From the course: Cisco Certified Network Associate (CCNA) v1.1 (200-301) Cert Prep

Virtualized devices

From the course: Cisco Certified Network Associate (CCNA) v1.1 (200-301) Cert Prep

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Virtualized devices

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(upbeat chiming) - [Instructor] In this video, let's talk about device virtualization. For example, let's say that we had a need for three different servers. We need to have an Ubuntu Linux server, we need a Microsoft Windows Server 2022, and maybe we need a Red Hat Enterprise Linux server. One option is to buy three physical servers and install the appropriate operating system on each of those servers, but now, we're taking up extra space, we might have extra power consumption, and if we look at the resource utilization of those individual servers, maybe one or two are just barely using any resources at all. An alternative to that, which might be more cost efficient, is to run those servers virtually on a single physical server, and that single physical server is running software called a hypervisor. And a hypervisor, that's software that can create start, stop, and monitor multiple virtual machines or VMs, and I say virtual machines instead of virtual servers because we can virtualize lots of things. We can have a virtual firewall, a virtual switch, a virtual server, and lots of other virtualized devices. And there are two types of hypervisors I'd like you to know about. The first one is called a Type 1 hypervisor, also known as a native or a bare metal hypervisor. This is where we install the hypervisor software directly on the physical server. In other words, that server's not running Microsoft Windows, and then we put the hypervisor on top of Windows. No, the operating system that server is running is the Type 1 hypervisor. That's what gets installed directly on the server. As an example, I have a couple of physical servers. They each have four network interface cards in them. And on those, I've installed Type 1 hypervisors. Specifically, I'm using VMware ESXi, and on those Type 1 hypervisors, I'm running multiple virtual servers, I'm running virtual routers, a virtual wireless LAN controller, and virtual switches. I'm able to have a complete topology contained in those servers. That's as opposed to a Type 2 hypervisor, also known as a hosted hypervisor. This is going to run on top of a traditional operating system. For example, the machine I'm on right now is a MAC Studio and it's running MacOS. However, from time to time, I need to use some Microsoft Windows applications. So I have a type two hypervisor, it's called Parallels. That is software that's running on this macOS operating system, and it lets me install a virtual Windows 11 computer. So I can be running my macOS apps side-by-side with Microsoft Windows apps, and each virtual machine or VM that we install on this physical server running a hypervisor, each of those VMs are going to have one or more virtual network interface cards or virtual NICs. And if our physical server running the hypervisor has a single physical NIC, then we can use that same physical NIC for all of our VMs to connect out to a switch. If we zoom in on what that looks like, let's say that we're running three VMs, they each have their own virtual NIC, we've got virtual NICs one, two, and three, they connect to a virtual switch that the hypervisor is running, and we can have that virtual switch connect out to a physical NIC, but typically on VMs that I set up, I'll get a physical server that has at least four physical network interface cards, and I can plug some of those network interface cards, maybe into switch ports on VLAN 10, maybe another one on VLAN 20, maybe another one on VLAN 30, all depending on the needs of the VMs running in this hypervisor. But a couple of terms I want you to know, I want you to know what a virtual NIC is. That's our virtual network interface card. That's actually software running on the hypervisor that's acting as a network interface card for a VM, and it's going to have a unique MAC address just as a physical network interface card would have its own MAC address, and we could have multiple virtual NICs plugged into one or more virtual switches running on this hypervisor. In fact, you can have a fairly elaborate topology within your hypervisor. You might have a couple of virtual machines going into one virtual switch, which goes into a virtual router, which then goes to another virtual switch on a different subnet, which then connects out to other virtual devices. All of this can be running inside of a single physical machine.

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