A lot of research, development, and standardization efforts are going on to extend the latest buzz in packet networks called Software-Defined Networking (SDN) to the optical domain. We argue though that a reasonable combination of packet layer SDN with dynamic optical transport (in whatever flavor) is already possible with some architectural adaptations. We therefore propose to combine a recently proposed networking scheme called SDN Partitioning with dynamic optical circuits used in the form of Optical Bypasses. The method uses a few SDN nodes in a hybrid SDN/OSPF network, such that they partition the OSPF domain into sub-domains, thereby already achieving traffic engineering capabilities comparable to full SDN operation only by manipulating OSPF routing protocol updates when they cross sub-domain borders. The method provides that local routing inside sub-domains remains stable at all times, while inter-sub-domain routes can be optimized. The Optical Bypasses among border nodes come into play to dynamically offload transit traffic from frequently traversed (transit) sub-domains to the optical layer in case of increased traffic demands. Our simulation results show that the combination of a few SDN nodes with a few Optical Bypasses allows to cope with traffic surges up to a degree that renders excessive over-provisioning of link capacities or full SDN migration completely unnecessary.
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