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There is a lot of posts regarding Hyper-V and network, but I found a lot people still don’t get it.

1. Network Design. How many nic’s we need for production environment for High Availiability:

• 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

But how about production environments when the blades have only 4 Physical NIC’s?

Option 1. If your vendor does support NPAR technology(Broadcom, QLogic), you will be able to create up to 4 “Virtual Logical NIC’s” per physical NIC ( VLAN/QoS ). Although this solution is not supported by MS, it’s the best solution in terms of performance and it is supported by the vendors. This solution will provide you 100% HA as you can have up to 16 Logical NIC’s.

Option 2. Supported by MS. Allocate 2(two) NIC’sfor the iSCSI using MPIO and then :

Note that the QoS configuration is based on “per port”  and Windows only allows you to cap specify caps – not reserves. This solution, although supported by MS, dos not give you 100% HA.

2. Network Configuration. What need to be enabled/disabled?

2. Network Prioritization. What need to be enabled/disabled?

By default, all internal cluster network 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, etc.

When you create CSV’s,  the failover cluster automatically chooses the network that appears to be the best for CSV communication. The lowest Metric value designates the network for Cluster and CSV traffic. The second lowest value designates the network for live migration. Additional networks with a metric below 10000 will be used as backup networks if the “Cluster & CSV Traffic” or “Live Migration Traffic” networks fail.  The lowest network with a value of at least 10000 will be used for “Public Traffic”. Consider giving the highest possible values to the networks which you do not want any cluster or public traffic to go through, such as for “ISCSI Traffic”, so that they are never used, or only used when no other networks at all are available.

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

To change the value of a network metric, run:
PS >Get-ClusterNetwork “Live Migration” ).Metric =800

If you want the cluster to start automatically assigning the Metric setting again for the network named “Live Migration”:
PS > Get-ClusterNetwork “Live Migration” ).AutoMetric = $true

How to override Network Prioritization Behavior?

Option 1. Change the network’s properties. 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 :

1. In the Failover Cluster Manager snap-in, if the cluster that you want to configure is not displayed, in the console tree, right-click Failover Cluster Manager, click Manage a Cluster, and then select or specify the cluster that you want.
2.  Select Properties
3. Change the radio buttons or checkboxes.

Option 2 (exclusively for “Live Migration Traffic”) :

To configure a cluster network for live migration:

Note : You don’t need to perform this action as per VM basis. When you configure a network for live migration for a specific virtual machine, the setting is global and therefore applies to all virtual machines.

Some other interesting articles:

http://technet.microsoft.com/en-us/library/dd446679(WS.10).aspx

http://www.hyper-v.nu/archives/hvredevoort/2011/03/windows-server-2008-r2-sp1-and-hp-network-teaming-testing-results/

http://blogs.technet.com/b/vishwa/archive/2011/02/01/tuning-scvmm-for-vdi-deployments.aspx

http://blogs.msdn.com/b/clustering/archive/2011/06/17/10176338.aspx

http://technet.microsoft.com/en-us/library/dd446679.aspx