We need to migrate rather than upgrade since we are changing the VCenter domain name.
While converting to a Standard switch is the suggested method I have been testing moving the distributed switch and have been successful but want to know is others had tried this and what types of problems they may have encountered.
I inquired with several People and VMworld 2018 and spoke to support all but one did not have a problem with this method. Two people at the VMWorld 2018."Ask the Expert" suggested I make one change and use use this method.
0) Record all the NIC and Port groups for all you VMs (use a script)
1) Export the VDS from 5.5 vcenter with port groups
2) import VDS into 6.0 VCenter
3) export VDS from 6.0 VCenter
4) import VDS into 6.5 VCenter but do not preserve Original distributed switch and port group identifiers
5) connect the the host from the old vcenter with running VMs to the new VCenter Cluster
6) At this point your systems are still available but your network will not look correct
7) Select add and manage hosts
8)select Add host and manage host networking (advanced)
9) select all tasks
10) You network adapters will show they are in use by the DVSwitch on the old VCenter (They have the same names) Move them to this DVSwitch
11) I am not using VMKernal adapters
12) You need select to migrate each VMs Vnics to the new Destination port group. Use the information recorded in the first step. The source Port Group will be empty
13) once compete you can delete the old DVSwitch
14) to roll back you reverse steps 5 - 13
I found I would lose one ping as the system transitions to the new Distributed Switch
I have also tried this selected "preserve Original distributed switch and port group identifiers" It was actually easier to re-point the VMs to the port group however I was advised this can cause problems later on due to objects left over from the old DVSwitch
