One new &quot;feature&quot;, or probably better described as an enhancement, introduced in vSphere 4.1 is Load Based Teaming.

Briefly, Load Based Teaming takes the traditional three load balancing choices (route based on originating virtual Port ID, IP hash, or Source MAC) and offers a dynamic, &quot;on-the-fly&quot; policy for better utilization of bandwidth.

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The default policies in parenthesis above statically map from the vSwitch port to the physical NIC / uplink to the physical switch. This is done initially, and again, is a static assignment.

&quot;With Load Based Teaming in vSphere 4.1, after initial port based assignment, the load balancing algorithm regularly checks the load of all the teaming NICs. If one gets overloaded while another one has bandwidth available, it reassigns the port-NIC mapping to reach a balanced status.&quot; In order for this to kick in, VMware defines &quot;overloaded&quot; as over 75% utilization of the pNIC for a period of 30 seconds.

In addition to dynamically adjusting to the load, VMware states that it also considers the speed of the links (1Gb, 10Gb-- even 100Mb). The only snag is that this can only be done with the Distributed Virtual Switch, and not a standard vSwitch.