  The centralized architecture in software-defined network (SDN) provides a
global view of the underlying network, paving the way for enormous research in
the area of SDN traffic engineering (SDN TE). This research focuses on the load
balancing aspects of SDN TE, given that the existing reactive methods for
data-plane load balancing eventually result in packet loss and proactive
schemes for data plane load balancing do not address congestion propagation. In
the proposed work, the SDN controller periodically monitors flow level
statistics and utilization on each link in the network and over-utilized links
that cause network congestion and packet loss are identified as bottleneck
links. For load balancing the identified largest flow and further traffic
through these bottleneck links are rerouted through the lightly-loaded
alternate path. The proposed scheme models a Bayesian Network using the
observed port utilization and residual bandwidth to decide whether the newly
computed alternate path can handle the new flow load before flow admission
which in turn reduces congestion propagation. The simulation results show that
when the network traffic increases the proposed method efficiently re-routes
the flows and balance the network load which substantially improves the network
efficiency and the quality of service (QoS) parameters.
