PPTP isolated on vlan

I’m trying to figure out how to isolate PPTP connections to their own vlan. I have the MikroTik connected to a Cisco switch configured with trunking for Vlan. The objective is to have access ports on the Cisco that are accessible only to the VPN connection. Do I use the firewall to isolate or is there a way to bridge the PPTP to just a Vlan?