Cataloged from PDF version of article.We propose an adaptive flow-level multi-path routing-based traffic engineering solution for an IP backbone network
carrying TCP/IP traffic. Incoming TCP flows are switched between two explicitly routed paths, namely the primary and
secondary paths (PP and SP), for resilience and potential goodput improvement at the TCP layer. In the proposed
architecture, PPs receive a preferential treatment over SPs using differentiated services mechanisms. The reason for this
choice is not for service differentiation but for coping with the detrimental knock-on effect stemming from the use of longer
SP that is well known for conventional network load balancing algorithms. Moreover, both paths are congestion-controlled
using Explicit Congestion Notification marking at the core and Additive Increase Multiplicative Decrease rate adjustment
at the ingress nodes. The delay difference between PP and SP is estimated using two per-egress rate-controlling buffers
maintained at the ingress nodes for each path, and this delay difference is used to determine the path over which a new TCP
flow will be routed. We perform extensive simulations using ns-2 in order to demonstrate the viability of the proposed
distributed adaptive multi-path routing method in terms of per-flow TCP goodput. The proposed solution consistently
outperforms the single-path routing policy and provides substantial per-flow goodput gains under poor PP conditions.
Moreover, highest goodput improvements under the proposed scheme are achieved by flows that receive the lowest
goodputs with single-path routing, while the performance of the flows with high goodputs with single-path routing does not
deteriorate with the proposed path switching technique. Copyright # 2011 John Wiley & Sons, Ltd
