Survivability schemes for dynamic traffic in optical networks

Abstract

Internet technology is becoming more and more complex with the continuously increasing demand for high bandwidth demands. Supporting over a billion users, it runs over a backbone transport network system serving not only the Internet but also other services including mobile communication, bank machines, leased lines, etc. Various services are accommodated in corresponding virtual networks built on top of the common infrastructure of the transport network. Therefore, the number of users supported by transport network is much greater than that by Internet.

The transport network has been supported by the photonic communication technology, notably wavelength-division multiplexing (WDM) and photonic ultra-high-capacity switching devices such as optical cross-connects (OXCs). With the WDM technology, hundreds of independent lightpaths are allowed to be multiplexed along a single fiber carrying huge amount of data traffic steered by the OXCs. Due to the potentially huge amount of bandwidth carried in a single fiber, the occurrence of a failure may affect thousands or millions of end users. Hence, network survivability, which is concerned with how to minimize the impact of failures when they happen, is of paramount importance to today's transport network and is the central topic of this research.

To minimize the impact of failures, survivability mechanisms have been developed in networks to provide service replacement solutions in the event of network failures so that service may fully or partially continue for some or all of the clients that would otherwise lose service. This research is comprised of four advanced studies of transport network survivability mechanisms for dynamic traffic based on p-Cycles and the extensions. The ultimate aim is to design economically viable communication backbones that survive network failures elegantly, simply and quickly.

The first study introduces the concept of PWLE and explores the design issues of PWLE, including Compatible Grouping and the Mixed Integer Linear Programming (MILP) formulation. The issues of the routing and operation of PWLE are addressed. Numerical studies are carried out on PWLE optimization, blocking performance as well as the control overheads of the routing algorithm designed for PWLE.

The second study explores the issues of cycle selection for PWLE. An algorithm, called AttachNode-Based Cycle Generation (ANCG), is developed for the pre-computation of candidate cycles. In addition, three Heuristic Algorithms of Lightpath-protecting p-Cycle Selection (HALCS) are developed to address the issue of cycle selection for PWLE.

The third study introduces the motivation and design of CAPWLE, where the Effective Envelope, the basis of CAPWLE, is defined followed by its calculation method developed based on the Maximum Concurrent Flow Problem (MCFP). Based on Effective Envelope, CAPWLE is optimized using MILP.

The fourth study discusses the issues of configuring span-protecting p-Cycles in a capacity-efficient way under time-variant traffic, where the key idea of Joint Static Configuration Approach (JSCA) is introduced. The optimization model of JSCA and its sub-optimal solution are provided. Then the approach is extended to other p-Cycle-based survivability schemes including PWLE.