Windows Server 2012 Virtualization Combat: Network (i)

Virtualization can be relatively familiar with computational abstractions, perhaps with the experience of using a single machine such as Virtual PC or virtual box. The first impression of using these virtualization software is that our CPUs can run multiple sets of different operating systems at the same time, and that the application runs in parallel. The abstraction of computation allows the operating system on the same set of hardware devices to be isolated from one another, as if a body had two or more souls, what the hell is this? So the next natural thing is, how do these souls communicate? There is still only one body, how to shake hands and communicate with each other, how to contact and provide services. Therefore, for virtualization, the most important infrastructure in addition to storage, and then the network, that is, the need to implement network virtualization. Here we outline the fundamentals of virtualization of the network for Windows Server R2 and System Center virtual machine Manager R2 (hereafter referred to as SCVMM). There is a need to learn more about Microsoft's ebook Microsoft System center:network Virtualization and Cloud Computing.

First, what is network virtualization

Now there is a popular saying is called software-defined network, there are different interpretations in the network, I myself simply understand is more through software programming to achieve the centralized management of the network. For example, before the VLAN function on the switch, need to be configured on each switch, different vendors have different configuration, complex configuration and high management costs, then through an open, unified and standard software platform to control network hardware, that will greatly improve this situation. Of course, due to the factors of commercial competition, so that each vendor has an open and inclusive heart, is not an easy thing, so software-defined network has a long way to go. Then back to network virtualization, it can be considered a special case of the software-defined network, that is, in one or more data centers to achieve a good picture of the software-defined network. In addition to the unified software platform to manage the network, network virtualization has its own special application purposes and requirements.

1, the need to implement each virtual machine can be like a single physical machine as the network functions. Between different virtual machines on the same physical machine, between virtual machines on different physical machines, between virtual machines and physical machines, virtual machines and external networks can shield the underlying hardware differences and interconnect on virtualized networks.

2, the need to achieve more efficient use of physical networks. On a physical network (the same physical NIC on a physical machine) hosts more isolated and load-balanced networks (similar to VLANs). Data centers often need to configure a variety of isolated networks to host a variety of applications, such as domain networks, cluster heartbeat networks, cluster management networks, virtual machine migration networks, and external networks, and so on, which can be a time-consuming and costly task if implemented on hardware via VLANs or directly by adding hardware.

3, the need to achieve high availability of the network. Physical devices, including network cables, network cards, and switches, are likely to be corrupted, requiring a solution that reduces the impact on the network when they are damaged.

4. Need to guarantee the dynamic migration of high availability virtual machines in the virtualization platform. When a physical network or physical host is damaged and dropped, a virtual machine with high availability on it will perform the migration, re-launch on another physical host, and even make it impossible for the outside world to perceive its migration process, which requires the virtualized network to ensure that all network configurations on the virtual machine remain valid on another physical host.

Each of these is not an easy thing to do, so let's take a look at how SCVMM achieves all of this on a unified software management platform.

Second, the network virtualization in Windows R2

The essence of network virtualization is to abstract the physical network, that is, to build a virtual network on the physical network to adapt to different application scenarios. The core technology here is the wrapper protocol for IP packets. The IP wrapper protocols used by each virtualization platform are different, such as: Virtual extensible Local Area Network (VXLAN), stateless Transport tunneling Protocol for Network Virtualization (STT) and generic Routing encapsulation (GRE). SCVMM uses a special GRE protocol called the Network virtualization using Generic Routing Encapsulation (NVGRE). The main purpose of these protocols is to encapsulate the original IP packets to achieve the isolation of network data transmission.

There are several levels in which SCVMM can redefine a physical network, where we consider the following scenario: Two physical hosts are connected by two separate physical networks, which should be the most common in the data center.

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Let's look at the configuration of the physical host network at each of the following levels:

1. Set up network card Group (NIC team)

Merging 2 and more physical NICs on the physical host into network card groups can form redundancy and load balancing between these physical network cards. As shown, on the physical host's operating system level, the merged NIC Group behaves as a network card and is connected to one another. The functionality of the NIC group is actually provided by Windows R2, and SCVMM can make full calls to all the resources and features of Windows R2, Hyper-V, and failover cluster.

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Enter the command lbfoadmin in Windows Server 2012 to view and configure network card groups, such as two network card groups created on the physical host cloud-pm-ds01, with 2 physical network cards in each NIC group.

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In the network connection interface, the physical network card has not been able to set the parameters, and transferred to the NIC set. Looking closely at the networking option in the NIC and Nic group properties, you can see that Microsoft provides a rich network protocol that implements a variety of functions that are different from the configured network protocols. The key protocol used by the NIC group should be microsfot Load balancing/failover Provider, IPv6, and IPv4. In the following article, more about the functionality provided by network virtualization is simply adding and configuring more protocols, which is, to some extent, the so-called software-defined network.

But here, please ignore logical switch so that the name of the NIC group, why not the name of the team, here can tell you that logical switch is a higher level of abstraction, the following will be covered.

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2. Virtual Switch

On the basis of network card or NIC group, we can establish a virtual machine switch, a physical network card or a NIC group we can build a virtual switch to further virtualize the network. As shown in the following:

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The virtual Switch feature is provided by Hyper-V, we install the Hyper-V role, and open Hyper-V Mananger, right-click the virtual Switch Mananger to create and manage it.

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On the Windows network connection interface, we see that the virtual switch can be configured together with the NIC group. Just a new protocol for Hyper-V extensible Virtual Switch. However, the configuration of IPv4 and IPv6 is also canceled because the two protocols will be transferred to the virtual network card for configuration. At this point, as in the device Management Logical switch is now the role of one or more physical network card abstraction, it can assume the role of network card group load balancing, but also assume the role of Virtual switch, Virtual Switch and virtual network card interconnection. This is not the same as the state of the physical switch, where the physical switch is in the middle of the network, while the virtual switch is at both ends, and the same virtual switch is configured for the host, meaning the two are connected through the underlying physical link of the virtual switch.

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3. Virtual network card (Adapter)

On the basis of a virtual switch, you can create a virtual network card to connect to different networks. A virtual network card typically appears on a virtual machine for a virtual machine to connect to that network, or it can appear on a physical host for a physical host to connect to that virtual network. The number of virtual network cards is almost unlimited, and if necessary, you can create multiple virtual NICs to connect to the same virtual network. Here "virtual Network" is the abstraction of the concept of SCVMM, such as connecting the virtual network card and the virtual card between the dotted line is like virtual networks, there is a virtual network, they are isolated from each other. It is possible to use VLANs for analogy, but not VLAN technology, but NVGRE packet encapsulation technology.

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If you are creating a virtual network card on a physical host that connects different virtual networks, the configuration protocol for these NICs is almost identical to the normal physical NIC, where you can configure IPV4 and IPv6. Of course it's more prevalent in virtual machines.

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Windows Server 2012 Virtualization Combat: Network (i)