Design and experimental demonstration of a variable-length optical packet routing system with unified contention resolution

This paper presents theoretical design, network simulation, implementation, and experimental studies of optical packet routing systems supporting variable-length packets. The optical packet switching network exploits unified contention resolution in core routers in three optical domains (wavelength, time, and space) and in edge routers by traffic shaping. The optical router controller and lookup table, implemented in a field-programmable gate array (FPGA), effectively incorporates the contention resolution scheme with pipelined arbitration of asynchronously arriving variable-length packets. In addition, real-time performance monitoring based on the strong correlation between the bit-error rates of the optical label and those of the data payload indicates its application in optical time-to-live detection for loop mitigations. Successful systems integration resulted in experimental demonstration of the all-optical packet switching system with contention resolution for variable-size packets.     

Advanced Subcarrier Multiplexed Label Swapping in Optical Packet Switching Nodes for Next Generation Internet Networks

This paper presents the recent achievements and main results of the optical packet switching node with label swapping capabilities that was developed in the framework of the IST-LABELS project. The implemented functionalities allows the routing and forwarding of optical packets at 10 Gb/s based on the information conveyed in the 18 GHz-subcarrier multiplexed (SCM) label at 155 Mb/s. Specific functions of the optical packet switching demonstrator such as label extraction and rewriting are based on high-performance fiber Bragg grating filters (FBG) whereas semiconductor optical amplifier (SOA) based wavelength conversion allows payload 2R regeneration. Advanced aspects implemented in the high speed electronic control unit such as traffic shaping, multicast, and for the first time to our knowledge, a contention resolution algorithm with priority processing are thoroughly described in this paper. This paper also presents simulations exploring the effect of these advanced features in the global performance of an optical packet switched network. In particular, we found that the contention resolution algorithm based on parallel converters with 16 wavelengths contributes to improve up to four orders of magnitude the packet loss rate for low traffic loads whereas the improvement from traffic shaping policies was of 1 order of magnitude for both low and medium traffic loads. Along with the experimental results, the feasibility of the approach as the basis for the next generation internet networks is demonstrated.     

High-performance optical-label switching packet routers and smart edge routers for the next-generation Internet

This paper discusses the architecture, protocol, analysis, and experimentation of optical packet switching routers incorporating optical-label switching (OLS) technologies and electronic edge routers with traffic shaping capabilities. The core optical router incorporates all-optical switching with contention resolution in wavelength, time, and space domains. It is also capable of accommodating traffic of any protocol and format, and supports packet, flow, burst, and circuit traffic. The edge router is designed to achieve traffic shaping with consideration for quality of service and priority based class-of-service. Simulation results show packet loss rates below 0.3% at load 0.7 and jitter values below 18 /spl mu/s. The traffic shaping reduces the packet loss rate by a factor of /spl sim/5 while adding negligible additional latency. The OLS core routers and the electronic edge routers are constructed including the field-programmable-gate-arrays incorporating the wavelength-aware forwarding and contention resolution algorithms. The experiment shows optical-label-based packet switching with a packet loss rate near 0.2%.     

End-to-end contention resolution schemes for an optical packet switching network with enhanced edge routers

This paper investigates contention resolution schemes for optical packet switching networks from an end-to-end perspective, where the combined exploitation of both core routers and edge routers are highlighted. For the optical-core network, we present the architecture of an optical router to achieve contention resolution in wavelength, time, and space domains. Complementing the solution involving only the core router intelligences, we propose performance enhancement schemes at the network edge, including a traffic-shaping function at the ingress edge and a proper dimensioning of the drop port number at the egress edge. Both schemes prove effective in reducing networkwide packet-loss rates. In particular, scalability performance simulations demonstrate that a considerably low packet-loss rate (0.0001% at load 0.6) is achieved in a 16-wavelength network by incorporating the performance enhancement schemes at the edge with the contention resolution schemes in the core. Further, we develop an field-programmable gate-array (FPGA)-based switch controller and integrate it with enabling optical devices to demonstrate the packet-by-packet contention resolution. Proof-of-principle experiments involving the prototype core router achieve an error-free low-latency contention resolution.     

Optical Packet and Burst Switching Technologies for the Future Photonic Internet

This paper reviews advanced optical burst switching (OBS) and optical packet switching (OPS) technologies and discusses their roles in the future photonic Internet. Discussions include optoelectronic and optical systems technologies as well as systems integration into viable network elements (OBS and OPS routers). Optical label switching (OLS) offers a unified multiple-service platform with effective and agile utilization of the available optical bandwidth in support of voice, data, and multimedia services on the Internet Protocol. In particular, OLS routers with wavelength routing switching fabrics and parallel optical labeling allow forwarding of asynchronously arriving variable-length packets, bursts, and circuits. By exploiting contention resolution in wavelength, time, and space domains, the OLS routers can achieve high throughput without resorting to a store-and-forward method associated with large buffer requirements. Testbed demonstrations employing OLS edge routers show high-performance networking in support of multimedia and data communications applications over the photonic Internet with optical packets and bursts switched directly at the optical layer     

A Data Burst Assembly Algorithm in Optical Burst Switching Networks

Presently, optical burst switching (OBS) technology is under study as a promising solution for the backbone of the optical Internet in the near future because OBS eliminates the optical buffer problem at the switching node with the help of no optical/electro/optical conversion and guarantees class of service without any buffering. To implement the OBS network, there are a lot of challenging issues to be solved. The edge router, burst offset time management, and burst assembly mechanism are critical issues. In addition, the core router needs data burst and control header packet scheduling, a protection and restoration mechanism, and a contention resolution scheme. In this paper, we focus on the burst assembly mechanism. We present a novel data burst generation algorithm that uses hysteresis characteristics in the queueing model for the ingress edge node in optical burst switching networks. Simulation with Poisson and self‐similar traffic models shows that this algorithm adaptively changes the data burst size according to the offered load and offers high average data burst utilization with a lower timer operation. It also reduces the possibility of a continuous blocking problem in the bandwidth reservation request, limits the maximum queueing delay, and minimizes the required burst size by lifting up data burst utilization for bursty input IP traffic.     

Performance of two-stage shared fiber delay line optical packet switch under bursty traffic

Packet contention is a major issue in an optical packet switching network. It is not a trivial task to resolve contention due to lack of optical RAM technology. This article proposes a two-stage shared fiber delay line (FDL) optical packet switch for contention resolution. In this article, shared FDLs are used to buffer optical packets, in which a pool of buffer memory is shared among all switch output ports. Most of the existing optical buffering schemes are output-based which require a huge number of FDLs as well as a larger switch size that incur extra implementation cost. However, a shared buffering approach is considered in this article in order to reduce implementation cost. In this article, FDLs are implemented in two stages using an extremely simple auxiliary switch. The proposed switch architecture leads to more efficient use of buffer space. The superiority of the proposed switch architecture has been established by means of extensive simulations. The performance of the proposed switch is investigated under bursty traffic. Simulation result shows that the proposed switch can achieve satisfactory performance at the price of a reasonable amount of FDLs. Moreover, the significance of the proposed switch is confirmed by simulation.     

High-Performance Hybrid-Switching Optical Router for IP over WDM Integration

Because pure electrical routers with their bandwidth limitations can hardly keep up with the tremendous traffic growth in the Internet, optical routers based on various optical switching techniques including optical wavelength switching (OWS), optical burst switching (OBS), and optical packet switching (OPS) have been suggested to cope with this problem. However, because OBS and OPS are both in their early experimental phase and OWS only provides coarse granularity switching, a hybrid-switching optical router with combined OWS and electrical packet switching is a necessity in order to accommodate the entire multi-granularity traffic with multi-service requirements in a cost-effective manner. Its coordination capability of optical circuit switching and electrical packet switching enables efficient/intelligent usage of network resources. In this paper, we first review research and developments of such IP routers employing optical switching/interconnection techniques and examine how these techniques can be used inside routers to scale node capacity and to improve optical Internet performance. We also present and study the performance of a terabit optical router with an optical-electrical hybrid-switching fabric. The node architecture is based on the idea of IP over WDM integration with Generalized Multi-Protocol Label Switching (GMPLS). The network-level performance evaluations show that the proposed hybrid-switching optical router is a cost-effective solution for building the next generation GMPLS-based multi-granularity optical Internet.     

A novel IP with MPLS over WDM-based broad-band wavelength switchedIP network

This paper presents a new technology for constructing IP over photonic systems. An IP with multiprotocol label switching (MPLS) over wavelength division multiplexing (WDM)-based broad-band IP network architecture and protocol is proposed and analyzed in this paper, which supports variable-length IP-like optical packet label switching and optical virtual path routing. This system tries to merge into one layer the functionalities of the wavelength switching, SONET mux/demux, and IP routing, and is sometimes known as the concept of optical MPLS. The label banding, forwarding/switching process, and node architecture of the proposed network are discussed and studied. A unique as well as important function of a lambda/label edge router (LER) is a flow assembly device that can encompass MPLS' forward equivalence classes, label stacking, and label switching path aggregation function. At the same time, a particular function of the core label switching router is wavelength merging. A fiber delay line is used to delay the data stream in order to process the label information and resolve contention. Transmission bit error rate measurements of the baseband data stream and back-to-back is also demonstrated to show its feasibility     

An optical packet contention resolution supporting QoS differentiation with LRWC wavelength converters for OPS

The wavelength conversion is regarded as an effective way to resolve the optical packet contention in the wavelength domain for optical packet switching. An optical packet switching node, based on shared-per-node equipped with limited range wavelength converters and parametric wavelength converters (SPN-LP), is designed to further reduce optical packet loss probability. A novel optical packet contention resolution with priority differentiation wavelength scheduling algorithm to support quality of service (QoS) for the SPN-LP architecture is put forward in the article. The simulation results show that proposed optical packet resolution enables a good QoS differentiation, namely the high priority contending optical packet has the sufficient low packet loss probability.     

基于标签的光突发交换网络

先进的OBS(optical burst switching)技术和MPLS的强大控制能力结合产生了一种灵活紧凑的IP/DWDM集成模型LOBS.(labeled optical burst switching).它充分发挥了电子处理的高智能和光子交换的大容量优势,是未来数据网络的理想光交换方案.文中从OBS技术的优越性开始,分析了LOBS实现的网络结构和控制协议,探讨了LOBS流量工程和网络生存性.     

On-the-Fly All-Optical Contention Resolution for NRZ and RZ Data Formats Using Packet Envelope Detection and Integrated Optical Switches

We present a packet-by-packet contention resolution scheme that combines packet detection, optical space switching, and wavelength conversion performed in the optical domain by integrated optical switches. The packet detection circuit provides the control signals required to deflect and wavelength-convert the contending packets so that all the packets are forwarded to the same output without any collision or packet droppings. We demonstrate the compatibility of the scheme with both nonreturn-to-zero (NRZ) and return-to-zero (RZ) modulation formats by recording error-free operation for 10-Gb/s NRZ and 40-Gb/s RZ packet-mode traffic     

未来光因特网中的光交换方式及其发展趋势

Internet的业务流量正以每六个月翻一番的速度快速增长,未来网络中,数据业务超过话音业务只是时间问题,因此,基于电路交换的电信网升级到支持基于分组交换的数据业务是不可避免的,但是对因特网来说,由于光逻辑与光存储等器件不成熟,发展全光分组交换,技术上异常困难。另一方面,近来新提出的光突发交换,技术上相对简单,性能特点优异,因而成为更理想的选择,本文介绍了全光分组交换和光突发交换的研究现状,比较了两者的优缺点,最后指出改进光突发交换性能的两种方式。     

Multiservice optical network: main concepts and first achievementsof the ROM program

With the tremendous introduction of internet protocol (IP) applications, the quality-of-service (QoS) becomes more and more an emergent issue. Concrete solutions can be adopted (IP/ATM/SONET/WDM) opening the way to new types of applications (interactive applications through the exploitation of voice and video) in a short-term approach. However, all the telecommunication community tries to provide new solutions offering capacity and flexibility in a simpler manner. In this paper, we present the concepts of a multiservice optical network studied in the framework of a French Research Program. The QoS could be offered through the combined exploitation of electronic memories in the edges and optical resources in the core of the optical network and through the coexistence of different types of connections. In particular, the traffic shaping in the edges is highlighted through simulation and demonstrates the real impact of this function to maintain the logical performance at its highest level. To propose concrete solutions for its implementation, two network scenarios are proposed. The first one, for the backbone, exhibits a novel optical packet switching architecture taking benefit of the massive presence of wavelengths to solve the contention. The second one, for the metro, shows a second optical packet switching architecture really adapted to the cost constraints (upgradability, compactness, granularity)     

Optical CDMA for All-Optical Sub-Wavelength Switching in Core GMPLS Networks

Generalized multi-protocol label switching (GMPLS) is a multipurpose control-plane paradigm that extends the MPLS scheme allowing switching without recognizing packet boundaries. In this paper, we present a novel extension that exploits a new physical layer for switching in optical GMPLS. The proposed extension is achieved through adding an optical code switching layer, or code switch capable (CSC) layer, to the existing label mapping layers. Our proposal enables finer granularity at sub-wavelength level in all-optical GMPLS core switches, resulting in significant enhancements to traffic isolation capabilities for all-optical GMPLS core switches. We employ mathematical analysis to derive performance bounds for the proposed scheme, from both the labeling capacity and network throughput points of view. We use our analytical model to derive several optimum operating points for the network, and show that our techniques significantly improve the overall performance of all-optical core networks     

Demonstration of the highly reliable Hikari router network based on a newly developed disjoint path selection scheme

Integration of multiprotocol label switching functions and multiprotocol lambda switching functions can enhance the throughput of IP networks and remove bottlenecks that are derived from electrical packet processing. To enhance the packet forwarding capability, NTT proposed a photonic MPLS concept that includes MP/spl lambda/S, and demonstrated IP, MPLS, and photonic MPLS integrated router systems called the photonic MPLS router. This router system is now called the Hikari router. The word Hikari is Japanese meaning beam, light, lightwave, optical, photonic, and sunshine. The amount of IP data traffic has grown remarkably. Massive IP routers and flexible route control mechanisms are now required to cope with the increased amount of traffic. The Hikari router can offer two solutions utilizing photonic switching technologies, and photonic network operation and management technologies. The first solution is utilizing photonic switching technologies realized using optical-switch-based crossconnect systems. The other solution is realized using the MPLS and MP/spl lambda/S signaling protocol and photonic network protection functions. In this article we report on the implementation of the Hikari router systems, propose a newly developed disjoint path selection scheme for generalized MPLS networks with shared risk link group constraints, and demonstrate the signaling protocol and network protection functions. The demonstration system achieves a distributed optical path set-up/tear-down protocol with an extended constraint-based routing label distribution protocol. Fast self-healing through automatic protection switching and a new restoration scheme are also implemented. These functions are successfully implemented, and the performance is verified on a demonstration network. The protection switching scheme achieves protection in less than 20 ms, and the optical path restoration scheme achieves restoration in less than 500 ms.     

SEAL2: An SDN‐enabled all‐Layer2 packet forwarding network architecture for multitenant datacenter networks

This paper presents the design and development of a new network virtualization scheme to support multitenant datacenter networking (MT‐DCN) based on software‐defined networking (SDN) technologies. Effective multitenancy supports are essential and challenging for datacenter networking designs. In this study, we propose a new network virtualization architecture framework for efficient packet forwarding in MT‐DCN. Traditionally, an internet host uses IP addresses for both host identification and location information, which causes mobile IP problems whenever the host is moved from one IP subnet to another. Unfortunately, virtual machine (VM) mobility is inevitable for cloud computing in datacenters for reasons such as server consolidation and network traffic flow optimization. To solve the problems, we decouple VM identification and location information with two independent values neither by IP addresses. We redefine the semantics of Ethernet MAC address to embed tenant ID information to the MAC address field without violating its original functionality. We also replace traditional Layer2/Layer3 two‐stage routing schemes (MAC/IP) with an all‐Layer2 packet forwarding mechanism that combines MAC addresses (for VM identification and forwarding in local server groups under an edge switch gateway) and multiprotocol label switching (MPLS) labels (for packet transportation between edge switch gateways across the core label switching network connecting all the edge gateways). To accommodate conventional IP packet architecture in a multitenant environment, SDN (OpenFlow) technology is used to handle all this complex network traffics. We verified the design concepts by a simple system prototype in which all the major system components were implemented. Based on the prototype system, we evaluated packet forwarding efficiency under the proposed network architecture and compared it with conventional IP subnet routing approaches. We also evaluated the incurred packet processing overhead caused by each of the packet routing components.     

A novel architecture of optical code label generation and recognition for optical packet switching

A novel architecture of optical code (OC) label generation and recognition for optical packet switching (OPS) by using super structured fiber Bragg grating (SSFBG) is proposed.The OC label is generated and recognized by a label generator and recognizer,respectively.The label generator is composed of N encoders in parallel,and it can generate 2N kinds of serial optical code labels (SOCLs) for indicating 2N network routing information.The label recognizer can decode SOCLs by N decoders in parallel and provides label information to the switching control unit so that clock information is not required during the decoding process.In the switch nodes,handling of the high-speed information payload stream and the recognition of the OC label are performed in the optical domain,while processing of the routing information remains in the electrical domain.This approach could be a promising solution for an OPS network with high capacity,good quality of service (QoS),multi-service function and high security.In this experiment,we demonstrate 40Gbps 256 label optical packet switching that employs clockless SOCL processing.     

Analytical MMAP-Based Bounds for Packet Loss in Optical Packet Switching with Recirculating FDL Buffers

The major goal of optical packet switching (OPS) is to match switching technology to the huge capacities provided by (D)WDM. A crucial issue in packet switched networks is the avoidance of packet losses stemming from contention. In OPS, contention can be solved using a combination of exploitation of the wavelength domain (through wavelength conversion) and buffering. To provide optical buffering, fiber delay lines (FDLs) are used. In this paper, we focus on an optical packet switch with recirculating FDL buffers and wavelength converters. We introduce the Markovian arrival process with marked transitions (MMAP), which has very desirable properties as a traffic model for OPS performance assessment. Using this model, we determine lower and upper bounds for the packet loss rate (PLR) achieved by the aforementioned switch. The calculation of the PLR bounds through matrix analytical methods is repeated for a wide range of traffic conditions, including highly non-uniform traffic, both in space (i.e., packet destinations) and time (bursty traffic). The quality of these bounds is verified through comparison with simulation results.     

Evaluation of packet scheduling in hybrid optical/electrical switch

This paper presents a hybrid optical/electrical switch for high-capacity future network development. A switch architecture to provide packet switching by solving contention in wavelength and time domains is considered relying on available optical and electrical technology. Physical and logical aspects regarding switch feasibility and management, in relation to the hybrid nature of the switch, are addressed. Scheduling algorithms to support multi-service packet forwarding are compared with optimally exploit optical and electrical subsystems according to traffic characteristics and needs. The main outcomes of the paper suggest criteria to design high-capacity packet switches, based on present-day technology constraints and quality of service requirements, to achieve a fair balance between optical transparency and loss performance.