As we saw from earlier chapters, hardware virtualization is a challenge. Virtualizing the network is also a challenge. If you think about it, when we collapse computers into virtual machines, the networks they had been connected to are no longer physical switches and routers. In the virtualization world, the networks are collapsed and virtualized as well.
Network virtualization is the process of combining hardware and software network resources, such as routers and switches, into software-based entities that are run inside the physical machine. In other words, think about connecting a server's NIC to a physical switch using an Ethernet cable and assigning the computer to a VLAN. Now, think of that computer running as a virtual machine and creating a logical connection from a virtual network interface card to an internal software based switch, and then assigning the VLAN there. The concept seems fairly simple to imagine; however, the details surrounding the new paradigm...