Amongst data center structures, flattened butterfly (FBFly) networks have been shown to outperform their common counterparts such as fat-trees in terms of energy proportionality and cost efficiency. This efficiency is achieved by using less networking equipment (switches, ports, cables) at the expense of increased control plane complexity. In this paper we show that cabling complexity can be further reduced by an order of magnitude, by reconfiguring the optical fully meshed components into optical “pseudo”-fully meshed components. Following established methods, optical star networks are obtained by exchanging the FBFly's regular (grey) optical transceivers for dense wavelength division multiplexing (DWDM or colored) optical transceivers and placing an arrayed waveguide grating router (AWGR) in the center. Depending on the data center configuration and equipment prices, our colored FBFly (C-FBFly) proposal yields lower capital expenditure than the original FBFly. The key advantage of our structural modification of FBFly, however, is that in large FBFly networks (e.g., > 50K nodes) it reduces the number of inter-rack cables by a factor as large as 48.

Power management is a critical issue for mobile devices, where a significant portion of the total system energy can be often consumed by heavy wireless network activity. In this paper we present a framework that reduces the energy consumption of wireless mobile devices during streaming video content over Wireless LAN networks by utilizing the power saving mechanisms defined in the IEEE 802.11e standard. The framework allows video applications to directly optimize the overall energy efficiency by controlling the sleep cycles of wireless network adapters based on video QoE. The framework employs a simple QoE estimation algorithm that estimates the user level video quality, and adjusts the sleep intervals of the wireless adapter to maintain video quality while maximizing power efficiency. As an important part of our paper the building and configuration steps of a working testbed system is carefully described, which demonstrates the availability and efficiency of the U-APSD power saving technology at hand. A preliminary evaluation of the proposed framework supports that by enabling the WMM Power Saving feature 20-30% of total system energy can be saved even in case of asynchronous video traffic.

This paper takes a first step towards generalizing compact routing to arbitrary routing policies that favor a broader set of path attributes beyond path length. Using the formalism of routing algebras we identify the algebraic requirements for a routing policy to be realizable with sublinear size routing tables and we show that a wealth of practical policies can be classified by our results. By generalizing the notion of stretch, we also discover the algebraic validity of compact routing schemes considered so far and we show that there are routing policies for which one cannot expect sublinear scaling even if permitting arbitrary constant stretch.

Research works concerning AS (Autonomous Systems) level Internet topology measurements typically aim at obtaining near-complete maps of the AS structure. In this paper, we take a fundamentally different approach by inspecting several concurrently visible local views of the AS graph stored at individual BGP route servers. We find that each of these views exhibits the characteristic properties of complex graphs having power-law degree distribution, large clustering coefficient and the small world property. As a main contribution, the intersection of these views is investigated to identify the skeleton of the Internet consisting of edges seen by most of the ASes. Our measurements support the surprising claim that this skeleton is a scale-free complex network, having a giant connected component with a dense part in its heart forming the critical AS level core. We identify the edges in the skeleton as critical infrastructure, any changes of which induces an Internet-wide effect with BGP updates propagating to all ASes. Finally, we reinterpret the path inflation metric using the local view approach and show that local path inflation can be very diverse in different ASes.