During host evacuation in Microsoft System Center 2012 R2 Virtual Machine Manager, the placement process may not find any appropriate hosts for virtual machine live migration. In this situation, you receive one or more of the following error messages:
23806 - All available ports on switch extension <Name> have been used.
23808 - All available ports on port profile <Name> have been used.
This issue affects switch extension users only (mostly Cisco-based) when almost all the ports on a switch extension or a port profile are being used.
Host evacuation represents a special case for the placement process. During live migration, switch extension ports should be reused, and a new requirement should not be created.
To resolve this issue, follow these steps:
Increase the maximum number of available ports on switch extensions and port profiles. There should be at least one available port for each virtual machine.
Manually live-migrate virtual machines that are using switch extensions. Do this one virtual machine at a time before you put the host into maintenance mode.