Methods, apparatus and systems for routing information flows in networks based on spanning trees and network switching element resources. One or more controllers are used to assign information flows to network switching elements (NSEs) through use of spanning trees derived from link path costs. NSEs generate status information relating to resources they employ to facilitate information flows that is sent to the controller(s). The status information is used to derive link costs, which are then used to generate spanning trees that support routing between the NSEs without any path loops. Information flows are assigned to the NSEs such that the routing paths for the flows use the links in the spanning tree. The link costs and spanning trees are dynamically computed during ongoing operations, enabling the network routing and flow assignments to be reconfigured in response to dataplane events and changes to the information flow traffic.