Virtual Switches

Before you install a virtual server on a Hyper-V host, the first step is to configure the virtual switches – in Hyper-V these are also called vSwitches. To help with this step, the Hyper-V Manager includes a Virtual Switch Manager. You first create a virtual switch for each individual physical network adapter in the server. Under MAC Address Range , the dynamic MAC range can be defined for the virtual network cards on the server.

Static MAC addresses can also be specified for virtual servers. This is especially important for operation in a cluster. If virtual servers are moved between the cluster nodes, the MAC addresses change on restart because each node has its own pool. This process can cause problems with Windows activation, as well as with Network Load Balancing clusters.

Virtual switches act as Layer 2 network switches and also allow integration of NDIS (Network Device Interface Specification) filters and of WFP (Windows Filtering Platform) drivers. In this way, third-party plugins that offer advanced network and security settings for virtual servers can be integrated into Hyper-V (Figure 3). The corresponding settings for each individual vSwitch can be reached via the Plugins menu item.

Figure 3: The plugins for virtual switches in Windows Server 2012 provide log and filter functions with the Windows Filtering Platform.

Once the physical network adapters of the server have each been assigned a virtual switch, they can be allocated to the individual virtual servers. You can do this while creating the virtual machine or afterward in the settings under Network Adapter . The first setting is the allocation of a virtual switch. The bandwidth control is found directly on the start page. In this way, the network usage of the virtual servers can be controlled more closely than in Windows Server 2008 R2.

New Guards

Two new settings are found under Advanced Features : DHCP guard and Router guard prevent uncontrolled use of virtual servers as DHCP servers or routers (Figure 4). This is to prevent virtual servers from undesirably acting as a DHCP server or router and disrupting the network.

Figure 4: Under the advanced network settings, you'll find the DHCP and Router guards, which prevent troublemakers from disrupting the network.

Windows Server 2008 R2 can transfer only one server at a time, which usually isn't very efficient, especially in cluster environments hosting multiple virtual servers. Windows Server 2012 with Hyper-V 3.0 can now perform multiple live migrations at once. These settings are found in the Hyper-V settings of the host under Live Migrations .

Conclusions

Hyper-V 3.0 is an outstanding feature of Windows Server 2012. With this version, Microsoft has corrected many weaknesses and efficiently developed the virtualization platform. The new Hyper-V replication offers significantly better possibilities for utilizing virtual network adapters, and the new capabilities for live migration provide a genuine improved value. For the foreseeable future, VMware will probably remain the top dog in the virtualization jungle, but Microsoft is slowly catching up.