Get-VDSwitch |

Select Name,

    @{N='Total Ports';E={$_.NumPorts}},

    @{N='Available Ports';E={

        $vds = $_

        $hPorts = $vds.ExtensionData.Config.Host.UplinkPortKey.Count

        $vPorts = (Get-View -Id $vds.ExtensionData.Summary.Vm | %{

                    $_.Config.Hardware.Device |

                    where{$_.Backing -and

                      $_.Backing.GetType().Name -match "distributed" -and

                      $_.Backing.Port.SwitchUuid -eq $vds.ExtensionData.Uuid}}).Count

        $vds.NumPorts - $hPorts - $vPorts

    }}