The communication between data-intensive applications in data centers often involves a collection of parallel flows, usually referred to as a coflow. A coflow between two groups of machines can capture diverse communication patterns observed in data centers. The static coflow routing and spectrum assignment (CofRSA) problem in optical orthogonal frequency division multiplexed data center networks is investigated, when the coflow traffic demands are given. The static CofRSA problem considers the spectrum constraints of the flows between different coflows and those within the same coflow. We formulate the static CofRSA problem as an integer linear programming (ILP) model. The objective of the ILP model is to minimize the used spectrum slots. However, the ILP model cannot achieve an optimal solution within tolerable time for large networks. To solve the problem, two highly efficient heuristic algorithms, the most cofSize first (MCSF) ordering algorithm and the greedy inserting (GI) algorithm, are proposed to achieve suboptimal solutions. The simulation results indicate that ILP provides an optimal solution for small networks, whereas GI and MCSF yield suboptimal solutions in large networks. The results also show that GI provides more efficient solutions than MCSF.
Optical burst switching (OBS) has been paid increasing attention as an attractive alternative for building future photonic Internet. Besides pure theoretical research, experimental prototype and proof-of-concept demonstration are also significant parts toward practical burst switched WDM optical networks. This paper describes hardware architecture, software module and experimental results of optical burst switching nodes using a just-enough-time (JET) protocol and contention resolutions. The core node forwards bursts in the optical domain with deflection routing resolution. It is designed to be transparent to the format, the protocol and the bit rate of traffic. The edge node performs burst assembly/disassembly, as well as burst forwarding, which makes it flexible to be applied to various topologies. The related control protocols and algorithms are implemented taking into account characteristics of being used commercial off-the-shelf devices. By the experiments, the basic function of optical burst switching is demonstrated, the delay measurement result is analyzed, and the effort direction is given.
Wavelength division multiplexing (WDM) optical network provides a platform with high bandwidth capacity and is supposed to be the backbone infrastructure supporting the next-generation high-speed multi-service networks (ATM, IP, etc.). In the foreseeable future, IP will be the predominant data traffic, to make fully use of the bandwidth of the WDM optical network, many attentions have been focused on IP over WDM, which has been proposed as the most promising technology for new kind of network, so-called Optical Internet. According to OSI model, IP is in the 3rd layer (network layer) and optical network is in the 1st layer (physical layer), so the key issue is what adaptation technology should be used in the 2nd layer (data link layer). In this paper, firstly, we analyze and compare the current adaptation technologies used in backbone network nowadays. Secondly, aiming at the drawbacks of above technologies, we present a novel adaptation protocol (DONA) between IP layer and optical layer in Optical Internet and describe it in details. Thirdly, the gigabit transmission adapter (GTA) we accomplished based on the novel protocol is described. Finally, we set up an experiment platform to apply and verify the DONA and GTA, the results and conclusions of the experiment are given.
Optical Add/Drop Multiplexer (OADM) is an important network element. In the ring architecture, OADM can be introduced to make efficient use of network capacity, network protection, wavelength routing and many more good features. In this paper, an OADM with high performance realized by us is demonstrated. The key technical problem , solving method and design rule for the OADM are given. The experiment results of long distance transmission by use of the OADM are illuminated by some figure . It shows that the OADM realized by us is advanced, practical, reliable, and applied in China Advanced Info-Optical Network (CAINONet).