Software-defined networking with Windows Server 2016

Virtual Cables

Actively Managing Network Traffic

The Network Controller is also generally able to control and redirect network traffic actively. If certain VM appliances are used in the network for security purposes (e.g., antivirus, firewall, intrusion, or detection VMs), you can create rules using the Network Controller that automatically redirect network traffic to the appropriate appliances.

However, this doesn't only play a role in terms of security, it is also important for collaboration with load balancers. The Network Controller detects servers with identical workloads and their load balancer. The server role can also actively intervene here and direct network traffic to the right places, increasing availability and scalability in the company without affecting the overview.

Servers that work as Network Controllers can be virtualized and pooled in a cluster. Microsoft recommends making the role highly available in productive environments. The best way to do this is to create a cluster or a highly available Hyper-V environment. Complete virtualization means that deployment in a cluster is not an impossible task.

Cmdlets for Network Controller

PowerShell 5.0 is integrated in Windows Server 2016 and is also used to control the Network Controller (Figure 3). It is possible to install the Network Controller's role service (in the cluster, as well) and to perform the setup and configuration in PowerShell. The installation is performed with:

Install-WindowsFeature -Name NetworkController -IncludeManagementTools
Figure 3: Numerous control options are available for the Network Controller in PowerShell.

To create a cluster, you first need to create a "node object" in PowerShell:

New-NetworkControllerNodeObject -Name <name of the server> -Server <FQDN of the server> -FaultDomain <other servers belonging to controller> -RestInterface <network adapter that accepts REST requests> [-NodeCertificate <certificate for computer communication>]

With PowerShell, you can set the cluster for the Network Controller before creating it (Listing 1). You will also find detailed options and control possibilities through scripts and PowerShell online [6], including the various cmdlets for controlling the Network Controller [7]. Installation of the Network Controller can also be automated using PowerShell, as shown in Listing 2.

Listing 2

Automated Installation of the Network Controller

01 $a = New-NetworkControllerNodeObject -Name Node1 -Server -FaultDomain fd:/rack1/host1 -RestInterface Internal
02 $b = New-NetworkControllerNodeObject -Name Node2 -Server -FaultDomain fd:/rack1/host2 -RestInterface Internal
03 $c = New-NetworkControllerNodeObject -Name Node3 -Server -FaultDomain fd:/rack1/host3 -RestInterface Internal
04 $cert= get-item Cert:\LocalMachine\My | get-ChildItem | where {$_.Subject -imatch ""}
05 Install-NetworkControllerCluster -Node @($a,$b,$c) -ClusterAuthentication Kerberos -DiagnosticLogLocation \\share\Diagnostics -ManagementSecurityGroup Contoso\NCManagementAdmins -CredentialEncryptionCertificate $cert
06 Install-NetworkController -Node @($a,$b,$c) -ClientAuthentication Kerberos -ClientSecurityGroup Contoso\NCRESTClients -ServerCertificate $cert -RestIpAddress

Listing 1

Creating the Network Controller

01 Install-NetworkControllerCluster -Node <NetworkControllerNode[]> -ClusterAuthentication <ClusterAuthentication> [-ManagementSecurityGroup <group in AD>] [-DiagnosticLogLocation <string>] [-LogLocation-Credential <PSCredential>] [-CredentialEncryptionCertificate <X509Certificate2>] [-Credential <PSCredential>] [-CertificateThumbprint <string>] [-UseSSL] [-ComputerName <Name>]
02 Install-NetworkController -Node <NetworkControllerNode[]> -ClientAuthentication <ClientAuthentication> [-ClientCertificateThumbprint <string[]>] [-ClientSecurityGroup <string>] -ServerCertificate <X509Certificate2> [-RESTIPAddress <string>] [-RESTName <string>] [-Credential <PSCredential>] [-Certificate-Thumbprint <string>] [-UseSSL]

The datacenter abstraction layer (DAL) is the interface to the Network Controller in PowerShell that enables remote management of compatible network components via PowerShell and PowerShell-compatible tools that have a graphical interface for scripts. However, the network components need to be certified by Microsoft. Cisco and Huawei are among the certified manufacturers, although other service providers likely will be added in the future. The Network Controller in Windows Server 2016 is also accessible this way, in parallel with the cmdlets that are already available for the service.

If you use compatible devices, they can be managed via PowerShell – either with or without the Network Controller (Figure 4). Microsoft goes into more detail about the functions and options of compatible devices [8], and you can find examples of script management online [9].

Figure 4: PowerShell cmdlets manage "Certified for Windows" network switches.

Separating Virtual from Physical

In Windows Server 2016, HNV can be used to separate individual virtual networks from the physical network. The virtual servers in these networks expect to be placed on a separate network, which was generally already possible in Windows Server 2012 R2, but is expanded in Windows Server 2016. HNV can also be connected to the Network Controller.

HNV plays a particularly important role in large data centers, but even smaller companies can benefit from this function if they need to better separate networks. Put simply, HNV expands the functions of virtual servers to include network configuration. Multiple virtual networks can be used in parallel in a physical network. They can use the same or a different IP address space. The exchange of data between the networks can be set up using HNV gateways and monitored using the Network Controller. Many Cisco hardware switches already work with this configuration. In this way, it is possible to combine multiple virtual networks so that servers can communicate with each other on this network, yet contact with other networks is filtered.

Since Windows Server 2012/2012 R2, it has been possible to control bandwidth in the network and integrate drivers from third-party manufacturers with virtual switches using Hyper-V Extensible Switches. In Windows Server 2016, Microsoft also wants to give third-party products the option to access network virtualization and connect to the Network Controller. Extensions are available, for example, to integrate virtual solutions against DDoS attacks or customized virus protection.

From Server 2012 R2, HNV also supports dynamic IP addresses used for IP address failover configuration in large data centers. In Windows Server 2016 and System Center 2016, Microsoft has expanded these functions and made the configuration more flexible. If you work with HNV, multiple IP addresses are assigned to virtual network adapters in the network. The customer address (CA) and the provider address (PA) work together. The CA allows virtual servers on the network to exchange data, just like a normal IP address. The PA is used for exchanging data between the VM and Hyper-V host, as well as the physical network. This can be controlled using the Network Controller and SCVMM 2016 or IP address management (IPAM).

HNV is not an upstream Network Driver Interface Specification (NDIS) filter; instead, it is integrated directly into the virtual switch. Both third-party products and the Network Controller can access the CA directly using this technique and can communicate on the PA, allowing virtual switches and NVGRE to work together better. Data traffic in the virtual switches under Windows Server 2016 also runs with network virtualization and integrated third-party products. HNV is not an interface between network cards and extensible switches; rather, it is an integral part of virtual switches themselves, which is why network interface controller (NIC) teams work very well with network virtualization, particularly the new SET switches in Windows Server 2016.

These functions allow large companies and cloud providers to use the Access Control Lists (ACLs) of the virtual switches and control firewall settings, permissions, and network protection for the data center – all using the Network Controller. To this end, Windows Server 2016 provides the option to also integrate the port in the firewall rules, not just the IP and MAC addresses for the source and destination. This function works together with network virtualization in Hyper-V and can also be controlled using the Network Controller. Network virtualization is especially useful in conjunction with System Center 2016 Virtual Machine Manager because it is possible to create and configure new VM networks through the wizards and then connect to the Network Controller.

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