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Basic elements of Microsoft network virtualization

Microsoft network virtualization may not get the same market mindshare as the competition, but you can pull off a software-driven, multi-tenant network for the cloud using Hyper-V and Systems Center 2012.

Microsoft's network virtualization and SDN strategy relies on Hyper-V as a virtualization platform, but is configured and managed through the System Center 2012 Virtual Machine Manager or Windows PowerShell.

The first step to Microsoft Hyper-V networking is to master the difference between a myriad of virtual network types.

Understanding the Microsoft virtual network maze

Hyper-V enables a range of virtual network types that range from VM networking for multi-tenant environments to logical networks that mimic the physical infrastructure and can be used for development.

Virtual networks are created and configured through the Hyper-V Manager. Typically a virtual network consists of a virtual switch that is bound to a physical network adapter (although other types of virtual switches can be created). Virtual machines use virtual network adapters to connect to the virtual switch.

VM networks, however, are generally an isolated, software-defined network segment. VM networks are sometimes referred to as "network tenants." Because VM networks are isolated from one another, they can use overlapping IP addresses.

In this environment, virtual machines connect directly to the VM network (as opposed to the Hyper-V virtual network), and the VM network exists on top of a logical network. It is common for multiple VM networks to share a common logical network.

Logical networks are created by default when you add Hyper-V hosts or host clusters to Virtual Machine Manager. A default logical network exists for each physical network. At its simplest, the logical network mimics the physical network. Oftentimes, however, organizations will define additional logical networks that are more purpose-oriented. For example, an organization might define a logical management network or dev-test network. Each logical network is linked to one or more IP subnets, and an IP address range is usually also associated with a logical network as a part of the configuration process.

Just as Hyper-V virtual networks rely on virtual switches for connectivity, logical networks use logical switches. A logical switch can be used to link a logical network to a physical network adapter. The same concept also applies to VM networks. Each VM network has a subnet and an IP address range assigned to it. Because VM networks are isolated from one another, IP address ranges can safely overlap from one VM network to the next.

Port classifications in Microsoft virtualization networks

Port profiles and classifications are central to Microsoft network virtualization. A port classification is essentially a named container object. It is used to identify various types of virtual network adapter port profiles.

The easiest way to understand what port classifications do is to think of the classification as a tag. If you had a port profile that supported a high-speed connection, you might create a port classification called "High Speed" and apply it to the port profile as a way of conveying its purpose. The advantage to port classifications is that they can be used for multiple logical switches and provide a consistent way of identifying port profiles.

There are two different types of port profiles. Port profiles for uplinks allow you to control which logical networks can connect to a physical network adapter. The other type of port profile is for virtual network adapters. They allow you to control bandwidth usage, security and offload capabilities for a virtual network adapter. For example, you could use a port profile for virtual network adapters to enable IPSec offloading or to specify a bandwidth reservation.

In part two of this series on Microsoft network virtualization and SDN, we provide the basic steps for building a Microsoft SDN using Systems Center 2012.

About the author:
Brien Posey is a seven-time Microsoft MVP with two decades of IT experience. Before becoming a freelance technical writer, Brien worked as a CIO for a national chain of hospitals and healthcare facilities. He has also served as a network administrator for some of the nation's largest insurance companies and for the Department of Defense at Fort Knox.

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This was last published in August 2014

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