Optimizing Hyper-V network settings

Flow Control

Article from ADMIN 06/2011

By Thomas Joos

Performance problems with virtual servers on Hyper-V are often caused by a network access bottleneck, but various optimization settings can help speed things up.

Version 3.0 of Hyper-V in Windows Server 8 offers several improvements in terms of networking that improve the system's performance. Examples include direct access by virtual machines to the network cards' hardware functions and improved control and configuration of the network connections. But, the current 2.0 version of Hyper-V in Windows Server 2008 R2 also provides optimization options that administrators can use to accelerate substantially the virtual network connections.

Hyper-V Networks

For a virtual server on a Hyper-V network to access the physical network, a connection must exist between the virtual and the physical network card in the Hyper-V host. The hypervisor uses a virtual network switch to provide this link. Because the various virtual servers on the Hyper-V host are forced to share the network card, conflicts and resource bottlenecks can occur. Network management is handled by the Virtual Network Manager in the Hyper-V Manager (Figure 1). Here, you can create three different types of virtual network:

External virtual networks support communications between the virtual servers themselves and the rest of the network. This type of connection includes the physical network cards. The connection is handled by a virtual switch that connects the Hyper-V host and the virtual servers that use the connection to the network. In Hyper-V Manager, you can assign only one external network for each network card. But, you can create any number of internal virtual networks because they are not connected to a physical network card; instead, they only handle internal communications.
Internal virtual networks only support communications between the virtual servers themselves and with the physical host on which the servers are installed. In other words, the servers can't communicate with the rest of the

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