We propose a novel traffic engineering architecture for IP networks with multiprotocol label switching (MPLS) backbones. In this architecture, two (primary and secondary) label switched paths (LSPs) are established among every pair of IP routers located at the edge of an MPLS cloud. Traffic between a source-destination pair is then split between the primary and secondary LSPs using an ABR-like explicit-rate feedback gathered from the network. Taking into consideration the packet reordering effect of packet-based load balancing schemes, we propose a novel traffic splitting mechanism that operates on a per-flow basis. We show, using a variety of scenarios, that deploying flow-based multipath traffic engineering not only provides significantly and consistently better throughput than that of a single path, but is also void of any packet reordering. © 2003 IEEE.