Cloudtidings.com

When it comes to network configuration, be sure to provide the right number of physical network adapters on Hyper-V servers. Failure to configure enough network connections can make it appear as though you have a storage problem, particularly when using iSCSI.

Recommendation for network configuration ( number of dedicated Physical Nic’s ):

• 1 for Management. Microsoft recommends a dedicated network adapter for Hyper-V server management.
• At least 1  for Virtual machines. Virtual network configurations of the external type require a minimum of one network adapter.
• 2 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.
• At least 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 Cluster shared volumes. 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

Some interesting notes when comparing FC with iSCSI:

• iSCSI and FC delivered comparable throughput performance irrespective of the load on the system.
• iSCSI used approximately 3-5 percentage points more Hyper-V R2 CPU resources than FC to achieve comparable performance.

For information about the network traffic that can occur on a network used for Cluster Shared Volumes, see “Understanding redirected I/O mode in CSV communciation” in Requirements for Using Cluster Shared Volumes in a Failover Cluster in Windows Server 2008 R2 (http://go.microsoft.com/fwlink/?LinkId=182153).

For more information on the network used for CSV communication, see Managing the network used for Cluster Shared Volumes.

It’s not recommend that you do use the same network adapter for virtual machine access and management.
If you are limited by the number of network adapters, you should configure a virtual local area network (VLAN) to isolate traffic. VLAN recommendations include 802.1q and 802.p.