We have tried our lab environment introduce vSphere Distributed Switch. We installed two ESXi host, (x.0.7 and x.0.4) and created one vCenter Server Appliance, that ran one ESXi. We created a distributed switch, than portgroups. Both of them ESXi host had 3 NIC, vmnic0 to Management, vmnic1 to vMotion and vmnic2 to iSCSI. The vCenter Server Appliance ran on x.0.4 host. First we assigned vMotion and iSCSI network to phisycal nics each hosts. That was right. The problem began when we tried to migrate from standard vSwitch to dist. vSwitch the managament network. vCenter Applicance always rollbacked the networks. We recognized the problem, after a few minutes. Becouse we had one uplink to vSwitch and dSwitch, the vCenter always disconnected from network, and wasn’t able to connect management network. Fortunetly we found solution ours problem.

Solution: https://www.youtube.com/watch?v=9A_9svZCovs and http://wahlnetwork.com/2013/11/22/migrating-esxi-host-running-vcenter-distributed-vswitch/