Best-Effort Network Layer Packet Reordering in Support of Multipath Overlay Packet Dispersion

Abstract

Simultaneous use of multiple disjoint Internet paths holds promise for exploiting available bandwidth as well as reacting more quickly to Internet path faults. While routing overlay networks have provided a method for accessing these paths, out-of-order packet delivery, which results from dispersion of packets across paths of varying latency, severely degrades the performance of highly optimized transport protocols such as TCP, which assume largely in-order delivery. While traditional approaches perform reordering at the transport or application layers, such approaches have the disadvantage of entangling the complexity of reordering with their own operation, as well as requiring reimplementation for each protocol or application. Herein, we address these issues by proposing the modularization of packet reordering functionality as an optional, best-effort, network layer service for routing overlay networks. We empirically demonstrate the feasibility of this approach by showing that it can realize performance and reliability gains even using unmodified TCP in the face of highly multipath environments and heavy packet reordering.