Efficient PCE-Based Survivable Path Computation in Multi-Domain Networks

Abstract-We consider the problem of finding end-toend shortest disjoint paths for a given sequence of domains in multi-domain networks. A Path Computation Element (PCE) serves as a computing entity in each domain, specializing in path computation and optimization. We propose a novel PCE-based scheme that computes the shortest path over multiple domains in the forward direction and computes the disjoint path in the backward direction. The proposed scheme has linear-time computation and message overhead in regard to the number of border nodes. Simulation results show that our proposed scheme can result in an optimal solution, while significantly reducing computation time compared to existing algorithms

A Survey on the Path Computation Element (PCE) Architecture

Quality of Service-enabled applications and services rely on Traffic Engineering-based (TE) Label Switched Paths (LSP) established in core networks and controlled by the GMPLS control plane. Path computation process is crucial to achieve the desired TE objective. Its actual effectiveness depends on a number of factors. Mechanisms utilized to update topology and TE information, as well as the latency between path computation and resource reservation, which is typically distributed, may affect path computation efficiency. Moreover, TE visibility is limited in many network scenarios, such as multi-layer, multi-domain and multi-carrier networks, and it may negatively impact resource utilization. The Internet Engineering Task Force (IETF) has promoted the Path Computation Element (PCE) architecture, proposing a dedicated network entity devoted to path computation process. The PCE represents a flexible instrument to overcome visibility and distributed provisioning inefficiencies. Communications between path computation clients (PCC) and PCEs, realized through the PCE Protocol (PCEP), also enable inter-PCE communications offering an attractive way to perform TE-based path computation among cooperating PCEs in multi-layer/domain scenarios, while preserving scalability and confidentiality. This survey presents the state-of-the-art on the PCE architecture for GMPLS-controlled networks carried out by research and standardization community. In this work, packet (i.e., MPLS-TE and MPLS-TP) and wavelength/spectrum (i.e., WSON and SSON) switching capabilities are the considered technological platforms, in which the PCE is shown to achieve a number of evident benefits

AS-level source routing for multi-provider connection-oriented services

International audienceIn this paper, we study the inter-domain Autonomous System (AS)-level routing problem within an alliance of ASs. We first describe the framework of our work, based on the introduction of a service plane for automatic multi-domain service provisioning. We adopt an abstract representation of domain relationships by means of directional metrics which are applied to a triplet (ingress point, transit AS, egress point) where the ingress and egress points can be ASs or routers. Then, we focus on the point-to-point and multipoint AS-level routing problems that arise in such an architecture. We propose an original approach that reaches near optimal solutions with tractable computation times. A further contribution of this paper is that a heavy step in the proposed heuristic can be precomputed, independently of the service demands. Moreover, we describe how in this context AS-level path diversity can be considered, and present the related extension of our heuristic. By extensive tests on AS graphs derived from the Internet, we show that our heuristic is often equal or a few percent close to the optimal, and that, in the case of precomputation, its time consumption can be much lower than with other well-known algorithms