Home > Microsoft, Virtualization > Hyper-V : Network Configuration and Prioritization

Hyper-V : Network Configuration and Prioritization

Every since I came along with questions regarding Hyper-V and Network

In fact there are good articles talking about, but let’s summarize here:

1. Network Configuration

In Production, use multiple networks in your cluster. For a complete HA environment, I recommend at least 8 :

  • 1 for Management. Microsoft recommends a dedicated network adapter for Hyper-V server management.
  • 2 (teamed ) for Virtual machines.Virtual network configurations of the external type require a minimum of one network adapter.
  • 2 (MPIO ) for SCSI.Microsoft recommends that IP storage communication have a dedicated network, so one adapter is required and two or more are necessary to support multipathing.
  • 1 for Failover cluster.Windows failover cluster requires a private network.
  • 1 for Live migration.This new Hyper-V R2 feature supports the migration of running virtual machines between Hyper-V servers. Microsoft recommends configuring a dedicated physical network adapter for live migration traffic. This network should be separate from the network for private communication between the cluster nodes, from the network for the virtual machine, and from the network for storage
  • 1 for CSV. Microsoft recommends a dedicated network to support the communications traffic created by this new Hyper-V R2 feature. In the network adapter properties, Client for Microsoft Networks and File and Printer Sharing for Microsoft Networks must be enabled to support SMB

Note: If your Hardware vendor supports NPAR ( Broadcom, Qlogic ), you can create “Virtual logical NIC’s” . The NPAR technology allows you to create up to 4 logical Nic’s, which means for example that a Blade with 4 10Gb NIC’s with NPAR that support the technology  it’s a good start.

2. Network Prioritization

To rank a network, it is given a unique integer from 1 to 268,000,000+, which is called a “metric”.    To view the networks, their metric values, and if they were automatically or manually configured, run the clustering PowerShell cmdlet:
PS > Get-ClusterNetwork | ft Name, Metric, AutoMetric

By default, all internal cluster network will have a metric value starting at 1000 and incrementing by 100.  The first internal network which the cluster sees when it first comes online has a metric of 1000, the second has a metric of 1100, …

To change the value of a network metric, run:
PS > $n = Get-ClusterNetwork “Live Migration”
PS > $n.Metric = 1050

Overriding network prioritization behavior:

–  Right-click on the network in Failover Cluster Manager
–  Select Properties
–  Change the radio buttons or checkboxes.  If you select “Do not allow cluster network communication on this network”, then it will not be possible to send any “Cluster & CSV Traffic” or “Live Migration Traffic” through this network, even if the network has the lowest metric values.  The cluster will honor this override and find the network with the next lowest value to send this type of traffic.

Overriding network prioritization behavior “Live Migration Traffic”   , by changing the network’s properties:

The networks for live migration can be configured more granularly :

– Right-click on any Virtual Machine resource
– Select Properties
– Click the Network for live migration tab and then specify which networks can and cannot be used for “Live Migration Traffic” and in which order they should be used.

Note: Even though it appears that this setting may be unique to that specific VM, it is actually a global setting for live migration.

Categories: Microsoft, Virtualization
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