Abstract: The Greek School Network (GSN) is the nationwide network that connects all units of primary and secondary education in Greece. GSN offers a significant set of diverse services to more than 15.000 schools and administrative units, and more than 60.000 teachers, placing GSN second in infrastructure size nationwide. GSN has relied on the emerging power of open source software to build cutting-edge services capable of covering internal administrative and monitoring needs, end user demands, and, foremost, modern pedagogical requirements for tools and services. GSN provides a wide set of advanced services, varying from web mail to virtual classrooms and synchronous/asynchronous tele-education. This paper presents an evaluation of GSN open source services based on the opinions of users who use GSN for educational purposes, and on usage and traffic measurement statistics. The paper reaches the conclusion that open source software provides a sound technological platform that meets the needs for cutting edge educational services deployment, and innovative, competitive software production for educational networks.
Abstract: In this paper, we demonstrate optical transparency
in packet formatting and network traffic offered by all-optical
switching devices. Exploiting the bitwise processing capabilities
of these “optical transistors,” simple optical circuits are designed
verifying the independency to packet length, synchronization
and packet-to-packet power fluctuations. Devices with these attributes
are key elements for achieving network flexibility, fine
granularity and efficient bandwidth-on-demand use. To this end, a
header/payload separation circuit operating with IP-like packets,
a clock and data recovery circuit handling asynchronous packets
and a burst-mode receiver for bursty traffic are presented. These
network subsystems can find application in future high capacity
data-centric photonic packet switched networks.
Abstract: In this paper, we review recent advances in ultrafast optical time-domain technology with emphasis on the use in optical packet switching. In this respect, several key building blocks, including high-rate laser sources applicable to any time-division-multiplexing (TDM) application, optical logic circuits for bitwise processing, and clock-recovery circuits for timing synchronization with both synchronous and asynchronous data traffic, are described in detail. The circuits take advantage of the ultrafast nonlinear transfer function of semiconductor-based devices to operate successfully at rates beyond 10 Gb/s. We also demonstrate two more complex circuits-a header extraction unit and an exchange-bypass switch-operating at 10 Gb/s. These two units are key blocks for any general-purpose packet routing/switching application. Finally, we discuss the system perspective of all these modules and propose their possible incorporation in a packet switch architecture to provide low-level but high-speed functionalities. The goal is to perform as many operations as possible in the optical domain to increase node throughput and to alleviate the network from unwanted and expensive optical-electrical-optical conversions.