Topological Design of Multiple Virtual Private Networks UTILIZING SINK-TREE PATHS

With the deployment of MultiProtocol Label Switching (MPLS) over a core backbone networks, it is possible for a service provider to built Virtual Private Networks (VPNs) supporting various classes of services with QoS guarantees. Efficiently mapping the logical layout of multiple VPNs over a service provider network is a challenging traffic engineering problem. The use of sink-tree (multipoint-to-point) routing paths in a MPLS network makes the VPN design problem different from traditional design approaches where a full-mesh of point-to-point paths is often the choice. The clear benefits of using sink-tree paths are the reduction in the number of label switch paths and bandwidth savings due to larger granularities of bandwidth aggregation within the network. In this thesis, the design of multiple VPNs over a MPLS-like infrastructure network, using sink-tree routing, is formulated as a mixed integer programming problem to simultaneously find a set of VPN logical topologies and their dimensions to carry multi-service, multi-hour traffic from various customers. Such a problem formulation yields a NP-hard complexity. A heuristic path selection algorithm is proposed here to scale the VPN design problem by choosing a small-but-good candidate set of feasible sink-tree paths over which the optimal routes and capacity assignments are determined. The proposed heuristic has clearly shown to speed up the optimization process and the solution can be obtained within a reasonable time for a realistic-size network. Nevertheless, when a large number of VPNs are being layout simultaneously, a standard optimization approach has a limited scalability. Here, the heuristics termed the Minimum-Capacity Sink-Tree Assignment (MCSTA) algorithm proposed to approximate the optimal bandwidth and sink-tree route assignment for multiple VPNs within a polynomial computational time. Numerical results demonstrate the MCSTA algorithm yields a good solution within a small error and sometimes yields the exact solution. Lastly, the proposed VPN design models and solution algorithms are extended for multipoint traffic demand including multipoint-to-point and broadcasting connections

On Providing Survivable QoS Services in the Next Generation Internet”, supported in part by NSF grant NCR 9506652 and DARPA under agreement No

Ahfrucf- In this paper we present a comparative study of two schemes to provide sunhability for guaranteed QoS connections in a possible Next Generation Internet network architecture. In the first scheme a QoS connection is provided standby backup resources on a disjoint path by reserving resources on both the working and backup path. In order to reduce the amount of backup resources required a method for sharing backup resources when the working connections have disjoint routes has been included. In the second scheme a dynamic search for restoration resources is conducted over a preplanned set of alternate paths upon notification of a failure. A simulation based performance study shows that the first scheme results in much higher connection blocking under normal operations, slightly faster restoration times, and longer transient congestion times after fault recovery due to non-optimal backup routing. I. INTRODUCTIO.

On Providing Survivable QoS Services in the Next Generation Internet

In this paper we present a comparative study of two schemes to provide survivability for guaranteed QoS connections in a possible Next Generation Internet network architecture. In the first scheme a QoS connection is provided standby backup resources on a disjoint path by reserving resources on both the working and backup path. In order to reduce the amount of backup resources required a method for sharing backup resources when the working connections have disjoint routes has been included. In the second scheme a dynamic search for restoration resources is conducted over a preplanned set of alternate paths upon notification of a failure. A simulation based performance study shows that the first scheme results in much higher connection blocking under normal operations, slightly faster restoration times, and longer transient congestion times after fault recovery due to non-optimal backup routing. I. INTRODUCTION The Next Generation Internet (NGI) will provide QoSbased services in additio..