Raimena Veisllari

Scalability analysis of SDN-controlled optical ring MAN with hybrid traffic

The development of software defined networking (SDN) has instigated a growing number of experimental studies which demonstrate the flexibility in network control and management introduced by this technique. Optical networks add new challenges for network designers and operators to successfully dimension and deploy an SDN-based in the optical domain. At present, few performance evaluations and scalability studies that consider the high-bandwidth of the optical domain and the flow characterization from current Internet statistics have been developed. In this paper these parameters are taken as key inputs to study SDN scalability in the optical domain. As a relevant example an optical ring Metropolitan Area Network (MAN) is analyzed with circuit and packet traffic integrated at the wavelength level. The numerical results characterize the limitations in network dimensioning when considering an SDN controller implementation in the presence of different flow mixes. Employing flow aggregation and/or parallel distributed controllers is outlined as potential solution to achieve SDN network scalability.

Field-trial demonstration of cost efficient sub-wavelength service through integrated packet/circuit hybrid network [invited]

Carriers are under constant pressure to meet the ever-increasing bandwidth demand while reducing cost per bit, enhancing network throughput, and offering a large variety of services. Hybrid packet and circuit network technologies are being widely investigated and considered as a solution for offering both the high network throughput of the packet domain and wavelength services, i.e., a low fixed latency and zero packet loss. To enable carriers to serve a higher number of customers requiring wavelength services, optical transport network (OTN)-based sub-wavelength switching is adopted to support finer granularity with similar performance to full wavelength services. However, OTN is not able to perform statistical multiplexing and achieve the throughput efficiency of packet networks. In this work an integrated hybrid optical network field-trial is described to demonstrate the ability to both aggregate and transport sub-wavelength circuits, and offer high throughput efficiency by statistically multiplexing traffic on transport wavelengths. Results show the transport of sub-wavelength services with packet-delay variation limited to only 15 ns and 82.4% wavelength utilization using statistical multiplexing.

Integrated packet/circuit hybrid network field-trial

We report the first field-trial of an integrated packet/circuit hybrid optical network. Bypassing routers with circuit quality of service and network throughput of 99% is demonstrated on a shared packet/circuit layer lightpath.

Integrated packet/circuit hybrid network field trial with production traffic [invited]

We report the first field trials of an integrated packet/circuit hybrid optical network. In a long-haul field trial with production traffic, the mean capacity utilization of an Ethernet wavelength is doubled. The transport shares a single lightpath between the circuit and packet layers. Router bypassing is demonstrated at sub-wavelength granularity in a metro network field trial. In both trials the circuit quality of service is shown to be independent of the load of the network. The vacant resources in the circuit are utilized by the packet layers statistical multiplexing in an interleaved manner without affecting the timing of the circuit. Inaddition, an analytical model that provides an upper bound on the maximum achievable utilization is presented.

Scheduling techniques in an integrated hybrid node with electronic buffers

Integrated hybrid optical packet/circuit switched architectures enable networks with the guaranteed service transport (GST) of circuit switching and the statistical multiplexing known from packet switching. The utilization of the optical lightpaths is increased by inserting low priority statistically multiplexed (SM) traffic in the guaranteed circuit switched traffic gaps. Previous studies of these nodes have used optical packet switches together with reservation techniques to minimize the SM packet losses while giving absolute priority to circuit switched traffic. In this paper we propose a novel scheduling technique that applies electronic buffers and multiple queues to find a suitable SM packet to fit in a GST gap. Additionally, two schemes of managing the output buffer are introduced, the dedicated queue per input and the length-aware buffering. Simulation results demonstrate that their combination significantly increases the utilization of the available capacity and the maximum rate of SM traffic inserted in the network.

Integrated packet/circuit hybrid network field-trial demonstrating sub-wavelength aggregation

We report aggregation of sub-wavelengths in an integrated packet/circuit hybrid optical network. Aggregation of packet streams with circuit quality of service combined with statistical multiplexing enables packet delay variation of only 15ns at 82.4% throughput.

Long-haul Ethernet-transport integrated packet/circuit hybrid network field-trial

In the first integrated packet/circuit hybrid network field-trial with production traffic, the mean capacity utilization of an Ethernet wavelength during a 24h period is doubled without timing-impact on the wavelength traffic.

A rate-adaptive segmentation algorithm for integrated hybrid optical networks

Integrated hybrid optical networks (IHON) add statistically multiplexed (SM) packet traffic to increase the utilization of the wavelength channels dedicated to optical circuit switched traffic. SM packets are inserted in the variable sized free gaps in-between circuit switched packets. Some packets are too large for fitting in a specific gap, hence the utilization of the gaps decides the achievable throughput efficiency of the network. Segmenting SM packets, allowing also small gaps to be exploited, comes with the cost of adding extra processing and segmentation overhead. Hence, the number of segmented packets should therefore be minimized. In this paper we propose a novel rate-adaptive segmentation scheme (RAS), increasing the gap utilization while minimizing the number of segmented packets. The algorithm dynamically adapts the SM packet length pattern to fill the fragmented bandwidth and increase the throughput. Simulation results show that the scheme heightens the utilization from 73% to 89%. Furthermore, we propose a bounded delay scheme that minimizes the delay and bounds the jitter by droppings old head-of-line packets reducing packet loss ratio by 3%.

Employing ethernet spanning tree protocols in an integrated hybrid optical network

Hybrid optical packet/circuit switched networking architectures combine the high resource utilization of statistically multiplexed packet switched networks with the circuit switched networks low processing requirements and guaranteed quality of service. Ethernet is emerging as one of the most important standards for the metro and core part of the network. This is motivated by cost-efficiency, and a significant effort from operators and system manufactures has been put into Ethernet standardization and research. While Ethernet relies on a loop-free topology, integrated hybrid networks offers multiple redundant paths enabling loops in the network. In this paper, we study how Ethernets loop-free topology protocols can be compatible with the redundant paths of an integrated hybrid network, such as OpMiGua. We analyse challenges and limitations of the network architecture. Based on this, we propose a viable loop-free approach through a novel topology solution called the SM chain-connectivity. By emulating Ethernet switches in a logical OpMiGua infrastructure, we confirm the results from our analysis.

Sub-wavelength granularity add/drop experiment in an integrated packet/circuit hybrid optical network

Add/drop with sub-wavelength granularity is demonstrated in an integrated hybrid optical network Ethernet test-bed. Ultra-low packet delay variation (PDV), 300ns peak, is achieved for high wavelength utilization of 88% using additional statistical multiplexing.