I have establiched a PPTP tunnell between to mikrotik devices. I can map network drives and do just about anything but i cannot get a new workstation to join and active directory domain through the tunnel. I have turned off all firewall rules to no avail. I have set the workstations DNS setting to point at the domain controller also.
EOIP work good ,but ,when use ,you must use bridges ,and some versions can crush.
If you have problems with pptp ,keep in mind that dns server on client machine must be domain server!