Used by the adventurers in Dominic's homeplanet. The basic function of the portals is this: There are two portals linked to each other. The first portal is in Dominic's homeplanet [in a lab to be specific] while the second is in another planet which is the destination. The portal leading to the B&RPverse is the only portal that seems to be magical and thus, does not count as part of the Portal System.
How it works (Complicated version) Edit
The portal used a field of quantum physics that was unknown to the adventurers, This kind was known as a Wormhole, It utilized a force in all of space, specifically the electromagnetic field. By exiting the field, the portal could cause a wrap-around in the universes "string", thus causing a quick loop around large distances.
How it works (Simple/Randy version) (< Canonical version)Edit
Basically it's a wormhole.
Two portals are connected to each other. Person goes in Portal A which is connected to Portal B so that person comes out of Portal B, arriving at his/her/its destination.