Methodologies and Approaches

Name: Methodologies and Approaches
Author: Matthew Mercaldi

Learn about the OSI model

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Course: On-Demand

Hello, my name is Matthew Mercaldy and in these lessons you'll learn about top down, bottom up and divide and conquer. So what is top down? Top down is a approach to troubleshooting network connectivity utilizing the OSI model. So the OSI model contains all the layers used for connectivity, except it's starting from layer seven all the way down to layer one. So you have your application layer, your presentation layer, session layer, transport layer network data link, physical. Your application layer, a good example of that will be SSH. SSH for those that you who are now aware is an application used to access switches, routers, firewalls, Linux, Unix servers. I think you can SSH into a Mac. I know you can install SSH server onto Windows, where you can just basically use a command line. Your presentation layer. One example the presentation layer is encryption algorithms. If you've ever SSH-ed into a device or you said to say VPN or VPN client for work, there's gonna be an encryption algorithm on there. Session, good example. You're browsing a website, google.com, use the certificate, that's TLS, CHAP, and PAP. If you're using RADIUS for authentication or SSH, again there's some form of PAP and CHAP on there, depending on what you're using for authentication on that. Transport is TCP, UDP, ICMP. These are your connection protocols that are used. Network, a good example of this is your IP address. If you know your layer three, you could do an ARP and find your MAC address of that. Your MAC address is the physical address of your network interface. I believe there's no two MAC addresses alike, just like snowflakes. Finally, your physical layer. This is your physical NIC interface, your wireless interface, anywhere that's part of a network, it's layer one For top down, we're going to be testing out a very common issue where user calls up their IT department and cannot access the internet. So you go over to their computer because hey they say they cannot access the internet and maybe your company doesn't have any remote access tools. So you just gotta walk over to their desk and take a look. So you go in, you see okay, Google.com is not working. So we're going to see if the application layer is broken. So we're gonna be testing out Edge, 'cause that's what we're using right now. Normally I would try and download another browser but some companies, they actually restrict what browsers you can use. Some will literally just say, you can only use Edge or Chrome, you can't use Firefox. It's a whole licensing thing or maybe they just have a very strict ISO department. So we're gonna take a look, make sure Edge itself is actually working. So it looks like Edge is working. You know, webpages, blank pages are showing up fine here. I see nothing, no issues with the graphics. So it's probably working fine. We'll try another site, KnowledgeCity.com is also failing, right? So we know it's not that. Now next we're we can try and see if it's a certificate issue. So that would be the presentation layer, right? So presentation layer, as we see certificates are not loading. Now this could be a certificate issue. So let's take a look, a little deeper in. And it says the site's not a certificate. Google.com has a certificate, KnowledgeCity.com has a certificate. Any website with HTTPS has a certificate. So if you are not getting a certificate that means you're not able to download it from the website. So let's take another look. See what else could be happening. For session layer again, everything looks fine here. So it's not a session layer issue. Next we have transport, so TCP, UDP. Let's see if this command works. So this is test-netconnection port 443 google.com Detailed, this will tell us if TCP is working, this will also confirm for us it's not application layer issue, just to be on a safe side and right here, everything fails, even ping fails. So let's take another look here. So let's see if, I even have an IP address. If I don't have my IP address, well this explains everything. And I don't have an IP address. And it says my media is disconnected, so I'm not even getting a MAC address. So that means my data link is failing. So that means I have a physical issue here. Now, in this example, I am on a virtual machine. However, if you're at user's computer, you're gonna have to, you know, check their cable, check the switch, make sure everything's plugged in. Make sure again you have link lights. For me since, I'm on a virtual machine. I see that I just, my NIC was disconnected, my network interface card was disconnected. Now, I'm getting IP and I'm able to browse. That's it for this lesson, thank you for listening.

Intermediate Provider : Matthew Mercaldi 3 Lessons · 14m in Arabic, German, English, Spanish, French, Portuguese, Chinese

Course Description

This course will teach you three common troubleshooting approaches and the OSI model. Each troubleshooting approach will include an example of how it is applied in real life. These examples will pertain to an application not working correctly, and how troubleshooting methods are used to systematically diagnose and resolve it. We’ll also go over the OSI model and its approach to network troubleshooting.

In this course, you will learn how to use the bottom-up, top-down, and divide-and-conquer models to analyze what could be wrong with your network. You will then determine which method works best for a given troubleshooting process. By the end this course, you will have the confidence and know-how to begin correcting and problems with your networking system.

What You'll Learn

Apply three common troubleshooting approaches: top-down, bottom-up, and divide-and-conquer
Understand the layers of the OSI model and its approach to network troubleshooting
Describe how an application relates to the OSI model
Determine which troubleshooting methodology works best for a given situation
Analyze what could be wrong with a network using systematic diagnostic methods
Diagnose and resolve an application that is not working correctly using real-life examples

Key Takeaways

The course covers three common troubleshooting approaches alongside the OSI model.
Each troubleshooting approach is illustrated with a real-life example of an application not working correctly and how the method is used to systematically diagnose and resolve it.
The bottom-up, top-down, and divide-and-conquer models can be used to analyze what could be wrong with a network.
Choosing the troubleshooting method that works best depends on the given troubleshooting process and situation.
By the end of the course, learners gain the confidence and know-how to begin correcting problems with their networking system.

Frequently Asked Questions

What troubleshooting approaches does this course teach?

It teaches three common troubleshooting approaches: top-down, bottom-up, and divide-and-conquer, along with the OSI model and its approach to network troubleshooting.

What will I be able to do after completing this course?

You will understand the layers of the OSI model, be able to describe how an application relates to the OSI model, and determine how each methodology applies to a given situation, giving you the confidence and know-how to begin correcting problems with your networking system.

How are the troubleshooting methods explained?

Each troubleshooting approach includes a real-life example that pertains to an application not working correctly, showing how troubleshooting methods are used to systematically diagnose and resolve it.

What lessons are included in this course?

The course includes lessons on Top Down, Bottom Up, and Divide and Conquer approaches.

What skills does this course help develop?

It helps build skills in problem solving, troubleshooting, hardware troubleshooting, network diagnostics, network troubleshooting, and system-level troubleshooting.