͑Doc. ID 83587͒ One of the difficulties of optical packet-switched (OPS) networks is buffering optical packets in the network. O(1) reading operation is not possible in the optical domain, because there is no equivalent optical RAM available for storing packets. Currently, the only available solution that can be used for buffering in the optical domain is using long fiber lines called fiber delay lines (FDL). However, FDLs have important limitations and may cause high packet drop rates due to the burstiness of Internet traffic. We propose an architecture using an explicit congestion control protocol (XCP) based utilization control algorithm designed for OPS wavelength-division-multiplexing (WDM) networks with pacing at the edge nodes for decreasing the buffer requirements at core nodes. We evaluate the FDL requirements on a meshed network with multiple-hop paths and show how FDL requirements change with slot size, utilization, FDL granularity, scheduling, and packet size distribution.
Recently, different nanophotonic computational design methods based on optimization algorithms have been proposed which revolutionized the conventional design techniques of photonic integrated devices. The intelligently designed photonic devices have small footprints and high operating performance along with their fabrication feasibility. In this study, we introduce a new approach based on attractor selection algorithm to design photonic integrated devices. In order to demonstrate the potential of the proposed approach, we designed two structures: an optical coupler and an asymmetric light transmitter. The designed photonic devices operate at telecom wavelengths and have compact dimensions. The designed optical coupler has a footprint of only 4 × 2 μm 2 and coupling efficiency of 87.5% at a design wavelength of 1550 nm with spatial beam width compression ratio of 10:1. Moreover, the designed optical coupler operates at a wide bandwidth of 6.45% where the transmission efficiency is above 80%. In addition, the designed asymmetric light transmitter with a size of 2 × 2 μm 2 has the forward and backward transmission efficiencies of 88.1% and 8.6%, respectively. The bandwidth of 3.47% was calculated for the designed asymmetric light transmitter where the forward transmission efficiency is higher than 80% and the backward efficiency transmission is under 10%. In order to evaluate the operating performance of the designed photonic devices, coupling losses are analyzed. The presented results show that the attractor selection algorithm, which is based on artificial neural networks, can bring a conceptual breakthrough for the design of efficient integrated nanophotonic devices.
Abstract. In this paper, we propose an AIMD-based TCP load balancing architecture in a backbone network where TCP flows are split between two explicitly routed paths, namely the primary and the secondary paths. We propose that primary paths have strict priority over the secondary paths with respect to packet forwarding and both paths are rate-controlled using ECN marking in the core and AIMD rate adjustment at the ingress nodes. We call this technique "prioritized AIMD". The buffers maintained at the ingress nodes for the two alternative paths help us predict the delay difference between the two paths which forms the basis for deciding on which path to forward a new-coming flow. We provide a simulation study for a large mesh network to demonstrate the efficiency of the proposed approach in terms of the average blocking rate and the average per-flow goodput.
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