SRLG inference in OSPF for improved reconvergence after failures

The ECODE FP7 project researches cognitive routing functions in future networks. We demonstrate machine learning augmented OSPF routing which infers SRLGs from network failure history. Inferred SRLGs are used to improve OSPF convergence and recovery times during subsequent (multiple) network failures

Dimensioning of an European backbone network in OPNET WDM Guru

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Influence of multilayer traffic engineering timing parameters on network performance

Recent advances in optical networking technology have moved the state-of-the-art from manually installed fiber connections to fully automatic switched lightpaths. Multilayer Traffic Engineering (MTE) in an IP-over-Optical network allows to leverage rapid lightpath setup/teardown as a cross-layer traffic engineering technique. It enables on-the-fly reconfiguration of the IP layer logical topology and up/downgrade of the capacity of IP links. Together with classical IP layer routing techniques, MTE intelligently solves problems such as IP layer congestion and packet loss and it may optimize optical layer capacity usage and total network throughput. In this, the rate at which MTE can make adjustments to the network is limited by technology and stability concerns. We present some example MTE techniques and discuss how the timing parameters of these mechanisms impact perceived network performance

Impact of topology on layer 2 switched QoS sensitive services

High-bandwidth QoS sensitive services such as large scale video surveillance generally depend on provisioned capacity delivered by circuit-switched technology such as SONET/SDH. Yet development in layer 2 protocol sets and manageability extensions to Ethernet standards propose layer 2 packet switching technology as a viable, cheaper alternative to SONET/SDH. Layer 2 switched networks traditionally offer more complex topologies; in this paper we explain general QoS issues with layer 2 switching and show the impact of topology choice on service performance

Logical topology design for IP rerouting: ASONs versus static OTNs

IP-based backbone networks are gradually moving to a network model consisting of high-speed routers that are flexibly interconnected by a mesh of light paths set up by an optical transport network that consists of wavelength division multiplexing (WDM) links and optical cross-connects. In such a model, the generalized MPLS protocol suite could provide the IP centric control plane component that will be used to deliver rapid and dynamic circuit provisioning of end-to-end optical light paths between the routers. This is called an automatic switched optical (transport) network (ASON). An ASON enables reconfiguration of the logical IP topology by setting up and tearing down light paths. This allows to up- or downgrade link capacities during a router failure to the capacities needed by the new routing of the affected traffic. Such survivability against (single) IP router failures is cost-effective, as capacity to the IP layer can be provided flexibly when necessary. We present and investigate a logical topology optimization problem that minimizes the total amount or cost of the needed resources (interfaces, wavelengths, WDM line-systems, amplifiers, etc.) in both the IP and the optical layer. A novel optimization aspect in this problem is the possibility, as a result of the ASON, to reuse the physical resources (like interface cards and WDM line-systems) over the different network states (the failure-free and all the router failure scenarios). We devised a simple optimization strategy to investigate the cost of the ASON approach and compare it with other schemes that survive single router failures

Multilayer traffic engineering performance in overlay networks

Multilayer Traffic Engineering uses fast switching optical networks to modify or up/downgrade upper layer logical topologies according to changing traffic patterns. The multilayer overlay model limits information exchange between layers and thereby impacts overall performance