Reduced flow routing: Leveraging residual capacity to reduce blocking in GMPLS networks

Traffic engineering has been extensively studied to maximize network resource utilization while minimizing call blocking [1]. As the the demand for high data rate services over wide area networks (WAN) continue to grow [2], and as traffic patterns become subject to more frequent changes, resource utilization and the ability to guarantee quality-of-service become more important. However, accurate, predictive traffic models are difficult to construct [3], implying that the routing mechanism will need to adapt to the difference between the anticipated and the observed loads. Online routing based on network residual capacity plays an important role in such settings, since optimal offline solutions require knowledge of future traffic, rendering long-term optimization nearly impossible. shortest path first (SPF) based routing is fast and is currently the most widely-used online algorithm for optical networks. Many variants of SPF, like CSPF (Constrained SPF), have been proposed to further reduce blocking and network congestion. This paper focuses on the problem of online open routing for connection-oriented optical networks. As part of the major contributions of this paper, we propose a novel online, link-state based routing algorithm called reduced flow routing (RFR), an oracular optimization model, and an efficient network provisioning algorithm. The RFR algorithm uses a fast analysis of each potential route’s impact on future requests to select amongst the available choices. The strategy of RFR leverages information about network topology and residual capacity to reduce blocking by rejecting 20% less connection requests relative to other online routing algorithms with little additional cost. The RFR algorithm can be integrated readily into current and future Generalized Multi-Protocol Label Switching (GMPLS) networks as well as many other relevant networks.