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Layer 4 (Transport Layer) Layer four transport The transport layer is the dividing line between what we call the upper layers and the lower layers of the OSI model. We’ve already covered the lower layers when we talked about the physical datalink and network layers, and we’re going to talk about the upper layers, the session presentation and application, in the next three lectures. Segments are our data type. When we’re dealing with the transport layer, we deal with segments and also datagrams, and we’ll talk about datagrams a little…

Open Systems Interconnection (OSI) Model Overview The OSI model So what is the OSI model? Well, it stands for the Open Systems Interconnection Model, and it was developed back in 1977 by the International Organization for Standardization, or ISO. Now, you’re usually going to hear it referred to as the OSI model. People don’t usually say the Open Systems Interconnection Model, but you will also heart referred to as the OSI stack. And this is a really fundamental thing in networking, and it is extremely important—so important that you’re going…

Overview of Networks An overview of networks So when you think of a computer network, what comes to mind? Do you consider a router and a switch? Do you think of your wireless network at home when you access this video over? Is it limited to just computers? Is it limited to just the Internet? Is it limited to Wi-Fi networks or wired networks such as Ethernet or Fiber? Well, no, there are a lot of networks out there. There are a ton of them. And when it comes down…

Networking Tools (Part 1) Networking tools. So now that we’ve covered troubleshooting, let’s move into the different tools we use to conduct some of this troubleshooting. First, we need to look at the physical cabling because it still serves as the backbone of our networks. Even with wireless networking and lots of virtualization, many network problems can be reduced through proper installation and configuration. So if you build it right the first time, it’s going to solve a lot of your issues. Next, we want to look at the multiple…

Network Security Attacks (Part 3) Network security attacks, part three Now, I know I said I was only going to give you two videos on network attacks, but we covered all of the aspects of confidentiality, integrity, and availability, and there were still a couple of more attacks that I wanted to go through. And so this is kind of our miscellaneous section on network attacks. Some other attacks that you should consider include things like insider threats, phishing, ransomware, logic bond DE authentication, and VLAN hopping. We’re going to…

Multifactor Authentication Multifactor authentication. Now, in the lesson on security policies, we talked about the importance of using multifactor authentication. But what does that really mean? Well, when you have multifactor authentication, it means you authenticate or prove your identity using more than one method. Now, that can be something you know, something you have, something you are, something you do, or somewhere you are. And we’ll talk about each of those as we go through this lesson. The first one is something you know, and this is the most…

The CIA Triad The CIA triad Our networks are no longer fundamentally secure. When they developed all these networking standards, security was never at the forefront. Now, we’ve tried to bolt them on and add security as we go to make them more secure. But to begin with, a network is a very insecure place. And to make matters worse, networks are increasingly becoming more connected with other networks. So if my company starts doing business in partnership with your company, we may tie our networks together during that time,…

Simple Network Management Protocol The Simple Network Management Protocol, or SNMP Now, SNMP is used to be able to send and receive data from managed devices like routers, switches, and servers back to a centralised network management station. The SNMP manager is going to be able to send and receive these messages to these devices using three different messages. There are two types of traps: set get and trap. With Set, your managed device is going to send information back to your manager. Get is when your manager is going…

High Availability Networks High Availability. So when we talked about the CIA Triad, we talked about confidentiality, integrity, and availability. And at that time, I said we would spend a lot of time on availability. Well, this entire section is going to cover availability. Now, when we talk about high availability, we’re talking about making sure that our systems are up. Availability is measured by what we call “up time,” or how many minutes or hours you are up. And often, this will be shown as a percentage. How many…

Media (Copper) Now, in this lesson, we’re going to talk about the different types of media. There are three categories of media: copper, fibre optics, and wireless. In this lesson, we’re going to talk specifically about copper media, though. Each of these categories is divided into subcategories and each of them has different specifications and uses. So sometimes I’m going to use copper media. Sometimes I’ll choose to use fibre optics because each one has its own benefits and drawbacks. Now, when we talk about copper media, the first and…