us if we want to go through the configuration window. So now we're back on the switch.

Checking the configuration register

Now we're going to take a look at that configuration registry value. It's going to look a little different in here, but you'll get the point.

In order to do a show versions command to take a look at that, I'm going to have to get into the privileged exec mode, so I have to type enable — one of the reasons why I also call it the enable mode. Once again, we'll talk about modes later on.

I'm going to do a show version, and that show version is going to show me a lot of information about my device. For instance, it's going to show me the IOS that it's loading, the image that's loading for the operating system, so we see some additional information about the software. Then when we scroll through here, we see the MAC address and some other information.

The thing that I'm looking for, though, is this configuration register. It is 0xf, so the f is what's telling it, hey, go and look for the IOS in the flash drive. So we see that the configuration register value is set. In later lessons we'll actually learn how to set that differently.

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