VPN service providers (VSP) and IP-VPN customers have traditionallymaintained service demarcation boundaries between their routing and signalingentities. This has resulted in the VPNs viewing the VSP network as an opaqueentity and therefore limiting any meaningful interaction between the VSP andthe VPNs. A key challenge is to expose each VPN to information about availablenetwork resources through an abstraction (TA) [1] which is both accurate andfair. In [2] we proposed three decentralized schemes assuming that all theborder nodes performing the abstraction have access to the entire core networktopology. This assumption likely leads to over- or under-subscription. In thispaper we develop centralized schemes to partition the core network capacities,and assign each partition to a specific VPN for applying the decentralizedabstraction schemes presented in [2]. First, we present two schemes based onthe maximum concurrent flow and the maximum multicommodity flow (MMCF)formulations. We then propose approaches to address the fairness concerns thatarise when MMCF formulation is used. We present results based on extensivesimulations on several topologies, and provide a comparative evaluation of thedifferent schemes in terms of abstraction efficiency, fairness to VPNs and callperformance characteristics achieved.
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