ccna 200 301 bookshare apps

ccna 200 301 bookshare apps.Before I go any further, let me define what I mean by "virtualization", because there are various definitions of virtualization. In our case, virtualization means using logical concepts, such as software or protocols, in place of physical concepts, such as ports, cables, or switches. We can do a lot based on this new definition, because by using this concept, we can shift tasks carried on old hardware to be taken over by less new hardware running advanced software! We'll discuss this concept later, starting with a look at the bottom layer of OSI, and working up from there.7.3.1 Layer 2 Network VirtualizationThe VLANs we are already familiar with are not really virtualized, but understanding VLANs helps us analyze and understand what virtualization really is. Figure 7.8 shows two completely physically separated Layer 2 networks, with the sales and marketing departments completely isolated from each other and using two separate switches - not a good practice! We say that we can build out 2 logical (or virtual) networks with a single physical switch.This is talking about VLAN technology, which achieves exactly this effect. Each port is assigned to a specificVLAN and shares local traffic only with other devices that belong to the same VLAN, as shown in Figure 7.9.In effect, we are using only one switch here, logically defining each network as a different VLAN, thus creating two separate networks. Even if we add another 20 VLANs, we don't need to add even one more switch, but if we run out of ports, that's a different story. The biggest benefit of virtualization is that it reduces the amount of hardware needed to accomplish the task.With that in mind, let's take a look at the cables.Virtualized Layer 2 Networks VLANs7.3.2 Switch Interconnect Link VirtualizationNetworking terminology has recently doubled the cable between two switches to "switch interconnect links (ISLs)." If you are new to the industry, you may not think this is new, but if you have been in the industry for a while, you may remember the Cisco ISL (Switch Interconnect Link) protocol, so don't get the two concepts confused. In order for everyone to come to a consensus and understand the concepts mentioned in this book, I will not go over this ancient protocol. By ISL, I simply mean the cable that connects the switch to the switch.