Logical topology design for IP rerouting: ASONs versus static OTNs

Abstract

. 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 (OTN) that consists of WDM links and Optical Cross-Connects (OXCs). In such a model, the Generalized MPLS (GMPLS) 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 Automatically 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. This way of making the IP layer survivable against (single) IP router failures can be 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,…) in both the IP and 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 in order to investigate the cost of the ASON approach and compare it with other schemes that survive single router failures.

Using decomposition techniques for the design of survivable logical topologies

“…Recently, Lin et al [12] introduced the concepts of weak and strong survivability: the weak case corresponds to the one studied so far, limited to the connectivity guarantee, while the strong one corresponds to logical topology mappings that satisfy two criteria: the logical network remains connected after any physical link failure, and there exists sufficient capacity on physical links to support all disrupted traffic. Other relevant references are Kan et al [13], Cholda and Jajszczyk [1], and Groebbens et al [2].…”

“…The design and the management of the future networks will rely on an all IP-design [1], [2], where more synergies will need to be developed between the IP and the optical layers in order to optimize the resource utilization, to reduce the energy consumption and the network costs, and to guarantee the Service Level Agreements (SLA) while bandwidth intensive applications, like video or IPTV services and on-line gaming, will continue to emerge [3].…”