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Photonic Networks, 2010 ITG Symposium on

Date 3-4 May 2010

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Displaying Results 1 - 25 of 30
  • A Multiperiod Expectation Model for Capital Expenditures in Optical Networks: Applicability and Limitations

    Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (381 KB)  

    We study a multiperiod expectation model which estimates capital expenditures of optical networks. Compared to cost optimization methods the expectation model speeds calculation times considerably up. However, for lightly loaded networks costs are underestimated by up to 44% compared to optimization. Albeit for multiperiod planning the expectation model leads to comparable overall capital expenditures, in some cases it hides the temporal costs allocations. Thus, for detailed multiperiod studies the use of optimization methods is recommended. View full abstract»

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  • Optical phase-sensitive sampling for high fidelity capture of advanced, high baud-rate optical waveforms and signals

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1649 KB)  

    We discuss all-optical sampling techniques to capture optical waveforms with both high fidelity and time resolution. Different approaches are possible, each with associated performance¿complexity trade-offs. We cover not only sampling of intensity waveforms but also complex modulation formats such as QPSK and 16-QAM and also discuss the distinctions between real-time sampling and equivalent-time sampling. View full abstract»

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  • In-band OSNR Measurement based on Spectral Correlation

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1424 KB)  

    The in-band optical signal-to-noise ratio (OSNR) is a fundamental performance metric for WDM transmission systems. This paper presents a new approach for measuring the in-band OSNR which is based on the fact that synchronous data signals with a fixed symbol rate 1/T and the channel noise have different correlation properties. View full abstract»

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  • Low-Complexity Optical FFT Scheme Enabling Tbit/s All-Optical OFDM Communication

    Page(s): 1 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2334 KB)  

    A practical scheme to perform the fast Fourier transform in the optical domain is introduced. Optical real-time FFT signal processing is done at speeds far beyond the limits of electronic digital processing, and at a negligible energy expenditure. To illustrate the power of the method we demonstrate an optical 400 Gbit/s OFDM receiver. It performs an optical real-time FFT on the consolidated OFDM data stream, thereby demultiplexing the signal into lower bit rate subcarrier tributaries, which can then be processed electronically. View full abstract»

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  • Implementation of an IFFT for an Optical OFDM Transmitter with 12.1 Gbit/s

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (739 KB)  

    This paper describes the design of an inverse discrete Fourier transform (IDFT) for an optical orthogonal frequency division multiplexing (O-OFDM) transmitter for a bitrate of 12.1Gbit/s. The complete transmitter was implemented on a Virtex 5 FX200T field programmable gate array (FPGA) from Xilinx. The main part of the transmitter, which needs the most signal processing hardware resources, is the IDFT. A 256-point radix-2 inverse fast Fourier transform (IFFT) was implemented. View full abstract»

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  • Soft-FEC Implementation for High-Speed Coherent Optical OFDM Systems

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1489 KB)  

    Nowadays one of the discussed solutions for optical transmission systems at 100 Gbit/s (N x 100 Gbit/s) and beyond is coherent optical orthogonal frequency division multiplexing (CO-OFDM). Commonly hard-decision forward error correction (FEC) with the redundancy of 7% is assumed. Recently the improvement of the receiver sensitivity was analyzed by using a low density parity check (LDPC) code that is one of the promising candidates for 100 Gbit/s soft-FEC. In this work we assess the efficiency and investigate the implementation of soft-FEC with LDPC codes with overheads between 7% and 50% in coherent optical OFDM systems. View full abstract»

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  • Towards a Security Architecture of IP-Based Optical Transmission and Cross-Connect Systems

    Page(s): 1 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (992 KB)  

    Optical transmission and cross-connect systems form the backbone of today¿s telecommunication infrastructure. While such systems were based upon proprietary technology in the past, embedded Linux and the Internet Protocol are widely used today. Because of their central role within the telecommunication infrastructure and their extensive remote management capabilities, such high-capacity network nodes are likely targets of attacks. In this paper, we first look at adversaries and their motivation as well as their capabilities for running an attack, thereby establishing a threat model for transmission network nodes. Based upon functional models, we present security requirements for components and their interconnections with respect to the threat model, thereby forming a security architecture for optical transmission systems. As integral part of the security architecture, we propose security zones to strictly separate sensitive internal com-munication from traffic originating from, or destined to, external endpoints. View full abstract»

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  • Topology Analysis of the Access/Aggregation Network Structure in Future Optical Access Networks

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1637 KB)  

    Increasing demand for higher bitrates in access networks requires fiber deployment closer to the customer as bitrates in copper based access networks are strictly limited essentially by the length of the copper cables. Besides enabling higher access bitrates optical access network technologies will also enable a change in the structure of the access/aggregation network segment due to the superior transmission characteristics of optical fibers: Larger service areas and a decreased overall number of access sites are feasible. Concentration of active network equipment in a fewer number of access site is expected to help to reduce the total cost of ownership of the whole network due to concentration effects and OpEx savings. In this paper we present results of a topology related network study investigating feasible network structures in next generation optical access networks. Starting from the structure of copper based access networks in Germany, traditional service areas are clustered to larger entities. We distinguish between different levels of access network concentration leading to various scenarios relying on a different number of required metro access nodes. A exemplary set of reference service areas is identified representing the majority of all service areas within a certain category and typical characteristics of the reference service areas are given. From the results of the topological analysis some requirements with respect to next generation optical access systems are derived. View full abstract»

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  • Machbarkeit kohÿrenter Einfaser-UDWM PONs mit 1000 Teilnehmern und 100 km Reichweite

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (610 KB)  

    Coherent UDWDM PONs establish virtual point to point links seperated by the wavelength and without need for TDM. Because of the high receiver sensitivity they clearly outclass TDM or TDM/WDM based PONs in view of flexibility, reach, splitting factor and management complexity. The talk deals with some physical problems and their mitigation in single fiber PONs e. g. backscattering and backreflections into the receiver, channel selectivity and properties of the network. View full abstract»

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  • Next-Generation Access based on WDM/TDM Solutions

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (470 KB)  

    This paper investigates Next-Generation Access for a given deployment scenario. Near-term hybrid WDM/TDM solutions for long reach and high subscriber count at high bandwidth are considered. Capital expenditures, energy cost, and duct cost are derived, and the systems cost of different partly passive solutions is analyzed. Finally, requirements on feeder fibers are discussed. View full abstract»

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  • Digital Signal Processing Schemes for Enabling Gigabit Transmission over Polymer Optical Fibre

    Page(s): 1 - 3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    In applications like automotive infotainment systems, industrial automation, as well as home networking, the step-index polymer optical fibre is used as a robust and low-cost transmission medium for 100 Mbit/s transmission. In order to overcome the limited bandwidth of both the transmitter LED and the fibre, different advanced modulation, equalization, and coding schemes are considered for next generation Gigabit Ethernet systems over SI-POF. As opposed to copper-based or wireless systems, the optical intensity modulated channel with direct detection (IM/DD) is peak-power limited. It is shown that this property has an important impact on the choice of the optimum modulation and coding schemes. An analytical comparison of multilevel pulse-amplitude modulation and discrete multitone is presented. View full abstract»

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  • Requirements of multi-layer architectures for future OTN networks

    Page(s): 1 - 9
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1547 KB)  

    There is certainly a clear trend of increasing traffic volumes in pure packet transport and higher bitrate capacities that motivates network operators to invest into next-generation optical transport networks (OTN). For packet routing and switching transport, a tree-like aggregation network interconnecting routers/switches would be adequate. Even in this network bypassing traffic on a photonic layer is mandatory for lowering the total energy consumption as well as cost per bit. Besides the packet transport, analysts claim carriersï¿¿ï¿¿ï¿¿ carrier and business leased line traffic volume to grow exceptionally fast. These business services, however, show a significantly different geographic distribution compared to carriersï¿¿ï¿¿ï¿¿ own platform services. While the internal platform services are quite static, business services are by nature somewhat unpredictable over time. Therefore, future multi-service OTN networks have to augment the configurability and operation flexibility on an agile photonic network layer. This paper defines the requirements of a national OTN network derived from the expected services. Without the claim of completeness, various transport network architectures are presented currently under investigations. Amongst them is an architecture integrating the business traffic directly into the hierarchically-structured packet transport platform via aggregation rings. This concept acknowledges the dominance of the internal platform traffic and does not primarily reflect the special needs for leased lines services. Second is a nation-wide transparent architecture flat on the optical layer. More realistic architectures rely on transparency domains which are i) partly meshed metro domains together with a separate dedicated backbone hierarchy built from one or several domains or ii) a multi-domain network without demarcating hierarchies connected by special inter-domain exchange sites. Finally, we present first results showing reasonably tailored transparency domains - - over the German landscape. View full abstract»

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  • Quantitative Analysis of Network Architectures for Future National Optic Transport Networks (OTN)

    Page(s): 1 - 7
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1004 KB)  

    The constant cost pressure and growing traffic volumes are pushing network operators to increase the efficiency of access, aggregation and core networks. The key target is reduced cost per transported bit. New developments in the standardization of OTN G.709, specifically the introduction of ODU0, allow an efficient aggregation and grooming of 1GbE and higher data services. A key element for this network function is an OTN node, which combines an electrical ODU switching on the ODU layer with an optical switching in the DWDM transport layer. In a multi-domain network the OTN node additionally acts as a demarcation point between optical transparency domains. In this paper several network architectures for future national optical transport networks are defined based on the requirements of network operators on the functionality of an optical transport network and of an OTN node. The base reference network model is a simple network architecture with a single domain, either with or without ODU switching functionality. However, the focus of this paper is on more realistic network architectures with multiple optical transparency domains ï¿¿ï¿¿ï¿¿ first a hierarchical multi-domain network with a dedicated core network and secondly a flat multidomain network with peering domains and inter-domain traffic exchange points. Both architectures fully support multivendor capability and resilience requirements. After the description of the proposed network architectures, this paper presents a quantitative network evaluation and cost analysis based on a realistic German reference network with aggregated traffic streams of business and residential services. In addition to the cost evaluation, the network architectures are evaluated based on the size distribution of the ODU switch fabric, as well as the wavelength utilization of the DWDM transmission system. The results show that an OTN node increases the flexibility and scalability of optical transport networks. This flexibility requires an- - initial investment in the transport network equipment, which is balanced with reduced operational cost and a better utilization of the fibre systems, which leads to an increased network lifetime. View full abstract»

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  • Multi Service OTN Design and Optimization of a Germany Wide Scale Example Network

    Page(s): 1 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1137 KB)  

    Service evolution and cost pressure motivate operators to converge networks to a packet-over-OTN architecture. In fact, the major part of the services requires packet routing and switching transport. However, multi-service carriers face a strongly increasing demand of wavelength services which impact the OTN design. In pure packet services networks the OTN design may be regarded as trivial, it may consist just of a tree of point-to-point connections between routers/switches. Even in such networks economical and ecological reasons exist to consider an active photonic layer. Energy consumption and cost per bit are by factors lower for those portions of the traffic which are bypassed on the photonic layer where routing and packet switching is not essential, as e.g. for storage and data centre connectivity. The focus of this paper, however, is on large multiservice OTNs not only interconnecting the carrierï¿¿ï¿¿ï¿¿s own packet layer devices but as well carrying a significant amount of carrierï¿¿ï¿¿ï¿¿s carrier and business leased lines services. Those services exhibit an explicitly different geographic distribution pattern compared to router interconnections, suggesting a different OTN architecture. They also imply different OTN networking requirements in terms of resilience and dynamic operations. Two basic OTN architectures for a Germany-wide multi service network have been modelled and investigated. The topology of the first follows the one of the superposed packet services network, the second is optimized considering the leased lines characteristics and the capabilities of present-day OTN technology. Service demands expected in the near future were applied to these models. Dimensioning the networks accordingly and analyzing the required resources indicates benefits of the optimized architecture both in terms of network costs and power consumption. The analysis further shows that the benefits grow with increasing bandwidth demands and network load. Some key parameters of the OTN- - optimization are outlined and discussed. View full abstract»

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  • Coherent Wavelength Selection for Cost Effective, Next Generation Optical Transport Networks

    Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1218 KB)  

    Coherent-detected Polarization-multiplexed Quadrature Phase Shift Keying (CP-QPSK) modulation format, combined with Digital Signal Processing (DSP) in the electrical domain is currently considered the most promising candidate for next generation 40 Gbit/s and 100 Gbit/s optical fiber transmission systems. The reasons for that are manyfold, among them the higher spectral efficiency and thus back compatibility with current optical networks' filtering and routing structures, the relative simplicity of the transmitter, and the fact that coherent detection of optical signals allows linear transmission impairments to be effectively compensated in the electrical domain at the receiver's side, thus allowing expensive optical components (like chromatic dispersion and polarization mode dispersion compensators) to be almost entirely removed from the link. Coherent detection also allows the de-multiplexing of wavelength division multiplexed (WDM) optical signals to be performed in the electrical domain instead of the optical domain, thus allowing further savings on optical filtering parts at the receiver's side. In this article, the potential of electrical de-multiplexing to perform the so called Coherent Wavelength Selection (CWS) will be investigated by numerical simulations. View full abstract»

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  • Deferring CAPEX Investments in Multi-Layer Networks through IP Traffic-Dependent Expansion Stages

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (619 KB)  

    Network design is performed for a traffic load in the future. This traffic load is far greater than traffic loads observed at intermediate stages. In this paper, we propose to plan a multi-layer network for such a future traffic load, but instead of provisioning the full network equipment at once, we suggest to defer the deployment of expensive IP interfaces and other enabling equipment only to stages when they are really needed to carry traffic. We develop an algorithm that concentrates IP traffic at an intermediate stage on a subset of those IP interfaces that are required to carry the full load in the future. This reduces the set of used IP interfaces which need to be installed at intermediate stages, and CAPEX investments for the other equipment can be deferred to the future. View full abstract»

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  • Higher-Speed Transmission Performance of DPSK-ASK Modulation Formats

    Page(s): 1 - 3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (506 KB)  

    Towards studying cost-effective 100G transport solutions for metro networks, we have assembled a DPSK-3ASK optical modulation and demodulation configuration that operates at a 40Gbaud line-rate, enabled with components from the 40G market. Our architecture has the flexibility to adjust the encoding and modulation scheme, without changes to the physical hardware or architecture, to create for example 86Gb/s DPSK-2ASK or 107Gb/s DPSK-3ASK channels. In this paper we report on optical transmission experiments with DPSK-ASK modulation, specifically 107Gb/s DPSK-3ASK and also 86Gb/s DPSK-2ASK, over standard single-mode fiber (SSMF). Additionally we compare the effects of pulse shaping using a RZ 33% duty-cycle format or a RZ 66% duty-cycle (CSRZ) format. View full abstract»

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  • Real-time performance characterization of 40G CP-QPSK Transponders

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1486 KB)  

    In this paper we review the optical performance characteristics of a real-time 40G CP-QPSK transponder. An overview is given of the optical performance characteristics, such as optical signal to noise ratio (OSNR) requirements, chromatic dispersion, differential group delay and polarization-mode dispersion tolerance. View full abstract»

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  • Terabit/s Single-Carrier Transmission Based on Coherent Time-Division Demultiplexing

    Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1224 KB)  

    We present a single-wavelength channel (single-carrier) Terabit/s transmission system and its application in transmission experiments up to 1040 km. The transmission system comprises a Terabit/s transmitter which uses in particular advanced modulation formats (RZ-QPSK, RZ-8-PSK, Star-16-QAM) and optical time-division multiplexing to generate optical data signals up to 5.1 Tb/s. For the receiver we employ a digital coherent receiver with a pulsed local oscillator to demodulate and simultaneously demultiplex the received data signal. This approach allows to overcome the speed and bandwidth limitations of the available electronic components (modulator, driver, A/D converter, DSP). Furthermore, the presented Terabit/s receiver comprises an electro-optical clock recovery to synchronize the pulsed local oscillator to the received data signal up to symbol rates of 320 Gbaud. This enables ultra-high speed fiber transmission experiments without the need for simultaneous clock transmission. We demonstrate error-free transmission of single-polarization 0.32 Tb/s RZ-QPSK data signals over 1040 km dispersion managed fiber and of alternating-polarization 0.96 Tb/s RZ-8-PSK data (net 0.90 Tb/s considering UFEC with 7% overhead) over 480 km. In comparison to the Star-16-QAM results we find significantly better performance for the pure PSK formats, even at comparable bit-rates. View full abstract»

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  • First Realtime Synchronous 16-QAM Transmission with Coherent Digital Receiver

    Page(s): 1 - 3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1093 KB)  

    This letter presents for the first time 1.25 Gb/s synchronous coherent 16-point Quadrature Amplitude Modulation (16-QAM) transmitted and received data in a real-time homodyne setup with external cavity laser (ECL). For powers larger than ?20dBm, the average bit error rate (BER) is below forward-error correction (FEC) limit. View full abstract»

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  • InP-basierte elektrische und elektro-optische Komponenten fÿr 112 Gb/s OOK Systeme

    Page(s): 1 - 7
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2275 KB)  

    The development of transmission technology for 100G long-haul transmission systems is mainly concentrated on systems with low symbol rate (up to about 50 Gbaud) in conjunction with higher-order modulation formats (e.g. QPSK) and coherent detection. These systems provide a high spectral efficiency and robustness against transmission impairments. For short-reach systems or future long-haul systems with higher data rates (400 Gb/s or above), the use of higher symbol rates (100 Gbaud or higher) is of interest. Such systems have comparably simple transmitter and receiver architectures, which could result in cost-efficient realizations. However, this is only true if compact and integrated solutions for the key-components (optical-to-electrical-, electrical-to-optical-conversion, electrical amplification and processing) are found at such high symbol rates. Within the European funded projects HECTO and GIBON, such key-components, based on InP technology, have been realized over the past 3 to 3.5 years. In this paper, we report on the application of the InP-based components developed in HECTO and GIBON, in particular the receiver components, in system experiments up to 112 Gb/s OOK. The investigated components are: 1) a high-speed photoreceiver (up to 112 Gb/s), comprising a photodiode and a traveling-wave amplifier, monolithically integrated on a single chip; 2) a bias-feeding photodetector with high bandwidth (90 GHz), which can be adapted to the subsequent electronic components by a variable output DC level and 3) a CDR-module, developed by the Fraunhofer IAF, which enables simultaneous electrical 1:2 demultiplexing and clock recovery up to 112 Gb/s. We show measurements of eye diagrams and bit error ratios up to 112 Gb/s. View full abstract»

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  • Higher Speed Transmission ¿ 100G and Beyond

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (728 KB)  

    The exponentially increasing demand on network capacity requires higher speed and cost efficient interfaces of 100G and beyond for scalable next generation networks. For the client side, the IEEE802.3ba standard for 40 Gb/s and 100 Gb/s interfaces is expected to be approved soon in June 2010. For the OTN (optical transport network) line side, the OIF proposed a 100G ultra long haul DWDM approach. In this paper, the traffic growth and resulting network requirements are enlightened. Higher speed technologies are discussed and higher speed transmission experiments over field installed DWDM systems of Deutsche Telekom are briefly summarized performed in the 100GET BMBF and Celtic project framework. View full abstract»

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  • Implementation requirements for Gbit/s optical receivers with Turbo detection and LDPC decoding

    Page(s): 1 - 7
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1761 KB)  

    In this paper, we investigate realization aspects of Turbo detection and LDPC decoding for an intensity modulated and direct detected optical transmission link. Target is to find dedicated LDPC codes with overhead of 6.7 % to 14.3 %. Furthermore the influence of quantization is examined. The BER analysis is based on a sophisticated channel model using analytical computation of the branch metrics. It turns out, that an LDPC code of code rate Rc = 0.889 and codeword length N in the range of 9000 bits is most suitable. Sampling of the electrial receive signal requires a resolution of the ADC of 5 to 6 bit. In combination with word lengths of 8 bit at the receiver a performance close to the ideal receiver without any quantization can be achieved. View full abstract»

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  • Introduction to EU FP7 Project OASE

    Page(s): 1 - 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (410 KB)  

    Effective January 1st, 2010, a new EU FP7 Integrated Project, OASE (Optical Access Seamless Evolution, Contract Number: INFSO-ICT-249025), started. OASE aims at the assessment and development of next-generation optical access (NG-OA) network architectures and systems configurations for the "2020" time horizon based on European requirements. View full abstract»

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  • The Routerlab - Emulating Internet Characteristics in a Room

    Page(s): 1 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1714 KB)  

    Designing infrastructures for automatically conducting controlled, reproducible Internet experiments poses substantial challenges. These include modelling the Internet structure in a useful way, and providing sufficciently Internet-like traffic. In this paper we describe a multi-purpose experimental platform, called Routerlab, enableing complex Internet measurement experimentation. Departing from the approach taken by many popular testbeds, the Routerlab is a router centric, customizable testbed that reflects the macroscopic structure of the Internet, with different clouds and tier levels and simulation of differing access properties via network emulation. This, in combination with a flexible traffic generation framework, enables us to conduct Internet-level experiments on a small scale, within the borders of our server room. Routerlab¿s management platform called Labtool supports heterogeneous hardware landscapes and user groups (e.g., labcourse student teams, individual researchers working on differing layers, developers). To accomodate the span of differing requirements of these user groups, it offers both virtualized and bare-metal, non-virtualized resources and can support versioned, controlled changes to the physical topology. View full abstract»

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