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We explain the notion of software-defined networking (SDN), whose southbound interface may be implemented by the OpenFlow protocol. We describe the operation of OpenFlow and summarize the features of specification versions 1.0–1.4. We give an overview of existing SDN-based applications grouped by topic areas. Finally, we point out architectural design(More)
In this paper we consider carrier networks using only OpenFlow switches instead of IP routers. Accommodating the full forwarding information base (FIB) of IP routers in the switches is difficult because the BGP routing tables in the default-free zone currently contain about 500,000 entries and switches have only little capacity in their fast and expensive(More)
Maximally redundant trees (MRTs) have been suggested in IETF as a new promising method for fast rerouting in IP networks. Unlike loop-free alternates (LFAs), they can protect against all link and node failures if topology allows. In this work, we compare MRTs and not-via addresses, which also guarantee full-failure coverage. We evaluate path lengths and(More)
Numerical solutions of the time-dependent Ginzburg-Landau equations show a new mechanism for plastic motion of a driven vortex lattice in a clean superconductor. The mechanism, which involves the creation of a defect superstructure , is intrinsic to the moving vortex lattice and is independent of bulk pinning. Other structural features found in the(More)
Loop-Free Alternates (LFAs) are a local fast-reroute mechanism defined for IP networks. They are simple but suffer from two drawbacks. Firstly, some flows cannot be protected due to missing LFAs, i.e., this concept does not provide full protection coverage, which depends on network topology. Secondly, some LFAs cause loops in case of node or multiple(More)
In this paper we propose a novel resilience scheme for OpenFlow-based Software-Defined Networking (SDN). To forward packets in line speed, OpenFlow switches store their flow tables in expensive, limited TCAM due to which the stored tables cannot be large. Most resilience mechanisms require additional entries thus the implementation in OpenFlow may quickly(More)
A systems approach in which computer automation is applied to a vacuum ultraviolet spectrometer and auxiliary components is described. The errors associated with the measurement of gaseous absorption coefficients in the vacuum ultraviolet are considered. The presence of scattered light introduces large errors particularly at those wavelengths where the(More)
The phonon spectrum of Ge₂Sb₂Te₅ is a signature of its crystallographic structure and underlies the phase transition process used in memory applications. Epitaxial materials allow coherent optical phonons to be studied in femtosecond anisotropic reflectance measurements. A dominant phonon mode with frequency of 3.4 THz has been observed in epitaxial(More)