Hitless network engineering of SONET rings

Shrinking capital expenditure budgets are forcing telecom service providers to explore engineering tools that extract greater utilization from their existing transport infrastructure. In this paper, we explore the challenges in engineering SONET rings to support higher traffic volumes. Unlike network design tools, engineering operations have to reconfigure live traffic and do so in a hitless manner. We present an efficient algorithm called MobiRing that accounts for the unique constraints imposed by the SONET standard. In spite of the hardness of the optimization problems, we show using extensive simulations that the greedy approach of MobiRing performs extremely well. More importantly, MobiRing is able to achieve hitless reconfigurations and therefore, very attractive to use in practice. This ability to do effective, hitless engineering opens the possibility that network engineering, traditionally a very infrequent operation, can now be done proactively to maintain high levels of network utilization.