In the talk I overview some recent results for optimization problems that originate in optical networks. They deal with optimizing the utilization of regenerators (switching components that regenerate a signal after a certain distance) and ADMs (Add-Drop Multiplexers).

Mobile phones and tablets can be considered as the first incarnation of the post-PC era. Their explosive adoption rate has been driven by a number of factors, with the most significant influence being touch-screens, sensors, app markets, and better cellular technologies.

The dominant paradigm in both IETF and IEEE 802.1 standards for shortest path bridges is based on link-state routing in layer two. This results on hybrid devices of router and switch.

It is notoriously difficult to make distributed systems reliable. This becomes even harder in the case of the widely-deployed systems that are heterogeneous (multiple implementations) and federated (multiple administrative entities).

BitTorrent is the most successful Peer-to-Peer (P2P) application and is responsible for a major portion of Internet traffic. It has been largely studied using simulations, models and real measurements. Although simulations and modelling are easier to perform, they typically simplify analysed problems and in case of BitTorrent they are likely to miss some of the effects which occur in real swarms.

Vishal Misra together with Dan Rubinstein launched at the beginning of 2011 the company Silver Lining. This company is a very ambitious tech start-up arising from two professors of Columbia University, and has already attracted a lot of interest and a substantial amount of funding from investors. Silver Lining is developing a very advanced product in the area of content distribution networks that is expected to have high impact. Vishal Misra, co-founder and its current CEO, will give a first-hand account on the development of this interesting initiative.

In multi-hop networks, conventional unipath routing approaches force the data transmission to follow a fixed sequence of nodes. In this talk, we widen this path to create a corridor of forwarding nodes. Within this corridor, data can be split and joined at different nodes as the data travels through the corridor towards the destination node. To split data, decode-and forward OFDMA is used since with OFDMA, one can exploit the benefits of opportunistically allocating different subcarriers to different nodes according to their channel conditions. To avoid interference, each subcarrier is only allocated once per hop. For the presented scheme, the problem of optimizing the network throughput by means of resource and power allocation is formulated and two suboptimal algorithms are proposed to solve this problem with feasible effort. Simulations show that in multi-hop networks corridor-based routing using opportunistic forwarding outperforms conventional unipath routing approaches in terms of achievable throughput.

By tweaking the BGP configurations, the network operators are able to express their interdomain routing preferences, designed to accommodate a myriad goals. Given the complex interactions between policies in the Internet, the origin AS by itself cannot ensure that only by configuring a routing policy it can also achieve the anticipated results. Moreover, the definition of routing policies is a complicated process, involving a number of subtle tuning operations prone to errors. In this paper, we propose the BGP Visibility Scanner which allows network operators to validate the correct implementation of their routing policies, by corroborating the BGP routing information from approximately 130 independent observation points in the Internet. We exemplify the use of the proposed methodology and also perform an initial validation for the BGP Visibility Scanner capabilities through various real operational use cases.

A thorough understanding of the power consumption behavior of real world wireless devices is of paramount importance to ground energy-efficient protocols and optimizations on realistic and accurate energy models. This paper provides an in-depth experimental investigation of the per-frame energy consumption components in 802.11 Wireless LAN devices. To the best of our knowledge, our measurements are the first to unveil that a substantial fraction of energy consumption, hereafter descriptively named cross-factor, may be ascribed to each individual frame while it crosses the protocol/implementation stack (OS, driver, NIC). Our findings, summarized in a convenient new energy consumption model, contrast traditional models which either neglect or amortize such energy cost component in a fixed baseline cost, and raise the alert that, in some cases, conclusions drawn using traditional energy models may be fallacious.

Visible Light Communication (VLC) is an emerging technology in which Light Emitting Diodes (LEDs) transport information wirelessly, using the visible light spectrum. While most of the research on VLC has focused on wideband white LEDs used in ambient illumination, narrowband and colored LEDs have received little attention. Short-range free-space optical communication based on narrowband LEDs as visible light transmitters and receivers enable a variety of applications, a scenario we refer as LED-to-LED communication. In this work, we introduce the communication and networking protocols of LED-to-LED communication. Our work addresses fundamental challenges such as efficient collision detection medium access protocol and elimination of light flicker. We build a prototype and demonstrate bi-directional data exchange in a network of up to four LEDs. We further study the trade-offs in the system design and measure the achievable bit-rate and transmission distances