System and methods are described for providing adaptive routing in the presence of persistent flows. Switches in a fabric have the capability to establish flow channels. Switches can adaptively route flows, while monitoring transmission characteristics of the flows channels to identify whether any flows are experiencing congestion towards a destination. In response to detecting congestion, it can be further determined whether the flow is related to a source of congestion, or alternative the flow is a victim of congestion. Flows that are a source of congestion have their routing constrained to prevent congestion from propagating. For example, new packets of a flow that is a source of congestion may be forced to only take the path of the data transmission that detected said congestion (preventing congestion from spreading). Alternatively, victims of congestion do not have their routing constrained, and packets can take any path as permitted by adaptive routing.