Migration with vMotion requires correctly configured network interfaces on source and target hosts.

Configure each host with at least one network interface for vMotion traffic. To ensure secure data transfer, the vMotion network must be a secure network, accessible only to trusted parties. Additional bandwidth significantly improves vMotion performance. When you migrate a virtual machine with vMotion without using shared storage, the contents of the virtual disk is transferred over the network as well.

Note:

vMotion network traffic is not encrypted. You should provision secure private networks for use by vMotion only.

Requirements for Concurrent vMotion Migrations

You must ensure that the vMotion network has at least 250 Mbps of dedicated bandwidth per concurrent vMotion session. Greater bandwidth lets migrations complete more quickly. Gains in throughput resulting from WAN optimization techniques do not count towards the 250 Mbps limit.

To determine the maximum number of concurrent vMotion operations possible, see Limits on Simultaneous Migrations. These limits vary with a host's link speed to the vMotion network.

Round-Trip Time for Long-Distance vMotion Migration

If you have the proper license applied to your environment, you can perform reliable migrations between hosts that are separated by high network round-trip latency times. The maximum supported network round-trip time for vMotion migrations is 150 milliseconds. This round-trip time lets you migrate virtual machines to another geographical location at a longer distance.

Multiple-NIC vMotion

You can configure multiple NICs for vMotion by adding two or more NICs to the required standard or distributed switch. For details, see the VMware knowledge base article at http://kb.vmware.com/kb/2007467.

Network Configuration

Configure the virtual networks on vMotion enabled hosts as follows:

  • On each host, configure a VMkernel port group for vMotion.

    To have the vMotion traffic routed across IP subnets, enable the vMotion TCP/IP stack on the host. See Place vMotion Traffic on the vMotion TCP/IP Stack of an ESXi Host.

  • 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.

    Note:

    By default, you cannot use vMotion to migrate a virtual machine that is attached to a standard switch with no physical uplinks configured, even if the destination host also has a no-uplink standard switch with the same label.

    To override the default behavior, set the config.migrate.test.CompatibleNetworks.VMOnVirtualIntranet advanced settings of vCenter Server to false. The change takes effect immediately. For details about the setting, see VMware knowledge base article at http://kb.vmware.com/kb/1003832. For information about configuring advanced settings of vCenter Server, see Configure Advanced Settings.

For information about configuring vMotion network resources, see Networking Best Practices for vSphere vMotion.