Question

Explain "In a virtual network, service is described in a data structure, and exists entirely in a software abstraction layer,  reproducing the service on any physical resource running the virtualization software.

The configuration attributes of the service can be found in  software with API interfaces, thereby unlocking the full  potential of networking devices."

Answer 1

• Virtualization is the basic act of decoupling an infrastructure service from the physical assets on which that service operates. The service we want to consume (such as Compute, or Network) is not described on, identified by, or strictly associated with any physical asset. Instead, the service is described in a data structure and exists entirely in a software abstraction layer reproducing the service on any physical resource running the virtualization software. The lifecycle, identity, location, and configuration attributes of the service exists in software with API interfaces, thereby unlocking the full potential of automated provisioning.
• The canonical example is Server Virtualization, where the familiar attributes of a physical server are decoupled and reproduced in virtualization software (hypervisor) as vCPU, vRAM, vNIC, etc., and assembled in any arbitrary combination producing a unique virtual server in seconds.
• The same type of decoupling and automation enabled by server virtualization is made available to the virtual network with Network Virtualization.
• One might have encountered such instances when setting up a virtual machine since they do not have any physical instance or hardware they need to act as a whole other computer by using a part of available resources from the host system.
• Servers use processors like Intel Xeon that have multiple threads and cores which can be divided to form virtual instances, for example, 24 cores can be given to various virtual machines as 2-4 cores each.
• Now coming to virtualization of the network capabilities.
• Network Virtualization reproduces the L2-L7 network services necessary to deploy the application’s virtual network at the same software virtualization layer hosting the application’s virtual machines – the hypervisor kernel and its programmable virtual switch. Similar to how server virtualization reproduces vCPU, vRAM, and vNIC – Network Virtualization software reproduces Logical switches, Logical routers (L2-L3), Logical Load Balancers, Logical Firewalls” (L4-L7), and more, assembled in any arbitrary topology, thereby presenting the virtual compute a complete L2-L7 virtual network topology.
• All of the feature configuration necessary to provision the application’s virtual network can now be provisioned at the software virtual switch layer through APIs. No CLI configuration per application is necessary for the physical network. The physical network provides the common packet forwarding substrate. The programmable software virtual switch layer provides the complete virtual network feature set for each application, with isolation and multi-tenancy.
• In simple terms network virtualization of a network is done by forming a NAT network which acts as a network connection that bridges the gap between your virtual machines or servers and the network hardware of host server, providing networking capabilities to the virtual machines.

And in the end, one may ask why do all this?

• It is simply the goal is to take all of the network services, features, and configuration necessary to provision the application’s virtual network (VLANs, VRFs, Firewall rules, Load Balancer pools & VIPs, IPAM, Routing, isolation, multi-tenancy, etc.) – take all of those features, decouple it from the physical network, and move it into a virtualization software layer for the express purpose of automation.