908 research outputs found

    Architecture, design, and modeling of the OPSnet asynchronous optical packet switching node

    Get PDF
    An all-optical packet-switched network supporting multiple services represents a long-term goal for network operators and service providers alike. The EPSRC-funded OPSnet project partnership addresses this issue from device through to network architecture perspectives with the key objective of the design, development, and demonstration of a fully operational asynchronous optical packet switch (OPS) suitable for 100 Gb/s dense-wavelength-division multiplexing (DWDM) operation. The OPS is built around a novel buffer and control architecture that has been shown to be highly flexible and to offer the promise of fair and consistent packet delivery at high load conditions with full support for quality of service (QoS) based on differentiated services over generalized multiprotocol label switching

    Loop detection and prevention mechanism in multiprotocol label switching

    Full text link
    The extended color thread algorithm is based on running a thread hop by hop before the labels are distributed inside a MPLS Cloud Since the path for the data packets is set beforehand, the loop formation occurs at the control path. The shortest paths between selected source and destination have been calculated using Dijkstra\u27s shortest path algorithm and threads are allowed to extend through the routers. With the passage of each next hop, a distributed procedure is executed within the thread, generating a unique color at nodes. This keeps a track on router\u27s control path and at the same time ensures that no loop formation occurs. In loop prevention mode, a router transmits a label mapping, when it rewinds the thread for that particular LSP. Likewise, if a router operates in loop detection mode, it returns a label-mapping message without a thread object, after receiving a colored thread. The scheme is a loop prevention scheme, thus, ensuring loop detection and loop mitigation. The same algorithm is then extended to a proposed MPLS environment with global label space. (Abstract shortened by UMI.)

    Advanced features of MPLS technology

    Get PDF
    Tato práce se zabývá technologií Multiprotocol Label Switching a to zejména moderními metodami, které je možné použít v rámci této technolologie. Jako příklad lze uvést využití podpory kvality služeb při směrování. V práci jsou navrhnuty a simulovány různé topologie a scénáře, které ověřují možnosti využití MPLS v podpoře kvality služeb.This work is considered to evaluate the needs of MPLS implementation in current IP networks with respect to Quality of Service guarantees. It shows many aspects and evaluations of the influence of different traffic classes. The best solutions are evaluated with simulations and can be implemented with respect to Quality of Service guarantees.

    Traffic Engineering in Multiprotocol Label Switching networks

    Get PDF
    The goal of Traffic Engineering is to optimize the resource utilization and increase the network performance. Constraint-based routing has been proposed as an networks effective approach to implement traffic engineering in Multiprotocol Label Switching. In this thesis, we review several algorithms on constraint-based routing from the literature and point out their advantages and disadvantages. We then propose several algorithms to overcome some of the shortcomings of these approaches. Our algorithms are specifically suitable for large densely connected networks supporting both Quality of Service traffic and the Best Effort traffic. In large networks the size of the MPLS label space in a node may become extremely large. Our algorithms allow for control on the size of the label space for each node in the network. In addition, explicit routes can be accommodated supporting both node and link affinity. We address an algorithm that implements the node and link affinity correctly. If the QoS traffic has stringent delay requirements, a path length limit can be imposed so that the number of hops on the path for such traffic is limited. Finally, we propose the 1 + 1 and 1 : 1 path protection mechanisms using the constraint-based routing in MPLS and establish backup for the working path carrying the primary traffic. Our approach appropriately overcome the problems and the result are satisfying

    IP forwarding alternatives in cell switched optical networks

    Get PDF
    Optical switching will enable core Internet packet switching to scale with future transmission rate increases. Currently proposed optical ATM switches do not allow packet reassembly, which is necessary for packet level forwarding. This results in the requirement to create end to end ATM virtual connections for flows even if they contain only one packet. In electronically switched networks MPOA and MPLS allow both cell and packet level forwarding to overcome this problem. This paper examines the feasibility of implementing such protocols over an optically switched network. Two different architectures are examined: use of an adjunct electrical router; and native optical packet reassembly. An examination of the optical reassembly buffer requirements show that the use of MPLS will require significantly more buffering than MPOA

    Analyzing the costs/tradeoffs involved between layer 2, layer 3, layer 4 and layer 5 switching

    Get PDF
    The switching function was primarily entrusted to Layer 2 of the OSI model, i.e. the Data Link Layer. A Layer 2 switch performs forwarding decisions by analyzing the MAC (Media Access Control) address of the destination segment in the frame. The Layer 2 switch checks for the destination address and transmits the packet to the appropriate segment if the address is present in its table of known destinations. If the entry for that address is not present, the switch then forwards the packet to all segments except the one on which it came from. This is known as flooding. When it gets a reply from the destination segment, it learns the location of the new address and adds it to its table of known destinations. As number of users are increasing on the network, the speed and the bandwidth of the network is being stretched to its limits. Earlier, switching was primarily entrusted to Layer 2 (Data Link Layer) of the OSI model, but now there are switches that operate at Layer 3 (Network Layer), Layer 4 (Transport Layer) and Layer 5 (Session Layer) of the OSI model. Going from one layer to the other layer does involve some costs/tradeoffs. My thesis explores the costs and tradeoffs involved with switching based on layers 2, 3, 4 and 5 of the OSI reference model

    Effective Planning and Analysis of Huawei and Cisco Routers for MPLS Network Design Using Fast Reroute Protection

    Get PDF
    This chapter deals with a description of the MPLS traffic engineering technology behavior on two heterogeneous, but nowadays the most commonly used network vendors are Cisco and Huawei. Compatibility and functionality between network devices Huawei and Cisco were verified by testing the appropriate network topology. In this topology, we mainly focused on the useful feature of MPLS TE called Fast Reroute (FRR) protection. It provides link protection, node protection and also bandwidth protection during the failure of the primary link, especially on backbone networks. After successful validation, compatibility and functionality of the network topology between the heterogeneous routers using the Fast Reroute protection will be possible to use this MPLS TE application in the real networks

    Deliverable DJRA1.2. Solutions and protocols proposal for the network control, management and monitoring in a virtualized network context

    Get PDF
    This deliverable presents several research proposals for the FEDERICA network, in different subjects, such as monitoring, routing, signalling, resource discovery, and isolation. For each topic one or more possible solutions are elaborated, explaining the background, functioning and the implications of the proposed solutions.This deliverable goes further on the research aspects within FEDERICA. First of all the architecture of the control plane for the FEDERICA infrastructure will be defined. Several possibilities could be implemented, using the basic FEDERICA infrastructure as a starting point. The focus on this document is the intra-domain aspects of the control plane and their properties. Also some inter-domain aspects are addressed. The main objective of this deliverable is to lay great stress on creating and implementing the prototype/tool for the FEDERICA slice-oriented control system using the appropriate framework. This deliverable goes deeply into the definition of the containers between entities and their syntax, preparing this tool for the future implementation of any kind of algorithm related to the control plane, for both to apply UPB policies or to configure it by hand. We opt for an open solution despite the real time limitations that we could have (for instance, opening web services connexions or applying fast recovering mechanisms). The application being developed is the central element in the control plane, and additional features must be added to this application. This control plane, from the functionality point of view, is composed by several procedures that provide a reliable application and that include some mechanisms or algorithms to be able to discover and assign resources to the user. To achieve this, several topics must be researched in order to propose new protocols for the virtual infrastructure. The topics and necessary features covered in this document include resource discovery, resource allocation, signalling, routing, isolation and monitoring. All these topics must be researched in order to find a good solution for the FEDERICA network. Some of these algorithms have started to be analyzed and will be expanded in the next deliverable. Current standardization and existing solutions have been investigated in order to find a good solution for FEDERICA. Resource discovery is an important issue within the FEDERICA network, as manual resource discovery is no option, due to scalability requirement. Furthermore, no standardization exists, so knowledge must be obtained from related work. Ideally, the proposed solutions for these topics should not only be adequate specifically for this infrastructure, but could also be applied to other virtualized networks.Postprint (published version

    An implementation of packet-switched communication for pilot protection at Tennessee Valley Authority

    Get PDF
    The utility network has long relied on Time Division Multiplexing (TDM) such as T1 and Synchronous Optical Network (SONET) as the main channel to transmit and receive data in a communication system. However, TDM technology is aging and its equipment becoming obsolete as vendors transition to Packet-Switched Networks (PSN) to make way for Ethernet-based network communications. Teleprotection is a critical element for a reliable power system as it provides high-speed tripping for faults on the protected line and is applied in various pilot protection schemes. Protection schemes cannot perform at their best without a fast and reliable communication system. The transition from a circuit-switched technology like SONET to a packet-based technology like Multiprotocol Label Switching-Transport Profile (MPLS-TP) has caused reservations for protection engineers as they express their concerns for lacking guaranteed 100% availability and potential latency. This paper will address this issue and the consistent test results at the Tennessee Valley Authority (TVA)\u27s lab have proven to satisfy the communication requirements in a teleprotection system. Teleprotection traffics make to its destination in order in microseconds, the symmetrical delay is less than 1µs, and especially the recovery from a failure occurs under 50ms (3 cycles). The results reassure the protection engineers that the Ethernet migration is necessary yet provides a better performance compared to the legacy system
    corecore