1. A method for determining a path calculation from a source node to a destination node over a multi-domain network, the method comprising: receiving a predetermined sequence of domains for communicating information from the source node to the destination node; using one or more processors of one or more path computation elements associated with the multi-domain network, determining a link type for each of a plurality of links in the predetermined sequence of domains; using the one or more processors, modifying the link type of one or more of the plurality of links such that the modified one or more of the plurality of links are unidirectional links towards a destination node, wherein modifying the link type of one or more of the plurality of links comprises at least one of: (a) modifying bidirectional links to unidirectional links towards the destination node, and (b) removing any unidirectional link towards the source node; and using the one or more processors, determining a path along the predetermined sequence of domains based on the modified one or more of the plurality of links.