Use one dedicated GigE adapter for vMotion. Consider using a 10GbE vMotion network. Using a 10GbE network in place of a 1GbE network for vMotion will result in significant improvements in vMotion performance. When using very large virtual machines (for example, 64GB or more), consider using multiple 10GbE network adaptors for vMotion to further improve vMotion performance.
If only two Ethernet adapters are available:
For best security, dedicate the GigE adapter to vMotion, and use VLANs to divide the virtual machine and management traffic on the other adapter.
For best availability, combine both adapters into a bond, and use VLANs to divide traffic into networks: one or more for virtual machine traffic and one for vMotion.
If you are constrained by your networking infrastructure and must have multiple traffic flows (for example, virtual machine traffic and vMotion traffic) sharing the same set of network adaptors, use the vSphere Network I/O Control (NetIOC) feature to partition the network bandwidth allocation among the different traffic flows.
On each host, configure a VMkernel port group for vMotion.
Ensure that virtual machines have access to the same subnets on source and destination hosts.
If you are using standard switches for networking, ensure that the network labels used for virtual machine port groups are consistent across hosts. During a migration with vMotion, vCenter Server assigns virtual machines to port groups based on matching network labels.
If you are using vSphere Distributed Switches for networking, ensure that source and destination hosts are members of all vSphere Distributed Switches that virtual machines use for networking.
Use of Jumbo Frames is recommended for best vMotion performance.
To determine the maximum number of concurrent vMotions possible, see the Concurrent migration limits at Limits on Simultaneous Migrations in the vSphere Web Client. These limits vary with a host's link speed to the vMotion network.
Note: You cannot migrate virtual machines that are attached to a virtual intranet with vMotion, even if the destination host has a virtual intranet configured with the same network label.