i use this pptp to conect from one client to two servers and it
works great i reach both servers, but i had to join another client to
both server but it generated 2 Mb traffic and everyting stops. I use
rstp in the bridges but it works not. i thing it come to be a loop.know someone how can i solve this problem?
i used this description!
http://blog.butchevans.com/2009/12/how-to-bridge-distant-networks-using-routeros-and-pptp/
What’s new in 6.0rc10 (2013-Feb-15 10:47):
*) ppp - added bridge-path-cost & bridge-port-priority to ppp profiles;
*) ppp - made RSTP work over ppp links as well;
very good 
and the Butch’s example is excellent
regards