Fibre-optic delivery of time and frequency to VLBI station

The quality of Very Long Baseline Interferometry (VLBI) radio observations predominantly relies on precise and ultra-stable time and frequency (T&F) standards, usually hydrogen masers (HM), maintained locally at each VLBI station. Here, we present an operational solution in which the VLBI observations are routinely carried out without use of a local HM, but using remote synchronization via a stabilized, long-distance fibre-optic link. The T&F reference signals, traceable to international atomic timescale (TAI), are delivered to the VLBI station from a dedicated timekeeping laboratory. Moreover, we describe a proof-of-concept experiment where the VLBI station is synchronized to a remote strontium optical lattice clock during the observation.Comment: 8 pages, 8 figures, matches the version published in A&A, section Astronomical instrumentatio

Energy efficiency considerations in integrated IT and optical network resilient infrastructures

The European Integrated Project GEYSERS - Generalised Architecture for Dynamic Infrastructure Services - is concentrating on infrastructures incorporating integrated optical network and IT resources in support of the Future Internet with special emphasis on cloud computing. More specifically GEYSERS proposes the concept of Virtual Infrastructures over one or more interconnected Physical Infrastructures comprising both network and IT resources. Taking into consideration the energy consumption levels associated with the ICT today and the expansion of the Internet in size and complexity, that incurring increased energy consumption of both IT and network resources, energy efficient infrastructure design becomes critical. To address this need, in the framework of GEYSERS, we propose energy efficient design of infrastructures incorporating integrated optical network and IT resources, supporting resilient end-to-end services. Our modeling results quantify significant energy savings of the proposed solution by jointly optimizing the allocation of both network and IT resources

PHOSPHORUS: Single-step on-demand services across multi-domain networks for e-science - art. no. 67842X

The Phosphorus(1,2) project focuses on delivering advanced network services to Grid users and applications interconnected by heterogeneous infrastructures. The project is addressing some of the key technical challenges to enable on-demand end-to-end network services across multiple domains. The Phosphorus network concept makes applications aware of their complete Grid resources environment-computational and networking- and its capabilities. Phosphorus enables and tests dynamic adaptive and optimised use of the heterogeneous network infrastructure interconnecting various high-end resources. The project will demonstrate on-demand service delivery across access-independent multi-domain/multi-vendor research network test-beds on a European and worldwide scope. Phosphorus enhances and demonstrates solutions that facilitate vertical and horizontal communication among applications middleware and the network resources across different domains, managed by existing Network Resource Provisioning Systems (NRPS), or domains that integrate a new Grid-GMPLS (G(2)MPLS) Control Plane, both under a new AAA architecture to support policy based on-demand network resource provisioning. This G(2)MPLS extends ASON/GMPLS in order to provide part of the fanctionalities related to the selection, co-allocation and maintenance of both Grid and network resources, by exposing upgraded interfaces at the UNI and E-NNI network reference points -i.e. G.OUNI and G.E-NNI-. The project outcomes are going to be demonstrated in a worldwide test-bed

PHOSPHORUS: Single-step

on-demand services across multi-domain networks for e-scienc