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Lead Image © Kirill Cherezov, 123RF.com

Software-defined networking with Windows Server 2016

Virtual Cables

Article from ADMIN 38/2017
Windows Server 2016 takes a big step toward software-defined networking, with the Network Controller server role handling the centralized management, monitoring, and configuration of network devices and virtual networks. This service can also be controlled with PowerShell and is particularly interesting for Hyper-V infrastructures.

The Network Controller needs to provide the same functionality for both physical and virtual networks as the "IP address management" role service for the management of IP addresses in the network. The difference is that the Network Controller can also centrally manage devices, software, and network appliances from third-party manufacturers. Microsoft has integrated and further enhanced Azure features in Windows Server 2016 for this purpose. In an optimally configured environment, the Network Controller can even provide a kind of software firewall for data centers, including various guidelines, rules, and controls.

In addition to the Network Controller, Microsoft also has expanded the Hyper-V network virtualization (HNV) features significantly. The new switch-embedded teaming (SET) function in Hyper-V on Windows Server 2016 can be used to assign multiple physical network adapters to a virtual switch without having to create a team beforehand. HNV and SET can, of course, also be monitored and managed using the Network Controller, together with System Center Virtual Machine Manager (SCVMM).

Particularly in larger environments, Hyper-V networks comprise numerous VMs, many virtual switches, and various network adapters that connect the hosts to the network. The VMs use virtual network adapters to communicate with the virtual Hyper-V switch, which in turn uses network teams that ultimately communicate with the physical adapters on the host. The physical adapters are connected to physical switches, routers, and firewalls. Special features include quality of service (QoS), HNV, and others.

Clearly, managing virtual networks is becoming more and more extensive, which is exactly where the Network Controller comes into play. Its purpose is to bring order to chaos and to manage and monitor optimally all the components involved. QoS for the various networks obviously plays a role in this area; the individual physical network adapters can be operated in different VLANs, which requires efficient management. On top of that, many more examples show how complicated networks can be today, especially when working with virtualization; then, if companies set up a private or hybrid cloud, everything becomes even more complex.

Network Controller and System Center

Connecting cloud services such as Microsoft Azure to the Network Controller and managing them centrally with local networks is also possible. In addition to hardware devices such as routers, switches, VPN servers, load balancers, and firewalls, you can use the Network Controller to manage software-based networking services – and not just those based on Windows Server 2016, but also on Server 2012 R2. Therefore, virtual switches, appliances, and other areas of virtual networks can be monitored and controlled centrally. The Network Controller works closely together with SCVMM for this purpose, and in turn, the service is monitored using System Center 2016 Operations Manager (SCOM). Microsoft also includes network function virtualization here.

The Network Controller only reveals all its capabilities when used in conjunction with SCVMM and Hyper-V in Windows Server 2016. The Network Controller can be added as a network service in SCVMM 2016 to this end by selecting Microsoft Network Controller in the corresponding wizard (Figures 1 and 2). Microsoft provides configuration files [1] on GitHub for this purpose with a detailed step-by-step guide in TechNet [2] that describes how to use the Network Controller with Hyper-V in Windows Server 2016.

Figure 1: To start using the Network Controller, it first needs to be installed as a server service via the Server Manager.
Figure 2: The Network Controller is provided best via SCVMM 2016.

The Network Controller works particularly closely with Hyper-V hosts and VMs that are managed with the SCVMM. The 2016 version of SCVMM provides improvement in the configuration of the virtual network adapter, which also works together with the Network Controller service. You can now, for example, provide multiple virtual network adapters when deploying virtual servers. Administrators can designate the network adapter in the templates for virtual servers – this works much like consistent device naming (CDN) for physical network adapters. However, the virtual server needs to be created as a generation 2 VM and be installed with Windows Server 2016. You can use logical networks, MAC address pools, VM networks, and IP address pools in SCVMM 2016 to create and centrally manage network configurations for VMs. The Network Controller also plays an important role because it can take care of management and monitoring.

Managing Virtual and Physical Networks

With the Network Controller, you therefore have the option to manage, jointly operate, and monitor both physical network components and virtual networks centrally. Configuration automation is the particular focus, which, among other things, includes access to individual devices via PowerShell. However, to work, support is required from the respective hardware manufacturer. The software components in Windows Server 2016, which work directly with the Network Controller, already support PowerShell 5.0.

The Network Controller provides two different APIs through the interface function: One API communicates with the end devices and the other with administrators and their management applications; therefore, all devices are managed through only one interface in the network. In the "fabric network management" area, the Network Controller also enables the configuration and management of IP subnetworks, VLANs, Layer 2 and Layer 3 switches, and the management of network adapters in hosts. Therefore, it is possible to manage, control, and monitor software-defined networks efficiently using the Windows 2016 Network Controller together with IPAM.

You can also create firewall rules for VMs of connected Hyper-V hosts via the Network Controller. The controller also has access to the associated virtual switches. The Network Controller therefore makes it possible to control and monitor firewall rules that affect a specific VM or a workload on a VM and, above all, to distribute them in the network if the rules are required on various appliances. In addition to central control, however, the Network Controller also manages the logfiles that determine which data traffic is allowed or denied using rules.

Furthermore, the Network Controller also assumes control over all virtual switches for all Hyper-V hosts in the network and, in this way, also creates new virtual switches or manages existing ones, allowing even virtual network cards to be controlled in the individual VMs. In Windows Server 2016, you can add and remove the network adapters in ongoing operations in Hyper-V in the VMs, which means you no longer need to shut down the VMs to do so. Hyper-V and the Network Controller work together particularly efficiently in this way, because flexible network control is also possible during operation.

You also have the option to work using network guidelines. The Network Controller supports Network Virtualization Generic Routing Encapsulation (NVGRE) and Virtual Extensible Local Area Network (VXLAN) in this area. As well as the physical network devices and adapters, you can also deploy and monitor Hyper-V network virtualization using the Network Controller.

Virtualized infrastructures in particular benefit from complex new technologies, such as network virtualization, which is supported by numerous new storage features and new functionality in Hyper-V. The virtual network adapters for each virtual server can also be deployed, managed, and monitored using the Network Controller. Guidelines can be centrally deployed, saved, monitored, adjusted, and automatically distributed on VMs, even if VMs move between hosts or clusters.

Managing Distributed VMs

The Network Controller can therefore control and configure both VMs and physical servers that are part of a Windows Server Gateway cluster. In this way, it is possible to link data centers and disconnect or connect the networks of different clients in hosted environments.

You can even deploy VMs in the network, which are part of a Windows Server gateway cluster, called the Routing and Remote Access Service (RRAS) Multitenant Gateway, which makes it possible to incorporate virtual servers in Azure. To this end, the Network Controller supports different VPNs, IPsec, and simpler VPNs with generic routing encapsulation. In addition to deploying such VMs, you can also control, monitor, and create VPNs and IPsec connections between the networks. Individual computers can also be connected to the data center via the Internet this way (e.g., for management by external administrators).

Border Gateway Protocol (BGP) routing allows the network traffic from hosted virtual machines to be controlled for the company's network with both Windows Server 2016 and Server 2012 R2 [3]-[5]. However, it is important that all functions – particularly the Network Controller – be used only if you completely switch the server over to Windows Server 2016.

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