Ahmed Triki

Scalable routing, scheduling and virtualization for TWIN optical burst switching networks

We propose a comprehensive scalable algorithm simultaneously assessing the routing, scheduling and virtualization in Time-Domain Wavelength Interleaved Network (TWIN). TWIN is an energy-efficient optical burst switching technology for metropolitan area and data center intra- and interconnections, with destinations using separate allocated sets of wavelengths for the reception. Given the costs of the optical transponders and the wavelength use per km of fiber length, the proposed algorithm solves the routing and wavelength assignment problem, and in the same time allocates the time slots to traffic flows (performs the slot scheduling), so that the total network cost is minimized. The algorithm also enables the construction of overlayed virtual networking domains at minimum cost, which share the transponders and network links, and can employ different scheduling policies. The performance of the algorithm is compared with the pre-existing optimal dimensioning solution for single virtualization domain based on Integer Linear Programing, for different scenarios. The obtained results show that the network cost is within 27% of the optimal.

CAPEX and OPEX saving in SDN-compliant sub-wavelength switching solution

The present paper attempts to answer the question ”is it worth implementing dynamic resource allocation in a metropolitan network ?”. Our study evaluates the gain (CAPEX and OPEX) to expect in a Time-Domain Wavelength Interleaved Network (TWIN) when the number of active Tx/Rx changes, over the day, according to the traffic matrix. We assume that TWIN is implemented in an SDN framework in which burst emission schedules can be periodically recomputed thus taking into account traffic matrix changes. A comparative study is carried out to assess, for different values of the computation period, the OPEX and CAPEX savings on the basis of the number of active Tx/Rx. Results show that such a dynamic network reconfiguration approach can bring some CAPEX savings and more significant OPEX savings in a realistic metropolitan network scenario, even for rather large configuration periods.

First experimental demonstration of real-time orchestration in a Multi-head metro network

We present for the first time the experimental demonstration of a Real-Time control-plane on the Multi-hEad sub-wavElength swiTching (MEET), Metro architecture. The key control assets are calculated and provided to the edge nodes in a form of grant files. These grant files eliminate the contention possibility at source nodes and destinations, thus they offer a lossless passive optical grooming and multiplexing/demultiplexing at the intermediate nodes. The experimental results validate the control plane structure designed based on a deterministic operating system well scalable for a regional metro network.

Carrier-grade performance evaluation in reliable metro networks based on optical packet switching

In this paper we assess the performance delivered in a metro network by two optical packet switching architectures, enabling sub-wavelength switching granularity. We compare POADM (Packet Optical Add/Drop Multiplexer) with TWIN (Time-domain Wavelength Interleaved Network). These technologies are envisaged to be deployed in the metropolitan area in order to improve bandwidth utilization and minimize energy consumption, thanks to their excellent switching granularity. In order to perform a realistic performance assessment, the study was carried out over a large set of traffic demands, for which the candidate architectures were first dimensioned taking into account network reliability. Then, the delivered data plane performance was assessed by simulation in terms of electronic packet loss, jitter and insertion delay. Two routing scenarios (any-to-any and hub-and-spoke) are mapped on a physical topology inspired from a European operator network. Simulation results show that both architectures easily achieve performance targets set by the Metro Ethernet Forum, as long as the network is properly dimensioned.

Adapting the EPON MAC protocol to a metropolitan burst switching network

This paper compares the respective efficiencies of the control and the management planes in performing resource allocation for TWIN (Time-domain Wavelength Interleaved Networking) optical networks used to aggregate and distribute traffic within a metropolitan area. While the Management Plane driven MAC (MP-MAC) protocol is based on an quasi-static configuration derived from optimization model, the Control Plane driven MAC (CP-MAC) protocol is based on adapting Passive Optical Network (PON) upstream traffic control, originally designed to access network, to the metropolitan network. The performance levels delivered by both approaches are compared by simulating a TWIN network applied to a Multi-hEad sub-wavElength swiTching (MEET) architecture that ensures an all optical aggregation between the regional metropolitan and the core networks. The simulation assesses the QoS delivered to three different classes of service, for a packet level traffic trace obtained from an operational network.

TWIN as a future-proof optical transport technology for next generation metro networks

The continuous growth of the traffic at a rapid pace raises challenges related to the efficient use of resources and saving of energy in the transport network. The new traffic pattern is characterized by faster growth of metro traffic compared with core, due in part to video content replication. In this paper, we compare the resource requirements of three different transport technologies (optical packet switching, opaque circuit switching and transparent circuit switching) within two architecture scenarios (the current hub-and-spoke architecture and the next generation distributed architecture). The comparison study takes into consideration the predicted traffic growth from 2014 to 2019 and the potential traffic decentralization due to content replication. For the optical packet switching, we focus on Time-domain Wavelength Interleaved Network (TWIN) solution which achieves passive switching at the intermediate nodes thanks to the precomputed optical packet emission schedule. Results show that TWIN outperforms the other transport technologies in terms of number of transmitters and receivers with a high ability to cope with scalability issues.