IPsec VPN Concepts – Part 2 Let’s continue our conversation on IPsec VPN concepts. So, in Part 1 of IPsecVPN concepts, we spoke about encryption. We understood the different encryption algorithms and authentication algorithms. We understood what hashing is and how it helps with authentication. We also understood how a phase-one tunnel is established, the different IC key exchange mechanisms, including the annual key exchange, and, using the IC protocol, how proposals are negotiated between VPN endpoints and the different versions of IC. Now let’s build upon those concepts and…

Introduction to VPNs It’s now time for the most interesting topic of the course: virtual private networks, or VPNs. I’m sure you’ve heard about this before. So in this section, we’ll understand what our VPNs are. Why did they even exist in the first place? What are the different types of VPNs, and how can we configure one? So, to understand why we have VPNs in the first place, we need to go back in time a few years back in time. Assume an organisations has two offices, or offices…

Routing Fundamentals Routing fundamentals. We’ve covered a lot of information up to this point in the course, but we really haven’t left the local area network. And that’s where routers are going to really start coming into play when we start talking about connecting to dissimilar networks or an internal network and an external network. Now, when we talk about routing fundamentals, the first thing you have to understand is the function of a router, and its function is to route traffic, which I know sounds kind of silly, but…

Wireless Networking (WLAN) Wireless Networks or W lands. Wireless networks are great because they extend your physical network into the wireless domain. It can allow your users to roam wherever they want inside a coverage area. So if you think about a college, for instance, you might have the entire campus with numerous buildings, the outdoor spaces, and everywhere covered by this wireless network. And you can just just take your laptop, open it up at a picnic table and gain access to the network. The popularity of wireless networks…

Wide Area Networks (WAN) wide-area networks, or wands. We finally made it to the point where we could get outside our local area networks. So we’ve covered routing and switching and wireless networks, but all of that was really inside our network. Now we want to move outside our network. Now, when we look at computer networking over time, back in the early 1990s, we had this thing that we called the Pareto principle, which is actually a business principle and that we also know as the 80/20 rule. Now,…

Virtual Network Devices Virtual network devices Now, virtual network devices represent a major shift in the way datacenters are designed, fielded, and operated. And we have started virtualizing everything. We started with virtual servers. Now we’re into virtual routers, switches, and firewalls. We even have virtual desktops where you don’t even have a physical computer anymore. You can operate everything through a web browser. There’s also VoIP, which is the virtualization of voice and phones. We have software-defined networking and cloud computing. Now, we’ll talk about cloud computing in a…

Network Troubleshooting Methodology Methodology. As a network technician, you will now spend the majority of your time answering trouble tickets or troubleshooting problems in your networks. Now there are three basic steps that are going to occur as you start going through this troubleshooting. The first is a problem report; the second is problem diagnosis; and the third is problem resolution. Now when we look at the problem report, this is going to be an issue that has been reported to you either by the end user, an administrator, or…

TCP/IP Model The TCP/IP model Now, if you remember all the way back when we did the OSI model overview, I mentioned that the OSI model was a reference model, but it wasn’t the only reference model out there. The other big one that we’re going to talk about here for Network Plus is the TCP/IP model. This is also known as the TCPIP stack or the DoD model. Now this is an alternative to the OSI model. And the nice thing is that it’s only four layers, so it’s…

GNS3 Walkthrough Example Wide-area network technologies We’re going to break this lecture into two parts because there are just so many technologies that we have to talk about. The first is a dedicated lease line. Now this is a point-to-point connection between two sites, and you get all of the bandwidth all the time, which is great. This will include T1, E1, T3, and other dedicated circuits. Now, when you get this digital circuit, it’s going to be measured in 64Kbps channels called digital signal zero. and based on which…

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…