Once you have created virtual switches in Hyper-V Manager, you can connect VMs to them by creating and configuring virtual network adapters. When you create a new VM, the default configuration includes one virtual network adapter. The New Virtual Machine Wizard includes0 a Configure Networking page, on which you can select one of the virtual switches you have created.
If you have created only the default external virtual switch when installing Hyper-V, then connecting a VM to that switch joins the system to the physical network. If you want to create additional network adapters in your VMs, you must use the following procedure.
1. In Server Manager, on the Tools menu, select Hyper-V Manager to open the Hyper-V Manager console.
2. In the left pane, select a Hyper-V server.
3. In the Virtual Machines list, select a VM and, in the Actions pane, click Settings.
The Settings dialog box for the VM appears.
4. In the Add Hardware list, select Network Adapter and click Add. A new adapter appears in the Hardware list, as shown in Figure 3-307.
FIGURE 3-30 A new network adapter in the Settings dialog box
5. In the Virtual Switch drop-down list, select the switch to which you want to connect the network adapter.
6. If your host computer is connected to a physical switching infrastructure that uses VLANs to create separate subnets, you can select the Enable Virtual LAN Identification check box and enter a VLAN identifier to associate the network adapter with a particular VLAN on your physical network.
7. To control the amount of network bandwidth allocated to the network adapter, select the Enable Bandwidth Management check box and supply values for the Minimum Bandwidth and Maximum Bandwidth settings.
8. Click OK. The settings are saved to the VM configuration.
You can create up to 12 network adapters on a Windows Server 2012 R2 Hyper-V server:
eight synthetic and four emulated.
Synthetic adapters and emulated adapters
Selecting the Network Adapter option on the Add Hardware page creates what is known in Hyper-V terminology as a synthetic network adapter. Hyper-V supports two types of network and storage adapters: synthetic and emulated (sometimes called legacy).
A synthetic adapter is a purely virtual device that does not correspond to a real-world product. Synthetic devices in a VM running on a child partition communicate with the parent partition by using a high-speed conduit called the VMBus.
The virtual switches you create in Hyper-V reside in the parent partition and are part of a component called the network Virtualization Service Provider (VSP). The synthetic network adapter in the child partition is a Virtualization Service Client (VSC). The VSP and the VSC are both connected to the VMBus, which provides interpartition communications, as shown in Figure 3-31. The VSP, in the parent partition, provides the VSC, in the child partition, with access to the physical hardware in the host computer; that is, the physical network interface adapter.
FIGURE 3-31 Synthetic network adapters communicate by using the VMBus
Because they have access to the hardware through the VMBus, synthetic adapters provide a much higher level of performance than the alternative, emulated adapters. Synthetic adapters are implemented as part of the Guest Integration Services package that runs on supported guest OSs. The main drawback of synthetic network adapters is that they are not operational until the OS is loaded on the VM.
An emulated adapter—sometimes called a legacy adapter—is a standard network adapter driver that communicates with the parent partition by making calls directly to the hypervisor, which is external to the partitions, as shown in Figure 3-32. This communication method is substantially slower than the VMBus used by the synthetic network adapters and is therefore less desirable.
To install an emulated adapter, you use the same procedure described earlier, except that you select Legacy Network Adapter from the Add Hardware list. Unlike synthetic adapters, emulated adapters load their drivers before the OS, so it is possible to boot the VM by using the Preboot eXecution Environment (PXE) and then deploy an OS over the network.
This is one of two scenarios in which using an emulated adapter is preferable to using a synthetic adapter. The other is when you are installing an OS on your VMs that does not have a Guest Integration Services package available for it.
Configuring hardware acceleration settings
Some physical network interface adapters have features that are designed to improve performance
by offloading certain functions from the system processor to components built into the adapter itself. Hyper-V includes support for some of these features, as long as the hardware in the physical network adapter supports them properly.
When you expand a network adapter in the Settings dialog box of a VM, you gain access to the Hardware Acceleration page. On this page, you can configure the following hardware acceleration settings:
– Enable Virtual Machine Queue Virtual machine queue (VMQ) is a technique that stores incoming packets intended for VMs in separate queues on the physical network adapter and delivers them directly to the VMs, bypassing the processing normally performed by the virtual switch on the parent partition.
– Enable IPsec Task Offloading Uses the components on the network adapter to perform some of the cryptographic functions required by IPsec. You can also specify the maximum number of security associations you want the adapter to be able to calculate.
– Single-Root I/O Virtualization Enables the virtual adapter to take advantage of the SR-IOV capabilities of the physical adapter.
Configuring advanced network adapter features
The Advanced Features page provides additional options for supporting network adapter capabilities, as follows:
– Static MAC Address By default, virtual network adapters receive a dynamically assigned MAC address from the Hyper-V server. However, you can opt to create a static MAC address by using this option. The only requirement is that no other adapter, virtual or physical, on the same network uses the same address.
– Enable MAC Address Spoofing When enabled, the port in the virtual switch to which the virtual network adapter is connected can send and receive packets that contain any MAC address. The virtual switch port can also learn of new MAC addresses and add them to its forwarding table.
– Enable DHCP Guard Prevents the adapter from processing messages sent by rogue DHCP servers.
– Port Mirroring Mode Enables the adapter to forward all the packets it receives over the network to another virtual adapter for analysis by using an application such as Network Monitor.
– NIC Teaming Enables the adapter to add its bandwidth to that of other adapters in the same guest OS in a NIC teaming arrangement.
This article is a part of 70-410 Installing and Configuring Windows Server 2012 Prep course, more articles in this course are :
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